Build thread - 3.08 to 3.42 front and rear gear change

[DaveO9]

They ought to be thoroughly inspected. I would also rotate the pinion with the carrier removed to check for binding from any corrosion it may or may not have.

Mine got rained on after we put the new yoke in the 2nd time and got the crush washer in and rotational torque to where it's supposed to be. We drained out the rainwater and poured 2 quarts of gear oil into the case and let it sit for a few days. All seems well.

So is removing the carrier a simple unbolt/bolt back in operation? All the shimming is done with pinion? I’ve never done anything with a diff before.

There was no oil in the case when I got it, whereas first one from LKQ was full. I was thinking that part of diff just dried out over time and then got surface rust from moisture in the air. Since there’s a vent, the air eventually equalizes humidity with atmosphere. Everything else I can see and feel in the case still has a good coating of oil.

 

[swathdiver]

So is removing the carrier a simple unbolt/bolt back in operation? All the shimming is done with pinion? I’ve never done anything with a diff before.

There was no oil in the case when I got it, whereas first one from LKQ was full. I was thinking that part of diff just dried out over time and then got surface rust from moisture in the air. Since there’s a vent, the air eventually equalizes humidity with atmosphere. Everything else I can see and feel in the case still has a good coating of oil.

I don't know for sure. I figure yours was stored upside down and all the fluid leaked out the vent. This happened to one of mine on the way home from LKQ once.

If yours was mine, I would measure the backlash first and maybe do a contact pattern on the gear teeth and then note the position of the adjuster on the right side and the cast iron shim on the right and pull the caps and then the carrier to inspect the bearings. Since nothing was changed, it all ought to go back together with the same clearances. If you change the bearings, it still should go back together with the same clearances to my way of thinking. But like you, I am not formally trained in this. Who here was?

 

[j91z28d1]

is it not shims on both side bearings in the diff?

I have done some Ford 9in center section that had adjustment, but I didn't know gm every did it.

 

[DaveO9]

I don't know for sure. I figure yours was stored upside down and all the fluid leaked out the vent. This happened to one of mine on the way home from LKQ once.

If yours was mine, I would measure the backlash first and maybe do a contact pattern on the gear teeth and then note the position of the adjuster on the right side and the cast iron shim on the right and pull the caps and then the carrier to inspect the bearings. Since nothing was changed, it all ought to go back together with the same clearances. If you change the bearings, it still should go back together with the same clearances to my way of thinking. But like you, I am not formally trained in this. Who here was?

Ah yes, maybe that's how the oil was drained. I was wondering about that since it seems like the gasket was original or at least hadn't been disturbed for a long time.

In any case, I looked at it much more closely tonight, but without removing the main caps. And I've decided I'm going to take a calculated risk and not pull the carrier at this time. I'm worried I could do more harm than good, and this project has ballooned in cost and time. I could see the rollers on both bearings (had to use a mirror to see the left side) and they are all coated in oil. I listened and felt carefully in making a full rotation and did not hear or feel any rough spots. I know the most prudent thing to do would be to pull the carrier and fully inspect all the bearings, and I do appreciate the input, but I feel like it's a low risk decision looking at everything else inside there. I'm an engineer that works on the asset management side of the house for a large electric utility - pretty common for us to have to make these types of decisions, but on a much large scale of course.

is it not shims on both side bearings in the diff?

I have done some Ford 9in center section that had adjustment, but I didn't know gm every did it.

There's a single adjustment mechanism on the right side.

On a different note, I picked up my 3.42 front today and (sigh of relief) it looks identical in every way to the 3.08 I pulled out. Also my Denso radiator was delivered today, several days early. And my single motor mount arrived a few days ago and have started, but not finished, getting the DS mount out. Will be a long weekend, hoping to get everything put back together by Sunday night, but we will see. Things have a way of not going as planned.

 

[swathdiver]

Ah yes, maybe that's how the oil was drained. I was wondering about that since it seems like the gasket was original or at least hadn't been disturbed for a long time.

In any case, I looked at it much more closely tonight, but without removing the main caps. And I've decided I'm going to take a calculated risk and not pull the carrier at this time. I'm worried I could do more harm than good, and this project has ballooned in cost and time. I could see the rollers on both bearings (had to use a mirror to see the left side) and they are all coated in oil. I listened and felt carefully in making a full rotation and did not hear or feel any rough spots. I know the most prudent thing to do would be to pull the carrier and fully inspect all the bearings, and I do appreciate the input, but I feel like it's a low risk decision looking at everything else inside there. I'm an engineer that works on the asset management side of the house for a large electric utility - pretty common for us to have to make these types of decisions, but on a much large scale of course.


There's a single adjustment mechanism on the right side.

On a different note, I picked up my 3.42 front today and (sigh of relief) it looks identical in every way to the 3.08 I pulled out. Also my Denso radiator was delivered today, several days early. And my single motor mount arrived a few days ago and have started, but not finished, getting the DS mount out. Will be a long weekend, hoping to get everything put back together by Sunday night, but we will see. Things have a way of not going as planned.

Sounds good. Got my carrier dropped in today and was at .003 backlash but did not have the special spanner to tighten the adjuster on the side. The brass drift I was using was bending. So I quit being a cheapskate and bought the $184 spanner. We were melting in the garage at 0730 anyway, too hot to work outside today for me.

 

[DaveO9]

Sounds good. Got my carrier dropped in today and was at .003 backlash but did not have the special spanner to tighten the adjuster on the side. The brass drift I was using was bending. So I quit being a cheapskate and bought the $184 spanner. We were melting in the garage at 0730 anyway, too hot to work outside today for me.

Awesome. Hot here this weekend, too, but probably not as hot. Worst time for me is late afternoon - sun dips down and shines into my west facing OH shop door. And I was working on the back of the rig this weekend.....

Got the rear end installed, all went in pretty easily. I'm to the point of mounting the rear wheels and install driveshaft and I'm done in back. Front, not so much. Finally got the old motor mount out today and the new one dropped into place with all but one bolt threaded in finger tight. I've had the most trouble with the front upper engine-to-mount bolt, both coming out and going in. I'll probably just have to bend the heat shield like I did to remove the old mount. After the mount is done, still have to
- remove and replace radiator/hoses
- run new Dorman oil cooler lines to new Denso radiator (new radiator has engine oil cooler, old one doesn't)
- Change oil and filter
- Install front carrier assembly
- change oil in front diff
- front driveshaft and axles
- hook everything up, etc. etc.

@swathdiver or anyone else: do you know where this hanger goes? Pretty sure it came from the passenger side, but it's not showing up in any of my before pics. There's a similar longer one on the pass side for parking brake cable, so I think that's what it is, but I can't find where it goes. It seems like the p-brake cable is already pretty well supported without it.

 

[swathdiver]

@swathdiver or anyone else: do you know where this hanger goes?

View attachment 435082

That one goes on the driver's side lower control arm bracket on the axle. It faces the differential housing. You'll see the threaded hole for it.

 

[5StarCustmSolutns]

Q: Dumb question: could you do a hummer mount on DS and stick with Tahoe OEM on Pass side? I'm not going to do this now, but something I've been thinking about if I DO have a failure on DS some day, or if I do some motor upgrades.

A: Yes, no problem. This is how my 2012 is currently.



More like a little high quality Q & A there!

 

[5StarCustmSolutns]

edit: Disregard this post.... In my drearyness, I somehow skipped everything below my post on page 4..... and no there were no spiral notebook lines indented into my face


I just woke up face down on my bench about 15min ago. So I apologize if I missed this but: Curious what the fluid looked like inside your 14 with 82k on it??

Mine had 92k on clock and it looked like golden caramel lol. Had to have just performed their 100k service before letting a mild accident retire a beautiful Denali XL....smh
Just made me think, I hit......correction: A deer hit me a couple years ago and my Ins. adjuster was suggesting I'd come out ahead if I just totaled it . Literally suggesting I total loss claim my truck from a 100lb fawn helicoptering from front tire to back.... No wonder premiums climbing everywhere

 

[5StarCustmSolutns]

is it not shims on both side bearings in the diff?

I have done some Ford 9in center section that had adjustment, but I didn't know gm every did it.

No sir. Not in the 14.

It has a threaded dial on the right hand side that looks like a vertically aligned preload dial on a coilover. Has the exact same function, only transversely pressing from the passenger side. It's the only one I've ever done, but it was much easier than the shim style setups lol...