RS Clatter at Idle - is it the Clutch or Gearbox?

kasbridge · Jul 4, 2008

All,
The infamous clatter that we get with the cars idling and in neutral - is it the clutch assy/release bearing that makes the "rattly" noise or is it the gearbox itself. My rattle seems to have got worse recently and makes a bit of a clatter when I stop the engine - sounds like someone shaking a tin of old nails as the engine comes to rest.

Had my gbox oil changed today and having an attack of combined inquisitiveness/paranoia - like you do....

Thanks,
Kevin.

clubsport · Jul 4, 2008

Noise from the gearbox being transferred up through the solid single mass flywheel and harder engine/box mounts.
The regular dual mass flywheel as fitted to C2/4 has a layer of silicon gel sandwiched between the 2 metal parts of the flywheel, this "flexible" middle reduces some of the noise and harshness, which is why the boxes are so much quieter than in the RS versions.
Of course, when you pull away the Lsd starts to move, which is the coffee grinder noise, you hear up to just over 2k rpm....hopefully the box/lsd quieten down as revs rise and the more interesting noise of the engine takes over.

65 mat · Jul 4, 2008

You're a poet but ya just don't know it![

]

kasbridge · Jul 5, 2008

Clubsport,
So the "tin of old nails" noise when turning off the engine is normal then?
My gearbox works fine btw,
Thx,
Kevin.

ChrisW · Jul 5, 2008

Interestingly the steel synchromesh on the RS is reputed to make the noise worse, I wonder if that was why the synchro on the first 996 GT3 was bronze ? --- then on the last ones changed to steel and then steel for the MkII which returned to a dual mass flywheel.

The lightweight flywheel on the 964 also seems much lighter than that on the GT3 !

993, I can't comment.

I have also found that LSD's differ very markedly, and are more aggressive when hot ?