hulm333

I have an 05 cts-v 45,000 miles on it just bought it a week ago and i have this vibration everyone has talked about. i cant quite nail it down to any exact symptom. in 6th gear i feel the vibration anywhere from 45-90, the trick is i do not feel it in the shifter what so ever and it only occurs on absolute decel ( when the engine is in braking mode and right in between coast and accel/ very light throttle) if you put torque/throttle to it it goes away. everything looks and feels good underneath. any thoughts?? ps there does almost seem to be excess play in the drivetrain (rear diff) not sure if the clunk is normal for sure or not, i do expect some being a manual transmission and all but out of curiosity...

punishmentcycle

iTrader: (6)

mine has always clunked..ive tried it all and between the diff and driveshaft i think its just something u gotta live with unless u spend stupid money

bamacaddy

iTrader: (1)

AGREED...I was super paranoid about it when I first got the V....I've gotten used to it for the most part....even though I swear that somethings gonna just fall out at times......I've put about 40k on it so far and nothing's fallen off so far.

rocket2ya

iTrader: (1)

i had this problem and got it taken care of under warranty, not sure exactly what it was because the replaced both my rear diff and trans

tweeter81

I also had a problem similar to this a long time ago with my car, and all they had to do was remove the driveshaft and re-index it and the vibrations went away. A lot of other people have had other big ticket items replaced, but the DS re-index is always a good place to start.

JNR_Design

iTrader: (3)

I've got some clunks here and there that have developed more pronounced and I am thinking it's more to do with the diff and/or engine mounts in my case...It's still nowhere near as bad as the 2006 GTO I had (bought brand new); that thing was embarrasing, in that way!

hulm333

was yours only in 6th? and what did they do to index? just rotate 180?

tweeter81

I believe it was only in 6th at highway cruising speeds (between 70-80). I don't know exactly what they did, but the DS will have paint marks on it from the factory, and they must have just rotated it just enough (possibly only 1 bolt over) to match up the marks.

P.S. The best way I can describe its sound was it was like a super-low exhaust drone at the speeds shown above. If your is different than that, you might have some other problem.

JNR_Design

iTrader: (3)

Yeah, driveshafts must be 'phased' correctly for smooth operation and why anytime you remove something like this, you should always mark both the shaft and mating pinion mounting with a scribe, so they go back in the same way.

Now, if you get a new driveshaft, or your rebalanced, I'm am not 100% sure what you'd do in that case?

pharoh

iTrader: (1)

Same thing happened on my '07 with only 18k miles.... They also re-indexed the driveshaft and the prob went away.

dieselp

i had an 05 with the same issue they tried ti re index but had to replace the trans there is a tsb out some where i dont remember where and the issue was something with the trans and cadillac new about mine was fixed free under warranty.

Nick Blake

I know this is an old thread but I'm having the exact same issue. What was the fix? I have the aftermarket torque arm and a few other goodies. Trans crossmember as well. Can't seem to nail down what it is.

lollygagger8

iTrader: (7)

Torque arm?
If it's the BMR curved thing, get rid of that time bomb.

Re-index your driveshaft.

Mark it, and turn it one bolt hole and go try it. If it doesn't help, move it one more bolt hole and repeat.

Nick Blake

I do have a BMR torque arm..... So indexing the driveshaft is known to be a fix? I'll give that a try. Probably do u joints at the same time. What should a shop charge?

Darkman

iTrader: (2)

Indexing the driveshaft can be a fix, if it is the problem. The driveshaft is not considered serviceable by GM although there have been some aftermarkets attempts at it.

The vibration issue can be attributable to a known weakness in the Tremec T-56. Specifically, 6th gear (and 5th gear for that matter) is not robust enough to support frequent acceleration as opposed to cruising at constant speed - it is a true overdrive. Consequently, 6th can fail (begin to vibrate) in CTS-Vs that have been driven conservatively - i.e. either short shifting into 6th to keep the rpms down, or failing to downshift when climbing hills or passing. If this is the issue the only fix is to replace certain 5th/6th-related components inside the transmission.