trying to figure out why my whole car shakes when i leave in first gear. i just had my clutch replaced and flywheel turned. Drained my rear end (no shavings) and replaced gear oil. theres not and out of the ordinary play in the u joints. although the rear by the pinion has a little more than the one by the tranny? could that be it? it only happens in first gear when taking off. not only launching. but when going reallllly slowly. it shakes real bad. the whole car, its not just a vibration, its more like an earthquake.
and help would be awesome

 

I've got some odd vibrations as well. I just swapped a T5 into my 86 IROC.

Need some more details.....

Does the shifter move (as if the trans mount/motor mounts are bad?)
It goes away in every other gear?
Vibration is not only from dead stop, also a roll or downshift?
Does the car seem square/stiff when driving (as in the rear suspension is all good and not moving around and affecting driveline angles?)


It sounds like the higher numberical 1st gear is able to change either driveline angles or maybe the lower driveshaft speed makes the problem of bad ujoints/driveshaft/yoke/pinion more apparent.



Let us know what you find out.

 

Also, what condition is the clutch/flywheel in? I've had some older 4 speeds that were finicky about the flywheel surface. The clutch would grab really early upon release on the high spots on the flywheel, and would shake the whole dang car until the car got moving.

 

Might want to check your bushings and mounts...

 

my clutch/flywheel are good, brand new basically. i checked all my bushings and mounts. i thought it might have been the torque arm mounts but those are fine. the tranny mount is a brand new poly mount. and i get slight vibration from the poly mount if i hold my idle @ 900 rpm.

it only happens from a dead stop.when i just about disengage the clutch fully. not any other times. i talked to a tranny shop today and he drove it, said that the backlash by the pinion might be way over. it doest happen into reverse really because the driveshaft is spinning the other way the pinion doest have to travel the backlash. i put it on a hoist and there is no play in the u-joints. but just over an inch in the pinion. its not vibration, the whole car shakes violentely, almost as if its gonna rip in half. the shifter does shake but if your under the car (i have open pits) the whole driveline shakes.

he said it might be the rear diff. and if so, time for a 3.73 posi. mines not even limited slip, pretty stupid for a z28 huh?

 

so its the diff. everything was loose, the bearings are shot and the gears are worn. time for an auburn posi with 3.73's! oh ya