Ok guys I need help,

I have rebuilt rear ends before (<--insert joke here), but I cannot find a good tutorial, article, post to help me out. I have several questions:

What's the preload (pretorque) on the pinion nut?

What's the torque on the pinion nut after the pretorque?

What's the Lash on the pinion gear?

What's the torque on the pinion gear carrier and u-joints?

If you have found a tutorial or write up on a 8.5 G80 differential I would greatly appreciate it!

TIA (Thanks In Advance)

 

hey i really dont know anything about the type of rear end we have in our blazers but ima just let you know i have lockers in front and back of mine and i cant belive how amazing it proforms was told they where detroit but dont know what type i know they only lock when you nail the gas or one tire slips but anyway i cant get my blazer stuck with these lockers

 

Pretty much any rebuild of a GM 10-bolt would work as a guide and there are quite a few on the net.


Here's some specs for you courtesy of Drive Train Specialists --> CLICK HERE


The pinion nut doesn't really get torqued down. You set it by the rotational torque after crushing down the crush sleeve. You should only crush the crush sleeve after you have done the setup of the gear-set to determine the proper pinion depth. Rotational torque should be checked without the pinion oil seal installed as the drag from this seal can throw off the in-lb torque reading you need to set for the bearing drag.


The u-joint bolts are torqued to 15ft-lbs if you really want to get technical, but good luck getting a torque wrench in there. I have always used good judgement on those and just not gone crazy with a wrench.


This is a section where you respond to help, not to brag...

 

True about the sleeve, but the pinion should have to be at least torque to rotational torque while setting up the pinion depth (lash?) so that the same depth is used every time? Is that not right?

After everything is set then the crush sleeve is installed and the rotational torque is used.

Thanks for the link on the torque values!

 

I have included a pdf from Richmond concerning installation of new pinion gears, break in period, etc.

 

The rotational torque is the only thing that matters when it comes to the pinion nut tightness with a crush sleeve involved. The rotational torque is listed in the link I provided.

 

Ok so after the original preload torque, what is the ending torque for the pinion nut after the preload torque is set with the inch pound torque wrench?

It doesn't really mention the rotational torque on the pinion not AFTER everything is said and done.

Here are some more links:

Differential Gear Ratio Calculator

General Installation Instructions

Differential ID

Set Up Specifications

 

Ok, you aren't getting what I am trying to tell you... There isn't any torque after the preload. Once you have established the rotational torque, the pinion is set, period.

To gloss over the process to get through this point for you, you have to first set the pinion depth either with a pinion depth tool or by using a setup bearing (definition at bottom) and doing a pre-build. If using a setup bearing & guessing at the necessary amount of shims to put between the setup bearing & the pinion, start with the shim stack that was on the old pinion. Install the pinion with the shims between the setup bearing & the pinion gear, but without the crush sleeve or the seal, only tightening down the pinion nut to meet the rotational (preload) torque requirement prior to dropping the differential into the axle. Drop the differential into the axle & install your shims that were previously removed. Measure back-lash. If the back-lash is out of spec, adjust the differential shims to move the ring gear in or out appropriately to adjust the back-lash into spec. Then paint the gear teeth & run the ring gear around while holding some resistance on the pinion shaft (or vice verse - rotate the pinion shaft while putting some resistance on the ring gear); this will give you the gear tooth pattern. You can google 'gear tooth pattern' for what to look for in that regard. The pattern will then tell you want you need to do with the pinion depth.

Once you get the pattern set, remove the pinion & press on the new bearing with the final shim stack in place. Slip over the crush sleeve and put it into the axle housing for the last time. Install the outer bearing, washer (if used - can't remember exactly if this axle uses a washer), and the yoke (not the seal yet) and then tighten the nut down until you get to the rotational (preload) torque setting again. Once you are there, mark the pinion flange & the nut, noting the number of threads exposed (a picture of the markings helps tremendously), and remove the nut. Install the seal, then reinstall the flange & nut until your marks line up with the correct number of threads showing. The pinion is now set correctly and you can move forward with reinstalling the differential.

Now, I've skipped over the replacement of the pinion races, bearings on the differential, carrier bearing shims/preload, and quite a few other things just to get to the heart of setting up the pinion.

setup bearing - a new bearing which has had its ID opened up such that it has a very slight slip fit to the pinion shaft.

 

OK I get what you are saying now.

We will see tomorrow how all this goes, I will try to get some pics but no promises.

Thanks for all your help!