Corvette Forum : DigitalCorvettes.com Corvette Forums banner
1 - 11 of 11 Posts

·
Registered
Joined
·
33 Posts
Discussion Starter · #1 ·
I have some noise in the rear of my Vette and have already taken it in for the rear differential last week and had that taken care of but I am still hearing a noise that sounds like a backfire when you let of the gas but it's not that but something rattling maybe, anyone else have this noise? Again, it's not a backfire but sounds like it, just to clarify in case someone tells me it's a backfire, lol. Thanks
 

·
Registered
Joined
·
50 Posts
Check the nuts holding the rear sway arm links. Mine was loose on my C6 from the factory and made a popping sound when taking off or cornering.
 

·
Registered
Joined
·
440 Posts
This post caught my interest becuase i've been noticing some noise from the rear as well. Its at a much different time though..when i'm going at slow speeds and turning it sounds like a grinding.

No backfires though.
 

·
Registered
Joined
·
33 Posts
Discussion Starter · #5 ·
Take it to the dealer, they will drain your differential and add an additive and if you still hear the noise after they do that, then they will replace it and put in a rear differential clutches. I had already done that but there is another noise I am hearing that is different from the rear diff.
 

·
Registered
Joined
·
50 Posts
Took mine to the dealer and had the rear drained, and the two bottles of additive added. Didn't correct the problem (at least this one) That's when we found out that the rear anti-sway bar linkage bolts were loose and making a popping sound at slow left/right turns.

A few moments with the torque wrench, and wala... No more noise.

Ron
 

·
Registered
Joined
·
5,119 Posts
Jaz,

The grinding is just the clutch packs in the posi. I put in mobil 1 gear oil with the additive and about once a year it will act up particularly if it is below 25 degrees or so - - the fix is simple. **make sure the car is fully warmed**

Go to a parking lot and turn the wheel as hard as possible and do about 8-10 tight left turns and the 8-10 tight right turns and the problem is gone. What you are doing is forcing lube into the plates and this stops the chatter.

My C4 did it once and then after the change never again in over 40K but that had a Dana 44 rear. My c6 does it but it has the GetRAG differential which belongs in a golf cart.

Can you tell I think the rear is trash??
 

·
Registered
Joined
·
580 Posts
Followed this TSB last week:

<begin TSB>

"Subject: Rear Axle Chatter Shudder On Turns - keywords bind differential #PIP3559F - (12/06/2006)

Models: 2004 - 2007 Cadillac XLR

2006-2007 Cadillac XLR-V

1999 - 2007 Chevrolet Corvette, Corvette Z06

-----------------------------------------------

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:

Rear axle chatter or shudder on turns on Chevrolet Corvette and Cadillac XLR.

Recommendation/Instructions:

Flush and fill the rear axle with synthetic axle lubricant GM P/N 89021677 (Canadian P/N 89021678) and appropriate amount of the friction modifier additive P/N 01052358 (in Canada 992694). See fluid amounts listed below.

Note 1: In some cases it has shown that a second flush procedure on a second repair visit will correct the chatter/shudder concern prior to replacement of the clutch packs.

Note 2: To properly flush the rear differential remove the left differential cover and get all of the old fluid out off the differential, wipe out the residue replace the cover o-ring and then reinstall the cover and fill with the appropriate amount of fluid and friction modifier additive.

If the complaint or the condition persists after the flush and fill, replace the right and left rear axle clutch packs following published service procedures.
After clutch pack replacement use synthetic axle lubricant GM P/N 89021677 (Canadian P/N 89021678). and the appropriate amount of friction modifier additive P/N 01052358 (in Canada 992694). See fluid amounts listed below.
Note 3: PRIOR TO INSTALLING THE FRICTION MODIFIER ADDITIVE FOR EITHER OF THE ABOVE REPAIRS THE BOTTLE MUST BE SHAKEN VIGOROUSLY FOR AT LEAST 1 MINUTE TO MIX THE ADDITIVE THOROUGHLY.

Once the axle fluid has been changed the car must be driven in 8 - 10 SLOW figure eights to work the fluid between the clutch plates.
Fluid capacity:

Model Year
Model
Differential Lube
Friction Modifier

2004-2006
Base XLR
1.69 qt (1.6L)
4 oz. (118 ml)

2007
Base XLR
1.95 qt (1.85L)
5 oz. (148 ml)

2006-2007
XLR-V Series
1.95 qt (1.85L)
5 oz. (148 ml)

1999-2005
Corvette ALL
1.69 qt (1.6L)
4 oz. (118 ml)

2006-2007
Base Corvette
1.95 qt (1.85L)
5 oz. (148 ml)

2006-2007
Corvette Z06
2.70 qt (2.55L)
6.4 oz. (190 ml)

Note 4: Export vehicles use 2.01 l (2.12 qt) synthetic axle lubricant GM P/N 89021677 (Canadian P/N 89021678) and approximately 150 ml (5.1 oz) limited-slip differential lubricant additive GM P/N 1052358 (Canadian P/N 992694).

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed."

<end TSB>

---------------------------------------------

This issue is more likely to be noticed on cars that are driven relatively infrequently. The reason is the fluid slowly drains out of the clutch packs over time if left parked. Once driven the fluid again finds its way back into the clutch packs and the problem disappears. This however can result in uneven wear patterns on the clutch discs thus further exacerbating the problem.

The clutch discs become glazed do to this uneven lubrication and slip, causing the noise you hear.

Note also, the noise is NOT detrimental and will not harm anything. It's simply annoying.

Have only been driving it a week but have only heard the chatter once now and it was real short, not like before.
 

·
Registered
Joined
·
5,119 Posts
Jaz,

What JohnieW said is correct but we found out that if you have a really good synthetic in all you need to do is the tight circles when the car begins to act up and the problem goes away.

He would no approve of our 'flush' technique and that's fine too; he sounds like he sure knows better. I never knew the additive had to be shaken either.

Since the Mobil 1 gear lube and the FMC additive the car has done this about three times and each time the tight circles make the problem go away.

I would try the tight circles especially if the fluid has been changed one time. If not, let them change it but take Mobil 1 gear lube with you.
 

·
Registered
Joined
·
580 Posts
Jaz,

What JohnieW said is correct but we found out that if you have a really good synthetic in all you need to do is the tight circles when the car begins to act up and the problem goes away....
Thanks. I will have to remember that if the noise comes back.
 
1 - 11 of 11 Posts
Top