Well, I have been experiencing a vibration/noise problem with me car for a while now, and can't seem to figure it out. I just recently rebuilt my trans (M6) and installed a new McLeod clutch, pilot bearing....etc.

Here is the problem: I have a major HIGH SPEED (over 100 mph) vibration. It is louder when I let off the pedal than when the driveline is under load. It rattles the crap out of my center console and is so loud at around 120 or so that it feels as if the car is going to explode.

I have heard that if the level of vibration is not constant, than it is most likely that it is not the tires/balancing, D.S., or trans.

Now, I am trying to find the culprit via process of elimination, and so far have removed the possibility that it is anything IN FRONT of the driveshaft.

I am going to balance my aluminum DS and install new U-joints next week (I need to do this regardless of whether or not this is the culprit) and following that I guess it's time to inspect the rear. The rear was rebuilt 21k ago with the best parts - Eaton Posi, Moser Axles, Motive Gears....etc. BUt this was done RIGHT before I bought the car, so lets just say I didn't really break it in...

I am almost positive that the rear is the problem, being that the car is just silky smooth until the high speeds. If it were the trans, the vibration would be evident at low speeds and high RPM. I am eliminating the tires/balancing due to the fact that the tires/wheels have less than 3k on them and I had this prob even before that. The only issue with the wheel/tire combo that I can think of is that I am using 120mm bolt pattern, but many of you do this with no issues.

The other reason I am eliminating the wheel/tire combo is that there is a completely noticable nite/day difference in the noise/vibration level in terms of acceleration and coasting...when COASTING down from high speed the vibration is much louder.

ANY THOUGHTS/SUGGESTIONS??? Driveshaft or Rear?

Does my reasoning/diagnoses seem to be correct?

Any help is appreciated- sorry for the long post.

-Matt

 

BTW: before everyone says : " sounds like Driveshaft, get an aluminum 1LE piece and you'll be good".....

I already have an aluminum DS and it looks good thus far...however I don't have a clue how many miles are on it, at least 21k though.

 

LOL!!!!!

I installed a 20k Mile LS1 aluminum DS today That I got from a friend for $50.

It's fixed!!!

I guess I must have thrown mine out of whack somehow!

Now I feel like an idiot for the previous post.....

 

I am having the same problem, and I just got a LS1 aluminum driveline, but I noticed its about 1/4" to 1/2" shoter was yours the same way. I need to know before I put in in the car and tear something up.