Hello all.

I just recently purchased an 07 C6.

6 speed
Z51 (if it matters)

While backing out of a parking spot (or the driveway) I hear a squeeking/clunking noise coming from my rearend. It doesn't seem to be prominent on one side or the other. It almost seems like something is binding but it doesn't effect the performance or drivability in any way.

I notice it most when I'm backing up. Maybe a little while I'm trying at slow speeds while in 1st gear.


Any suggestions on where to look first?

Car is bone stock, 25k miles.

 

Does it do it when you're backing up in a straight line, or only when the wheel is turned?

 

Turned only. Also noticed it while going forward making a sharp slow turn

 

You sure it's not the tires skipping? Real common scenario with the wide tires on these cars.

 

It's a possibility but it really sounds like gear noise or something to do with the diff. I have owned 3 f-body's before this car so the IRS is all new to me.

 

Maybe have someone observe from outside the car while you cut the wheel and move. My Vette & CTS-V both do it all the time. It does sound pretty bad though when it happens

 

I'll check it out thank you!

 

If it's coming from the rear, it's most likely the limited slip differential. The noise is harmless and has been the subject of numerous TSBs over the years. The final fix is to refill the case with GM fluid part #88862624 (and _no_ other additives).

 

This may help you too.

Like 'Torquetube' mentions, the TSB states DO NOT add anything else to the DexLS fluid if you change the rear diff fluid. The additive is already in the fluid..

 

You probably need to have the rear diff fluid changed. Right after I got my (new to me) 2005 Corvette, I had the dealer change the transmission fluid and the rear differential fluid. Within a day of having this service done, I started getting weird scrubbing and crunching noises in low speed, tight turns (like in the cul de sac at the end of my street). I checked the dealer invoice to see what diff oil they had used and it was GM part #88900401 full synthetic 75w90. I looked this up online and it is not a limited slip diff oil and there was nothing on the invoice to indicate that they had added any limited slip additive. I called the dealer about this and was told that 88900401 is the diff oil listed in their computer as the correct oil for a 2005 Corvette and no limited slip additive is needed. Okay, but what about this noise? They wanted me to bring the car in and leave it with them for a full day so they could diagnose the noise. I had an appointment for them to do that a couple weeks ago and they were going to give me a loaner car gratis for the whole day. However, two days before the appointment, I did a lot of research about this online and I discovered 88900401 is NOT the correct fluid for C6 differentials. GM issued a TSB (#07-04-20-002A) in 2008 detailing this noise from the differential and specifying a new gear oil that was specifically developed to eliminate chatter from the clutch pack of the limited slip diff on the C6. The new oil is Dexron LS 75w90, GM part #88862624 and it's been the factory fill in all Vettes (C6 and C7) since the 2008 model year. So, long story short, I decided to forgo the appointment with the dealer and bought three quarts of the Dexron LS ($26 a quart!) and had my local shop change it out. Noise gone. Problem solved.

So, if you do have the diff fluid changed on your C6, be sure to use the Dexron LS, part #88862624.

 

I had the same thing happening and did the fluid change myself. It is recommended to find an open parking lot and do about 8-10 figure 8's to help get the new fluid into the differential clutch plates. In a couple of days, all was good!

 

Awesome, looks like I'll be draining the fluid and adding new. Is there a drain plug or do I have to pop off the cover?

 

I had the same issue and it was also resolved by changing the fluid and using the GM fluid.

There's a fill and a drain plug if I recall correctly. I bought a $5 bottle pump from Walmart to make filling it a hell of a lot easier.

Also like someone else said, doing figure 8's in an empty parking lot will work the new fluid in.

 

Here is a link that will give you all the info you need. I hope it works. If not, search Differential fluid TSB. You'll see a DIY for a C6 within the top 15 results.

https://www.corvetteforum.com/forums...1497063&page=1

 

The figure 8s are a good idea, but in my case, I knew the new fluid had cured my noises the second I backed the car out of the bay where the shop had just changed it. As soon as I turned the wheel to turn the car around, there was dead silence, whereas before I'd get all sorts of crunching and grinding noises while backing up and turning. I drove about 3 miles down the road to a huge church and used their large parking lot to do 10 figure 8's just for good measure. The rear end has been silent ever since.

 

Yup, Dexron LS should fix it. Mine was done under warranty back in '08.

 

I realize this is an old subject, but I need advice on what to do next. I have had the differential fluid changed three times on my 06 with 30K. The clunking problem when backing keeps getting worse, The last dealer I took it to unbelievably couldn't duplicate the problem even after leaving it overnight so it would be cool in the AM. I had them change the fluid anyway, but it made the same noise when I picked the car up and backed out of the parking spot. I had my independent mechanic do it with the Amzoil product and it was a little quieter for a while but now it is worse than ever. Both dealers I took it to acted like they had never heard of this problem. So to the question- It may be the time to get the clutch packs changed. How much should this cost, and does anyone know a competent dealer or other mechanic in the N. Houston area I could trust to do the work?