Finally figured out noise in diff on my 2015 ZL1

[mixitup]

The car has 98000km on it and it always had a "wuh wuh wuh" cycling sound from the diff. The noise wouldn't begin until reaching 50kph, which almost sounded like a bad tire(shifted belt/bad tread etc...) Noise couldn't be heard until reaching 50kph+. Even cruising at 110kph you could hear the noise under slight throttle.

I removed the diff this morning and measured backlash at each tooth and found backlash from .004 to .017

I then reset the dial indicator near the side top of the gear, set the dial indicator to .004 where the tooth backlash read .004 and rotated the gear. The readings followed my backlash measurements exactly, all the way up to .017

Its looks as though the gear is machined incorrectly and is oval in shape than round.

I know there really aren't any parts to purchase out there, but I do know where I can purchase a new original AAM gear and carrier , but I'm afraid that these new gears may also be machined incorrectly.

Any thought or suggestions?

[Revster]

I have same issue with my 2015, a little whine on deceleration also, at 3000 miles rear end was replaced under warranty. Now at 29000 miles noise is back.

[ZMEnow]

Originally Posted by mixitup

The car has 98000km on it and it always had a "wuh wuh wuh" cycling sound from the diff. The noise wouldn't begin until reaching 50kph, which almost sounded like a bad tire(shifted belt/bad tread etc...) Noise couldn't be heard until reaching 50kph+. Even cruising at 110kph you could hear the noise under slight throttle.

I removed the diff this morning and measured backlash at each tooth and found backlash from .004 to .017

I then reset the dial indicator near the side top of the gear, set the dial indicator to .004 where the tooth backlash read .004 and rotated the gear. The readings followed my backlash measurements exactly, all the way up to .017

Its looks as though the gear is machined incorrectly and is oval in shape than round.

I know there really aren't any parts to purchase out there, but I do know where I can purchase a new original AAM gear and carrier , but I'm afraid that these new gears may also be machined incorrectly.

Any thought or suggestions?

The gears aren’t machined incorrectly , the lash is off and after driving it so long it maybe difficult to reshim them. By the way you say you can find a new complete carrier/pig unit? Because I have only seen rebuilds or used taken from wrecks starting around 4K. I know I bought the last 3 AAM piñon seals several years ago.

[mixitup]

if only lash is off, then my backlash would be off the same amount around the whole gear. My backlash starts at .004 up to .017 and back down to .004. this means either the gear isn't mated flush to the carrier/case or the gear is not machined properly. Ill try and post pics.

This high spot on the gear is creating the "wuh wuh wuh" sound.

[mixitup]

how to I upload images?

[mixitup]

The number next to the tooth is the measurement in thousands. I started the pics at the smallest backlash (.004), you'll then see incrementally reach .017 and back down to .004 again. Either the ring gear is not sitting flush against the carrier/case, or its mad improperly.

Revster has already had his diff replaced at 3000m and it noisy again only driven 26000m more. This is an AAM issue.

[ZMEnow]

The 2012 and 13’s had some bad carriers and you couldn’t side shim the ring out for noise because it wasn’t ever flat, and your backlash would pattern uneven. Not saying you have one but if somebody has already changed the gear set, you really have to be good to set these up where they will run 50k before you hear lash noise again.

[mixitup]

I removed the carrier assembly and measured runout on the edge of the carrier. I positioned the dial indicator as displayed in the pic. I started at the tooth that had the least amount of backlash .004 and rotated until the tooth that had .019 (which is 180 degrees across) and runout hit .012 and went back down to .000 when rotating back to the tooth with .004 backlash. So the edge of the carrier is machined improperly.

Next I removed the gear and and found that 2 ring gear bolts were not as tight as all the rest were. I measured runout of the carrier face where the gear mounts and I measured runout of .012 Again I started at the teeth that were at .004 and again directly across from this point (180 degrees) measured .012 and back down to .000 I also measure the top surface of the carrier and came up with the same measurements. The case is warped. Did it warp because the ring gear bolts were not torqued properly?

[mixitup]

I next measured the thickness of the carrier and measured between .289 and .291. Only has .002 runout. That appears good.

[mixitup]

I ended up taking the carrier apart. I removed the differential flange to inspect the bellville washers and clutch packs. The bellville washers are not cracked (this washer used to crack and many C5/6 vettes. I've rebuilt many). The clutch pack/frictions do not look like there in good shape. It has very little friction material left on them. I decided to compare the size of a C5 friction (much smaller).

[mixitup]

So what do we do from here? I guess that I can order another 3.23 gear. Do we order another original AAM gear or aftermarket gear? Can I take this carrier to a machinist to have it machined true? Was this a result of having a few ring gear bolts under torqued? Do I order an aftermarket Speed master Torque Worm carrier?

A few other questions:

Who makes any aftermarket carries for our diffs?

Are there clutch packs available to repair these worn out ones?

Are there belleville washers available in case these ones crack?

This/these diff faults make it seem bleak for other ZL1 owners. GForce diff conversions is out of the question.

Any thoughts?

[bsn]

Never heard of any aftermarket carriers or gears for these. Parts are hard to get since it is a limited production piece. You can see if any dealers have clutch packs. If not check with an aftermarket transmission parts supplier and see if anyone can reline yours. A decent machinist can true the carrier and fabricate a spacer. I am sure Belleville washers can be sourced from an industrial supply source. If all else fails Hawks Motorsports carries used carriers for $3K, Lee C Parts may also have one, shipping is going to be expensive

[ZMEnow]

Originally Posted by mixitup

So what do we do from here? I guess that I can order another 3.23 gear. Do we order another original AAM gear or aftermarket gear? Can I take this carrier to a machinist to have it machined true? Was this a result of having a few ring gear bolts under torqued? Do I order an aftermarket Speed master Torque Worm carrier?

A few other questions:

Who makes any aftermarket carries for our diffs?

Are there clutch packs available to repair these worn out ones?

Are there belleville washers available in case these ones crack?

This/these diff faults make it seem bleak for other ZL1 owners. GForce diff conversions is out of the question.

Any thoughts?

Finding the parts are going to be tough, but if you are in Toronto give these guys a call and share the pics they might have some suggestions as they know rear ends for the Detroit area.. https://www.drivetrainspecialists.com/about-us

[70T/A400]

Are the teeth of the gears with the higher backlash showing more wear than the lower backlash gears?

I would also like to look at the wear patterns on the mating gear.