bad drivetrain vibration...

[toolboy62]

Well, I got a chance to change the axle that had the bad CV boot today... no change. Apparently the bad CV boot is unrelated to the vibration problem I've been having.

Basically - I have a vibration that starts around 70 MPH and gets bad enough by 80 MPH that I don't want to try going any faster. It actually feels like two vibrations almost in sync, as there's a beat frequency of less than 1 Hz which makes it even worse. All CV's are less than a year old, and wheels turn freely with no apparent drag or "crunchiness."

It feels like it may be coming from the rear of the car, although I couldn't say for sure that it's not a front wheel. Front wheel bearings were repacked less than a year ago with Redline grease; all old grease was washed out before repacking and all bearings looked OK.

The car was hit fairly hard in the LR while parked beside my house - it actually just came back from the body shop last friday after having a new quarter put on - and I can't say that the wheel wasn't bent, but I'll be pissed if that's the problem as they put a new tire on the car for me (because when I moved the car from the side of the house to the front, the tire hit the fender lip a couple times and chewed up the tread.) Could the bearing still be bad/loose even though it feels OK when checking by hand?

Is it possible that a hard hit could have damaged the transmission in some way? (doesn't seem possible, as the CV's allow the driveshaft to change length...) Is there even a failure mode of the tranny that could cause this? (I tried coasting with the clutch disengaged, and also with the trans in neutral, no change...)

Any ideas, before I make an appointment to take it in? This is starting to suck; I was so looking forward to having a functional car again. And I just fixed the sunroof, replaced the bushings on my sway bar (had a busted bracket) and bought the little duct I was missing for the alternator cooling setup! (was going to be nice to the car and fix a few things that'd been bothering me for a while...)

thanks,

nate

[nynor]

bent wheel is where i'd start.

[pokey]

Check the alignment yet?

[Brando]

while getting your alignment get all wheels balanced.

[JivenJim]

Jack with parking brake on, and see if wheel is loose while bolted tight. Maybe Rear Bearings?
Could also double check that the body mounts are tight. (Look up in wheel well) Check all rear Bolts on trailing arms and toque Bar Tub. See Clarks Garge for pics. Rims could be bent. Get em ballanced if all else fails.

[Pesfaria]

Hi guys!

I am owner of an 1983 944, not turbo, and my car has a vibration too, but it is when I start moving the car, I need to acellerate it to 2.000rpm and leave clucht a little at a time, this way it does not have vibration, it came from rear too. The vibration starts again always when I reduce the gears without acellerating togheter (punta-taco) if I do the punta-taco, acellerating it togheter with reducing gears it does not have vibrations too... do you know what it can be?

[JivenJim]

Pesfaria,

Sounds like a clutch going bad to me. IF you are driving at speed and push the clutch petal in all the way and the vibration stops, if when accelerating hard and letting out on the clutch it take a few seconds for the full acceleration, or if you have low RPM's easy acceleration vibrations, might get up to get that Clutch and pressure plate checked.

[Pesfaria]

I was thinking on clutch too, but the older owner told me that he changed it and the vibration get lower but does not stopped... but he was a pig on car maintance, did only bad services, I am going to check the clucth!

Thanks!

Paulo