12 Bolt Chevy problem
 

Ive been fighting a problem with keeping pinion shims from coming apart & out.car is a 95 camaro stocker but I run it in SS with SS motor.weighs 3400lbs with p/g & 99% of the time it is foot braked.it has a Strange housing ,which I figured would be better for making things last longer,but after 50-60 runs,it will start making noise & when I check,the shim is gone.this has happened 3 times in the last 2 years.I use the ratech collar instead of crush sleeve and always get pinion depth within .003-.004 of what is written on gear.Pinion nut is still "tight" from the loctite but of course has some slack from the lack of shim.The nut backing off doesnt seem to be the trouble as I have marked it before to see if that was the case.any ideas,suggestions(dont want to change housings),something I am missing???got lucky this time and didnt hurt gears,not so in the past....let me know............thanks Vic Penrod

Re: 12 Bolt Chevy problem
 

Vic what rear end cover are you using? Not sure if its the problem or not but you should use a cover like the one T/A sells. Moser does also (think T/A makes them for them). Ive heard stories about the 12 bolts where the main caps actually "flex" on the launch. Maybe its flexing causing things to beat around in the pinion?????just a guess, something worth looking at maybe.

Re: 12 Bolt Chevy problem
 

I don't know what's causing the problem, but why don't you put a shim under the bearing race, like on a Dana?

Re: 12 Bolt Chevy problem
 

Thats what I do in my 12 Bolt

Re: 12 Bolt Chevy problem
 

Sounds like not enough pre-load on the pinion. How much do have on inital set-up? I've always set mine 15-17 inch pounds. I see where Ratech now has a "Smart Sleeve" that you may want to try instead of the solid spacer. Good luck. Danny

Re: 12 Bolt Chevy problem
 

Never had a good pinion shim fail, unless the pinion nut is backing off, or not tight enough to begin with. It is also possible that the bearings are not getting enough preload. Ordinarily, it will kill the shims on the spacer before it hurts the shim on the pinion bearing.

Re: 12 Bolt Chevy problem
 

You're not honing the forward pinion bearing to make it easier to set up the pinion depth??

Are you???

Bob

Re: 12 Bolt Chevy problem
 

Mark is correct. I had similar problems years ago with mine, shims getting damaged, but the Ratech severe duty pinion shim kit #1901 solved the problem. Kit relocates shims between the housing and the race.

Re: 12 Bolt Chevy problem
 

Guess I have been lucky. I've never had that happen. I think you need to get closer with your pinion depth, but that won't effect the shim problem. I have broken teeth on one ring gear, and found them cracked on another a few weeks back, but my shims have always lived. That's a new one for me.

Re: 12 Bolt Chevy problem
 

Thats what I'm thinking Bob, The pinion bearing still needs to be a press fit. If not the bearing will spin, even with a Ratec solid collar. Alot of racers hone the bearing so they can change gears or repair at the track.This may work at time but not all the time. I'd use a new bearing or if the pinion was sanded some loctite sleeve retainer on it. That should help your problem...