BJ67

Decided to check the torque on my rear axle nuts today 08 Z with 17000 miles. Just removed the wheel center cap, torqued both sides to 120 ft lbs .Now when I first take off I get a clunk. When I back up, I get a clunk when I first let out the clutch, just like taking off. Definitly coming from the rear of the car in the axle area? . Both sides took maybe a 1/8 turn, definitely less than a 1/4 turn. Any ideas anyone??

Mad*Max

timd38

It has been posted that axle ends have broken after being torqued several time. Hope that is not the issue.

Flying24

I had the clunking or scratching sound issue when driving in tight circle in either direction. I replaced my axle nuts and I want to say torque was 160. When taking off the old nuts one side was very easy to remove and that is the only side that still makes noise. But after driving in a circle a number of times it goes away. Now I'm thinking clutches plates I switched to red line this past year and it says it has the extra friction additive. I may go back to the GM brand.

timd38

If you think it is clutch noise,just add a little of this.

http://www.redlineoil.com/product.aspx?pid=41&pcid=4

I have put Red Line in many Corvettes since 2006. Just so that I give full disclosure, I retired last year, and I went to work them earlier this year.

Boomer111

The axle nuts cannot be reused/tightened. They are a one time tighten item. Get new nuts and use loctite and wait 24 hrs to cure.

The ft lbs. recommendation had been bounced around so much I cannot remember the correct lbs, be it 140 or 160. I am pretty sure it isn't 120.

Flying24

Yes I remember I have talked to you in the past. So you think I should add this after what I put in says this on the label: Contains additional friction modifiers for suitability with clutch-type limited slip differentials - for most LSDs, no additional friction modifiers are required
But I'm willing to add it but is more better? is this something you have came across with your experience

BJ67

This was the first time these axle nuts were torqued. Noise not there before. Used the 120 ft lbs as they are the original 33 mm nuts. Why the one time click/cluck on each from a dead stop take off or from a dead stop back up. Once the car is moving no noise. Drove car 15 miles, There is no way the axles are broken. I also think if your crawling in first gear and just get on and off the throttle quick, I get the same click/clunk.

BJ67

It doesn't sound like a rear end clutch chatter, this is a single clunk each time you let out the clutch from a stand still

Flying24

No I had the clunking before the axle nut replacement while driving in circles. Then had the scratching sounds on one side, but goes away after several circle turns.

Flying24

I did read where people added additional friction modifier and were happy with the results of course it wasn't redline but with a different brands

timd38

It will work if that is the issue. To be frank, I think something else is wrong. Chatter is what normally happens when you need more friction modifier, not clunking. Friction modifier is cheap. http://www.jegs.com/p/Red-Line-Oil/R...15741/10002/-1

Have you checked to make sure the sway bar links or some other part of the suspension isn't causing the noise.

Flying24

Clunking was solved by the axle nuts, then the scratching or chatter noise on one side. Which after a number of circle turns goes away, I checked to make sure my rear was full as well. No leaks

Dano523

Huge fan of Redline fluids, but when it comes to the C-6 diff, GM tested a lot of brands/types of fluids until is came up with one out of the bottle that did not make the diff clutches to cause noise. Pretty sure that it just a re-branded Pennzoil, but any who, its Dextron LS Gear Oil 75W-90, part #88862624.

As for the additive trick, it works, but is also on the same lines as trying to adjust over-all clutch lock up slip with it as well.

SUB VETTE

Buy a new pair of axle nuts from your dealer, they are about 3 bucks each if I remember right, get a tube of red locktite, and replace them properly by torqueing to the right value and letting them sit overnight. Mark them after you are done with a paint stripe so you can inspect them in the future to see if they have moved. The old nuts can't be re-torqued and should be discarded. The TSB for replacing the nuts is posted in another axle nut thread here, do a quick search.

Sayfoo

I agree with some of the above that you may have stressed the trans or diff.
I would definately redo the nuts since this is the only change. You might have to remove the wheels to get any rust or locktite off the threads in order to get a correct torque reading. Maybe do 1 at a time, then check for the noise. That way you can isolate which side is making the noise, if it is at a wheel.
I made sure that my trans was in neutral and the em brake was on when I did mine.
After redoing the nuts, I would try the figure 8's a few times, the try the fluid change. I used the current GM fluid. Try to get it up to temp.
If this doesn't help, you may have a mechanical problem.

BJ67

the clunk or cluck started immediatly after i torqued the axles, never heard it before i did it.

Boomer111

End links can make noise but usually more present over bumps.

The noise when taking off sounds like the axle nuts click.

The diff chatter is a different sound, more grinding.

Maybe have a local corvette mechanic take a listen.

To my best knowledge these are usually corrected with the normal mentioned steps. Not something that needs screwing with to get corrected.

Gearhead Jim

IIRC, the GM bulletin specifies Loctite 272.
There are several different grades of red, I don't know if it would make a difference but took the trouble to get (order) the correct stuff.

Dealer did the bulletin on my car a long time ago, eventually the nuts got lose again. I didn't want to keep doing this over and over, so I carefully cleaned the old Loctite, used new nuts, and didn't move the car for 24 hrs. So far, so good.

BJ67

I am picking up the new nuts tomorrow, I am flushing the splines with wd40 and working the axle back and forth. I believe the new torque spec is 140 ft lbs. When I just checked the axle nut torque originally I set the torque wrench to 120ft lbs as the orig spec was 118ft lbs. I did not check the torque because of any noises, didn't have any. I keep coming across the loose axle nuts on the forum enough to make me check them, after that the single clunk/cluck every time you back or go forward from a stand still reared its ugly head.