DIFFERENT differentials - do you beg to differ?

[jimmy]

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

[Jonny_H]

Originally Posted by elvo

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/new...a=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]

Originally Posted by Jonny_H

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]

Originally Posted by jimmy

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

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

Originally Posted by Jonny_H

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]

Originally Posted by MiCk B.

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! I'd also prefer to have the gears in nylon, I don't fancy the noise from the Durango steel gears...

[peetbee]

Originally Posted by SHY

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

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

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 And whey you occasionaly drive well.... what do people say then? "Oh man, your CAR looks good!"

[Razer]

Originally Posted by 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 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]

Originally Posted by SHY

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

LOOOOL So true!

[fastinfastout]

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