vibration when not moving.

[mitch500]

ok so i strated up the e30 yesterday(m20b27) and i noticed a bad vibtation coming from the motor. i immediatley thought oh one of the motor mounts has crapped out. anyways i really need to drive only a couple of blocks so i did anyways because i really didnt care. soo i started driving and it got alot worse. i could feel the whole drive line was out of wack. ther drive shaft felt like it was playing jump rope and the rear diff was also vibarating violentley. when i came to a complete stop at the light it started to go away then when i started moving it was gone? what gives? but heres the thing im still set on motor mounts because
1. it vibrated when not moving during start up
2. i was in nutral so nothing past the motor would have been in motion.

so what do you guys think am i correct?. im going to be getting under it soon enough here its just i work so damn much i never have time to get under it.
thanks in advance.
-mitch.

[brandon11130]

look for cracks in the motor crossmember, i had this happen in a car, the motormounts were fine, after closer inspection part of the motor crossmember had cracked and was causing the extreme vibration

[Teaguer]

I doubt your diff was actually vibrating . ;)

Is the engine running and idling as it should ?
Or is it running rough and stumbling ?

[mitch500]

I doubt your diff was actually vibrating . ;)

Is the engine running and idling as it should ?
Or is it running rough and stumbling ?

engine runs fine. there is just a vibration when im not moving. and when i start to drive it transfers all the way down the drive line. then as i said i stopped at a light and it all went away.?

[mitch500]

k i checked the crossmember for cracks and came up with nothing, aslso the motor mounts look great. what else could it be it didnt do it today so maybe it was just a freak thing.? could it be the harmonic balancer on the front of the motor>/?

[uofom3]

check the flexdisk.

[maco325e]

Low RPM?

[AndrewBird]

check the flexdisk.

Flex-disk isn't moving when stopped.

[Elephant]

Pressure plate, clutch, flywheel....those can all cause horrible vibration if something is wrong with them. And that won't matter if the car is moving or not. Clutch disc is least likely.

Though you seem to have ruled it out, I might also, first, think injector misfire or running on 5 cyls.

Cheers.

[mitch500]

yeah ive been driving it for a while since it happend with no issues. i took it on a 300km trip and had nothing wrong with it. also checked the flex disc and it looked new. no shredding. maybe it was just a freak thing and all is good. but i guess we will see.

[bimmer_E30]

hahaha like what happened to me in winter the car idles like shit and now idles so smooth . maybe e30's hate cold and winter.