Strange Clutch Behaviour

[AHM]

The clutch on the S3 is driving me mad! Where to start?

The clutch operates normally, I ease the clutch in, feel the biting point and off I go. Except that sometimes the biting point is in a different position and sometimes the clutch grabs. Sometimes it drags so much that I have to knock it out of gear with my foot to the floor (Particularly in reverse).
When pulling away I sometimes ease forward and sometimes lurch, in traffic sometimes it will drag... sometimes not

I've read the archive.
The clutch plate and bearing were, new and the engine rebuilt 3000 miles ago.
The master and slave cylinders were rebuilt.
I thought it was a problem with the master cylinder - so I bought a new one.
Then I though it was a problem with the slave cylinder - so I bought a new one
And I've bled, and bled, and bled!
I've checked the clearance.
I've checked the operation whilst on a ramp - engine off and on (out of gear!)

Ideas?

[UAB807F]

It's not a very helpful suggestion I'm afraid, but was the clutch cover replaced at the same time as the plate/bearing ? I recently had similar problems of dragging clutch and times when I just couldn't get it out of gear on the Europa. (cable operated but otherwise similar) Driving normally was ok, a bit grabby at times but workable, I only really noticed it when I had the clutch depressed for a few seconds, for example turning round when backing out of the garage and everything was cold.

Strange though it sounds, I'm convinced the problem was the diaphragm springs on the cover because eventually I pulled it apart and changed the lot. The old plate & bearing looked fine but the new cover seemed much stiffer in a crude comparison, so I just assumed the fingers were bending under load on the old one.

Brian

[gjz30075]

Could the bellhousing 'loop' that holds the slave be cracked? The slave already floats a bit in the loop but maybe its moving too much, if its mounting is cracked.

Greg Z

[el-saturn]

silly question: you did bleed the brakes properly, right? I've spent many an hour (alone) getting em bleeded and working: bought the same stuff you did: then i took a pressure bleeder (?) home, fitted it to the master, used 100ml dot4 - and perfect it was!? sandy 36 4982

[Europatc]

AHM
Ive just had something similar. The fork from the slave cylinder up through the bellhousing had folded on the pivot point. Just my experience. Its in having a new one fitted as we speak
all the best
Stuart

[rgh0]

What sort of clutch line do you have? The original red plastic one can become soft and swell under pressure especially when hot and can cause the sorts of problems you describe.

Otherwise keep bleeding I think and check how the arm and slave cylinder moves in proportion to the clutch pedal to confirm no issues with the system. You may have an intermittent problem with the valve that seals the master to the reservoir also.

If the arm and slave cylinder move properly as the pedal is depressed then your problem must be inside the bell housing unfortunately.

cheers
Rohan

[gjz30075]

AHM
Ive just had something similar. The fork from the slave cylinder up through the bellhousing had folded on the pivot point. Just my experience. Its in having a new one fitted as we speak
all the best
Stuart

Aha! Completely forgot the clutch fork can crack. Good possibility.

Greg Z

[AHM]

Goodrich braided hose
I have bled both new and old systems from scratch 3 times with and without an assistant, using a broom handle, pressure bleeder, on a 4 post lift with the slave cylinder in my hand. The pedal is good, and I've checked displacement against operation of the pedal.
I have checked the operation and clearance several times twice on a lift with assistance.
I checked and replaced twice the end seal in the old M/C and replaced the M/C completely with a new one.
The bellhousing is fine. I will check the arm for cracks.


Rohan, If it is internal I don't mind taking the engine out, but I would like to identify the cause before I do.

I have a USB boroscope anything in particular I should check.

There is no underfelt or carpet under the pedal.

[el-saturn]

.................as there?s a water pump solution which minimizes the hrs for a new on------- WHY doesn?t someone design a bellhousing which would allow certain repairs or part exchanges without all of the 12 (?) other main bolts and nuts (engine out. it?d sometimes just be nice to change those springs, maybe a fork, check the clutch, pressure plate etc... without the 8 hrs of the in + out. it wouldn?t take much engineering and there?d be a structural advantage/300gr weight disadvantage: double walls in that area, 4 new bolts, a new top ! sandy 36 4982 -- PS maybe someone already has soemthing ready

[rgh0]

Goodrich braided hose

Rohan, If it is internal I don't mind taking the engine out, but I would like to identify the cause before I do.

I have a USB boroscope anything in particular I should check.

.

Look at all the mechanical components you can see - lever arm, pivot, spring clips, thrust bearing and carrier, C spacer etc to see if anything bent or loose or damaged. watch how it all move as you depress the clutch to see if anything jamming or distorting under load.

How is the adjuster on the push rod of the slave cylinder set? Is it around the middle of the adjustment range? If it need to be screwed all the way out to eliminate excessive free play, that may indicate a problem with some internal component also.

cheers
Rohan

[Panda]

As you seem to have changed all the hydraulics and still have the problem, I think it may be the spigot bearing in the end of the crankshaft breaking up and intermittently seizing. It will have the steel roller bearing type. I had one seize so badly, I drove the car some yards with the clutch fully disengaged and yet there was very little noise. Unfortunately it needs gearbox off and clutch out to check. The symptoms don't indicate a broken/cracked release lever.
Alan P.

[AHM]

Hi Alan,
I replaced the spigot bearing when I rebuild the engine and gearbox.
I have never had problems selecting a gear so it isn't dragging per se. It grabs sometimes when I let the clutch out and sometimes doesn't disengage fully.
Are there symptoms of a failing spigot bearing? Or a means of checking?

Rohan, is there a way to check the clutch springs or that the splines aren't sticking? The adjustment seems normal and the operation feels normal - I will compare to the S4 tomorrow.

[reb53]

I'm watching with interest as I have all the same problems and have yet to find the time from house painting duties to investigate in any depth.

Started with dragging, and difficulty moving the gear lever out of gear.
This has been intermittent for a few years and hasn't responded to cylinder changes or bleeding.
Has now moved to the point that sitting at a stop sign with the clutch depressed I sometimes get a little kick as though I've momentarily lifted, and depressed, the clutch pedal. Usually results in a stall.

I'm thinking it may be moving to the point of being permanent in which case we'll both know what's going on !
I'll let you know if I come up with anything.
Cheers,
Ralph.

[rgh0]

Hi Alan,
Are there symptoms of a failing spigot bearing? Or a means of checking?

Rohan, is there a way to check the clutch springs or that the splines aren't sticking? The adjustment seems normal and the operation feels normal - I will compare to the S4 tomorrow.

Generally when a spigot bearing fails you will either get it seizing itself or the misalignment causing the clutch plate to drag and to not disengage and the end result is inability to change gear. Alternatively it just may cause noise when the clutch is depressed and the engine spins at different revs to the input shaft.

No real way to check what's going on behind the clutch pressure plate assembly in terms of springs or spline. The best you can do I think is just watch the clutch thrust bearing action on the diaphragm spring with your boroscope to see if it all moves smoothly with no with no apparent distortions or jerkiness in action. If you have a broken or cracked leaf in the diaphragm spring you may be able to see this with the boroscope but the clutch plate itself you cant see

cheers
Rohan

[Robbie693]

I've had similar problems with the clutch bite moving around (no dragging though) in the past but, this isn't particularly helpful I'm afraid, it went away of it's own accord. This I must assume was down to air in the system, which I wouldn't have believed at the time after the amount of bleeding and amount of different methods I'd tried in an attempt to fix it. The most effective thing I've found whenever I am bleeding however is leaving the pedal depressed overnight afterwards.