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Just rebuilt the ball diff with WBD-4 pressure plates and it seems these make the diff too wide for the gear box. Any advice on how to make this work? Doesnt look like there is much I can outside of machining the stock pressure plates down a bit to allow for the diff rings. Seems odd to me that you'd have to replace the original countersunk pressure plate vice a ring like the other ball diffs out there.

Screw it, bought part WBD-1. Since it's a shelf queen the new outdrives will be nice to have anyways.

There's two different designs for the outdrives, one for use with separate plates and one for use without (older design). So if you have the latter, you'll need to replace the outdrives to be able to use diff plates, because of the problem you mentioned and because the diff plates won't be held in place properly with the old diff outdrives.

Awesome, thanks for the info. On that note, how do find the correct outdrives to support the diff rings? I havent been able to find a difference in part numbers. Guess it doesnt matter now as I have the rings now.

There are an newer and an older ball diff.

The newer one has the changable diff rings ( wbd4 ) and the other dont
There are more differances, springs instead of washers and T-nut instead of threaded outdrive.

You can still get the parts from www.rw-racing.co.uk so that you can have the changable ones and if i dont remember it all wrong the ones from RW uses stealth rings.

WBD -5 are the newer parts from kyosho but im not sure it fits the ultima
it was like 20 years ago i last held in an ultima diff.

mvh Isobarik

Ahh, thanks. Since it's going on a shelf, the WBD-1 will work out best anyways.

madweazl wrote:Awesome, thanks for the info. On that note, how do find the correct outdrives to support the diff rings? I havent been able to find a difference in part numbers. Guess it doesnt matter now as I have the rings now.

I think they are a case of Kyosho's infamous "Same part number on bag with updated parts inside" habit. You can see the difference by looking at where the plates would fit. Diff outdrives that can hold the plates will have a step machined in, while the ones that don't lack the step.

WBD-5 is the new part it has the spring and T-nut and using WBD-4 plates and it does fit the ultima balldiff.

mvh Isobarik