Ball Diff or Gear Diff?

[whites75]

Being pretty new to hobby I wondered is there was any pro's or con's of running with a ball or gear diff and which is the best option to go for?

My bmax2 has the gear diff as per kit but I have noticed others using ball diffs in theirs and wondered why?

Cheers
Phil

[DynaMight]

Most people seem to prefer the ball diff.

The general rule of thumb is gear diff is better for high traction like carpet/astro but ball is better for low grip, but like I said, most of the top drivers in my area tend to prefer ball diffs for every type of surface.

I recently ran a gear diff & ball diff back to back (thanks to the shafts popping out on the DEX210) and I could tell straight away that the gear diff seems to push the front wider when putting some power down mid corner & also the rear snapped out alot easier when hammering it out of corners.

[vrooom]

Depend what fluid in it.. Gear diff is build once and forget, where ball diff need regular maintence.

[Dkfream]

I have ran my B5m with both gear and ball diff, ball diff deffo better feel and more controllable but I always struggle with them and forever rebuilding and replacing balls, I can't make them last for some reason, then noticed how free the ball diff was compared to the gear diff, tried lots of different diff oils but they all seem so gloopy and thick, so out of a moment of madness I stripped my gear diff and filled with 30wt shock oil( yes very strange ) but now feels and handles exactly the same as a ball diff but no worries of slipping or turning the balls square, ran it on carpet and slippy gym floor and works perfectly so gonna stick with it for a while but looking good so far ........ Have ordered some new ceramic balls for yet another diff rebuild to have incase I feel like a change lol

[Xracer]

In theory there should be no difference, no pun intended!
A gear diff cannot slip under load whereas a ball diff can due to the very small contact patch between each ball and thrust plate, they are lubricated too!
The reason they 'feel' different when driving is because the ball diff IS slipping even when tightened down hard, the evidence to this is the maintenance required to replace the washers due to 'grooving' and pitting and the balls because they have become micro-faceted from slipping.
Using ceramic balls prolongs the ball life but the rings still suffer!
The initial tightening down also initiates pitting of the rings as they are relatively soft compared to steel and more so with ceramic balls.
It was interesting when discussing gear diff oil viscosity with a Schumacher member recently that they had reduced the recommended viscosity dramatically from their original build instructions to get closer to the ball diff handling 'feel' but of course a gear diff can never feel the same.
So it is down to preference when driving along with the acceptance that maintenance will always be the bane of the ball diff if this is the choice!

[SlowOne]

A ball diff will always be freer than a gear diff as the gears have to run on shafts and will have friction due to the gear bearing on the shaft. The shafts will 'twist' in the plastic housing due to the loads put on them by a heavy car, a lot of power and quite a bit of grip, especially on grass and astro. and, lastly, there is the friction from four gears imperfectly made rubbing each other.

However, because the ball diff will not be that free for that long (See post above from Xracer) it should be possible to make one feel like the other. The tighter the diff is, the more the tail of the car will slide - drift cars have locked diffs to make then slide! - so the more grip the track has the tighter the diff can run. That's one of the problems with a ball diff, it isn't that adjustable for grippy tracks.

It's not my class, but when I did run off road I wish the manufacturing capabilities could have produced a decent gear diff. If I did go back into it I would certainly try one over a ball diff. HTH

[dodgydiy]

ball diff works better on low grip in my experience, and surprisingly little adjustment can make a good difference to handling too. if they are built well with good lubricants they can also last quite a long time too, the one in my 2wd has done all this years welsh league meets and several hours on my local track and is still silky smooth without a rebuild... personally i think i would stick to ball diff in 2wd whatever the grip as it will be more predictable, but in 4wd gear is fine

[fencer39]

20 years ago all diffs were geared, then it became popular to have a ball diiff (because they were apparently better) funnily enough geared diffs have made a come back and they are now even better !!

Like everything in the rc car world it follows fashion and there are plenty of folk on here that believe all the hype and nonsense to get them to spend even more money on something they feel the must have to be the next world champ !

[shark]

Think most diffs 20 years ago were actually ball diffs .
From what I remember any way, buggies and touring cars .
Although as always I could be wrong

[mattr]

TBH listening to the start of many races and the noise from the half dozen or so slipping diffs persuades me that my initial guess on returning to RC was correct. Modern brushless motors are, on the whole, far too powerful for ball diffs.


Unless you are racing a stock class, on a low traction track......

[dodgydiy]

well if the ball diff is slipping audibly, 1 its not set right and 2 the slipper clutch aint set right!! ball diffs work better on low grip and as others have said, gear seems to suit high grip

[bigred5765]

The simple answer is both,
both have there own characteristic's and uses and advantages have both use both

[whites75]

thanks for all the input guys and apologies in the delayed reply I will get a ball diff when I have a few spare quid and give it a whirl on the slippy surface at somewhere like cullingworth and even at the outdoor tracks come spring/summertime but for the time being I will stick with what I have in my yokomo which is a geared one

[smokes]

the Yokomo ball bmax 2differential is really good but follow the tips on the link for sanding and greasing the differential will make very smooth and last a long time.

http://www.teamirsrc.com/techtips.html

I do have the gear diffrential for the yokomo but you still have to maintain it and replace the gaskets and o-rings and replace the oil when it goes black. I also think you have to bed the gear mesh in as well as the gears are die cast and don't have a nice smooth hardened surface that you would get with a machined gear.

[AntH]

In theory, I think there should be a difference. If you were to try and characterise the 2 different types of diff by rotating one input at a variety of speeds and then measuring the torque to turn, they would be quite different. The balls diff would give a reasonably constant torque regardless of input speed. Not so with the gear diff due to the nature of the viscous friction... The torque would rise with input speed. This is the main reason for the difference in characteristics IMO.

Originally Posted by Xracer

In theory there should be no difference, no pun intended!
A gear diff cannot slip under load whereas a ball diff can due to the very small contact patch between each ball and thrust plate, they are lubricated too!
The reason they 'feel' different when driving is because the ball diff IS slipping even when tightened down hard, the evidence to this is the maintenance required to replace the washers due to 'grooving' and pitting and the balls because they have become micro-faceted from slipping.
Using ceramic balls prolongs the ball life but the rings still suffer!
The initial tightening down also initiates pitting of the rings as they are relatively soft compared to steel and more so with ceramic balls.
It was interesting when discussing gear diff oil viscosity with a Schumacher member recently that they had reduced the recommended viscosity dramatically from their original build instructions to get closer to the ball diff handling 'feel' but of course a gear diff can never feel the same.
So it is down to preference when driving along with the acceptance that maintenance will always be the bane of the ball diff if this is the choice!

[dodgydiy]

if we are looking at principles behind the diffs and their actions, the ball diff doesnt feel different because it is slipping, it shouldnt be slipping if it is built correctly, the acvtion of the ball diff changes when torque is applied due to the pressure of the plastic diff cage against the balls partially locking up the diff. i can remember people experimenting with holes filed to different shapes in an experiment to change this effect in the days of the old cat xls, with elliptical and triangular holes instead of the ordinary round ones to change the feel of the diff

[Ashlandchris]

Originally Posted by shark

Think most diffs 20 years ago were actually ball diffs .
From what I remember any way, buggies and touring cars .
Although as always I could be wrong

I can't comment when the change from gear to ball happened, but when I used to race in mid 80s I had never come across a ball diff.

I resurrected this thread as I'm thinking of getting a yoke yz2 which comes with a gear diff, but im hearing the ball diff is better. Is this noticeable for your average racer or would I be better going witha the "fit and forget" (relatively speaking) gear diff?
I only came back to racing last year and have used a variety of 2nd hand car since my return, in each case I have stripped down the cars and cleaned, rebuilt etc, but I still don't really know how to set them up so I actually have no idea how a good set up should feel - as I pointed out to someone recently, the last 2wd car I drove was a tamiya frog, so in comparison, everything feels good.

[J77MYF]

Originally Posted by Ashlandchris

I can't comment when the change from gear to ball happened, but when I used to race in mid 80s I had never come across a ball diff.

I resurrected this thread as I'm thinking of getting a yoke yz2 which comes with a gear diff, but im hearing the ball diff is better. Is this noticeable for your average racer or would I be better going witha the "fit and forget" (relatively speaking) gear diff?
I only came back to racing last year and have used a variety of 2nd hand car since my return, in each case I have stripped down the cars and cleaned, rebuilt etc, but I still don't really know how to set them up so I actually have no idea how a good set up should feel - as I pointed out to someone recently, the last 2wd car I drove was a tamiya frog, so in comparison, everything feels good.

Hi Chris,

I've got a YZ-2 and I've only run a ball diff in it so far.

I raced at worksop yesterday and a guy in my race had the same car and was using the gear diff. He was really struggling so switched to a ball diff and found the car much easier to drive.

[Ashlandchris]

Originally Posted by J77MYF

Hi Chris,

I've got a YZ-2 and I've only run a ball diff in it so far.

I raced at worksop yesterday and a guy in my race had the same car and was using the gear diff. He was really struggling so switched to a ball diff and found the car much easier to drive.

Cheers Jim,

Sold the man in last place

I'll give it a try

[h0m3sy]

Originally Posted by dodgydiy

ball diff works better on low grip in my experience, and surprisingly little adjustment can make a good difference to handling too. if they are built well with good lubricants they can also last quite a long time too, the one in my 2wd has done all this years welsh league meets and several hours on my local track and is still silky smooth without a rebuild... personally i think i would stick to ball diff in 2wd whatever the grip as it will be more predictable, but in 4wd gear is fine

+1 on this