On a drive home from L.A. my (2003, 110,000 mile) S2000 suddenly became impossible to smoothly launch from a stop. Reverse seems even worse than first. No matter what the driver input it shudders, bucks, and jerks from the point it starts to grab until the clutch is fully engaged. Engaging while already rolling, 1st-2nd, and higher shifts are not nearly as violent, but still don't feel "right" anymore. Here is the related work I've done lately, based mostly on searches here:

Changed fluid with a turkey baster (three times now, it gets dark after a few hundred miles). Checked for leaks (none found, fluid level doesn't drop). Removed nipple/polished ball joint at slave cylinder, greased the ball and fork, adjusted clutch engagement.

 

sounds like a slight misfire? Compression, spark plugs would be where I'd look next..

 

I don't think it's the motor; everything feels normal once it's in gear. In the higher gears it's much more driveable but I can still feel a harsh vibration while the clutch engages, almost as if the surface is warped.

 

Any noises? Diff? Check the small things, like engine mounts or transmission mounts. Even differential mounts. Could be things like wheel bearing. Any work recently?

 

There's some noises here and there, but a worn out clutch was the main culprit. I'll get some photos of the carnage next week.

 

Bearing was installed dry and and failed, destroying the clutch. Unfortunately the shop found several other signs of amateur bungling, but it's all being put right.

 

That'll do it. Glad you found the problem.
A similar thing happened on my son's Del Sol. The cage that holds one of the springs in the disk failed and allowed the spring to come loose. Very scary clutch issues when that happened. Weird grinding noises, engaging quickly, etc.

good luck
Mike M.

 

I'm glad I did some searching first and took it to the experts (Infinite Motion in San Marcos, well worth the drive)--got rear brakes, tranny/diff fluid, a valve adjustment, and a TCT while I was at it.

 

Your 2K loves you.