rattling clutch, vibrating rear end

[Fizzy]

took my car out yesterday, only for a short trip to the shop, and got a new rattle.

with the engine running, the car in neutral and the clutch up, i get a rattling noise coming from forward of the drivers seat. when the clutch pedal is pushed in, the rattle dissapears, then comes back if you let the clutch up again.

i plan to replace the clutch anyway as it is slipping, so im hoping the rattle will vanish aswell. any chance of that happening ?

also, my mk3 spit has a mkIV engine. is there anyway to know if i have a mkIV or mk3 gearbox without looking ? i.e would a mk3 gearbox work with a mkIV engine or vice versa. so i could possibly eliminate one or the other.

finally, when at about 40-45, the rear end vibrates. im guessing it could be something to do with driveshafts or UJ's ? when it comes to mechanics on my car like those parts, as Manuel said, "i know nothing". :-/

[Clive]

Rattle, could be all sorts, but if clutch then should go with a clutch change, but replace the clutch pivot pin/bushes/crinkly washer all at the same time.
Gearbox, the difference is mk3 has no synchro on first, mkIV does. So if it crunches into first when moving a lot then probably MK3! Otherwise no differences to worry about. Well, the output flange is square on the MK3 and has 5/16 bolts, the later cars round flange and 3/8 bolts. But they can be swapped etc.
Vibration could be: bent driveshafts, tyres iffy, bent wheel, worn UJ's in driveshafts or propshaft. Plenty to investigate!

[Fizzy]

right then. i dont have synchro so it must be a mk3 gearbox. i should have relaised that haha. the tyres are all new and the wheels were refurbed just before i brought the car, so im hoping that wont be the problem. cheers for the help, plenty to consider................

[sparky_spit]

Do you have to push the clutch pedal down all the way to get rid of the rattle? Or just take up some pressure? If the noise goes with just a light pressure it could be the clutch release bearing causing the noise.