1Loudz28

iTrader: (47)

My car (99 m6 z28) has recently developed a horrible vibration.

i did a bit of driving this weekend to try and track down at what speeds it starts, stops, etc.

starts around 65-70mph @ 1500rpm, and its really bad. shifter shakes a decent amount and my seats feel like theyre a freakin massage chair. if i run it up to around 80mph, the vibration is still there, but slightly less.

throw it in neutral, its still there. does NOT get worse if im up to speed, in neutral and i rev it to the revlimiter, making me believe its not the clutch/flywheel..plz tell me if im mistaken.

im pretty sure its either a bent input shaft on my driveshaft or bad ujoints. i went under the car and couldnt find any play in the ujoints, pulled the driveshaft and noticed there was a faint black line going around the input shaft. is this a bad sign?

also have a new poly trans mount.

ideas, thoughts?

fleetmgr

Bad u-joints will usually chirp at you as they die. A bend somewhere in the driveshaft is possible, or it may have thrown a balance weight.

First thing I'd check is tire balance, though.

1Loudz28

iTrader: (47)

funny, ive been noticing that after i back up my car, then go forward, it feels like theres a minor clunk that i can feel throught shifter...that sounds like the ujoints?

gonna have the tire balance cehcked today.

4WOFURY

iTrader: (2)

Are the tires/wheels balanced properly? Just throwing that out there.

1Loudz28

iTrader: (47)

update: just had the wheels balanced, they definitely needed it but the vibration is still there.

veddersbetter

iTrader: (7)

Theres another post on this .. Seems the M6 and poly trans mount are common factors
https://ls1tech.com/forums/general-m...nce-issue.html

1Loudz28

iTrader: (47)

hm, guess ill swap a stock mount in this weeekend.

veddersbetter

iTrader: (7)

Please let us know if it helps