Clutch shudder

[John McCormack]

When my TR6 is cold the clutch works fine. When the car is warmed up/hot the clutch shudders. I counter it by using a few more revs when taking off and slipping the clutch a little bit. I don't always get the timing right and get a fairly severe shake.

The car is a CP which has had a J type overdrive gearbox installed. The gearbox mount is a hybrid based on a BMW mount which I suspect could be the problem. The engine mounts are quite new.

However, countering the view the gearbox mount is the problem is that it is ok before the car is warmed up. It could be the clutch itself, the operation of which which would change when hot.

Has anybody experienced these symptoms and what was the solution?

 

Edited January 27, 2023 by John McCormack

[Mike C]

I had this happen and I could see the engine move when I released the clutch with the engine hot, bonnet up.

My problem was caused by excess movement in the rear mount in the centre of the OD, just under the propeller shaft. I replaced it which fixed the problem- with the old mount oil leakage had de-laminated the rubber from the steel and the GB was just sort of sitting on it unrestrained.

[harlequin]

John

Two of the bellhousing bolts are a fractionally larger diameter and are a close fit in their holes, this is to ensure good alignment of the gearbox and prevent clutch shudder. These bolts are often lost and swapped for standard bolts so worth checking 

The brown book will show the locations, what is required is to slacken all the bolts insert the close tolerance ones which takes a bit of wiggling then re tighten the others.

George 

[John Morrison]

2 and 8 O’Clock

3/8 shouldered bolts

John

[Kevo_6]

[matt george]

As pointed out by the guys above, the use of the correct dowel bolts is crucial. I was plagued by a shuddery clutch for years on on my 2000 saloon, clutch starting to 'stick' just as you got to the biting point. Also, with the gearbox out, there was a wear mark on the final inch or so of the gearbox nose piece. Clearly the release bearing carrier had been catching on it, which also wouldn't have helped. I ended up mixing and matching from a few spare nose pieces and bearing carriers to find a pair that fitted together smoothly, so to speak. The combination of that and the correct dowel bolts sorted the issue, resulting in a lovely and smooth clutch action.

Matt

Edited January 27, 2023 by matt george

[John Morrison]

Assuming that John has his gearbox correctly aligned to the engine, and 

considering that the clutch works fine when cold, might be thinking about oil on the friction plate? getting there when hot.

 

John.

[Mike C]

John,

I assume that the clutch judder is a fairly recent development and you haven't done any work on the clutch for a while, if that's the case I find it difficult to accept misalignment as the cause.

[FatJon]

The exhausts run right under the gearbox mount. It's probably a bit marginal and when it's hot and softer it's got too much movement.