993 C2S advice please - wobbling like mad at speed

[mmm355]

I was buzzing up the M11 on Thursday and my 993 2s suddenly developed a serious vibration which unnerved me somewhat. I checked the tyre pressures, they were fine. Steering seems ok but it definitely feels very shaky. Not an expert at all - I was guessing it was something to do with suspension. I also got worried someone had undone my wheel nuts in the drive - Porsches do make you a bit paranoid sometimes don't they? Anyway - any ideas before I tak it in for a check up

Thank you!

[james_j]

Has a wheel balance weight fallen off?

[mmm355]

that's a thought - not sure I'd be able to tell though!

[pdV6]

mmm355 said:

that's a thought - not sure I'd be able to tell though!

Small clean patch on the inside of the rim?

[cyberface]

I've had an odd vibration like this at speed 3 times now in my 993. It only happens when accelerating hard to high speed, at which point a deep thrumming comes from the back of the car, related to road speed rather than engine speed.

On stopping the car, and driving off again, it's all fine. I originally thought the engine had let go.

Wheels / tyres all OK - however on getting under the car I noticed that the rear PU valance was loose, because one of the thin metal strips that hold it to the main body had corroded through, leaving the PU free to 'flap' on the passenger side.

Perhaps this is what flaps, only at high speed, causing the vibration? Does this sound like your problem?

[softinthehead]

what condition are your tyres in? if worn (especially uneven wear) you will get resonance at a specific speed which will change if you go slower, or sometimes quicker.
either way, sounds like a job for a clever chap with a spanner

[mmm355]

thanks guys. sounds like it could be a number of things. I've booked in for a check up

[silver993tt]

Mine did that about a year ago, got the wheel alignment sorted and problem went away.

[mmm355]

Thought you might like to know that the reason my car was wobbling around so much was because it appears that someone forgot to tighten up the wheel nuts after a bit of work I had done two weeks ago! You might question why I didn't spot this - I just would never have expected that in a million years so it didn't cross my mind! Oddly I also had a nail in the tyre and another in the right rear. I had a puncture two weeks ago in the front drivers side. I'm wondering if it's being sabotaged although the locking nuts were not tight so it does suggest that the wheel was taken off and then put back on.

Someone was asking about cars being vandalised not long ago. Seems a bit odd to have 3 nails in 3 different tyres doesn't it. Hoopefully it's just coincidence.

>> Edited by mmm355 on Friday 24th June 14:27