GM 10-bolt Build-up, Part I


This feature will be done in three parts.  Part one will be all the "prep" work done to the axle. Part II will be the ring&pinion setup, and Part III will be the replacement of the rear axle.  All of this was done to a 2.73:1 ratio, posi, disc brake axle out of an '88 IROC as a disc to drum conversion.  To clear up some confusion I have seen out in the "F-body message boards", all thirdgens were equipped with two axle options.  Either the Saginaw 10-bolt 7.65", or the Borg Warner 9-bolt.   No 12-bolts, no 8.5" ring gears, none of that stock. Since this was a 2.73, I had to order the 3.73 gears that are specially made for "2 series carriers". If you want a deal, you have to: A) Be very patient,  B)be very observant, and C) be willing to travel.

To pick up the "jewel" that I did for $150, I had to drive over 6 hours roundtrip, and rent a pickup truck to retrieve it.  Well worth it, I felt.  I picked up the whole assembly (in pieces) for a great price. 

This leads me to another point.  Know what you are getting into before buying.  Some of the things I MADE SURE OF before buying was: Were the main caps in the original position (they CANNOT be mixed side to side), is the pinion shim present (I will talk about this later), did the posi work, what series carrier is it, etc...  Know what you need, and what you are talking about.  There are some people who have junk, who want to pawn it off on some unsuspecting person.  Everything needed was present and accounted for, consider it a deal.

Here a a few things you will need when building it up, and/or doing the drum to disc conversion.

In the picture, there is Richmond ring & pinion, wheel bearings and seals (x2), side carrier bearings (x2), front and rear pinion bearings, pinion seal, crush sleeve (spacer), J65 E-brake cables (conversion only), and of course, posi additive.


BEFORE YOU DO ANYTHING, read the instructions that come with the ring and pinion.  The instructions are written by the people who design the gear, so they know best about what it needs to function properly.  Also good to have a service manual handy.  Once you read the instructions fully, read them again!  Trust me, you will be glad you did!

The first step is to totally dissasemble the axle.  Keep the main caps on there respective side.  Mine were painted, so it was easy to tell. You will need to have the bearings pressed off the pinion and carrier, a local shop can do this if you don't have the capability.  Make sure you save the old bearings, they will come in handy. Also knock out the old bearing races, save these also.

One quick pointer, to save from rounding the pinion shaft lockscrew, use a 6 point 5/16 socket to break it loose.

You will also need the save the pinion shim when you take the bearing off the pinion.  Richmond gear reccomneds that you check pinion depth with the proper tool.  Since 95% of the people reading this will not have access to this tool, I will not bother.  Instead, we will use Richmond's approved "alternative" method.  If you have the old shim, re-use it.  If you don't have the shim, use a .035" pinion shim for starters.  You will check this later with a "tooth pattern".

This pinion shim goes between the pinion, and the bearing.  It will get sandwiched when the bearing gets pressed on.  Both the rear pinion bearing, and side carrier bearings need pressed on.  This is where the old bearings come in handy.  You will need to knock the rollers off the inner race, and use the inner race to press the new bearings on by its inner race..  By no means press the bearings on by the outer race!  They will be damaged.  If you take this to a shop, politely remind them of this! The yellow arrow shows the inner race being used to press on the new bearings inner race.


You will now need to bolt the ring gear on.  PLEASE NOTE: ring gear bolts are REVERSE THREAD!!  You need to turn them CCW to tighten, and CW to loosen. Also don't be afraid to use loctite, it will be your best friend!  Once all the ring gear bolts are torqued to spec (consult your instruction sheet/repair manual) then set it aside, its ready to install.


Nows a good time to go ahead and do the wheel bearings and wheel seals.  You should have removed them during dissasembly, but if not, do it now.  I use a seal puller to remove them, but any similar method will work.

Then you will need to remove the bearings.  This isn't as easy as the seal.  There is a special tool for it, but since this article is for the average DIYer, I will explain an alternative.  I used all of my 3/8" socket extensions all put together, and "rodded" all the way through the axle housing, and rested the end against the inside of the bearing, and hammered the end of the extensions (opposite end of housing).  Granted, not everybody has three and a half feet of socket extensions, but any metal rod or the like will work.  Just beat the both out without damaging the axle tubes.  Then use a suitible tool to hammer the new bearings in.  I used a FWD axle nut socket.  Tap it in untill fully seated.  You will hear a change in pitch of the hammering when its seated. Tap the seal in after that so its flush with the axle tube.

You will need to tap in the new bearing races. Onc method that works well is to use the old bearing race, a flat piece of metal a little larger than the race, and a brass drift or something similar. Since the old race is the same size as the new one, it works great for tapping the new one in without damaging it.  Then you just need the metal and drift to beat on the old race.


Thats about it for the "prep" work.  Part II will be the ring and pinion setup.

[Part II] [Home]