[StopShoe]

17 2SS with 55k miles.

I have a problem I have been trying to track down for a month now. Starting around 40mph, I have what can best be described as a whirring noise coming from the rear end. It is loudest at 49mph, doesn't matter what gear or if I'm in neutral and coasting.

I have had the wheels road-force balanced at 3 different places, and swapped the rears to the front because we thought it was the tires, but nothing changed. The noise still came from the rear. They are the stock SS wheels with Michelin PS4s, roughly 8 months old, 6k miles.

I lifted the rear and got it up to speed and you can still hear the noise, so I am very confident it is not the wheels or tires. The hub bearings seem fine, no play at all. I took a stethoscope to various parts and couldn't hear any odd noises, but it was also hard to hear anything over the exhaust while the car was running. The rear diff and transmission fluid were changed maybe 20k miles ago.

Does anyone have any ideas on what this could be? Is it worth changing the rear diff fluid to see if that makes a difference?

[BLACK Z]

It could be gear whine, You didn't hear with the scope on the rear end housing? Check both sides by the axles and the front near the pinion.

[jeffrop]

Any update on this? I just picked up a 2020 ZL1 manual and getting loud "whirring" sound, almost like a siren really at highway speeds (60+) from the rear.

Tires are Toyo Proxes but I don't think it's the tires. It has to go into the dealer tomorrow for a defective trunk release so I'm going to have them check out the rear diff

[WhiteMale]

correct amount and weight of oil with the limited slip additive?

[arpad_m]

Originally Posted by jeffrop

Any update on this? I just picked up a 2020 ZL1 manual and getting loud "whirring" sound, almost like a siren really at highway speeds (60+) from the rear.

Tires are Toyo Proxes but I don't think it's the tires. It has to go into the dealer tomorrow for a defective trunk release so I'm going to have them check out the rear diff

If these tires are of the R888R "persuasion", well they whine almost like a monster truck tire, starting at 45-50 mph and getting louder the faster you go, to a point. Initially I didn't think it would bother me, turned out I was wrong... then I got me some nice Michelin PS4Ss and never looked back. The extra grip from the Toyos was rarely useful as opposed to tolerating the constant whine.

[jeffrop]

Originally Posted by WhiteMale

correct amount and weight of oil with the limited slip additive?

Normally I would put it on the lift and check it myself but it's still under warranty and, as mentioned, its going in to the dealer tomorrow.


There's some road noise from the tires but this other sound is a high pitched whine, almost like a tornado siren but at a constant high pitch above 60mph.


I sure as hell hope its a warranty item as I just bought the damn thing last Friday

[jeffrop]

Originally Posted by arpad_m

If these tires are of the R888R "persuasion", well they whine almost like a monster truck tire, starting at 45-50 mph and getting louder the faster you go, to a point. Initially I didn't think it would bother me, turned out I was wrong... then I got me some nice Michelin PS4Ss and never looked back. The extra grip from the Toyos was rarely useful as opposed to tolerating the constant whine.

Yeah this is the first set of Toyo's I've had on a car, I will say the little driving I've done so far they seemed pretty sticky (30's & 40's here) compared to the Goodyear Eagle supercars that were on my '13 ZL1.


I've run the Michelins on a previous car and really like them but $$$

[jeffrop]

Originally Posted by arpad_m

If these tires are of the R888R "persuasion", well they whine almost like a monster truck tire, starting at 45-50 mph and getting louder the faster you go, to a point. Initially I didn't think it would bother me, turned out I was wrong... then I got me some nice Michelin PS4Ss and never looked back. The extra grip from the Toyos was rarely useful as opposed to tolerating the constant whine.

Looks like you were right. Just spoke to the dealer and they said the noise I'm hearing is the tires.

Looks like new tires are on the short list now

[cmitchell17]

Originally Posted by jeffrop

Looks like you were right. Just spoke to the dealer and they said the noise I'm hearing is the tires.

Looks like new tires are on the short list now

They need to put the chassis ears (microphone on a battery terminal clamp) and listen to several points on the chassis and differential to ensure the noise is not the differential since what you describe is what it sounds like. If it really is the tires I think you would hear a greater difference in the noise over different road surfaces, obviously if it's a differential noise, the noise would stay the same.

I took apart my 100k SS 2.77 differential when I heard a similar noise to find the Bellevue spring washer things in the clutch stack for the LSD cracked in 2 on both sides and looked like some material got loose and went through the spider gears causing some damage.

I think this could be caused from someone who hit me at around 50k in the side and hit the wheel but not sure or if these rear ends are just sorry, I think for the 6th gen they switched suppliers to I think GKN from AAM and I also had the center driveshaft carrier bearing isolator go bad as well.