Clutch judder

[rob07]

I have a classic Austin Healey sprite which I replaced the whole clutch a long time ago. Since then it never worked great but recently after getting a bit hot the clutch judder was worse than ever so I pulled the engine to have a look. There is no discoloration on the flywheel face,no cracks or uneven wear. The clutch (Borg and Beck) disc/cover/release bearing are almost as new with no visible defects whatsoever. There is no oil on the surfaces and my engine and gearbox mounts are good.
I don't want to put in another clutch as it's likely to be of inferior quality to what I installed many years ago,but I still need to find out the cause of the judder.
Any suggestions?

[xstian]

Have you put a dial gauge on the flywheel?

[GreenV8S]

State of the spigot bearing?

[rob07]

I've just spotted that the small cast iron thrust plate (which the release bearing acts on) has a non concentric wear pattern on it's face. This may well be the cause of the judder.

[littleredrooster]

Probably worth checking the engine and gearbox mounts, too.

[GreenV8S]

rob07 said:

I've just spotted that the small cast iron thrust plate (which the release bearing acts on) has a non concentric wear pattern on it's face. This may well be the cause of the judder.

Yeah, that can't be good. Maybe a clue you're getting unbalanced forces on the clutch due to contamination, weak finger spring, uneven wear, worn spigot bearing and so on. If you found a way to get the clutch cover installed off-center I'm sure that would cause similar havoc.

[rob07]

Clutch cover has locating pins so mounts perfectly. The thrust plate is not the issue. It seems the three locating levers are somehow misaligned.