Vibration on S1 Elise under acceleration

[moosetvr]

Hi, first post on here so please be kind!!
Wife has an S1 Elise 99 and under heavy acceleration, especially around 4000 revs (usually most of the time when I am driving!!!) there is a very severe vibration/wobble that appears to be coming from the rear.
I have had the rear tyres replaced (and balanced), new rear discs and pads, and this still hasnt solved the problem. Had the issue checked out @ last service and Lotus specialist couldnt see anything wrong.
Any ideas would be gratefully received as it is spoiling driving such a fun car.

[greysquirrel]

is it actually a vibration that is affecting the handling or just a squeak/annoyance?

[tonyhetherington]

Hi! Firstly, welcome to PistonHeads

The wobble and such like - I'm surprised your dealer couldn't find anything.

Dumb question; is it at 4000 revs in all gears, or only in one? (to suss whether it's engine related or speed related).

The wheels getting balanced is the first point of call, which I see you've done, so it's obviously something more severe. Perhaps an engine mount?

Can you describe in more detail the wobble/vibration?

[moosetvr]

You can actually feel the car shake as you accelerate. Feels like a buckled wheel, but they have been balanced and are ok.

[tonyhetherington]

Do you feel the shake through the steering wheel?

Have you had the front wheels and tyres looked at also?

[moosetvr]

All four wheels have been balanced. It actually feels as if the whole car is shaking, you can feel it through the seat!!!

[anonymous-user]

Check that the rubbers on the exhaust mounts haven't cracked or perished. Those on my S1 went and the car felt like it was shaking to bits between 3-5K revs.

[scuffham]

long shot.....

if this only happends under hard acceleration, but not at the same speed on cruise, etc, then it sounds like the in-board tripode joint is on it's way out (the gearbox end of the drive shaft)

[markie*mark0]

i have the same problem on my 98 s1 elise, i recently bought a new flex section for my exhaust and since i fitted it when i accelerate (@ 3-4k) it rattles like i dont know what ive had it up in the air and i couldnt see the exhaust touching the belly pan or any mounting loose anyone got any ideas?

[moosetvr]

Funny you mention it but I had my flexi section replaced recently and it has been happening since then!!