Rear 3.42 rebuild odd axle bearing wear

[West 1]

Pulled the new axle bearings, carrier bearings and installed the new pinion races for this rear end today. No signs of any problems that would make noise. The new 3.42 pinion set will be here Wednesday so I guess I am on hold till they arrive. I hope the set up goes quickly. At least with everything replaced it should be good for the rest of its life.

 

[West 1]

This is the rear axle being fixed. The bearings all looked pretty good, none of them spun in the housing or overheated. The pinion and axle bearings showed some wear but I was afraid they were not the cause of my axle whine so I am replacing the ring and pinion gears just to make sure it is quiet when I am done. New pinion gears not arriving till tomorrow so I am still on hold. Everything is ready for install but I need the parts.

 

[West 1]

Follow up, got the rebuilt 3.42 rear diff done and installed, replaced all bearings and the ring and pinion. Had it apart 5 times to verify the correct pinion depth and backlash, gear pattern looked good. First test drive there is still a whine in the drive system on gentle acceleration, goes away when I let off the gas? Since this is a full time system I was not able to run it on jack stands to verity what axle was whining prior to the tear down. Driving the car it sounded like the rear axle. With every bearing new and the ring and pinion replaced It is pointing to being the transfer case or front axle.

My son has a chassis Dyno but it was down for repairs when I did this job. Should have waited, run it on the Dyno and checked the noise for sure. Oh well, at least I know I have a good rear axle now and I did find it had a wheel bearing leak that had ruined one of the brakes so some of this work was needed but not all.

 

[swathdiver]

Follow up, got the rebuilt 3.42 rear diff done and installed, replaced all bearings and the ring and pinion. Had it apart 5 times to verify the correct pinion depth and backlash, gear pattern looked good. First test drive there is still a whine in the drive system on gentle acceleration, goes away when I let off the gas? Since this is a full time system I was not able to run it on jack stands to verity what axle was whining prior to the tear down. Driving the car it sounded like the rear axle. With every bearing new and the ring and pinion replaced It is pointing to being the transfer case or front axle.

My son has a chassis Dyno but it was down for repairs when I did this job. Should have waited, run it on the Dyno and checked the noise for sure. Oh well, at least I know I have a good rear axle now and I did find it had a wheel bearing leak that had ruined one of the brakes so some of this work was needed but not all.

What was your final backlash?

 

[West 1]

.08 or .09, checked many times. The whine is most noticed around 45-52 mph and only on very gentile acceleration.

 

[j91z28d1]

is the whine exactly the same as before? Definitely sounds like gear whine from the description.

could be a good excuse for a set of mechanics ears. i got some and found my odd noise was a front wheel bearing, and on the opposite side of the car as I thought the noise was coming from. little prices for the nice wireless ones. but I'm happy I have them for things like this.. maybe it's the front diff? or tranny? transfer case?

 

[SpareParts]

Sounds like my van. Had to have the rear end rebuilt after i got it because of a whine between 45 and 50 that was LOUD!!.
Still has a whine between 45 and 50, but way less. Has all new bearings and gears. So i dunno it's not bad now i just drive it for camping trips anyway.

 

[swathdiver]

.08 or .09, checked many times. The whine is most noticed around 45-52 mph and only on very gentile acceleration.

Did you take photos of the pattern?

This was mine and she's quiet as a mouse, backlash was .005".

 

[West 1]

No photos, looked good so I was happy. My pattern was about 1/4 more to the outside but centered top to bottom. I tried shims under the pinion bearing from .038 to .020, I think the final set up had it at .029. Backlash at .008 or .009 seemed fine, no clank moving from Fwd to rev. Odd that the sound is almost identical before and after rebuild with all new bearings and the ring and pinion replaced. No whine on coast, no whine accelerating harder just on gentle acceleration like normal driving. Maybe it is the front diff and I just can't tell due to sound travel.

I will get it on my son's Dyno when he has it repaired. I can run it at speed all 4 wheels loaded and spinning to listen. He will laugh at my power with the 6.2L all stock. His Audi's are making over 900 HP and his Corvette is at 1000 HP. Turbo engines of course.

Your drive pattern looks perfect by the way, did you have a photo of the coast pattern? I don't know about yours but my shim pack was very tight, it was a bugger pulling the diff out each time and getting the shims back in. I played with the shims also and moved the backlash up to almost .020 and then tightened it back up while trying to find the right set up.

 

[swathdiver]

No photos, looked good so I was happy. My pattern was about 1/4 more to the outside but centered top to bottom. I tried shims under the pinion bearing from .038 to .020, I think the final set up had it at .029. Backlash at .008 or .009 seemed fine, no clank moving from Fwd to rev. Odd that the sound is almost identical before and after rebuild with all new bearings and the ring and pinion replaced. No whine on coast, no whine accelerating harder just on gentle acceleration like normal driving. Maybe it is the front diff and I just can't tell due to sound travel.

I will get it on my son's Dyno when he has it repaired. I can run it at speed all 4 wheels loaded and spinning to listen. He will laugh at my power with the 6.2L all stock. His Audi's are making over 900 HP and his Corvette is at 1000 HP. Turbo engines of course.

Your drive pattern looks perfect by the way, did you have a photo of the coast pattern? I don't know about yours but my shim pack was very tight, it was a bugger pulling the diff out each time and getting the shims back in. I played with the shims also and moved the backlash up to almost .020 and then tightened it back up while trying to find the right set up.

I could have shimmed this a little more but didn't want to take it all apart again. No side shims, the 14-bolt axle has an adjuster on the side. I don't remember how we set it but it's probably recorded over on my build page, Useless Information.

For pinion depth, We only used the original cast iron shim and I forgot what size it was offhand. We got the rotational torque to 15 foot pounds.

A year or so before the axle build, mine was whining like crazy and I thought it was the front axle going out. It would whine like crazy when coasting to a stop. Turned out to be the old KO2s! LOL They were over 4 years old with over 50K miles and had a little abnormal wear from a bad ball joint that slowly caused an irregular wear pattern and the noise.

The front axle was still nice and quiet after the new tires went on.

 

[West 1]

I had the rotational effort to spin the pinion shaft at 19 inch pounds, was lucky, hit that on the first try tightening with my Milwaukee 18v impact. First time using that. In the past I have done the torque job crushing the pinion sleeve with a 4 foot breaker bar and that was a ton of work. My whine is not tires.
Thanks for the consultations.

 

[dkad260]

OP, did your pattern by chance run off the heel? You said it was centered but was that also centered toe to heel?

Have you considered the transfer case as the culprit? If you don't have any chassis ears, maybe clip a Go Pro to the tailshaft housing of the transfer case, give it a test drive, then clip it to the rear diff housing and drive again, then compare sound clips.

Another possibility.....Are the tires the same make, model and similar tread depth? If not, you could have something going on in the transfer case since it needs the front and rear to rotate pretty much the same speed being a single speed TC.

 

[West 1]

Tires only have 500 miles on them and are matched and smooth. The contact patch was about 1/4” toward the heel but not the edge. It was centered top to bottom. I would need to pick up the listening device you mentioned but not a bad idea. When my son gets his dyno fixed it will be as simple as running it and listening.

 

[dkad260]

You did state the axle shafts had marks in the same area of those marks on the bearings, but later sounded like you said they were ok. Was it just a more polished looking area from being the inner race or was there any pitting? Did you get any pics of the axle shafts?

Those bearings definitely look like they saw ALOT of tongue weight and/or low diff fluid.

The narrower speed range of the noise is a head scratcher, did this noise start before or after the tires were installed? Just gathering a timeline that's all. If after the new tires and not to imply any lack of incompetence, but double-check the size on all 4 and load range to ensure proper tread depth. This would likely cause a stabilitrak code anyway but just a base to cover. I had a set of Premier LTX's for a possible wheel change for a few hundred miles and they did not like to be at 34-35 psi and had a slight buzz with emphasis on the outer tread, at 38-40 they quieted up.

 

[dkad260]

About 2 years ago, I had a pinion seal start to leak, had it replaced, leaked again and I did start to hear some noise from the rear. Had someone put it on a lift and they ran it up to about 50 MPH, with a stethoscope, we heard noise at the pinion and the RR axle bearing area.

I decided to just rebuild it and here's the pinion bearing roller and race, along with the RR axle shaft. The shaft had a good amount of pitting so I replaced both axle shafts. Not sure what yours looked like but these were definitely noisy.

 

[Geotrash]

About 2 years ago, I had a pinion seal start to leak, had it replaced, leaked again and I did start to hear some noise from the rear. Had someone put it on a lift and they ran it up to about 50 MPH, with a stethoscope, we heard noise at the pinion and the RR axle bearing area.

I decided to just rebuild it and here's the pinion bearing roller and race, along with the RR axle shaft. The shaft had a good amount of pitting so I replaced both axle shafts. Not sure what yours looked like but these were definitely noisy.

View attachment 463679

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Captain obvious reporting for duty here, but that looks like classic signs of spalling caused by poor lubrication, to me. I'll bet the root cause was the pinion seal leak leading to low fluid level in the diff.

 

[West 1]

The axle bearings showed the odd wear or damage posted early in this post. It was on the outside of the bearings not on the rollers. The axles looked perfect. The axle housing showed the identical marks that the bearings showed which had me thinking someone welded on this truck maybe or very heavy load was hauled.

 

[dkad260]

Captain obvious reporting for duty here, but that looks like classic signs of spalling caused by poor lubrication, to me. I'll bet the root cause was the pinion seal leak leading to low fluid level in the diff.

Yeah, was leaking slightly when I bought it, I checked all the fluids and were at the correct levels but I changed them anyway...damage may have been done but wasn't noisy at the time.

The axle bearings showed the odd wear or damage posted early in this post. It was on the outside of the bearings not on the rollers. The axles looked perfect. The axle housing showed the identical marks that the bearings showed which had me thinking someone welded on this truck maybe or very heavy load was hauled.

Yeah I saw that, my guess was alot of tongue weight and since the load is at the top of the bearings they could have heated up and coked a film of oil on the top of the outer race since that's the only stationary part and doesn't really see any recirculating oil flow. The welding part is surely plausible.

 

[West 1]

Went on a 200 mile trip yesterday with the rebuilt rear axle. We had the truck loaded with furniture to deliver. Truck ran great, the rear axle did make noise, I was towing about 2,000 pounds on this trip, Noise was consistent, did not increase or decrease. Slight chance it is the front diff making the noise.

 

[West 1]

Follow up #2, took the 08 Denali on a 1000 mile trip over the weekend, interior loaded from the front seats to the rear hatch, packed, probably 1500 pounds of gear for family reunion. With all the gear in the truck, floor to ceiling the whine was there even on flat ground steady cruising, went between 65 and 80 mph the entire trip. With the sound deadening of this load the noise does seem like it may be the front differential making the noise. I don't feel bad about doing the rear axle first, it did have a couple issues I am glad are fixed, the bearings showed some wear although all rolled smooth and I never felt I had found a part bad enough to be noisy. Soon as I get time I will look into the front axle and report back. The Truck got 16.3 mpg for the entire trip, couple hours stuck in traffic jams and almost the entire trip on the highway with a couple hundred miles in rolling hills with traffic speeding up and slowing down constantly. I think a clean trip would be over 17 mpg at the same speed. This is a 08 6.2L non AFM, non variable cam timing. 6 speed with the 3.42 gears. I did feel the 3.42 are too high at least with my loaded truck on this trip. At 75 it stayed in 6th gear and pulled well, at 65 it kept shifting down on the mild hills. I bet the 3.73 gear ratio would be a better choice with this engine and tranny. With 3.42 gears it is taching about 1800 RPM at 75 mph.