Vibration on 996 C4S...

Bradmc · Jul 10, 2020

Hi all,

Would really appreciate your thoughts on a vibration which occurred yesterday.

It was a pleasure to finally stretch the legs on my 2002 996 C4S as we drove through France, Belgium and Germany. Being faster roads I was able to get some speed, but for the first time I experienced a vibration, occurring from 81mph onwards. Anything below 80mph is ok, no vibration.

I can feel the vibration through the seat, possibly from the rear if I had to guess, yet nothing via the steering wheel. I took it out of gear while at speed, i.e. coasted, and still vibration, which tells me it’s not engine related?! As you've guessed I'm not a mechanic!

What areas do you feel is worth investigating? Wheels and/or tyres? Anything else?

As I say, it only happens from 81mph onwards and as we drive overseas each month I’d like to eradicate the vibration.

Your thoughts would be greatly appreciated.

Thanks

wibble · Jul 10, 2020

Difficult to diagnose without being checked on a ramp. Anything from a wheel balance weight come adrift, bearing, suspension bushes, drive shaft or uneven tyre wear ..... I would start with simple check of wheels/tyres/pressures and go from there.

don alexander · Jul 11, 2020

Had a similar problem with my 2002 C4S a few years ago. Car was very low mileage and tyres although not worn were about 6years old. These were replaced and vibration was reduced but not eliminated. A further careful balance of wheels virtually cured the problem although I was subsequently told that this was not an uncommon problem with these cars. Like you it only really showed up on continental trips.