Putting in a True Trac and new set of AAM 4.10 rear gears.

What size is the pinion nut? Larger than 30mm as thats the largest I had in the box.

Before pulling the G80 I measured the back lash at .008. Everything I've read says to install them at .003-.006. Should I shoot for paper specs or what they were?



I also painted up the gears. Maybe I didn't do it right but these look like the pinion is to shallow from all the install stuff I've read, but this is a factory install and worked absolutely fine.

 

I agree that does look too shallow, set your lash at what the gear manufacturer says to, AAM is the OEM supplier right?

 

Yes AAM (American Axle and Manufacturing) is OEM.

 

I would get the lash at ~.006 from what I have read and done that seems to work best for a quiet operation. PM Axis T6 he does local gear installs in Houston and knows his stuff. To me the wear pattern seems off but Im no expert of course. When we did the gears on Closet Red Necks truck the wear pattern was right in the middle and I think we got .008 lash and it is nice and quiet although he doesnt have too many miles on the setup.

 

I just had my Eaton and AAM 3.73's installed and backlash came out to .007 and I have zero noise. I have heard that OEM (AAM) require .004-.006 backlash but in the end its whatever gives you a good mesh pattern and not necessarily what the book calls for.

 

if you were getting your pattern by yourself, it can cause it to look funny... you need to apply pressure so to speak with a pry bar or the ebrakes to get an actual pattern

 

Thanks for the tips guys. If its not obvious this is my first attempt at one of these.

I did apply pressure with my hand to the carrier as I spun it around for the marking. Maybe not enough pressure? I had really hoped that I would be good to go with the stock pinion shim. Looks like I need to plan on pulling the pinion bearings a few times. I've seen where you can grind down the inner diameter of the old bearings to make them easy to slip on and off and install the new pinion with old bearings, old pinion nut and no crush sleeve. Adjusting shims until you get a good pattern.

 

Here is a pic of what a good pattern should look like. PIC Always read the drive side to dial it in. Keep the backlash under .006 and apply marking compound thin but cover well. With that gear you should probably have a .036" or .037" shim on the pinion.

 

Ok, this is what I did. New gears, install the pinion bearing onto the pinion gear until it bottoms out. Install the new crush sleeve onto the pinion shaft. Install the pinion shaft into the carrier and install the outer bearing, flat washer & pinion nut, tighten the nut just to hold the pinion shaft in place(you will know when that is). Install the carrier with the races, bearings(should be pressed on) and the stock shims(just how you took them out). You can leave the stock shims in the pinion shaft and the carrier in the order that they were in. Set your BL to what the instructions say for that gear manuf. I have .012 in my gears. My gears are Motive and they recommended .008 to .012. Now, from what I went through on this, the Chevy gears like alot of lash, Fords not so much and don't care about Dodge. When you tighten up the crush sleeve, you will get a "deeper"(more to the outside of the gear) pattern when you tighten up or crush the sleeve. I'm no expert on this, but I went through hell and back on my LSD.

I hope some of helps.

James

 

Great looking setup. Hope I can get there. Going back in with all the current shims. If I don't get a good pattern, like your pic, with .004 - .006 backlash is where I will run into problems.