rsc350

Richmond states to start with .035 shim for GM pinion depth if you dont have access to the origional shim, leading me to believe GM used .035 in most vehicles? I got my origional out and it is (and even stamped) .027

Start with the .035 or .027?

sofakingdom

iTrader: (1)

I have never taken apart a factory-built one of these rears (or a 8½" 10-bolt either), and found ANYTHING BUT a .035". I guess maybe they got the machine that cuts that surface into the housing, set up right? (since that's what you're REALLY shimming in the first place, is the housing.... gears and carriers, except for the Richmond drag-race gears, are all within a couple of .001" always, so if you imagine suspending a set of perfectly aligned gears in space somewhere, and then hanging a random housing around them with shims to locate the housing properly around the moving parts, that's REALLY what you're doing)

I've also never seen one with a thickness stamped into it.

Those 2 facts lead me to suspect you don't have a factory setup.

I'd follow Richmond's instructions regardless; not least because of the above, but also, if you have trouble and you didn't, they might choose not to support you.

TTOP350

iTrader: (8)

Reuse the .027 if its a factory gearset.
There are soooo many little tricks to help quickly set up gears but I have to head to work.
I've seen ink and stamped shims in factory rears thru the years.
You can locate or buy a cheap pinion depth tool these days so you can do it correctly the 1st time.

big gear head

Almost every 7.5 and 8.5 rear end that I have disassemlbed had the shim thickness stamped into the pinion shim. I've seen factory installed pinion shims from .025 to .042 in the 7.5 and 8.5 rear ends. The best place to start is with the original pinion shim and work from there. Just make adjustments by what the contact pattern tells you.

rsc350

I am the third owner and this rear end needed rebuilt when the second owner bought it which I am still good friend with. It definately has 190K miles on it along with GM stamped 2.73 gears in it. This car did come off the end of the 92 line so possibly the .035 was way more common than the others in previous years, I would suspect richmond would not say to use the origional if there was no chance it could be different.


I used the .027 shim and have the Ratech tool, I am having a hard time getting an accurate reading from it though.

rsc350

.027 shim got me within .001 on my pinion depth.

And now on with the show!

rsc350

The directions for the Ratech 4111 bearing spacer say torque pinion nut to 125 ft lbs, then remove the spacer and shims and reduce by .002 thickness increments and install to proper bearing preload.

Torque on the pinion nut should always be re-torqued to 125 before checking pre-load, right?

sofakingdom

iTrader: (1)

Probably so; you want to make sure everything is fully assembled in there, although with the 4111, there's no "crush", nothing "soft" so to speak, that has to take up any slack. You just need to make sure the yoke is pressed all teh way down onto the bearing which is pressed all the way onto the gear etc. Which that should do, even though a pretty light torque.

That's alot looser than you would want to leave it though. You can go ahead and actually TIGHTEN it when you get done.

big gear head

I've seen several solid spacers that recommend 125 foot pounds of torque, but I don't use less than 150. You can actually make very small adjustments to the bearing preload by changing the torque on the pinion nut, even though the spacer is solid. I've made 1 to 2 inch pound changes in the preload by increasing the torque on the nut to around 200 foot pounds. You do want to be sure that the bearing preload is set the same for each trial assembly and the final assembly. Just remember that the preload might increase slightly on the final assembly because of the drag on the pinion seal.