[CTSV05]

Well, with 2800 miles, the '06 unit seems to be holding its own.

I have done a couple of burnouts without drama, and I have done many spirited upshifts.

I however did not get it back to the track for a 1/4 mi. run as the truck consumed all the track time.

Positive observations:
The solid feel is still there.
The whine that started at 400 mi. has not increased and is only present at 40 mph in a steady state cruise.
My confidence in driving the V is much increased.

Negative observations:
There is a minimal amount of clunking, say as I back up and push in the clutch.
Only minor "parade clunk", this may well be in the rest of the drivetrain.

Comments on the GM bushings. They are a joke. At least for serious shifting.

Why? Glad you asked, at or above 6200, they allow a horrible amount of action on the cradle. Below this they do make a marked difference, I am going to reinstall the metal spacers I had in there at some point, but for now I am just a little less aggressive on my shift points.

 

[Joey'sVee]

That's great to hear about the new diff. I'm getting mine put in today and it's free (under warranty)...so that is REALLY good news. Thanks for the update!

 

[TampaV]

I am a relatively new member of the CTS-V community. I bought a Light Platinum, 2005 at the end of August and have about 2,000 miles on it now. I've had two C-5 Z06 Corvettes. I still have a yellow 2002 Z06 that I actively autocross in national SCCA events all over the country.

I am good friends with Joe Aquilante who owns Phoenix Performance Inc. They build and race many of the National SCCA road racing C-5 Z06 and C-6 Corvette race cars that dominate the T-1 road racing class in SCCA Club Road Racing. Phoenix Performance has built all of the cars that John Heinricy (of GM Performance Division) has won with at the SCCA Runoffs at Mid-Ohio. If you've never seen John drive, make sure you don't miss the SpeedTV coverage of the T-1 Class from this year's SCCA Runoffs being shown on November 26th, sometime in the afternoon.

Besides building Corvettes and Firebirds, Phoenix Perfromance has also built about 5 CTS-V race cars that compete in the T-2 Road Racing class.

That brings me to the point of this post. I was talking with Joe Aquilante about the differential issues and also the parade clunk known to be problems with our cars. Joe acknowledged that the 2004 and 2005 CTS-V has an under engineered differential. However, he says the parade clunk is an unrelated issue. I described to him how I get the clunk when accelerating lightly in 1st or 2nd and lifting off while depressing the clutch. He tells me the clunk comes from the fact that the drive shaft is direct coupled between the transmission and the differential. The Corvette has an aluminum torque tube with rubber isolators on either end that absorb drive line shocks caused by disengagement of the clutch when the driveline is under load. In the CTS-V the drive line is direct coupled and therefore generates the clunk we get under these circumstances. I hope my explanation makes sense.

Sorry for the long post, but thought I'd add to the discussion of bad differentials and clunk complaints. Hopefully, the 2006 differential will resolve the problems of whining and differential failures, but it won't do anything to eliminate parade clunks.

 

[Natedog]

:stirpot: very interesting... gonna follow this thread

 

[CTSV05]

Well, that may well be, but I have driven many standard shift rwd cars and trucks, and the V is the only one I've ever noticed with such a dramatic clunk.

The V also has a carrier bearing which should help absorb some of the "transfer shock".

Also, when the new diff was first installed, the clunking was all but not even there.

But regardless, I'm very pleased so far with the upgraded diff.

 

[6104696]

There is a very good explanation of one possible cause of the parade clunk on Reed's FAQ. Though Rob's analysis on the FAQ may or may not be correct, it does make sense.

There is certainly some differences between the C5 and the CTS-V, and in one of those differences lies the clunk. But the CTS-V is a more conventional drivetrain than the Vette, and like CTSV05 I have driven numerous performance cars that did not clunk so easily. Of course any manual will clunk or bang if you unload the clutch at the wrong time (during a torque reversal?), but the CTSV design has something that is plain old wrong, and should be able to be repaired or remedied.

Let's see what the feedback is from the 2006 owners, when they start to get some miles on their cars.

Sorry to hear that the clunk is back.

D