its a stock 5spd. 81' ZX (my other daily driver). just got her and the driveline has some seriously noise clunks in between shifts and vibrates the hell outta you past 45mph. for instance, if im at a stop light. i can put the car in first gear. then, i can put her in Neutral, let out the clutch, and "CLUNK" .it sounds just like when my 260 had a bad u joint in the halfshaft. i got under there the other day and cant seem to find any play in either halfshaft. so im going to take the shafts out of my other 280 today and put them in and see if that makes a difference.

MY question is this: if it is not the halfshafts, then what in the driveshaft would do that? some transmission guy told me the center bearing? so now im picking the guru's brains. thanks ahead for your input!

I would check all of the cushioned mounts for the diffy/rear suspension, and even verify the motor mounts, sounds like a couple of those are at the very least contributing to another problem. Because they are all external to the drive train, they will be relatively easy to check, without completely disabling the car-not that you should be driving it as it is...

Verify that the vibration is only present under power. coast at 50mpg and put her in neutral, if the vibration does not stop, check your tires for a telltale wear pattern. If the vibration stops, you have driveline issues.

Will

yeah, forgot to mention that. only vibrates under accel. put in neutral and coast, its fine.

Does it happen only in one gear(wind out the lower on to see if it still happens, or under drive the next one up for the same reason) if it one gear, pretty obvious as to the cause, if in each of the three, still not too hard to figure.

Here is some help...

Will

problem solved, bad rear u-joint. are these driveshafts servicable? im talking about the main propeller shaft not the halfshafts.

what year is your Z? I know that on my 72, the driveshaft u-joints can be replaced with a hammer and a socket. If they aren't serviceable, any driveline shop should be able to remove your current u-joint, and press in another one.

nah, the ZX is supposedly not replacable, but a *GOOD* driveline guy can do it. i just pulled a good shaft off a buddy's parts car, only cost me 35$. cant beat that!