Rear vibration under hard acceleration?

[R1 Indy]

Ive just replaced the tired springs/shocks with coilovers and replaced the bushes with polybushes on my S2000.

The good news is the handling is in a different league, so there was obviously something wrong with the old!

The bad news is Ive got some vibration coming from the rear when accelerating hard, generally once VTEC has kicked in!!

Ive got the coilers set on the hardest setting, could this cause a slight vibration seem a lot worse than it is?

The only other thing i can think of is the P/S driveshaft fell out while wrestling with the lower arm, I'm sure i put it back right, i.e. the 3 round bearings on the 3 pegs, and then slotted back in the grooves?


Ive just had a basic 4 wheel alignment done so everything is relatively aligned. (i have got it booked in for a full alignment/corner balancing etc in a months time)


Anyone any ideas what could cause this?

Or is this normal with stiff suspension and bushes?

Cheers

[Vaud]

A slightly misbalanced wheel? Slightly warped alloy? Tyres pressures all even and accurate? Are you running the right tyre (thinking sidewall stiffness)? Are both rear tyres matched?

[Jurgen]

It's the inner cv joints (near the diff) that cause the vibration. You either need to swap the cv joint cups around (not the entire drive shafts) of buy some driveshaft spacers (or ideally do both). There's plenty to be found on the subject on most s2000 forums!

[R1 Indy]

Jurgen said:

It's the inner cv joints (near the diff) that cause the vibration. You either need to swap the cv joint cups around (not the entire drive shafts) of buy some driveshaft spacers (or ideally do both). There's plenty to be found on the subject on most s2000 forums!

Great thanks will look into this. Would this be caused by me disturbing the shaft?


The tyres etc are all new and balanced and correctly pressured.

[Jurgen]

R1 Indy said:

Great thanks will look into this. Would this be caused by me disturbing the shaft?

The tyres etc are all new and balanced and correctly pressured.

Very unlikely that you caused it. The cv joints wear in a certain way (pitting in the cups). When you lower the car the axle will be at a different angle in the cup and the wear pattern will cause vibrations (mainly under load). If you swap the cups they will effectively turn the other way around and have no wear on that side.

My explanation is a bit hopeless, but you should be able to find a load of threads about it on specific S2000 forums. It's unfortunately a very common issue when lowering the car, especially when it has already done quite a few miles in original configuration.

[R1 Indy]

Jurgen said:

Very unlikely that you caused it. The cv joints wear in a certain way (pitting in the cups). When you lower the car the axle will be at a different angle in the cup and the wear pattern will cause vibrations (mainly under load). If you swap the cups they will effectively turn the other way around and have no wear on that side.

My explanation is a bit hopeless, but you should be able to find a load of threads about it on specific S2000 forums. It's unfortunately a very common issue when lowering the car, especially when it has already done quite a few miles in original configuration.

Excellent you were spot on!

I took the passenger side apart first and there was very little wear.

However when i got to the drivers side, there was very little grease left and some very obvious pitting/wear.

The bearings where black and obvious lumps of crud in the cup.




So its pretty obvious the vibration was coming from here, even though i was sure it was coming from the passenger side!


Swapped them around, vibration gone!

Cheers