DIFFERENT differentials - do you beg to differ?

[SHY]

Back in the 80s we had the gear diffs. Those were quite smooth I thought back then, and practically maintenance free.

Then the ball diffs came (I now know that Cecil Schumacher invented it, and that their logo illustrates just that, thx)... They cost more than the whole car and were much better it was claimed.

Can someone do a short story about why this is better?

I'm quite sure I read that Serpent is making a gear diff for their S400 (TC), that would be adjustable? Anyone got more on this? Will they try it also in the S500?

Personally I think the ball diffs work fine, but they don't last very long. For 1:12 it sucks big time! One single run and it's not smooth anymore... Not far as troublesome in 1:10 OR, but still I find it too much work (I'm lazy by nature).

1:8 OR cars use gear diffs because of the abuse right?

Give your thoughts and ideas! Can the ball diff be improved? Can gear diffs be just as good? New and even better solutions?

1:8 TR has a solid rear axle and a front one-way... now that's easy for ya! :thumbsup:

SMP tried with a one-way in the rear axle many years ago... why? To stop the WHOLE transmission when coasting... :woot: Has this been tried in 1:10 OR?

[Chrislong]

SMP tried with a one-way in the rear axle many years ago... why? To stop the WHOLE transmission when coasting... :woot: Has this been tried in 1:10 OR?

How would 1/10th OR perform with two one ways, and brakes via servo and disk?

Id like to cut out the maintenance of ball diffs, when they are good they feel great but when they go they're a pain at times. Plus the quality of the chinese AE and Losi stuff is far lower than what the Losi and AE stuff were like back in the early days of the B4 and Losi xxx/xx4.

Chris

[Lee]

How would you slow the car down with one ways at either end? :confused:

[SHY]

How would you slow the car down with one ways at either end? :confused:

http://www.ymr.no/bilder/SMP/FASTBAK.jpg

The Slide had a brake disk directly on the rear axle ;)

They gave it up for 1:8 TR though, too much power so they never got it to be reliable...

@Chris: I'd love to try an RC car with a dedicated servo for the brakes! (not legal) You'd operate this with your foot, so you could brake and give throttle at the same time, to keep the momentum through the corner - just like when racing 1:1 scale :cool:

[Chrislong]

How would you slow the car down with one ways at either end? :confused:

LOL, Disk brakes via a servo dude :thumbsup:

SHY guy, that'd be cool - proper toe and heal racing with a buggy.

[josh_smaxx]

Serpent HAVE made a geared diff for the S400, most of the team drivers are using it and think its great. Its adjustable by changing the thickness of oil in it (same as 1/8th OR diffs). Its only 5g heavier than the ball diff (are there light!) and the people using it much prefer it due to the reduced maintence and much more reliable tuning (its the same everytime you use it whereas with building a ball diff every 3 or 4 races its difficult to get it exactly the same every rebuild).

[Chrislong]

(its the same everytime you use it whereas with building a ball diff every 3 or 4 races its difficult to get it exactly the same every rebuild).

If I have 5 new ball diffs to build, all 5 will be identical once built. its easy.

Your comment is only valid if talking about rebuilding a ball diff with used parts. What tends to happen then is it'll be smooth until the grease is run in, then it'll just be dog rough again.

[DCM]

unless you are using a vernier torque meter, it is hard to get a diff exactly the same each time, even using new parts each time, plus the diff has to settle too, which adds to the work, whereas a geared diff, once built, will operate right away, and if rebuilt, with the same oil, will operate exactly the same way.

The only down side of the geared diff, is it removes any 'give' in transmission if you are not running a slipper, hence why the rallyx stuff is well over engineered.

[josh_smaxx]

If I have 5 new ball diffs to build, all 5 will be identical once built. its easy.

Your comment is only valid if talking about rebuilding a ball diff with used parts. What tends to happen then is it'll be smooth until the grease is run in, then it'll just be dog rough again.

When i rebuild my serpent diff i cant afford to use brand new balls and plates everytime, its opne so it needs a rebuild every 7 or 8 races. And how long have you been racing Chris? meaning how long have you had practice at rebuilding diffs? it does take some skill to get a ball diff identical every time, i can feel 1/16th of a turn difference in my S400, it takes a few runs to get it back to the same as it was.

Also, the comment was made about Serpent cars and Serpent diffs.

[bigred5765]

also a geared diff ie 1/8th style, can be run much looser than a ball diff with zero slip
and can also be run much stiffer than a ball diff and 100% smoother win win

[Lee]

LOL, Disk brakes via a servo dude :thumbsup:

SHY guy, that'd be cool - proper toe and heal racing with a buggy.


I understand it would need a disc brake but you would have to have them in the drive shafts if you wanted each wheel to be independent:confused:


Also, i have never rebuilt diffs every few races, i raced open diff cars for years and i only ever rebuilt them after a wet race, a lot of it is down to the grease you use;)

[mole2k]

I've often thought with a servo brake it would be quite good to have an xbox style controller with a seperate throttle and brake as triggers then normal steering stick.

Then left-foot braking comes into the equasion!

[josh_smaxx]

Also, i have never rebuilt diffs every few races, i raced open diff cars for years and i only ever rebuilt them after a wet race, a lot of it is down to the grease you use;)

I used the Serpent stuff that came with it, then i moved onto the schumacher stuff and its ALOT better, would highly recommend it.

I have raced it twice now on one build, its getting raced again then rebuilt, i like to keep on top f the maintenance, would hate to loose and think its because the diff wasnt up to scrath ect.

[Lee]

AE green slime;)

[josh_smaxx]

AE green slime;)

For diffs? :o never knew that.

[Lee]

its very good, i also use it on the bevel gears in shaft driven cars;)

[josh_smaxx]

its very good, i also use it on the bevel gears in shaft driven cars;)

AWESOME!!:thumbsup::thumbsup:

I'll give it a try sometime.

[Lee]

Craig drescher told me about it years ago when we first ran the tc3`s;)

[werner1619]

put my name down for a geared diff,

I always have problems with my 501's diff :(

[mark christopher]

If I have 5 new ball diffs to build, all 5 will be identical once built. its easy.

Your comment is only valid if talking about rebuilding a ball diff with used parts. What tends to happen then is it'll be smooth until the grease is run in, then it'll just be dog rough again.
yup and all five will be different once run so unless you use em for one run and fit another the performance will change on each unit

(oh and im not picking on you :p)

also a geared diff ie 1/8th style, can be run much looser than a ball diff with zero slip
and can also be run much stiffer than a ball diff and 100% smoother win win
the best bit off gear diffs, run em in my S400 and all my ic cars bar the 835 which is a mans car with a front one way and solid rear axle. turn,power,go, hang on :thumbsup:

[sparrow.2]

I understand it would need a disc brake but you would have to have them in the drive shafts if you wanted each wheel to be independent:confused:

You could make it work with center one-ways and brake discs on the gearbox input shafts.

You would be adding a lot of weight though for a very questionable advantage.

You can achieve a si,ilar effect by turning off autobrake altogether on brushless setups. I tried this and basically found that the car tends to understeer more than if you have autobrake dialled higher since it doesn't transfer as much weight to the front when you let off the power.

Hope that made sense...

[mark christopher]

You could make it work with center one-ways and brake discs on the gearbox input shafts.

You would be adding a lot of weight though for a very questionable advantage.

You can achieve a si,ilar effect by turning off autobrake altogether on brushless setups. I tried this and basically found that the car tends to understeer more than if you have autobrake dialled higher since it doesn't transfer as much weight to the front when you let off the power.

Hope that made sense...
then you would still be running diffs!!!

[SHY]

I understand it would need a disc brake but you would have to have them in the drive shafts if you wanted each wheel to be independent:confused:


Also, i have never rebuilt diffs every few races, i raced open diff cars for years and i only ever rebuilt them after a wet race, a lot of it is down to the grease you use;)

The actual car that had this had a ventilated brake disk as part of the outdrive:
http://www.ymr.no/bilder/SMP/gml_brems.jpg
The oneway sat inside the rear pulley. So this worked just fine, except for the 1:8 power being too brutal for the one-way. Keep in mind that the driving force applied to the front wheels are a joke compared to what's going on in the rear!

Anyways, for electric we would need a small brake servo in addition to the ESC to be able to brake and give throttle simultaneously... not legal but I've always wanted to try this! Electric motors respond quickly, but for a gas engine you could keep the clutch engaged and the revs up... and for all classes you'd keep the car more stable going through fast sections!

I've been doing RC all my life, and I've learned to hate a few things:
-radio interference
-cleaning bearings
-maintaining brushed motors
-rebuilding diffs

I find it very difficult to build two identical diffs. Not to mention that they should be broken in after each rebuild (incl. sanding down the plates and so on), and gradually tightened. Takes a lot of time! I'd LOVE to just be able to tune a gear diff, and note down my setup... Btw I seem to recall that Serpent had on its Impact some years ago a special diff. I think the diff itself was always the same. And there was an adjustment of some friction plastes in addition... think it worked very well! (don't recall if that was a ball or gear diff though)

Is it really as good as a ball diff??? Why did we then get ball diffs in the first place??? :confused:

And more: if we go back to gear diffs... we can then have torsen diffs, tactyl diffs... or would that not be as suitable as for 1:8 OR? Keep in mind that with LiPos next year we can add some weight back on the cars...

You could make it work with center one-ways and brake discs on the gearbox input shafts.

You would be adding a lot of weight though for a very questionable advantage.

You can achieve a si,ilar effect by turning off autobrake altogether on brushless setups. I tried this and basically found that the car tends to understeer more than if you have autobrake dialled higher since it doesn't transfer as much weight to the front when you let off the power.

Hope that made sense...

I just make these presumtions, I'm not quite sure:
-the tranny should be as free moving as possible. When coasting I'd wish it was "gone". And no motor brake / drag whatsoever
-the only thing slowing the car down (except when braking) should be the friction between the wheels and the ground

I feel this caters for smoother, more consistent & faster cornering. And in many cases it's faster not to use brakes at all...

[mark christopher]

710 and impact 835 had ball diffs with adjustable friction collers


gear diffs have seen alot of development in quality and weight reduction, a true LSD is the way to go, when some one masters that, they will make a fortune

[sparrow.2]

As far as I know the touring car guys went for ball diffs because of the reliability over a ball diff and the fact they couldn't put down the power as well with the stupid fast brushless motors they are using now. The newer delta winds put out massive amount of torque and revs their nuts off at something silly like 11000-12000RPM per Volt. That makes 66000-72000 RPM at the shaft at 6V :wtf:


Back in the day of old geared diffs the major problem was the binding at speed and the fact that they channeled the most power to the wheel with the least traction. Ball diffs operate smoother under power. I suppose materials and tolerances have improved to the point where you can make a small gear diff wirk reliably.

Has anyone tried running the ATD diffs in Associated or Jconcept cars. It's the one with the ring in the middle of the diff gear made out of slipper pad material. Gives you a much stiffer ball diff. What would it do to the cars handling???

[SHY]

LSD? What's that?

I wanna get high... :cool:

Edit: Limited Slip Differential?... How does it work?



Back in the day of old geared diffs the major problem was the binding at speed and the fact that they channeled the most power to the wheel with the least traction. Ball diffs operate smoother under power. I suppose materials and tolerances have improved to the point where you can make a small gear diff wirk reliably.

Now that does ring a bell yes...

[Zedman]

Seams ther is no perfect solution, espesialy considering we are talking tiny scale model engineering (

http://auto.howstuffworks.com/differential7.htm

[SHY]

Can someone please explain the physics behind the ball diff? Which I guess can be partially seen in the Schuey logo...

Has this ever been used in real cars???

And can someone who knows about torsen and tactyl diff etc have a say?

[sparrow.2]

Torsen diffs get progressively stiffer the higher the difference in output speeds gets. (at least full-size ones one big cars)

A mate of mine who builds them for Porsches explained it to me once and I got a nosebleed halfway through the explanation....:wtf:

Not actually sure you could build a torsen diff small enough to go into a 1/10 scale buggy without making it too big/thick, which would entail bigger drawbacks than could be compensated by the advantage.

Geared diffs would get a right kicking in a buggy...

[SHY]

This is for anyone on here named Lee:
http://www.youtube.com/watch?v=_RgL2MKfWTo

:lol:

Special bonus: MJ...
http://www.youtube.com/watch?v=jvzfjPQ0WiE

[sparrow.2]

Frick! That's ace! :woot:

[Lee]

Amazing:woot:

tulibudibu douchooo:thumbsup:

[showtime]

another good diff page for those that like reading the theory

http://www.houseofthud.com/differentials.htm

[SHY]

Great link Showtime! Very interesting!!! I didn't know that full scale cars had "spider gears" in the diffs, and not bevel gears in the centre like in model car diffs. Why? Same with the "input shaft"...
http://www.houseofthud.com/images/vc3.gif
1:8 OR diffs are more like real car diffs right?

OK, let's get down to business! Can anyone check if the Serpent gear diffs will fit in any buggy on the market? Maybe with some modifications?

Part numbers? Webshop?

I'd be glad to get rid of my balls... :lol:

Imagine having several sets of complete diffs, with different hardnesses... and no fuss! :drool: Me want!

Has center diffs ever been uses in 1:10 OR?

I'd also like to know how a center one-way is like to drive compared to a front one-way, is it like something inbetween a front diff and a front one-way?

And I'd still really really like to know the physical explanation behind the ball diff! Understandig a gear diff seems quite straightforward.

[mark christopher]

Great link Showtime! Very interesting!!! I didn't know that full scale cars had "spider gears" in the diffs, and not bevel gears in the centre like in model car diffs. Why? Same with the "input shaft"...
http://www.houseofthud.com/images/vc3.gif
1:8 OR diffs are more like real car diffs right?

OK, let's get down to business! Can anyone check if the Serpent gear diffs will fit in any buggy on the market? Maybe with some modifications?

Part numbers? Webshop?

I'd be glad to get rid of my balls... :lol:

Imagine having several sets of complete diffs, with different hardnesses... and no fuss! :drool: Me want!

Has center diffs ever been uses in 1:10 OR?

I'd also like to know how a center one-way is like to drive compared to a front one-way, is it like something inbetween a front diff and a front one-way?

And I'd still really really like to know the physical explanation behind the ball diff! Understandig a gear diff seems quite straightforward.
your pic shows a centre diff not a front or rear diff
most car diffs (1:1) have sun plannet gears which are bevel gears as in the pic, spider gears i believe are just multiple bevel gears


for starters the serpent diffs are belt drive only, so that limits most id say closest would be a tamiya as tamiya diffs can fit in the s400

[SHY]

your pic shows a centre diff not a front or rear diff
most car diffs (1:1) have sun plannet gears which are bevel gears as in the pic, spider gears i believe are just multiple bevel gears

for starters the serpent diffs are belt drive only, so that limits most id say closest would be a tamiya as tamiya diffs can fit in the s400

Yeah, I know. The other illustration was very crude, I wanted to show how the gears looked (as opposed to RC diffs with gear diffs "inside" the gear (centre).

But the XX4 and X-5 are belt drive, are the teeth the same mesh? What's the number of teeth?

[bigred5765]

the nice thing about the new geared diffs is
as you use thicker oil in the sealed diff you get more of a LSD action to them just as you would in 1/8th cars, the only down side to this is in 1/10th we have no centre diff

[sparrow.2]

We do have limited slip diffs in BJ4's. The ATD diff does just that.

There was a guy on here who had rigged his D4 or BJ4WE with a diff in the middle and it was rubbish because he had no way of hardening the action. I'm not actually sure an adjustable middle diff would actually be much of an advantage in a 1/10 over a slipper clutch...

[elvo]

I'd be glad to get rid of my balls... :lol:



Don't worry. A few more months....
(SHY gets married this summer)


And I'd still really really like to know the physical explanation behind the ball diff! Understandig a gear diff seems quite straightforward.


How can you understand one and not the other? The explanation is the same. Except it's balls and plates instead of gears and gears.

[bigred5765]

We do have limited slip diffs in BJ4's. The ATD diff does just that.

There was a guy on here who had rigged his D4 or BJ4WE with a diff in the middle and it was rubbish because he had no way of hardening the action. I'm not actually sure an adjustable middle diff would actually be much of an advantage in a 1/10 over a slipper clutch...

thats a atd diff
im pretty sure theres no propper lsd diff for any toy cars as of yet

[sparrow.2]

thats a atd diff
im pretty sure theres no propper lsd diff for any toy cars as of yet

Works exactly the same though... What would a "proper" LSD do differently apart from maybe different states of lock depending on load???

[bigred5765]

whats a atd diff please
as fare as im aware theres nothing that even comes close to a lsd diff

[SHY]

Don't worry. A few more months....
(SHY gets married this summer)
LOL! You can have them in a jar for Christmas if you like! :lol:


How can you understand one and not the other? The explanation is the same. Except it's balls and plates instead of gears and gears.
I'm not THAT stupid! :lol: But why does the ball diffs not bind as much as gear diffs at speed? And put more drive to the wheel with less traction compared to a gear diff? And what does that Schuey logo actually try to illustrate? With that "askew line"???

TC have more traction, is that why geared diffs work good for them? And for 1:10 OR you would still prefer a ball diff?

[Zedman]

Next issue looks like it will be brake balence, how do u channel more brake force to the front wheels in an electric setup ?

On a side note are u allowed to run rear wheels on the front in competition ?

[bigred5765]

Next issue looks like it will be brake balence, how do u channel more brake force to the front wheels in an electric setup ?

On a side note are u allowed to run rear wheels on the front in competition ?

i would say like the schueys of old with a double sided slipper tcs system i think they called it
im sure someone will correct me if i got it wrong

[SHY]

Next issue looks like it will be brake balence, how do u channel more brake force to the front wheels in an electric setup ?

On a side note are u allowed to run rear wheels on the front in competition ?

I think the XX4 "clicker" allows you to adjust brake balance front/rear

[mole2k]

The schumacher TCS system was a slipper clutch to the rear wheels and then an adjustable one way so you could adjust the amount of braking to the front wheels from full to none and any step inbetween. The slipper clutch to the rear wheels meant you could have it mostly fwd accelerating out of the corners, I never had one in my cat but I did have the adjustable braking to the front wheels which I quite miss in other cars.

[Jonny_H]

I did once see a picture of a 'proper' plate-and-ramp diff for a model car, probably a 1/8th. It only appeared to have one plate each side though, so it had ridiculously shallow ramps angles - maybe 15-20°.

In theory, a ball diff provides more torque-dependent locking than a gear diff, because for the ball to rotate it has to slide inside the hole in the 'cage', whereas a gear diff's planets rotate on small pins.

In practice, I once measured a pan car ball diff at about 1.4:1 torque bias ratio (changing how tight it was only affected the initial 'preload' torque, and made almost no difference to the TBR under load) - but 1:1 'open' gear diffs also produce about 1.4:1, so it would be interesting to measure a typical model gear diff the same way I did on the pan car.

Having sealed diffs so you can fill them with thick oil/grease seems like an excellent solution to me - that way you get some speed-dependent locking, exactly the same as a 1:1 viscous coupling (VC) diff.

Torsen diffs provide torque-dependent locking (not speed dependent, Sparrow) and 1:1 ones can do 4:1, maybe a bit more. Presumably a Torsen with thick grease then also adds some speed-dependent locking...

As mentioned though, it's difficult to design something effective in 1/10th size, which is probably why we use spools and one-ways a lot - basically a spool is a diff with infinite TBR, and a one-way is the same but only in one direction (a bit like different drive and coast ramps in a plate-and-ramp diff).

I haven't seen the ATD but it sounds like it effectively gives adjustable preload - but it would be nice be use actual TBR as a setup tool as well.

Careful now, you've got me started on diffs... ;)

[SHY]

Very good! :woot:

[sparrow.2]

Torsen diffs provide torque-dependent locking (not speed dependent, Sparrow) and 1:1 ones can do 4:1, maybe a bit more. Presumably a Torsen with thick grease then also adds some speed-dependent locking...


I meant the relative difference in output speed (left-right). But then I had a nosebleed already when my friend got to that part of the explanation ;)

I haven't seen the ATD but it sounds like it effectively gives adjustable preload - but it would be nice be use actual TBR as a setup tool as well.

The ATD diff has a ring in the middle made of the same material as slipper pads. This pad touches the diff rings slightly before the balls and gets compressed, giving a very stiff feeling diff. Somewhere between a straight axle and a diff.

Here is a pic where you can see the bits.

http://www.losipartshouse.com/catalog/ASC2334-450.jpg

[Lee]

One thing i tried whilst racing on road was a spool up front with a centre one way on the layshaft and a ball diff at the back, i found this gave a smoother entry and more steering where the spools tend to wash out mid corner and on power it was just like a spool again, it was quite quick for me:thumbsup:


I cant see it being great with bumps though in off road:thumbdown:

[Lee]

I meant the relative difference in output speed (left-right). But then I had a nosebleed already when my friend got to that part of the explanation ;)



The ATD diff has a ring in the middle made of the same material as slipper pads. This pad touches the diff rings slightly before the balls and gets compressed, giving a very stiff feeling diff. Somewhere between a straight axle and a diff.

Here is a pic where you can see the bits.

http://www.losipartshouse.com/catalog/ASC2334-450.jpg

Thats what comes with the aero, i didnt like it so filed the centre spacer down, now i have a ball diff:lol:

[elvo]

Careful now, you've got me started on diffs... ;)

Hi J! Have you seen XRay's Ramp-ish locking-ish front diff for their XB8? Comes with 2 ... ramp things.

http://www.teamxray.com/teamxray/news/newsdesc.php?news_id=1305&kategoria=1305&catName=

[Gayo]

How do they work ? I don't get it.

[sparrow.2]

Thats what comes with the aero, i didnt like it so filed the centre spacer down, now i have a ball diff:lol:

Did you try running it like that first? I've seen one with that diff on carpet and astroturf and it went like poo off a shovel :)

[bender]

What about this one then:

[Lee]

Did you try running it like that first? I've seen one with that diff on carpet and astroturf and it went like poo off a shovel :)

Yes i did try, it for a few meetings like that, whilst the grip was high it was very good but it made it difficult to get the power down on a low grip surface, the car is much more predictable on our multi surface tracks with a ball diff.

It may work on a smooth blue groove track:)

[jimmy]

what is this badboy then, does it stiffen the action without crushing the balls to death? is that the idea?

[Lee]

Jim, from what i can gather, it is to stop the car diffing out when one wheel goes light, but it does also hinder the diff action to a degree.

[SHY]

What about this one then:

Where's that from?

[jimmy]

it looks old! :lol: is it from a yankee electra or something mad like that?

[Jonny_H]

Hi J! Have you seen XRay's Ramp-ish locking-ish front diff for their XB8? Comes with 2 ... ramp things.

http://www.teamxray.com/teamxray/news/newsdesc.php?news_id=1305&kategoria=1305&catName=No, I hadn't seen that - nice, trust Hudy!

Still only one working surface per side - interesting that they offer 45/45 ramps as standard (the optional "120" is what's usually called 30/30), but presumably they think it gives enough locking. Again, it would be really interesting to actually measure the TBR - and to fill it with 3-in-1 oil and see how well it works without the viscous element!

Bender, that also looks like it does much the same.

Do you get much/any engine braking in a noisy smelly thing? Their comment about the 30/30 being more free off-power seems odd if so...

[SHY]

Do you get much/any engine braking in a noisy smelly thing? Their comment about the 30/30 being more free off-power seems odd if so...

With a centrifugal clutch you never get any engine braking, the clutch releases the second you back off the throttle.

[bender]

it looks old! :lol: is it from a yankee electra or something mad like that?

:lol: It is from my Nichimo Luminous - that diff was their crowning achievement (and patented too), and was on all their 4wd buggies, including their first one (443 Exceed) released in 1986.

On the Nichimo cars it was not used as a front diff, but as a third diff between the central shafts that drive the front and rear diffs. You could actually hear it work too because when the pressure rings were forced apart enough for the small bevel gears to rotate it would make a clicking noise :thumbsup:



Bender, that also looks like it does much the same.

Yes that's what I thought too - the XRay one is very similar, but has the advantage of being sealed so you can change oil viscosities - the Nichimo one is open in the gearbox.

[showtime]

BBF make powerlock diffs very similar to the Xray active diffs that don't use a thick silicone to change the off power characteristics but do have plenty of different ramp options :)

http://www.bbfmodels.com/Tactyl.htm

[fastinfastout]

bump to an old thread.

finally the tides have turned.

gear diffs all the way, onroad and offroad.

spec r, and yokomo are the ones making the onroad diffs.

if only they could make them for the offroad cars!

have a look at the durango, nearly maintenance free diffs with aftermarket seals.

when will kyosho, AE, losi come to the party?

[MiCk B.]

You can run a gear diff in the B4 and in the Losi 2wd.


MiCk B. :-)

[Apricot Slice]

Why don't they make grooved race ways in ball diffs?
Ok, a flat washer is cheap to make. Is there some technical reason why they don't??????????

[RogerM]

More contact area on the ball would mean you had to run it tighter to stop it slipping and it wouldn't be anywhere near as smooth

load = force/area

Once you get a groove worn on the plates that is when you have to replace them.

[SHY]

You can run a gear diff in the B4 and in the Losi 2wd.

MiCk B. :-)

But can I put a SC (gear diff) into a B4 housing? I need a 4.1 house no?

I'm trying to have Durango diffs custom made to fit a B44, but it's hard to do as the steel is hardened :(

AE should get a move on there! :woot: I'd also prefer to have the gears in nylon, I don't fancy the noise from the Durango steel gears...

[peetbee]

But can I put a SC (gear diff) into a B4 housing? I need a 4.1 house no?

Yes, 4.1 housing and I believe 4.1 chassis T piece. outdrive bearings are also a different size to B4.

[MiCk B.]

I've put the gear diff in a b4.

So if you are running the B4.1 it's a direct fit.

If you are running the b4, then as well as the gear diff you will need the following parts.

B4.1 gearbox (9826), 4.1 t-plate (9621), 4.1 metric out-drive bearings, (10x16mm 9832).

The old gearbox will fit on the new 9621, t-plate.

MiCk B. :-)

[Lonestar]

Now that people start experimenting with diff gears in comp-level 2wd mod that used to only offer ball diffs until now (thinking B4.1's here)... can you folks feel the difference when driving? Is the absence of the legendary unavoidable slip from the ball diff really a hamper on the track (comparing super-free ball diffs with super free gear diffs, of course)???

Thanks
Paul

[SHY]

Thx guys!

Well, I think that on a track with low or medium traction a good ball-diff will outperform a gear-diff.

But if you're lazy (like me) a gear-diff may be better than a messed up ball diff :woot:

Jokes aside, on astro (high grip) though I think the gear-diffs may have a future in 2WD, but need to test first...

How about the X-6 or S2, can I make the AE gear diff fit in there???

[Razer]

Here's my story of diffs. Based on experience from Touring Modified, R/C drifting, fullsize drifting with an RX7, rallying in an old Volvo and racing with a Formula First:cool:

Open diffs are never a good thing. It's makes a car quite unpredictable and unprecise. For a full size drift car it means unpredictable and unprecise entry, full unloading and the mother of all pendulum comebacks when the diff unloads and your outer wheel finds grip. For rallying it's that, plus that you lose a lot of forward grip and corner speed when it's unloading all power to the inner wheel, and the same thing goes for R/C drifting and Formula First.

Wheelspin = Unloading = Death.

And heres my first point. ALL 10th SCALE R/C CAR GEAR DIFFS ARE OPEN DIFFS!! At least so far. You can slow down the movement by adding thicker oil or lube, but the movement will never be predictable, it will never truly limit slip.

This winter I've missed clipping points, hit curbs and F****d up several runs without getting my mind around it. I even started to lose faith in my driving. I have always tried to be tight on my lines, and I have previously been very good at it, but this indoor season i've been terrible, and it got me thinking lots.

No matter how cleanly I turned into a corner, I really never made a clean even clip every lap. I turned in on the same spot, washed out, and ended up two feet from the curb. Next lap, same line, hit the curb and rolled over.

Why?

A gear diff never really works similar each lap, and while coasting into a corner it loads-unloads-loads-unloads, and same while braking into a corner. You could as mentioned put in a higher viscosity oil, but this will only be a compromise, as it would fuck up the things you do like. You want a smooth diff that doesn't do unpredictable stuff.

It's called a ball diff. The ball diff has a preset load, and if it's in good shape, it's as predictable and smooth as nothing else out there.

This is also my experience from my Ovlov rallycar. As soon as I got a true LSD in it, slowing it down and balancing it with engine braking through the gears worked brilliantly, and on power you just have so much more forward traction.

On my XXX-CR, the gear diff didn't really give anything forward until I was done cornering and both wheels had equal load. Damn, it was a rocket from then on. But still an unpredictable rocket:)

[Mr. Pink]

One thing that I consider to be a advantage with ball diffs is the friction.
A gear diff basically only has viscous resistance (oil) when the output shafts is spinning at different speed. With a ball diff you have to apply a small amount of differentiated torque before it start to diff. So you basically have a pre defined diff-torque that you can adjust. But this "diff torque" is also depending on the friction between the balls and the input gear (friction between balls and the sides of the holes that holding the balls in place) This friction force is depending on the total input torque going through the diff.

So the more torque you apply with the throttle the more "diff locking" you get.

[SHY]

OK, Martin (Razer), I have full confidence in you. If that's your experience I truly believe it. So that means that also on astro outdoors 2WD is better off with a ball diff surely? (I've read one other driver on oOple say the same as you)

So what about 4WD? It obviously works better then for 2WD, considering the DEX410 doing very well? My experience from B44 and Atomized B44 on astro is that the ball diffs have a very short life. If oil filled gear diffs give the same speed and handling I'd really prefer that! (Yes, I HATE re-building diffs!)

When Cecil Schumacher invented the ball diff (dunno the year), it was a massive improvement over the previous gear diffs. The Schuey logo depicts the ball diff principle. And I think it's just what you say Martin, it's preloaded! >> smoothness!

Sidenote: Any chance we will se Torsen diffs etc. in 4WD? (like in 1:8) Have Team Durango tested this already?

@Razer: I've lost faith in my driving many times :thumbsup: And whey you occasionaly drive well.... what do people say then? "Oh man, your CAR looks good!"

[Razer]

OK, Martin (Razer), I have full confidence in you. If that's your experience I truly believe it. So that means that also on astro outdoors 2WD is better off with a ball diff surely? (I've read one other driver on oOple say the same as you)

So what about 4WD? It obviously works better then for 2WD, considering the DEX410 doing very well? My experience from B44 and Atomized B44 on astro is that the ball diffs have a very short life. If oil filled gear diffs give the same speed and handling I'd really prefer that! (Yes, I HATE re-building diffs!)

When Cecil Schumacher invented the ball diff (dunno the year), it was a massive improvement over the previous gear diffs. The Schuey logo depicts the ball diff principle. And I think it's just what you say Martin, it's preloaded! >> smoothness!

Sidenote: Any chance we will se Torsen diffs etc. in 4WD? (like in 1:8) Have Team Durango tested this already?

@Razer: I've lost faith in my driving many times :thumbsup: And whey you occasionaly drive well.... what do people say then? "Oh man, your CAR looks good!"

First of all, TAKK! :)

On a high grip surface, one would think it should be less noticeable, but on carpet that was not my experience. I did also run the Serpent S400 on a few occasions for a couple of years ago, in the modified class. Thinking back, I remember I felt unprecise with this one as well, but that was after being away for a couple of years, so that could just be the rusty fingers.

The good thing, there is NO maintenance. None. Nada. Geen. Tak Satupun. I liked it best with just a bit of grease, that means no difference in action over time, and no leakages. Brilliant in that area.

On a 4wd it's seems to work well, but I have no experience from that. I did discuss it a bit with former B44 privateer, then Durango Team driver, and now B44 Privateer again Ole Steen Karlsen, and his message was quite interesting. He felt he could be more precise and smooth with the B44.

But if that is due to the cars design or the diffs, I have no clue.

Now, over to someone who has experience with a 'Rango? Anyone?

Edit: About that last part: Stirling Moss has stated he always tried to make it look good when he was driving, therefore the straight arms and relaxed style. In R/C cars, that is actually more important than you think. The better it looks, the better you are;-)

[Gayo]

I've lost faith in my driving many times :thumbsup: And whey you occasionaly drive well.... what do people say then? "Oh man, your CAR looks good!"

LOOOOL :lol: So true!

[fastinfastout]

so the best drivers in the world are all wrong by going to gear diffs?

[Apricot Slice]

RogerM[/LEFT];461219]More contact area on the ball would mean you had to run it tighter to stop it slipping and it wouldn't be anywhere near as smooth

load = force/area

Once you get a groove worn on the plates that is when you have to replace them.

wouldn't a larger contact area mean more grip?

[SHY]

so the best drivers in the world are all wrong by going to gear diffs?

Is that the case for 2WD 1:10 OR???

Examples?

[Razer]

so the best drivers in the world are all wrong by going to gear diffs?

Not at all.

But they go to gear diffs in touring cars and 4wd. That's a different story all together.

I can try to make it more understandable with this statement though. It just as fast, but more unpredictable and harder to drive, on the plus side it means less maintenance.

[SHY]

This makes me think of front one-ways for 4WD. When I started with 1:10 OR a few years ago, I got the impression that everyone used them. It was simply faster.

But when I finally tried with a front diff everything went way better for myself! Much easier to control, and I really cannot say that I got more steering from the one-way either. And MUCH better in the air of course.

It's not always a good idea to copy the set-up from the very best drivers... unless you have out of this world hand-eye coordination, an easy to drive car is always faster on average!

[fastinfastout]

Is that the case for 2WD 1:10 OR???

Examples?
Touring Car.

I'm not sure about gear diffs in 2wd's.

from what I have heard, ball diffs are more precise in 2wd. Have not heard of any AE team drivers using gear diffs.

[blue_pinky]

so the best drivers in the world are all wrong by going to gear diffs?

Hehe...slightly sweeping statement!!! :p

Whilst some of the worlds best may be driving gear diffs...in 1/10th offroad there are certainly a lot of the top guys who are still on Ball diffs! The 2 UK National winners from 2010 are both driving ball diffs, and will be again in 2011 as far as I know!

Sponsored drives aside ;), the top guys could drive any style of diff and make it look like the best thing since sliced bread!!!

I'm really interested to hear this talked about...from an average driver point of view the gear diff looks like a good idea. But from what I'm hearing...only from a building/maintenance/reliability point of view!

I'm really interested in running a durango for myself to see if I can tell the difference, so Razers comments on the lack of consistent driving feel are very interesting!

Good discussion :thumbsup:

[fastinfastout]

Not at all.

But they go to gear diffs in touring cars and 4wd. That's a different story all together.

I can try to make it more understandable with this statement though. It just as fast, but more unpredictable and harder to drive, on the plus side it means less maintenance.
harder to drive?

Well my durango is quite hard to drive compared to other 4wd's I have/had. Cannot put that down to the car itself or cos of the gear diffs. I have also heard of people using kyosho ball diffs in their durango's, so maybe you are right!

[fastinfastout]

Hehe...slightly sweeping statement!!! :p

Whilst some of the worlds best may be driving gear diffs...in 1/10th offroad there are certainly a lot of the top guys who are still on Ball diffs! The 2 UK National winners from 2010 are both driving ball diffs, and will be again in 2011 as far as I know!

Sponsored drives aside ;), the top guys could drive any style of diff and make it look like the best thing since sliced bread!!!

I'm really interested to hear this talked about...from an average driver point of view the gear diff looks like a good idea. But from what I'm hearing...only from a building/maintenance/reliability point of view!

I'm really interested in running a durango for myself to see if I can tell the difference, so Razers comments on the lack of consistent driving feel are very interesting!

Good discussion :thumbsup:
maybe cos they dont have the gear diff option to use in their cars. Maybe they would be using gear diffs if an aftermarket company like SpecR produce them.

[SHY]

If I could just get my modded B44 diffs ready... I'd be really interested to hear how it feels to drive with gear diffs!

But there's guys on here that's tested gear diffs in their B44s, speak up!

Gayo for instance! :woot:

[fastinfastout]

this gear diff by specR, made for the tb03 'could possibly' fit some current offfroad 4wd's with some work.

http://www.spec-r.com/specrr2/modules/zox/index.php?main_page=product_info&cPath=7&products_id=108

I'm going to order a couple of these diffs, and see if they fit in some of my 4wd's eg. D4, zx5sp.

[Razer]

Keep opinions coming, this is one of the more interesting threads for me in a while:thumbsup::thumbsup:

[Gayo]

But there's guys on here that's tested gear diffs in their B44s, speak up!

Gayo for instance! :woot:

Argh :D I didn't want to give my poor advice as I feel I didn't gave the gear diffs a fair test, but if you want it, here it goes :

B44 : I tried with the help of Olivier "The Brain" Langlet Durango diffs on my B44. I liked the adjustability, running stiffer diffs (specially front) helped to make the car less twitchy. Sadly the diffs leaked (solved now with Kyosho o-rings and good grease). As I fell in love with K-cars, I sold my B44 quickly. I sold the Langlet-made transmission to a mate (hey, I gave the money back to Olivier!) and he seems to like them on his B44.

CR2 : I built my car with the Desert Truck gear diff. Franckly I found the car bad, a bit twitchy on carpet and hopelessly understeery on slippy indoor floor. Again I sold the car quickly but I'm afraid all the problems came from the gear diff. It was also badly made with very soft outdrives, not something I would recommend to anyone.

So, to sum it up, I feel that to perform well and if you run on different kinds of tracks like me, gear diffs have to be tweaked to each track to perform best, so they actually give more work on the car, not less. They are also heavier and quite messy. I didn't feel they gave me any edge on track, so unless experience shows that a gear diff is faster, I will stick with ball diffs.

Wow, lots of english words for me :bored:

[SHY]

:cry:...

[qatmix]

On Tc Gear diffs are for the Mod racer running on large sweeping tracks at 65mph.

I tried one in my car and Its almost like a spool, I could muck about with different oils but a ball diff is much easier to tune (a slight twist on the screw) And if you make a ball diff properly they last for ages before maintenance on 10.5 or less.

[Razer]

On Tc Gear diffs are for the Mod racer running on large sweeping tracks at 65mph.

I tried one in my car and Its almost like a spool, I could muck about with different oils but a ball diff is much easier to tune (a slight twist on the screw) And if you make a ball diff properly they last for ages before maintenance on 10.5 or less.

That's also something to bring into the equation.

High power brushless motors is what starts this problem. I remember running the TC3 in modified, and on a hot summer day with a 12 turn(european limit), I got about 6-8 packs of running through the original diff with plastic outdrives. And I remember the power as very good, it spun all four of my Sorex 36, fully sauced and heated.

Try that diff now with a 3.5-5.5 turn, and you've come to a dead stop in probably two minutes....

I run an 8,5 turn in my 2wd, and my diffs last for 2-3 practice days on carpet. That is usually around 900 laps with high grip, and outdoors they last a lot longer.

What I have figured out is that your balls and rings should match. I tried running ceramic balls, and they're great. Never wear them. But the rings get crappy in half the time because all the wear is on the rings, so the overall value of using ceramic balls is low.

[SHY]

Yeah, I didn't make very good friends with ceramic balls either!

My experience is also that the diff lasts longer with steel balls. I also find it easier to adjust the diff with steel balls. It feels a bit on/off with the ceramic balls (too loose or too tight is very close to each other).

And as I understand most UK racers just re-use the steel balls and only grind down the rings. Which must mean that even the steel balls don't wear. Never tried myself though, always replace the balls...

[jimmy]

This makes me think of front one-ways for 4WD. When I started with 1:10 OR a few years ago, I got the impression that everyone used them. It was simply faster.

But when I finally tried with a front diff everything went way better for myself! Much easier to control, and I really cannot say that I got more steering from the one-way either. And MUCH better in the air of course.

It's not always a good idea to copy the set-up from the very best drivers... unless you have out of this world hand-eye coordination, an easy to drive car is always faster on average!


I was talking to someone this week about oneways - and they made a point I'd not considered and that's just the sheer power and speed of the cars might be too much for a one way now. A lot of drivers I knew running one-ways in years gone by have stopped running them.

[mark christopher]

I was talking to someone this week about oneways - and they made a point I'd not considered and that's just the sheer power and speed of the cars might be too much for a one way now. A lot of drivers I knew running one-ways in years gone by have stopped running them.

10th and 8th ic run then... so they should not be weak?

[Cockerill]

10th and 8th ic run then... so they should not be weak?

It's not necessarily strength, but other reasons. For me, the amount of speed we now carry into corners means I need the braking that you can't get from a one-way.

[Jan Larsen]

Precisely. The biggest problem with one-ways today is the inability to brake. I tried one in my Tamiya 511 on a big outdoor track. At the end of the 50m, 105km/h straight (we had a speed gun) there was a hairpin. With the oneway I had to brake almost 20 meters before. With the diff I could get that down to 5 meters and 4 tenths on the laptime. Its the sheer amount of speed we carry towards the corner that dictates the need for brakes and the main reason oneways arent used anymore, at least not in the faster classes.

[Legacy555]

CR2 : I built my car with the Desert Truck gear diff. Franckly I found the car bad, a bit twitchy on carpet and hopelessly understeery on slippy indoor floor. Again I sold the car quickly but I'm afraid all the problems came from the gear diff. It was also badly made with very soft outdrives, not something I would recommend to anyone.
:bored:

Agreed on the soft outdrives, but I've actually found the gear diff to be better than the ball diff on carpet. I use the desert truck diff with 35wt shock oil in it. With the ball diff, I was suffering through a high speed hairpin where the inside wheel was getting light on the exit and I was loosing a bit of drive. I put the gear diff in and although the car's steering does seem more dosile I find that you can hang onto a huge amount of speed through the corner and the traction out of the hairpin is almost like a 4wd. I'd recommend trying it, but we're not talking a huge difference, just that extra couple of %.

[Col]

This makes me think of front one-ways for 4WD. When I started with 1:10 OR a few years ago, I got the impression that everyone used them. It was simply faster.

But when I finally tried with a front diff everything went way better for myself! Much easier to control, and I really cannot say that I got more steering from the one-way either. And MUCH better in the air of course.

It's not always a good idea to copy the set-up from the very best drivers... unless you have out of this world hand-eye coordination, an easy to drive car is always faster on average!

I was talking to someone this week about oneways - and they made a point I'd not considered and that's just the sheer power and speed of the cars might be too much for a one way now. A lot of drivers I knew running one-ways in years gone by have stopped running them.

I was under the impression that we simply didn't need them anymore due to better geometry built into the more modern cars. Everybody ran a one way in their xx4 to give them better initial turn into the corner and made do with rear wheel braking, whereas with (for example) the B44 has far superior steering built in that a diff is faster due to later braking? That's how I see it, anyway!

[SlowOne]

10th and 8th ic run then... so they should not be weak?It's a question of how the power is made up, not the absolute power.

Power = torque x revs. Strength of the system is a function of torque. Gas cars get their power through revs, so their systems can be smaller than electric cars, who get their power through torque. It doesn't follow that a system that works in a gas car will work in an electric car.

A Veyron has twice the power of a 38 tonner, but if you put the driveshaft from a Veyron in a Volvo truck, the Volvo would snap it with one lift of the clutch! All that luvverly torque...!

This is a great thread, full of interesting information. One thing I would be interested in is how you guys measure the torque limiting capability of the various diffs, and how you measure the percentage of lock-up. If this area is well understood, you'll be making good progress, and I'd love to apply your calcs to a 12th diff!

As for Torsen diffs, I doubt they could be engineered into the space provided. However, a smaller version of the Ferguson fluid clutch diff should be possible - imagine a Losi Hydra slipper scaled down and popped in a diff and you get the idea. A clutch-based LSD would also be possible - imagine a PTFE slipper clutch popped in the diff to give you adjustable amounts of limited slip.

If Cecil Schumacher is still up for a challenge, he could make a second living with a proper LSD for On- and Off-Road!!

[Richard Lowe]

Power = torque x revs. Strength of the system is a function of torque. Gas cars get their power through revs, so their systems can be smaller than electric cars, who get their power through torque. It doesn't follow that a system that works in a gas car will work in an electric car.
Remember the diff is at the slowest rotating part of the drivetrain, 1:1 with the wheels, and therefore at the highest torque point in the car. If an electric car has equal sized wheels and power to a nitro the overall load will be about the same I'd imagine :)

I'd love to be able to run a one-way diff in 4wd, I'm sure I'd be faster over a single lap - but that's the problem. There's a much bigger chance I'll make a mistake on big stops into slow corners. Also a one-way has a bit of a mind of it's own accelerating through bumps in a shaft drive car, less of an issue on those rubber band cars ;)

[Apricot Slice]

A 10th scale one of these couldnt be that hard to make.
http://tlcequipment.files.wordpress.com/2008/07/imgp1838e.jpg

[SHY]

Precisely. The biggest problem with one-ways today is the inability to brake. I tried one in my Tamiya 511 on a big outdoor track. At the end of the 50m, 105km/h straight (we had a speed gun) there was a hairpin. With the oneway I had to brake almost 20 meters before. With the diff I could get that down to 5 meters and 4 tenths on the laptime. Its the sheer amount of speed we carry towards the corner that dictates the need for brakes and the main reason oneways arent used anymore, at least not in the faster classes.

Whaaaaaaaaat!!! You're saying a 1:10 OR car does 105 km/h on the straight???

I'm an experienced 1:8 TR driver, which is the fasted RC class. They do approx 110 km/h on the straight, and that's with super wide sponge tires, a 2-speed and a combustion engine doing 50.000 revs/min...

I know touring cars are faster now with brushless and Lipo, and can show equal or better laptimes than 200mm. But a 1:10 OR being as fast on the straight as a 1:8 TR... sceptical... :D

Very interesting about the braking!

[Bagman]

I do know that I would pay good money to anyone able to put Durango diffs in my spare FS2. PM me if you are that man.

[SHY]

A 10th scale one of these couldnt be that hard to make.
http://tlcequipment.files.wordpress.com/2008/07/imgp1838e.jpg

Cool! :thumbsup:

As I understand there's a guy in Germany that has made something like this for his B4- which works very well! But he wants to keep it a secret it seemed...

[SHY]

I do know that I would pay good money to anyone able to put Durango diffs in my spare FS2. PM me if you are that man.

Search and you'll find a tread about that on this forum. I think they were a direct fit vs. the B44 where you need some serious equipment in order to do the conversion...

And remember to order replacement Kyosho O-rings (JE Spares carry them)

Can those of you that know 1:8 OR list all the types of diff existing for those cars? Plus give a quick explanation of the "felt difference"?
-regular diff
-Torsen diff
-Fiorini diff?
...

[dodgydiy]

have been messing with a plated diff, only at early stages really, no friction plates as in a full size diff, just relying on the viscosity of the sillicon oil to provide the limited slip effect, how it compares i cant tell you as it hasnt been put in a car yet, but it feels when rotated to lock up harder than just oil and gears under pressure

[dodgydiy]

have a look at the quaife ATB differential, that would be easy enough to minaturise, they work well too, ond mugen 1/8 diffs were laid out like this but not with helical gears

[Hog]

However, a smaller version of the Ferguson fluid clutch diff should be possible - imagine a Losi Hydra slipper scaled down and popped in a diff and you get the idea.

Didn't Ford try some of its Rally and Rallycross Capri's from the 70's era with Ferguson diffs and they were notoriously haphazard? Understeer one moment, oversteer the next - that's why you only see photos of them sideways as it was the best way to overcome it.

[Razer]

Didn't Ford try some of its Rally and Rallycross Capri's from the 70's era with Ferguson diffs and they were notoriously haphazard? Understeer one moment, oversteer the next - that's why you only see photos of them sideways as it was the best way to overcome it.

I don't know how this compares to the Viscous LSD's that came with the Nissan S13-S14 200SX and my old Mazda RX7, but I remember them as totally horrible. As you mention with the Capris, it was oversteer/understeer/alloversteer/andtowardsthetreessteer in my RX7 as well....

I'm very skeptical towards a fluid based LSD, as I can't really see how that will deliver the precision we want in the size we demand.

Of course, I do not know what technology active differentials from WRC 5(?) years back were based on, but in all my experience, a purely mechanical diff that can be preset as you like it, is a lot more predictable than any viscous and oil based solution. At least with available technology to be put in a 10th scale car:)

But then again, I'm not familiar with all options, and I'm not an engineer:)

[Apricot Slice]

http://i471.photobucket.com/albums/rr74/Zogg538/lsd.jpg

[SlowOne]

I had a couple of FF diffs in my Sierra XR4x4, and they were excellent. :confused:

Any of these diffs can be scaled to fit into a model, that's the easy bit. What you can't scale is the Laws of Physics, and they start to give different results when things get bigger and smaller. Those results don't always mimic in a model car what is experienced in a full-size car. The clutch-style LSD might not work correctly when the area on the clutch plates gets to be so small, for example. An example of this is the size of dampers we use. If a TC damper were scaled up to a full-size touring car, it would be so big it wouldn't fit in the space provided, but if the touring car one was scaled down, it would have so little fluid and movement it wouldn't work at all in a TC!

That's the challenge, finding a solution that does what you want it to do. Simply looking to full size and trying to scale it is probably not what is needed. Something different is likely to succeed IMHO.

[Apricot Slice]

I had a couple of FF diffs in my Sierra XR4x4, and they were excellent. :confused:

Any of these diffs can be scaled to fit into a model, that's the easy bit. What you can't scale is the Laws of Physics, and they start to give different results when things get bigger and smaller. Those results don't always mimic in a model car what is experienced in a full-size car. The clutch-style LSD might not work correctly when the area on the clutch plates gets to be so small, for example. An example of this is the size of dampers we use. If a TC damper were scaled up to a full-size touring car, it would be so big it wouldn't fit in the space provided, but if the touring car one was scaled down, it would have so little fluid and movement it wouldn't work at all in a TC!

That's the challenge, finding a solution that does what you want it to do. Simply looking to full size and trying to scale it is probably not what is needed. Something different is likely to succeed IMHO.

Have found out about the scale/physics thing first hand building shocks. (that project is still alive. been hibernating.)
Was going to have a shot at making some durable diffs out of grooved race way thrust bearings but this LSD thing has got the old coconut thinking.

one daft idea was to have a cog on each outdrive meshing into an idler and then to another cog that carries a slipper linking each side.
It was the only manufacturable way within my means to do it as far as last nights thinking was concerned.
Probably take up too much space and too much rotating mass.
http://i471.photobucket.com/albums/rr74/Zogg538/lsd2.jpg

[Razer]

Fun fact: My latest ball diff did about 350 laps on Thursday and 440 on saturday, on carpet, and it still feels brand new;-)

Also, the B-fast stuff gets a lot of good words, I'll be trying that soon...

[SHY]

I had a couple of FF diffs in my Sierra XR4x4, and they were excellent. :confused:

Any of these diffs can be scaled to fit into a model, that's the easy bit. What you can't scale is the Laws of Physics, and they start to give different results when things get bigger and smaller. Those results don't always mimic in a model car what is experienced in a full-size car. The clutch-style LSD might not work correctly when the area on the clutch plates gets to be so small, for example. An example of this is the size of dampers we use. If a TC damper were scaled up to a full-size touring car, it would be so big it wouldn't fit in the space provided, but if the touring car one was scaled down, it would have so little fluid and movement it wouldn't work at all in a TC!

That's the challenge, finding a solution that does what you want it to do. Simply looking to full size and trying to scale it is probably not what is needed. Something different is likely to succeed IMHO.

Indeed! This was why Team Associated were so successful from the get go! They designed their RC cars as purely RC cars with new ideas, and not trying to downscale a 1:1 car :thumbsup: Those who did try to downscale 1:1 car more than anything else ended up with way too complex solutions, and WAY WAY(!!!) too heavy cars!

We also need to remember the INSANELY big jumps our cars face! Only thing that slightly resembles an upscaled RC as I can think of right now are those Paris-Dakar buggies. They have very long suspension travel and can jump like a kangaroo :D

one daft idea was to have a cog on each outdrive meshing into an idler and then to another cog that carries a slipper linking each side. It was the only manufacturable way within my means to do it as far as last nights thinking was concerned. Probably take up too much space and too much rotating mass.
http://i471.photobucket.com/albums/rr74/Zogg538/lsd2.jpg

I'm no engineer, but that looks like a simple and good solution to me!!! :thumbsup:

Fun fact: My latest ball diff did about 350 laps on Thursday and 440 on saturday, on carpet, and it still feels brand new;-)

Also, the B-fast stuff gets a lot of good words, I'll be trying that soon...

B-fast stuff???

--------------------------------

But guys, have you all read about this?
http://www.oople.com/rc/photos/euros2010/day2/

Georg Kotzinger from Germany was running a pretty standard looking Associated B4.1 buggy - but we got a tip off about his unique gearbox which looks like nothing special from the outside.

Inside however - he's got something pretty strange going on. The differential is a geared diff that he's been running for the past three years and ABSOLUTELY won't give away it's internal secrets to us mere mortals.

The differential has the usual 'differential' action so one wheel will turn more around a corner but most of the time it locks or has a limited slip action. If the car lifts a wheel when going round a corner for instance, the car wont lose momentum and the wheel with the most grip (the one on the ground) will have full drive. Interesting - wish we could get to see inside! :(

http://www.oople.com/rc/photos/euros2010/day2/kotzinger/DSC_2215.jpg (http://www.oople.com/rc/photos/euros2010/day2/kotzinger/DSC_2215.jpg)

If any of you guys were there to see it... did it perform well or not??? Often hard to tell if these home-made solutions are good or not, as "mad scientists" like these seldom are the best drivers... :lol:

[Razer]

Indeed! This was why Team Associated were so successful from the get go! They designed their RC cars as purely RC cars with new ideas, and not trying do downscale a 1:1 car :thumbsup: Those who did try to downscale 1:1 car more than anything else ended up with way too complex solutions, and WAY WAY(!!!) too heavy cars!

We also need to remember the INSANELY big jumps our cars face! Only thing that slightly resembles an upscaled RC as I can think of right now are those Paris-Dakar buggies. They have very long suspension travel and can jump like a kangaroo :D



B-fast stuff???

But guys, have you all read about this?
http://www.oople.com/rc/photos/euros2010/day2/

Georg Kotzinger from Germany was running a pretty standard looking Associated B4.1 buggy - but we got a tip off about his unique gearbox which looks like nothing special from the outside.

Inside however - he's got something pretty strange going on. The differential is a geared diff that he's been running for the past three years and ABSOLUTELY won't give away it's internal secrets to us mere mortals.

The differential has the usual 'differential' action so one wheel will turn more around a corner but most of the time it locks or has a limited slip action. If the car lifts a wheel when going round a corner for instance, the car wont lose momentum and the wheel with the most grip (the one on the ground) will have full drive. Interesting - wish we could get to see inside! :(

http://www.oople.com/rc/photos/euros2010/day2/kotzinger/DSC_2215.jpg (http://www.oople.com/rc/photos/euros2010/day2/kotzinger/DSC_2215.jpg)

If any of you guys were there to see it... did it perform well or not??? Often hard to tell if these home-made solutions are good or not, as "mad scientists" like these seldom are the best drivers... :lol:

It must be a miniature Eaton Detroit Truetrac then:) Used the big version in my Ovlov, absolutely brilliant! Doesn't look too advanced in terms of making a miniversion either...
http://www.eaton.com/ecm/groups/public/@pub/@eaton/@per/documents/content/ct_126000.jpg

Shy, don't you read anymore? B-fast is mentioned for balls and rings every time someone complains about their balldiffs;-)

[SHY]

Tell me more about that diff! Looks like a medieval torture instrument! :woot: Sure does look long lasting!!!

Only audio books these days! :thumbsup: Link please kiddo!!!

Ovlov? Lada model??? :eh?:

Btw got a 22 yet? Tempted to get one myself...

Then there's this thing: Fiorini center diff ("torque reactive differential")

http://www.rctech.net/forum/electric-off-road/413792-fioroni-tractive-iv-center-differntial-mbx6.html

http://i46.tinypic.com/2ep2epu.jpg

Would center diffs be worth having in a 1:10 car? Or why not vs. 1:8?

[Razer]

Tell me more about that diff! Looks like a medieval torture instrument! :woot: Sure does look long lasting!!!

Only audio books these days! :thumbsup: Link please kiddo!!!

Ovlov? Lada model??? :eh?:

Btw got a 22 yet? Tempted to get one myself...

Then there's this thing: Fiorini center diff ("torque reactive differential")

http://www.rctech.net/forum/electric-off-road/413792-fioroni-tractive-iv-center-differntial-mbx6.html

http://i46.tinypic.com/2ep2epu.jpg

Would center diffs be worth having in a 1:10 car? Or why not vs. 1:8?

It's basically quite similar to a torsen diff, but it has a more consistent action as far as I'm aware of... And it's the best upgrade ever for any Ovlov(Volvo) 240 owner:)

B-fast : http://www.bfastrc.com/

Ain't got the 22 yet, It's due to be released on March 25th. But I love my CR, and I got it working extremely well, so no stress:)

[SHY]

B-fast : http://www.bfastrc.com/


Thx! I've checked it out now... but I can't really see anything new here. All they do is sand the diff rings flat for you (which we've already done ourselves for years). Good for those who wouldn't bother doing it themselves though!

[Razer]

Thx! I've checked it out now... but I can't really see anything new here. All they do is sand the diff rings flat for you (which we've already done ourselves for years). Good for those who wouldn't bother doing it themselves though!

I think the fact that they flattened them with machines is better than our way with sandingpaper...

We rough them, but we can't tell if they're truly flat.

[B-Fast R/C]

That is true. B-Fast uses machine tools to resurface the rings to a flatter state before doing the two step hand finishing/flattening steps.


.

[Razer]

That is true. B-Fast uses machine tools to resurface the rings to a flatter state before doing the two step hand finishing/flattening steps.


.

Ah, brilliant, you're here:)

I assume this flattening process is done to both sides of the ring, of course?

[SHY]

I think the fact that they flattened them with machines is better than our way with sandingpaper...

We rough them, but we can't tell if they're truly flat.

Agreed, I forgot to type that. I'll give them a try of course! :thumbsup:

[B-Fast R/C]

Ah, brilliant, you're here:)

I assume this flattening process is done to both sides of the ring, of course?

Yes, both sides of the diff rings are processed.

[SHY]

http://www.fioroni.com/inglese/prodotti_dett.asp?gruppo=400&ID=TRC-ASSO/A&cerca=&lingua=ita&pag=2

Looks like those "tractive" diffs are used front, center and rear for 1:8...

Considering how much weight we re-add to our cars with LiPo, fitting diffs like this wouldn't be a problem weight wise at least...

Oh! And I remember reading about THE car and some very small diffs... are they std. diffs?

[Apricot Slice]

http://www.fioroni.com/inglese/prodotti_dett.asp?gruppo=400&ID=TRC-ASSO/A&cerca=&lingua=ita&pag=2

Looks like those "tractive" diffs are used front, center and rear for 1:8...


I didn't know proper clutch type LSD's were made.

C'mon Schumacher, Durango, whoever.. make some of these for 10th

[SlowOne]

Going back to the Eaton Truetrac diff...

It's not for us. This is from their instruction manual "Note: TrueTrac differentials require a certain amount of resistance at the ground in order to start the power transfer. A TrueTrac differential may not transfer power if the spinning wheel is off the
ground. If spinning occurs, often a light application of the brakes, while carefully applying power, will slow the spinning wheel enough to allow the TrueTrac differential to transfer torque to the other wheel."

Although it's open until one wheel spins, if that wheel lifts or spins too much, it goes open again.

Torsen diffs are a better option, but the amount of work needed to tune the helical angles of the gears to get the performance we need is probably a cost beyond the reach of most manufacturers. Love it or hate it, a friction or fluid clutch is probably the best-cost option to see if an LSD is a performance enhancer or not compared to the beloved ball diff.

[SHY]

http://www.ymr.no/bilder/Lars&SHY/1NMR10OR09/bilder/BRUK/diff.jpg

...my lazyness + rain races...

-I guess one of the advantages of an oil filled gear diff is no rust! :lol:

[Neil Skull]

I dont wheter to laugh at this!!!

I have used ball diffs and geared etc etc.
the simple rule is a good quality car should have good diffs. ball or otherwise. You need to know how to first build and run in and maintain.
If you ask about benifits of different diff type i think its purely to fit in the car design to get best weight and power transfer.
But an oil filled diff will have problems if you get water into the gearbox and bearings just like your picture.



BTW I thought Cecil Schu was the first to transfer bevel diff into model cars??

[SHY]

I dont wheter to laugh at this!!!

I have used ball diffs and geared etc etc.
the simple rule is a good quality car should have good diffs. ball or otherwise. You need to know how to first build and run in and maintain.
If you ask about benifits of different diff type i think its purely to fit in the car design to get best weight and power transfer.
But an oil filled diff will have problems if you get water into the gearbox and bearings just like your picture.

BTW I thought Cecil Schu was the first to transfer bevel diff into model cars??

Nono! He invented the ball diff!

http://www.racing-cars.com/images/schumacher_logo_cougar.jpg

The top left Schuey logo depicts the principle of the ball diff I've heard.

I hope you understand that the last post was a joke :D

[SlowOne]

Cecil did indeed invent the ball diff, and that was the first product of Schumacher Racing. They were made during the week in the evenings, bagged and shipped off the kitchen table at weekends!

I did an article about Cecil for Model Cars many years ago, and spent a wonderful afternoon at his house hearing about his life and times. He is a remarkable man, and one of the great pioneers of RC. If we ever got to have an RC Hall of Fame, he would be in my top three nominations as an inaugural member.

Maybe if Cecil could be persuaded out of retirement, this problem would get solved a bit quicker!

[SHY]

Cecil did indeed invent the ball diff, and that was the first product of Schumacher Racing. They were made during the week in the evenings, bagged and shipped off the kitchen table at weekends!

I did an article about Cecil for Model Cars many years ago, and spent a wonderful afternoon at his house hearing about his life and times. He is a remarkable man, and one of the great pioneers of RC. If we ever got to have an RC Hall of Fame, he would be in my top three nominations as an inaugural member.

Maybe if Cecil could be persuaded out of retirement, this problem would get solved a bit quicker!

Could you please scan and email me that article? I'd love to put it into my Model Car History web page! www.ymr.no/historie.htm

[TomC]

It must be a miniature Eaton Detroit Truetrac then:) Used the big version in my Ovlov, absolutely brilliant! Doesn't look too advanced in terms of making a miniversion either...
http://www.eaton.com/ecm/groups/public/@pub/@eaton/@per/documents/content/ct_126000.jpg

Shy, don't you read anymore? B-fast is mentioned for balls and rings every time someone complains about their balldiffs;-)

that diff looks like a quaife automatic torque biasing diff (the one found on the focus RS)

Fioroni made a 1/8 buggy version of the quaife ATB diff called the Storm traction diff. A series of worm gears that mounted together inline with the drive/outputs

Before the Storm traction fioroni had the Hyper traction torsen style diff and the original (older) Japan traction torsen diff

main difference between Hyper and Japan was the Hyper had 3 pairs of worm gears perpendicular to the inner gears and the Japan had only 2 pairs.

The Storm diff was available with different worm gear sets which had more or less angle on them to change the aggressiveness of the action.

[SlowOne]

Shy, sorry but I don't have anything to scan with, and I don't hold the copyright. I suggest that you write to Alan Harman at RC Car Racer magazine and see if he knows who holds the copyright. HTH :)

[Aaran]

i think we get most of the diffs mentioned here for our 1/5th scale cars, from self locking to manual blocking using plates etc

we also get this: http://www.rctek.com/phpBB/viewtopic.php?t=5614

http://www.rctek.com/technical/oddie_magnetic_differential.html


magnetic diff thats self ajusting to always give the best drive and traction in any condition, from people that have them they say its a huge improvment over the stock alloy gear diffs

[SHY]

i think we get most of the diffs mentioned here for our 1/5th scale cars, from self locking to manual blocking using plates etc

we also get this: http://www.rctek.com/phpBB/viewtopic.php?t=5614

http://www.rctek.com/technical/oddie_magnetic_differential.html


magnetic diff thats self ajusting to always give the best drive and traction in any condition, from people that have them they say its a huge improvment over the stock alloy gear diffs

http://www.rctek.com/technical/images/oddie/oddie_mag_diff_126.jpg

Magnetic!!! Funky shit!!! And it works?!!!

How cool is that! :thumbsup:

Looks hardcore Mad Scientist!!! :D

[Razer]

http://www.rctek.com/technical/images/oddie/oddie_mag_diff_126.jpg

Magnetic!!! Funky shit!!! And it works?!!!

How cool is that! :thumbsup:

Looks hardcore Mad Scientist!!! :D

Now this is interesting:thumbsup::thumbsup:

[Aaran]

yup they work, cost a fair bit though, i think a HARM mag diff new from HARM is £200+ odd then ian oddie mods them at extra cost (adds the internal wires and does some other stuff to them)

then again a stock alloy diff is £180 odd new for most cars lol.

not sure if they would work as well being scaled down for 1/10th as your diffs are about 5 times smaller than the 1/5th units we use (my stock diff was not much under the weight of my x10 without wheels and radio and running gear lol) not sure if the magnetic feild it generates would have the same effect (might do as the cars are smaller/lighter and the diffs do rotate alot faster than our 1/5th things)

[dodgydiy]

i wonder if mr oddie has made one for that psychotic reliant kitten yet (if he still has it!) he's worse than me, he will modify anything!!

[SHY]

yup they work, cost a fair bit though, i think a HARM mag diff new from HARM is £200+ odd then ian oddie mods them at extra cost (adds the internal wires and does some other stuff to them)

then again a stock alloy diff is £180 odd new for most cars lol.

not sure if they would work as well being scaled down for 1/10th as your diffs are about 5 times smaller than the 1/5th units we use (my stock diff was not much under the weight of my x10 without wheels and radio and running gear lol) not sure if the magnetic feild it generates would have the same effect (might do as the cars are smaller/lighter and the diffs do rotate alot faster than our 1/5th things)

I volunteer to test a prototype from Mr. Oddie! :thumbsup::woot:

[Aaran]

send him an email then:

http://www.oddified.com/index.php

im sure he has all the gear to make them as he makes his own parts for 1/5th cars etc (also the lovely 1/5th ecu's)

[SHY]

Sent! :thumbsup:

[fastinfastout]

following this very interesting thread, after some posts of gear diff inconsistency/difficultness in handling/performance, I decided to install a ball diff into my durango to see for myself if a ball diff will make this car handle better.

testing to follow in the next couple of weeks.

will keep you posted! :thumbsup:

[RogerM]

Is that a Kyosho ring gear? They are bullet proof when properly meshed with the Kyosho pinion gear but I am not sure (because I don't know anybody who has tried it) how well it will last with such a small meshed area with the Durango pinion. Might be worth trying to get the mating Kyosho part in there if at all possible.

[Richard Lowe]

It's right at the outside though so it'll stand the best chance it could of surviving! It might be an idea to fill in the inner half of the teeth on the diff gear with epoxy to give the outer part of the the teeth that's being used a bit more support.

I bet the car has loads more grip with ball diffs ;)

[SHY]

ASAIK the D diff is a direct fit in the K, so should be the same vice versa

[fastinfastout]

Is that a Kyosho ring gear? They are bullet proof when properly meshed with the Kyosho pinion gear but I am not sure (because I don't know anybody who has tried it) how well it will last with such a small meshed area with the Durango pinion. Might be worth trying to get the mating Kyosho part in there if at all possible.
correct, its a ball diff straight off a zx5sp. All it needed was a 1mm thinner bearing. Mating with the original durango drive gear was the easiest option, if it fails I'll try mating with kyosho to kyosho.
It's right at the outside though so it'll stand the best chance it could of surviving! It might be an idea to fill in the inner half of the teeth on the diff gear with epoxy to give the outer part of the the teeth that's being used a bit more support.

I bet the car has loads more grip with ball diffs ;)
good idea!

I'm betting that too.

ASAIK the D diff is a direct fit in the K, so should be the same vice versa
on the FS at least.

I'm not going to bother getting an FS and putting a gear diff in, as I feel ball diffs in offroad will be superior, IMO.

[SHY]

I'm not going to bother getting an FS and putting a gear diff in, as I feel ball diffs in offroad will be superior, IMO.

I understand that fully :lol: Just thought it might be a good idea to use also the plastic planetary gear (small one) from the Kyosho, as that one is also plastic. Looks like you've kept the Durango steel gear as for now.

[Razer]

I understand that fully :lol: Just thought it might be a good idea to use also the plastic planetary gear (small one) from the Kyosho, as that one is also plastic. Looks like you've kept the Durango steel gear as for now.

Remember the ball diff I was telling you about, that was still good as new after a few thousand laps on carpet?

I've been running a month or so now, I would guess about 5000 laps or so, still good as new...... :P

The new 22 uses two more diff balls, which means 14% more surface area, that should mean a lot more solid, and a lot less wear and maintenance!

[fastinfastout]

I understand that fully :lol: Just thought it might be a good idea to use also the plastic planetary gear (small one) from the Kyosho, as that one is also plastic. Looks like you've kept the Durango steel gear as for now.
will see how it goes as the durango gear was the easiest option. I cannot see the kyosho drive gear fitting at all to be honest the way the durangos front shaft is arranged.

[SHY]

Remember the ball diff I was telling you about, that was still good as new after a few thousand laps on carpet?

I've been running a month or so now, I would guess about 5000 laps or so, still good as new...... :P

The new 22 uses two more diff balls, which means 14% more surface area, that should mean a lot more solid, and a lot less wear and maintenance!

You're starting to sound like Cramer now, in that episode where he wanted to see how far he could get before filling up the gas tank... :D

[njc11]

Have you run the car yet with K diffs?

Did you have to modify the Kyosho out drives for the durango shafts to fit in?? The pin is thicker then the kyosho ones so you will need to open up the outdrivs, slots to fit..i wonder about the ball with pin through it as well.. this is bigger and maybe to tight in the outdrive..

Ive tried Durango diffs in the FS2... good but too brutal..pretty straight forward to fit, just make sure all meshing is spot on.
:thumbsup:

[fastinfastout]

Have you run the car yet with K diffs?

Did you have to modify the Kyosho out drives for the durango shafts to fit in?? The pin is thicker then the kyosho ones so you will need to open up the outdrivs, slots to fit..i wonder about the ball with pin through it as well.. this is bigger and maybe to tight in the outdrive..

Ive tried Durango diffs in the FS2... good but too brutal..pretty straight forward to fit, just make sure all meshing is spot on.
:thumbsup:
I only have a K diff in the front.

had a run yesterday, failed within 5 minutes. I couldn't tell you how it handled any differently as the track was blown out from all the rain we have had. Metal bevel gear ate up the kyosho diff gear fairly quick. I dont know if I can fit a kyosho bevel in, as durango setup has a cvd 2cm coming out of gearbox. It sure would be nice to know someone handy with a lathe at this time lol

I used kyosho sp drive shafts, along with kyosho hex.

gear diff in fs2 no good? if you could explain how it handled.....thanks. That just makes me want to make this durango ball diffed even more.