Differential Whine?

[mpwersh221]

I have a 2015 SS LS3 M6 with 28000 miles. I just had the rear differential built with Eaton Truetrac, Yukon 4:11s, BMR poly bushing, and the Speedmaster diff cover.

Originally, I purchased the parts myself planning on building the diff myself. The more I read about swapping gears, I decided best to have a local reputable shop do the install.

After the shop had the car for almost two weeks, I got the car back and been working on the break in period. I currently have about 300 miles in the break in period. I believed the shop put roughly 40 miles of that break in.

Since I have gotten the car back, I have what I believe is a whining noise. It is only noticeable during cruising speeds (35mph and 80mph, 1200 RPM to 2200 RPM, and when in 4th, 5th, or 6th gear). And only noticeable when lightly in the throttle. The whine does increase with the RPM increase, meaning it is louder and more noticeable. During normal acceleration, the whine goes away, and seems to go away when completely off the throttle and deacceleration. I do not notice a while when coasting to a stop either.

I was told due to the stiffer bushings being used that there would be an increase in road noise, and also because of the helical design of the Truetrac as well.

But I have read through other reviews here that a lot of those who have the BMR diff mount bushing state they are quiet. I also read the same about how the Truetrac is quiet, too.

I am no expert in differentials, so I was wondering everyone else’s experience with either the BMR bushing, Truetrac, or both together if anyone else can give their opinion or experiences with the results.

I plan on changing the gear oil at 500 miles. I will be using 80w-90, and I was told that 80w-90 with no friction modifier was used.

I do have 3 inch exhaust, so it would be tough to get a video capturing the whine.

I haven’t gone back to the shop and asked for their thoughts on the whine yet, but I was thinking about finishing the break-in period. I also wanted to get some other opinions and experiences first before I talk to the guy who did the work.

Appreciate the thoughts and feedback!

Thanks all!

[gtstorey]

My Diff Bushings and the Speedmaster cover made what turned out to be bad wheel bearings sound just like a noisy diff.

[mpwersh221]

Originally Posted by gtstorey

My Diff Bushings and the Speedmaster cover made what turned out to be bad wheel bearings sound just like a noisy diff.

I did have the shop supply the needed new bushings, races, and bearings for the install. I should have added that to my original post.

I did not have any noise prior to the install, but I'll keep that in mind and check the wheel bearings and verify. Thanks for the input!

[kevint]

I have factory everything (aftermarket headers but the exhaust is stock from the cats-back) in my 2013 SS auto and my differential has audibly whined for as long as I can remember; at this point my car has over 180k miles.

I believe whining happens when there is too much play between the gears. Play is set within a range at assembly, but it increases as the gears wear.

[gtstorey]

Originally Posted by mpwersh221

I did have the shop supply the needed new bushings, races, and bearings for the install. I should have added that to my original post.

I did not have any noise prior to the install, but I'll keep that in mind and check the wheel bearings and verify. Thanks for the input!

You may not have noticed a noise but the load bolts on the cover and harder bushings will magnify any noise in the axel.

[mpwersh221]

Originally Posted by gtstorey

You may not have noticed a noise but the load bolts on the cover and harder bushings will magnify any noise in the axel.

And that makes sense as well. The more I search on this and other forums for reviews, I am finding that is the case as well.

[gtstorey]

I don't want to overstate that I "know" the problem is the wheel hubs. It's just a possibility.

[SlowLS1]

Whiny gears bring back not so fond memories of the 4th gen 10 bolt rears.

Hope it is just wheel bearings, but if it were me, I would prepare myself to accept that is may just be a noisy ring and pinion.

[mpwersh221]

Originally Posted by SlowLS1

Whiny gears bring back not so fond memories of the 4th gen 10 bolt rears.

Hope it is just wheel bearings, but if it were me, I would prepare myself to accept that is may just be a noisy ring and pinion.

I am leaning that way, too. Doing more and more research and reading on other similar differential builds, it does sound that having noise is the likely the case.

Still always good to research possibilities and other things to check, and make sure that nothing will be wrong.

[chevy pilot]

Originally Posted by SlowLS1

Whiny gears bring back not so fond memories of the 4th gen 10 bolt rears.

So familiar,and klak.. klak.. klok.. klok sounds when turning...

[LS1Formulation]

It's well known that anything but GM gears will whine in a factory center section. Hell, my GM 3.91's are kind of noisy, but I've got all poly bushings and an LPW cover too.

[PaulsSS]

I've rebuilt many rears and let me tell you the results always vary. What you describe doesn't sound bad at all. Bad wheel bearings are a rushing roaring noise so i doubt it has anything to do with them. A little whine is normal I would note it now and as long as it doesn't get worse forget about it. You could try some different oils to mask it some, I always had great luck Amsoil Severe Gear 75-140 I run it in both my Camaros from new. !st thing I change @3000 miles is the rear oil.

[mpwersh221]

Thanks for the input, everyone.

I talk to the installer again about the noise, and he is mentioned everything what lot of you have said.

I haven't gotten to the 500 miles yet to change the oil, but I have been reading on gear oil everyone recommends. I think I will change out the oil to a 75w-140 or something similar to see the results.

Thanks again all!