Bye-bye Gov-Lock, Hello Tru Trac, plus gear swap and brakes

[n8in8or]

FWIW, I went with Yukon's (per the tranny shop's recommendation). Only noises I hear are the motor, exhaust, and clutch. If the differential does make any noise, it has too much competition to get heard

I almost went with Yukon as I've heard good things about them, but I found a good price on AAM, so I went that route. Good to know another first-hand experience with the Yukons.

 

[n8in8or]

This is what the same setup looks like with the Richmond compound. Man that Ratech compound sucked.

Time to take some shim out of the pinion and see if I can get this done finally.

 

[n8in8or]

I realized I never showed a pic of my dial indicator setup that I am using for measuring backlash. It’s the magnetic base and dial indicator that came in my Summit cam degreeing kit.



So this is the pattern with .023” of pinion shim and .006” of backlash. My amateur eye thinks this is pretty close - the pattern is spread across most of the tooth - especially on the coast side. The pattern on the drive side of the tooth is skewed a little to the toe side, but what I’ve read says that is ok because when power is applied and parts start flexing the mesh will moved to the center of the tooth (I’m not sure I explained that well). However, if that makes the gears noisy, then that’s not really what I want. Oh, and I did use the rag and wrench tip - it was very helpful, thanks!




Hopefully @THEFERMANATOR can weigh in on how this pattern looks. Thanks in advance. I think I’ll try playing with backlash in the meantime and see what that does to the pattern.

 

[n8in8or]

.023” pinion shims and .008” backlash.

 

[n8in8or]

Decided to try a little more pinion shim because I was afraid that maybe the pattern was a little close to the crown of the tooth. I went from .023” of pinion shim to .024” of pinion shim. It changed a LOT! I think I’ll double-check everything since it changed so much with just .001” difference. Backlash is .005”. If this is how .024” looks, then I will try .021” next - I don’t have the shims to try .022”.

 

[THEFERMANATOR]

FWIW, I went with Yukon's (per the tranny shop's recommendation). Only noises I hear are the motor, exhaust, and clutch. If the differential does make any noise, it has too much competition to get heard

I don't have that problem with the duramax. When I'm cruising empty, it's pretty quiet inside up to 70(at 2K rpm's I get pretty bad drone now, used to be 2200 rpm's, but the new sac injectors lowered the rpm's it drones at).

 

[THEFERMANATOR]

I was gonna say it looks like you need to take some more shim out and try it. I like to find the pint where the pattern crosses over and go in the middle. That was a nice thing about the 10.5", set the pinion up, then you can just pop the 3rd member in and out without changing anything else. I also found GM diff's to be very sensitive tochange compared to Dana's. The odd part is the way Dana cut's it's gears, the adjustment's are bass ackwards. You would adjust backlash on them to correct the cross pattern, and pinion depth to change gear mesh. It's what threw so many people off setting them up.

 

[n8in8or]

Ok thanks. I’ll try .021” and see how that looks.

 

[n8in8or]

I was gonna say it looks like you need to take some more shim out and try it. I like to find the pint where the pattern crosses over and go in the middle. That was a nice thing about the 10.5", set the pinion up, then you can just pop the 3rd member in and out without changing anything else. I also found GM diff's to be very sensitive tochange compared to Dana's. The odd part is the way Dana cut's it's gears, the adjustment's are bass ackwards. You would adjust backlash on them to correct the cross pattern, and pinion depth to change gear mesh. It's what threw so many people off setting them up.

As far as backlash goes, which do you like better? .006” where it’s skewed more towards the toe or .008” where it’s pretty close to centered?

 

[THEFERMANATOR]

I always liked to have a little more backlash myself. You get more gear train noise going into gear, but they tended to run quieter. We would run .008-.013 on some of the Dana's, it threw me when I did a Ford as they like to run about .004-.005. I think mine printed best around .008 when I set it up with aam gears.

 

[n8in8or]

I always liked to have a little more backlash myself. You get more gear train noise going into gear, but they tended to run quieter. We would run .008-.013 on some of the Dana's, it threw me when I did a Ford as they like to run about .004-.005. I think mine printed best around .008 when I set it up with aam gears.

Thank you so much for your help, Ferm!

 

[n8in8or]

I’m glad I set that up again. I was afraid I made a mistake - and I knew what that was: with Ferm’s rag trick, I didn’t bother tightening the nut up quite as much on the pinion because the rag was giving the drag I was looking for before.....I just took the slop out. Well when I got that weird pattern I realized that I could have introduced an error. And in hindsight of course that was a bad idea. So I took it all back apart to double-check the shim thickness and then put it back together the way I had been, which was tightening the pinion nut so it took 10 in-lbs to rotate the pinion. I put it together with the same carrier shim stack as the .023” pinion shim setup. This time I got .008” of backlash and the pattern in the pics below. A bit higher on the teeth, but not terrible. I think I like the .023” better. I have shims to be able to do .021” and .026”. I guess I’ll try both of those and see what happens.

 

[Big T]

Actually, thinking about this some more....... I bet the larger wheel cylinders WOULD help my problem. The larger volume of the cylinder should reduce the sensitivity of the rear brakes because it would take longer to fill the inside of the cylinder. But then, once fully engaged, the larger diameter of the piston would apply greater force to the brakes. This might be just what I need to make this work properly! Hmmmmm. I'm thinking now that I may be wise to change my shoes too since I'm running the Autozone Duralast shoes in the rear as well....

Do it. The larger cylinders are better, but it will be hard to notice the difference.

 

[n8in8or]

.026 pinion shim and .007 backlash

 

[EWC]

What do you do with the marking compound after setting up the R&P ? Run it or clean it off ?

 

[n8in8or]

What do you do with the marking compound after setting up the R&P ? Run it or clean it off ?

I think last time I set up the gears I washed it off the best I could with brake clean. I think it’s essentially lithium grease though, so if you leave a little I’m sure it doesn’t hurt anything.

 

[n8in8or]

.021” pinion shim and .009” backlash.

Looking at the 4 patterns (.021, .023, .024 & .026) .023 and .024 are pretty close, but I feel like .023 is the most in the middle. I’ll be interested to see what @THEFERMANATOR thinks.

 

[n8in8or]

Do it. The larger cylinders are better, but it will be hard to notice the difference.

I did it. I put the 1-3/16” cylinders in.

 

[NVW]

That is a job I think I would hire out

 

[n8in8or]

That is a job I think I would hire out

Yeah. It isn’t the most fun thing to do. It wouldn’t be so bad if it wasn’t in the truck I normally drive daily (I miss driving a fast, comfortable truck!) and if the axle was out on stands so it was easy to work around. If I did it more frequently it wouldn’t be so bad either I’m sure.