The guy that's going to help me install my zexel diff & 28 spline moser axles told me to get a GM shim kit ahead of time so that we'll have them if we need them.

Does anybody know if GM has such a shim kit and what the part number is? This is for a 7 5/8" 10 bolt. It's my my stock 85 rear axle.

 

Last I new there wasn't a kit, you had to buy them individually.

Screw GM; get a Ratech kit. They're a better part anyway.

 

several gm dealers i've bought shims from just had a big box of shims and you took what you needed, the price was the same for each shim. i've got shims laying around from several richmond install kits.

 

Thanks for the info. I looked at the Ratech stuff at Summit. They have a regular kit for $50 and another kit for $100. The $100 kit includes axle seals and wheel bearings. It seems logical to me that as long as I'm in there changing the axles that I should go ahead and change the seals and bearings as well, no?

 

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What makes Reider's shims better? Are they stronger? Are shims prone to breaking? If not, why is stronger better? Sorry for the newbie question. Thanks
Matt

 

:lala:

 

Heres a picture, if you look close enough you can tell they are good quality parts. Here is the description for the picture.
"The adjustable differential shims directly replace the stock non-adjustable cast iron shims. Adjustable differential shim kits consist of thin shims of varying thickness sandwiched between two hardened interlocking steel flanges forming a single insert able unit. Thickness adjustments as small as .001" are thereby attainable for correct setting of ring gear backlash and carrier bearing preload. "

 

It seems like something as simple as a shim is kind of hard to screw up.

 

 

the ones in the pic look just like the Ratech kit. the carrier shims in a GM rear end normally come out to be around .250"; so they give you 4 .100" ones and a whole bunch of thinner ones, like anywhere from .010 up to about .040", and you just stack them up to get the preload you want.

There is in fact a big difference in shims, even the simplest things can be screwed up. For example, GM carrier shims are cast iron. They break very easily when you try to re-use them. Plus, the outer race turns sometimes, and it will wear the cast-iron rapdily, and your preload goes away. That's usually the first failure in a rear that's subjected to one-wheel peels, even before the side gears get ground up. The ones on the pinion gear are real narrow, and get subjected to an enormous amount of force; ones that aren't strong enough will split and get squeezed right out of the place they're supposed to be in. THat's why you should always use one solid pinion shim if possible in a high-power application.

I've personally never had trouble with the Ratech kits, they've never seemed to be of inadequate quality in any way, I've never used Reider though... i might think otherwise if I did.

I also prefer to use a crush sleeve eliminator rather than a crush sleeve. That allows you to tighten the nut as much as you want, and also there's no way the pinion bearing preload will ever change as long as the bearings survive (which they will much longer if they're kept preloaded correctly).

 

It seems like something as simple as a shim is kind of hard to screw up.

Read this http://www.ratechmfg.com/myth.htm

Now look at the flat washers in the ratech kit in this picture. You have to look close at the picture of the reider shim to appeciate the difference.
I'm trying to give the best advice possible by saying go with the reider kit, take it or leave it. And btw I am doing this on my own time, these are not products that I sell and I make no commision off of this.