Weird Drivetrain Vibration... U Joint or Mount?

[craig0ry]

I have this weird drivetrain vibration that started lately. It even affects my exhaust note, BUT ONLY in gear. In neutral the car is perfectly fine and acts just like before. As soon as I throw it in drive, it starts "shaking" and the exhaust gets a rhythmic "thumthumthumthumthum" noise to it.

I can't figure out if this is a U-joint or a trans mount? The motor mounts looked fine.

Any help would be appreciated!

 

[jmccloud]

Vibration

If the noise occurs when the car is stopped, it's not likely the u-joints.

The motor mounts and trans mount are most suspect, but I had a car (long time ago) with similar symptoms and found an exhaust pipe too close to the frame. Putting the car into gear torqued the mounts just enough to cause the pipe to touch the frame and make an irritating hum with a beat noise (loud - quiet - loud -quiet). Holding the brake and giving a little gas changed the noise. When it warmed up, the noise was again different, sometimes gone.

Can you get it on a lift to check it out? A 3-4 foot piece of garden hose in one ear and the other end poking around (like a stethoscope) aids noise location and you might even find the source with the car on the ground (block the wheels).

Hope this helps