DIFF carrier- THICK Shims?

[Myles]

Hey guys,

Building my 12 bolt from a 70 chevelle.
(Previous owner modified to go in Gbody)

I dont have the origional thick shims, those are apparently around +/- .250"

I just have an install kit with a ton of thin shims. (All shims combined will barely fill 1 side). My builds have been ok but always had the original parts.

Cant find the OEM shims anywhere, not GM, not Jegs, or local diff shop. no scrap yards here.

Anyway around this? I dont want to buy 2 more install kits and put like 15 shims per side.

Anyone deal with this before? Iv read some guys use a bunch of 1/8 shims, plus smaller ones. Will be a real pain plus clearences can shift under strip beatings according to local shop owner.

Let me know what you think,
Thanks!
Myles

4.56 strange spool and kit all new

 

[Max Headroom]

See the link

Link 1
Link 2 Summit
Link 3 Hot Rod How To

 

[Bonnewagon]

At the factory the installer carefully assembled the rear using smaller shims just like in the shim pack kit. When he had it perfect he then measured the shim pack thickness and chose a solid shim that exact thickness from his parts bin. He then installed the two thick exactly perfect shims in the rear using a special installaltion tool that would not damage them. It looks like a long handle with a big "C" shaped end. Because if you bang them in with just a hammer you risk cracking them. You will never get another chance to use the two big solid stock cast iron shims once anything has been changed. Now you are required to do as the factory dude did and carefully assemble the rear using the shim packs to get things right. When you have all the specs perfect like pinion depth, pinion pre-load, backlash, tooth pattern, carrier bearing pre-load, etc, then you leave the shim packs in place and button it up. I have a selection of the thick cast iron shims and it is a rare occasion indeed when I can use one in a rear installation. And when I do it is a fairly thin one that needs additional thin steel shims to get my needed thickness. Also the good shim packs include a few fairly thick ones so you don't need a hundred thin ones to get your thickness.

 

[Myles]

thanks guys,

yes iv seen the kits but they dont include the thick ones.

and the older 12 bolts used thin shims indeed, however the later ones from factory like my '70 had 1 thick one on each side, between .240 and .280 or something, these are needed, plus the additional small shims. The Jegs, Summit, i called Moser, and local shop iv spoken to have all used them for years but they all claim they arent avalible anymore. and yes i have the correct spool.

I would need 2 or 3 install kits to make up for the missing thick OEM shim that are still required.
im looking into a possible solution, ford offers a lot more newer / more availbe parts for their 8.8 rear, witch has compatible shims according to some gm&ford kits.

 

[gnvair]

Ford 8.8 shims work. I have used them to build a 12 bolt

 

[bracketchev1221]

Summit sells many sets of carrier shim kits. And as far as having a thick spacer compared to thin ones, not an issue. I am going to guess that my 12 bolt took quite a few hits over the last 22 years of running it and NEVER had an issue due to shim thickness. 3200 lbs, 1.21 60' time.

 

[fleming442]

When my buddy came over to bail me out on my 7.5, he brought a "Super Shim" kit. It had a register in the center where you could stack several thin shims together to create the thickness you need. These? https://www.summitracing.com/parts/mgr-ss12/overview/

 

[Bonnewagon]

he brought a "Super Shim" kit

That's the ticket. All the shim kits I've used included several thicker shims. I just went and measured the thickest and they were .100". It doesn't take many of those to fill up the space and then you fine tune with the thin ones ranging from .020" to ,001". I used to get my rebuild kits from Gevo's Gears and Rears whenever I saw John at Englishtown. http://www.rearsgears.com/ But any name brand like Rateck or Richmond will include the correct shims you need. I especially liked the kind Flemming mentioned as you get a neat holder to position the shims in and insert the whole thing into place. Very handy. http://www.ratechmfg.com/toc.htm

 

[79 USA 1]

Check with Toms Differentials, He carries factory shims as well as aftermarket.
http://www.tomsdifferentials.com/

 

[L92 OLDS]

I learned something recently while installing an Eaton posi carrier in this 14 bolt 9.5" rear end. I really like the adjustable set up shown on the right side. A shim pack is still required on the left side though. This rear came from a 2x4 Escalade and bolted into the LSA powered Avalanche. Should be plenty strong.