View Full Version : ball diff - gpm vs. kyosho

2002.01.06, 09:58 PM
i was just wondering which is a better ball diff? gpm or kyoso?

kyosho has bigger ball bearings in their diff about 7 if i remember it right, while gpm has smaller bearings in their diff about 12, i think.

what effect would this have? and which is better? although i've got both, i really cant tell the difference... :confused:

thanks for any input:D

my guess the the only advantage gpm has over kyosho is that you can change spur gear on gpm ball diff :D

2002.01.06, 11:31 PM
I can say that the Kyosho diff uses standard size balls... I replaced them myself thinkin they might be out of round. That may or may not be important. I would think that more balls is better since the load would be distributed along more surface area.

I'm also not a huge kyosho diff fan because I had to add more shim to my motor, but I seem to be the only case of this.


2002.01.07, 02:18 AM
hey jeff, glad to hear that you got your car fixed... any loud noises thus far?

2002.01.07, 04:11 AM
In contradiction to Jeff again :D

I could only get a Kyosho ball-diff.
I am thrilled with it, best hop up yet for me..

As for the amount/size of the balls within the diff, this is one of those arguments from 1/10 scale racing days, although 1/10 scale ball-diffs are slightly different as it uses wafer springs and has recesses for the thrust balls in the pressure plates of the diff. A heavier duty ball-diff overall!

I personally came to the conclusion that it's six of one and half-a-dozen of the other. The same!

Kyosho use 5 or 6 thrust balls of a larger size. GPM use more for a smaller size. I think it works out the same.

The upside is that GPM have different sized spur gears, but I ask the questionas to whether anyone would use them?
Most tinkerers make adjustments on the pinion gear as it's simpler.
From 1/10 racing I know it can be hard to keep track of the various spur/pinion combinations that work best!

I think buy what suits ytou best, price, availability and backup.

One thing I do know, is that every little part of the Kyosho ball-diff can be purchased seperately. Can GPM's ball diff be ordered in parts?
Would anyone want to replace a diff if they only needed a solitary part for it? I wouldn't!


2002.01.07, 10:55 AM
I use the spur gears alot actually :) If you have the stock motor mount, using the 40T spur will let you fit up to a 13T pinion, where if you leave the 42T on, you can only fit up to about a 10T.

2002.01.07, 11:14 AM
The K ball diff has worked out nicely since I added a little (1/32 inch) of shim to it. Even raced and took 2nd, 1st, and 2nd in the amature league last thursday with it! I don't know why my diff was oversized but it seems to be fine now that I added the paper shim in.