clutch judder S4

[triumphelan]

Having done EVERYTHING to try and cure this it`s still happening [see my past posts].It dosent happen from cold but gets worse after a few miles especially in traffic, could it be the close proximity of exhaust and clutch cylinder that it some how "boiling " the fluid.What fluid should I be using?

[512BB]

Good morning John,
In my experience, the judder on my elan some 25 years ago, was caused by oil contaminating the clutch plate. The only cure was obviously to remedy the source of the oil onto the plate, ie oil leak from the engine, and replace the complete clutch assembly. I believe that judder can also be caused by either the clutch driven or pressure plate being warped.
You might want to try some high rev starts in the car before taking the engine apart. This will burn off the oil on the clutch plate. If everything is ok after this, you will know that its oil causing the problem. That will only cure it until oil leaks back down onto the clutch again.
All the best and good luck,
Leslie

[Elanintheforest]

If there is no oil contamination, and the pressure plate and friction plate are good, and the flywheel was machined properly, there are only a couple of other things that I can think of, all of which will require engine out.

Firstly, are the splines OK on the gearbox input shaft, and does the friction plate move smoothly up and down it? Little bits of swarf or jagged edges on the splines can cause judder.

Is there any play in the spigot bearing / input shaft bearing? Having the shaft wobbling about wouldn?t help.

Is the end float on the crankshaft OK?

There isn?t anything else that moves or can contribute to a juddering clutch that I can think of. From your last post on the subject, it seems that all was fine when you put it back together?so the problem has come back. That would seem to eliminate any of the big issues identified above, and point back, as Leslie suggests, to contamination of the friction plate, or something going wrong with the friction and / or pressure plate?did you use a good make? It?s not unknown for ?new? parts to fail pretty quickly. If you do have to pull it apart again, get the best setup you can find from TTR (without it being a racing clutch).

Good luck?I can just imagine how bloody frustrating it is.

Mark

[steveww]

The clutch judder on my S4 was caused by worn out diff mounts. Especially bad when reversing. I replaced top and bottom diff mounts and no more clutch judder.

[david.g.chapman]

I have had clutch judder caused by the engine mount softening on the exhaust side. The considerable heat given off by the exhaust manifold only millimetres away seemed to be the cause.

I have fitted a re-enforced engine mount from Tony Thompson - same as standard, but with the top air space filled in with black RTV- on that side only.

I also covered the top of the mount with aluminium tape to help reflect back some of the radiant heat.

That has improved matters.

I would check all of your mounts for cracks, separation and perishing anyway before looking elsewhere.

Dave Chapman

[rjaxe]

This is what the top differential mounts can look like when they are worn, if yours are anything like these then it creates all sorts of problems in the drive line including juddering. Worth having a good look at them and the torque rod bushes.

[triumphelan]

Thanks for all the replies .I have replaced the clutch plate,release bearing ,diaphram ,spigot bearing,had the flywheel skimmed ,there was no sign of oil contamination.Fitted new engine and gearbox mounts.Had the propshaft refurbished,fitted TT drive shafts.Fitted poly bushes to rear and new mounts to top of rear suppession.
It would seem I can only change the diff mounts to try and cure this problem.
What about the clutch hydraulic fluid "cooking"?? and what fluid should I be using?

[rgh0]

It would be unusual for boiling brake fluid to cause a problem and it be more like a very soft clutch pedal than cuasing a judder.

Use a good quality DOT 4 fluid like Castrol LMA and ensure no clutch lines touching the exhaust pipe.

If true clutch judder rather than an issue elsewhere in drive train then it is due to a poor match between the flywheel, clutch plate and pressure plate such that you do not get a smooth relationship between pressure and slip speed and slip coefficent of friction.

You have done all the obvious things so it must be something more subtle or you still have a problem with some of the obvious things that you have done and the problem is still there.

Usually at this point i start measuring everthing very carefully looking for some run out or out of flatness problem in the total clutch assembly or some looseness anywhere else in the drive from engine to rear wheels

keep looking
cheers
Rohan

[gjz30075]

Is the end float on the crankshaft OK?

I think this has validity. This was the cause on another car I own. I went through EVERYTHING. I finally took it to a vendor and while putting in his components (to rule out mine) he found excessive crank endplay. Fixing the endplay solved it.

It's difficult to measure with the engine in the car. Your best bet is to drop the pan and pry the crank fore and aft to check but its best to have the engine on a stand for this.

[elansprint71]

If replacing top diff mounts, get Tony Thompson heavy duty ones (see forum threads on this subject); the 2ordinary" ones are crap these days and will not last long.

Cheers,
Pete.

[david.g.chapman]

As Rohan says, the run-out of the flywheel is important. If you had the flywheel skimmed off the car it is worth (if you have not already done so) to measure the run out with the flywheel mounted.

Up to 4 thou is OK. Try re-mounting the flywheel in a different position if you have problems.

Dave Chapman.

[65 Lotus]

Bad rubber tranny mount was the cause in my S1, especially evident in reverse.

[triumphelan]

Hi
Thanks again for the replies ,Can I relpace Diff mounts with Diff in place ??

[512BB]

Hi John
Yes you can. You will need someone up top to undo the nylock and someone underneath with a spanner on the bolt to stop it from turning. Undo them nice and evenly, i place a thin piece of wood under the dif to stop it marking the chassis. Then just undo the bush mounting bolts and out they come. You may have to trim away a small piece of fibreglass, where the bolts come through to the boot, if it is very close to the bolt heads.
Good luck
Leslie

[billwill]

>someone underneath with a spanner on the bolt to stop it from turning

The MOLE Wrench is your friend for this sort of thing.