Shudder/Vibration while slowing to a stop
 

Hey,

My 97 Boxster (2.5L, 64k) has a weird quirk, and since my pre-owned warranty will expire in December, I'd like to figure out what it is before then (or at least know whether it's something to be concerned about at all).

When I exit off the interstate every day, I let off the gas around 60-65 mph in 5th gear, and let the car slow itself down (clutch still engaged, though). When it reaches around 50 mph or so, it will shudder/vibrate for about 2-3 seconds as it's slowing down. If I recall correctly, it happens just north of 2krpm.

I've also noticed it less pronounced when slowing in 3rd gear at slower speeds -- but I think it happens right around the same point -- 2k-2500 rpm, and only with the clutch engaged.

Otherwise, the car is in superb mechanical condition.

Any thoughts??

When is the last time the tires were balanced?

Definitely not a tire balance issue -- it only happens when the clutch is engaged, and you are slowing down (foot entirely off the gas).

Besides, it's RPM-sensitive, not speed-sensitive. Hence, it happens around 2k rpm whether you're in 5th gear or 3rd gear.

But since you brought it up, for comparison's sake, it's quite a bit LESS violent than a car with badly balanced tires.

Thanks for the reply!

It's probably the flywheel balance or a deteriorating pilot bearing. We have the same problem between 2700-3200rpm. It's a little worse in the lower gears than the higher ones. Watch the rpm and see if it's the same no matter what speed you are going, then you'll know if it's a driveshaft issue (flywheel, pilot bearing, clutch) or an axle/wheel issue.