Why did my diff die?

[Captain nemo]

Cougar SV, only done 6 heats with it, yesterday it started to run slow, toward the end of the heat it was hardly moving, when i stripped it back the diff was fubar.

the seats for the ball race had worn right through the gear and almost cut it in half, in fact when i prized the bearing out of the centre of it, it fell into 2 pieces.

im assuming that the diff either came lose or i didnt tighten it enough originally, id guess the latter, it must have been loose enough for the balls to come out of their seats and wear away the gear,

everything else in the diff was fine, with exception that the circlip could turn
when i took the diff apart the grub screw and the screw through the outdrive didnt seem loose?

so was this my own dumb fault when i built it originally ?

[joker]

its not your fault its just cuz its a sche diff, they arnt the best and they can be a real pain to get rite. i rebuild mine after every meeting and have three spare diffs in my box just in case one lets go. the main problem ive found is the cone washers and thrust race. just try and keep it as clean as poss and swap the washers from time to time depending on how often you run the car and on what surface you run on

[Captain nemo]

surely they cant be that bad?, strip after every meeting??

wow , i dont have the time to do that, itll drive me nuts, its been run for less than an hour, either indoors or on clean dry tarmac, and it deffinately want crapped up, how do you know if the washers are bust?, they look fine, but then again it looked fine when i built it up

[ian h]

Did you check diff tightness after first run? All ball diffs can loosen off whilst "bedding in". I usually rebuild every couple of months or so. Your issue isn't normal, something mustn't have been right from the start.

[Captain nemo]

I expect it was my error to be honest, I didn't realise to tighten after the first run, it's the first kit I've built in 25 years, it's been a steep learning curve

[Cockerill]

There's nothing wrong with a Schumacher diff, and certainly don't need rebuilding after every meeting. I generally do 10-15 meetings worth of running on a diff before rebuilding.

An important part to any ball diff build is to run it in and set it properly. There's a good guide on it here: http://www.rctech.net/forum/electric-off-road/512013-how-properly-build-break-ball-differential-slipper-clutch.html

If you need any more info on building/setting/running a Schumacher diff feel free to email me at Tom at racing-cars.com and I'll help you out.