low speed vibration

[paulm01]

Hello,
I just bought a 97 M3 several weeks ago and I'm trying to figure out a rear end vibration. It happens between 2500 and 3500 rpm in second gear and about the same rpm in third when cold. It's not noticeable at higher rpm's and other gears. The vibration was there when I bought the car, since then I've installed new tires all arond and done an alignment. The vibration tends to go away when the car is driven for a while (over 5 miles). I looking for suggestions, of all the things I've read that may be the culprit, nothing seems too obvious. (guibo etc)
Thanks for your help.
Paul

[paulm01]

the car will be going up on jackstands this evening. Curious to see what condition the guibo is in. The car has 81500mi so it could be time to replace the tranny mounts and also guibo, center bearing etc.
How can the tranny mounts be too tight?
thanks for your replies.
Paul

[fiveightandten]

If it's engine speed related, and not related to vehicle speed, I wouldn't point the finger at the Guibo (though, initially that's what I would've been suggesting). The drive shaft spins according to vehicle speed, independently of engine RPM.

Check your exhaust hangers. Check your tranny and motor mounts. Check your cooling fan for any signs of the blades contacting anything.

That being said..definitely check the Guibo out, as it could just be a coincidence that it's causing vibrations at 2 different speeds which happen to coincide with equalivant engine RPMs in 2 different gears.

-Nick

[paulm01]

No signs of wear and tear on the guibo, the tranny mounts look as though they have been replaced although the whole car is very clean, it's hard to tell if they're original or replaced in the last year or so.

Motor mounts look somewhat suspect, just because they were the oldest looking of the bunch, but no cracks or tears breaks, not loose. Everything looks and feels just as I would think it should be.

I'm contacting the previous owner to get a handle on what service had exactly been done on the car. He mentioned it had been dealer serviced, and he owned the car for seven years so any of the work more than likely had occurred while he owned it. guibo, mounts, clutch etc.

thanks for the suggestions.
Paul