Noise in driveline, pinion bearing?

[B-train]

I'm stumped, but after seeing both videos, I see what you are staying. In my experience, a pinion will make more steady noise as rhe rpm of rhe driveshaft increases. It won't be rhythmic. A driveshaft will give a rhythmic drone. The run-out seems a bit much, but I don't know what GM spec is, nor have I put my own on a lift to look at it. There have been numerous complaints over the years with aluminum driveshafts, to the point of litigation. I've had a rhythmic drone on my 2017 Denali at 75-85 mph forever. I found a bad u-joint and that helped a lot.

If you bent an ear doing a u-joint, I'd start there. Since you said it was there beforehand, is it possible that there was previous wear from a tight joint that you are now hearing? Resonance problems can be a *****....just have to sort them out process of elimination.

You could try removing the rear shaft and driving it. Since it's AWD, the front should pull it along. Maybe then you can see if the noise is still there or gone.

Just like an old school straight axle with a blown rear driveshaft......Limping home in 4wd. Not that I've ever done it....LOL

 

[j91z28d1]

I beg to differ. I have changed many pairs of u-joints and heated the keeper/epoxy to melt it out. The heat is not that much really. You are not heating it like you are getting ready to cut metal.

I get it, but I don't think I'd trust anyone I didn't know personally to do it. I don't think I'd try it myself. his looks alum like mine? I guess the steel ones would be easier. but eh.

 

[OR VietVet]

When I did my first heat 'em up and melt them out, I was amazed but I did see one thing though, PITA to clean out the grooves for the new snap rings. But was doable. I honestly never had a problem doing it. Patience helps so you don't overheat.

 

[donjetman]

You could try removing the rear shaft and driving it. Since it's AWD, the front should pull it along.

It won't budge with a driveshaft removed.

I tested that theory a while back.

 

[donjetman]

Me and many friends in the past 50 yrs have had many driveshafts built from scratch by local driveshaft service companies without issue.

 

[B-train]

It won't budge with a driveshaft removed.

I tested that theory a while back.

Interesting.....I learned something new today. It doesn't seem logical though.

 

[Donal]

I won't get to it today, but will dive into tomorrow hopefully. My luck will be it's too tight and I would need to replace the crush sleeve and likely the bearings, or rebuild the rear.


I can't tell for sure but under a good load if there is a faint growl starting, it might be masked by the exhaust. That leads me another topic I've been meaning to bring up. The exhaust looks OE but it seems like it has a little more bark than other 6.2 GMT 900's I've heard. Steady cruise is quiet, but under acceleration it has a nice exhaust note..or how crazy would it be that it's actually a pinion.




Thanks for that.

For the 8.6", does this rotational torque include the axles or with them pulled? Or just the calipers removed?

calipers removed

 

[dkad260]

his looks alum like mine?

Mine is steel.


Sorry for the late update but here's what I have found. I removed the brake rotor and saw the seal was wet, so I pulled both axle shafts and the RH had nociceable pitting on the shaft, as well as small very fine pieces of metal laying between the bearing and seal. There was about .030" of vertical movement of the axle, maybe a little more. The LH axle looks good but has some verttical movement as well but only about .010 but still alot.

The backlash is .010, which is a bit more than I hoped but right at the limit, mesh pattern looks like it may have a slight bias towards the heel, could be from the pinion seal replacement or could be what was there from the factory, that part I won't know. Coast side did look good.

There were no shavings further down the RH axle tube, none in the pumpkin and none in the LH tube and barely anything on the magnet...so I think I caught this early enough. Safe bet that would cause a fair amount of noise.

I have two new axles/bearings to go back in, I also saw a good bit of tearing on the ABS tone ring where it grips the axle so I will replace both of those as well, which is proving to be a chore finding the right tool to install them, but another story.

 

[Geotrash]

Mine is steel.


Sorry for the late update but here's what I have found. I removed the brake rotor and saw the seal was wet, so I pulled both axle shafts and the RH had nociceable pitting on the shaft, as well as small very fine pieces of metal laying between the bearing and seal. There was about .030" of vertical movement of the axle, maybe a little more. The LH axle looks good but has some verttical movement as well but only about .010 but still alot.

View attachment 404264


View attachment 404265

View attachment 404266



The backlash is .010, which is a bit more than I hoped but right at the limit, mesh pattern looks like it may have a slight bias towards the heel, could be from the pinion seal replacement or could be what was there from the factory, that part I won't know. Coast side did look good.

View attachment 404267



There were no shavings further down the RH axle tube, none in the pumpkin and none in the LH tube and barely anything on the magnet...so I think I caught this early enough. Safe bet that would cause a fair amount of noise.

I have two new axles/bearings to go back in, I also saw a good bit of tearing on the ABS tone ring where it grips the axle so I will replace both of those as well, which is proving to be a chore finding the right tool to install them, but another story.

Fantastic update, thank you. Looks like you’re on the right track.

 

[swathdiver]

Mine is steel.


Sorry for the late update but here's what I have found. I removed the brake rotor and saw the seal was wet, so I pulled both axle shafts and the RH had nociceable pitting on the shaft, as well as small very fine pieces of metal laying between the bearing and seal. There was about .030" of vertical movement of the axle, maybe a little more. The LH axle looks good but has some verttical movement as well but only about .010 but still alot.

View attachment 404264


View attachment 404265

View attachment 404266



The backlash is .010, which is a bit more than I hoped but right at the limit, mesh pattern looks like it may have a slight bias towards the heel, could be from the pinion seal replacement or could be what was there from the factory, that part I won't know. Coast side did look good.

View attachment 404267



There were no shavings further down the RH axle tube, none in the pumpkin and none in the LH tube and barely anything on the magnet...so I think I caught this early enough. Safe bet that would cause a fair amount of noise.

I have two new axles/bearings to go back in, I also saw a good bit of tearing on the ABS tone ring where it grips the axle so I will replace both of those as well, which is proving to be a chore finding the right tool to install them, but another story.

We know all the right tools to pull and install them.

Axle shaft end play can be no more than .012 inches per side. Radial play between .002 and .003 inches. Ring and pinion ought to be between .005 and .007, .010 is the max.

 

[dkad260]

Thanks again for the measurements @swathdiver, the 1.75" seating depth translates to 44.45 MM so this is close enough. My goal was no less than 1.75" but really can't go too much farther, almost centered in the boss. Maybe it can be bottomed out, but GM likely did this for a reason.

Ready to go, new parking shoes also done, just need fluid and a test drive today.

Why MM you may ask...I always measure imperial but it's easier for me to visualize 1MM increments over feeler gauge increments...lol.

 

[dkad260]

Late update, all is back together and I have driven it for a few days. The light droning sound that seemed to follow the exhaust note is gone, much, much quieter ride under load, almost no noise.

However, the faint noise is still there, and I went back to see if the pinion yoke had any movement with a prybar but found some slop in the transfer case output shaft.

I assume this is a bushing? What is the acceptable amount of movement?

Can I split the case and replace the bushing, or do I need to replace the whole case half?

 

[Geotrash]

Late update, all is back together and I have driven it for a few days. The light droning sound that seemed to follow the exhaust note is gone, much, much quieter ride under load, almost no noise.

However, the faint noise is still there, and I went back to see if the pinion yoke had any movement with a prybar but found some slop in the transfer case output shaft.

I assume this is a bushing? What is the acceptable amount of movement?

Can I split the case and replace the bushing, or do I need to replace the whole case half?

I believe it’s a bearing. Mine is very similar on my 2007, and I haven’t worried about it for 40,000 miles now. Lol.

 

[dkad260]

I believe it’s a bearing. Mine is very similar on my 2007, and I haven’t worried about it for 40,000 miles now. Lol.

Ha, copy that.

Well, I spoke to a company who remanufactures the transfer cases and they said a little movement is ok...so I need to see exactly how much movement there is.

Yesterday and today, I wanted to at least try a different fluid in the diffe. Currently I'm using Amsoil 75-90 front and rear, and just for the sake of science, I went with Valvoline synthetic, 2 quarts of 85-140 and 3/4 qt of 75-90. For the front, one quart of 85-140 and 1/2 at of 75-90. I wanted to thin it out a little.

Having .010" backlash at least on the rear, I felt ok with this thicker concoction.

Upon changing the front, I came across the LF axle shaft had a decent amount of play at the diff.

I put about 3 miles of highway and it does seem slightly quieter, but could be placebo, but it seems quieter.

I can still hear the faint noise though and it's hard to say how much the sound can travel under the vehicle. I want to speculate there should be very little movement on the front axle, this seems like alot.

I strained and saved the old fluid from the front diff, not much came out, hard to decipher with the bubbles but not too much metal flake, but still a little concerning.

 

[Geotrash]

Ha, copy that.

Well, I spoke to a company who remanufactures the transfer cases and they said a little movement is ok...so I need to see exactly how much movement there is.

Yesterday and today, I wanted to at least try a different fluid in the diffe. Currently I'm using Amsoil 75-90 front and rear, and just for the sake of science, I went with Valvoline synthetic, 2 quarts of 85-140 and 3/4 qt of 75-90. For the front, one quart of 85-140 and 1/2 at of 75-90. I wanted to thin it out a little.

Having .010" backlash at least on the rear, I felt ok with this thicker concoction.

Upon changing the front, I came across the LF axle shaft had a decent amount of play at the diff.

I put about 3 miles of highway and it does seem slightly quieter, but could be placebo, but it seems quieter.

I can still hear the faint noise though and it's hard to say how much the sound can travel under the vehicle. I want to speculate there should be very little movement on the front axle, this seems like alot.

I strained and saved the old fluid from the front diff, not much came out, hard to decipher with the bubbles but not too much metal flake, but still a little concerning.

View attachment 405181

If it ain't leakin', it's good. I've replaced the pax front axle seal on my '07 because it was leaking but the bearing seemed fine. I also have similar play on the drivers side though.

 

[dkad260]

Late update, but I was able to get some chassis ears on the front diff, TC, and rear diff. Both the front and TC seem quiet, however the rear pinion sounds like something is going on.

This is under load, coast, and decel. Oddly enough, it seems rather quiet in the cabin, turn the radio up and you might not hear it.

I think I'm just going to finish refreshing this rear axle, already did axle bearings and axles, this week hopefully the remaining bearings along with OE ring and pinion gearset.

 

[j91z28d1]

how did you record that?

seems very high pitch for a pinion bearing. but I've never had a mic on one while driving. so maybe?

 

[dkad260]

how did you record that?

I used Chassis Ears, clamping the mic to the front of the rear diff, and ran the output through the aux input of the Yukon's radio, recording the audio as a video clip through my cell phone.

For comparison, this is the front diff I recorded at the same time. The clicking was some light interference.

 

[dkad260]

I almost have the diff torn down, just need to remove the pinion races but so far I have .011" backlash and some wear on the pinion race.

 

[Geotrash]

I almost have the diff torn down, just need to remove the pinion races but so far I have .011" backlash and some wear on the pinion race.

View attachment 405814

I’d say that’s accurate!