Vibrations (not good ones)

[Tanguero]

My Cerb has gradualy developed a speed related vibration, at 75-80 mph it starts to shudder, this disappears by 85. It doesnt feel as if it is from the steering, more like the whole car vibrating. I recently upgraded all the suspension (and diff) bushes to the Polybush ones (and had a full realignment after) and this made no difference at all. I have also had all 4 wheels rebalanced - again without improving it. The severetiy of the vibration seems to be very slowly getting worse :-(


The other vibration problem I have is since I changed my clutch, when I pull away in 1st gear I get a very brief (but irritating) judder. Different revs, different speed of releasing the clutch make no difference. It also seems to be there in reverse. I guess its possible the slave is not moving smoothly but I really dont want to have to take it apart again!

Any suggestions as to what to look at for either of theset gratefully received!!

Edited by Tanguero on Friday 24th April 03:15

[Demondad]

I have a very slight vibration about the same speed most noticeable on smooth roads and I spoke to Martin at Racing Green about it. He says it can sometimes be the prop shaft alignment/balancing which IIRC means getting it balanced. If you removed the prop shaft from the diff then be sure you reconnected exactly in the same position.

[Tanguero]

Unfortunately it started before I disconnected the prop-shaft :-(

[ridds]

Does it only do it while releasing the pedal?

Sounds like dodgy friction discs or pressure plate to me.

[JensenA]

It's hard to picture what sort of 'vibration' your getting. But the exhaust can come into contact with the chassis and this gives a really noisy, buzzy vibration at certain rev's.

[Tanguero]

The vibration is a shudder that affects the whole car - I feel it in the seat rather than the steering wheel or pedals. It seems to fade and return with a period of a second or so. The best I can describe it is a repeated 'thrummmm-thrummm-thrummm' with each 'thrummmm' lasting a second or so and not quite fading away. Outside that particular speed range - either slower or faster - there is no hint of it what so ever.

It isn't affected by braking or steering and seems to be a pureley speed related resonance. It doesnt make any difference if I lift off or power through it, i.e. it happens in the same speed range regardless of if I am accelerating up through the range or decelerating down through it.

Edited by Tanguero on Friday 24th April 12:46

[methodwares]

get your wheel bearings checked... could have a flat spot

[jonbarrett]

I had that, dissapeared after new tyres.

[southendpier]

Wehn I had my raceproved clutch put in it took maybe 800 miles to bed in - before that the judder on take up was terrible. Now as smooth as a baby's ass.

[Tanguero]

southendpier said:

Wehn I had my raceproved clutch put in it took maybe 800 miles to bed in - before that the judder on take up was terrible. Now as smooth as a baby's ass.

Thanks for that - I will live with it for a while and see if it goes :-)

[Tanguero]

jonbarrett said:

I had that, dissapeared after new tyres.

Was that new tyres of the same type or a new type?

[Tanguero]

methodwares said:

get your wheel bearings checked... could have a flat spot

I will have a look at that - thanks!