Creepin' clutch

[Dave Nichols]

Hey guys,

Here's another tech question for ya:

How do you cure a creepin' clutch. It seems to be more prevalent once the car is hot. This also causes it to be difficult to get into 1st gear after sitting in neutral unless I rev the engine. The hydraulic fluid is topped off and everyting else works perfectly.

Any ideas? How do you adjust a hydraulic clutch?

--Dave

[BMWRACER]

Dave.

I don't know how to adjust the clutch on a Caterham. On BMW's the hydraulic clutch is self adjusting.

Sounds to me that you may have a hydraulic problem, if it's not loosing any fluid it could be the master, if it's loosing fluid it could be the slave cylinder.

When you do get it in gear. At what point does the clutch engage? If its very close to the floor it could be a leak or adjustment. If it's higher up, kinda like how it normally is, you could have a pilot bearing hanging up

Sorry, I've probably given you more questions than answers. Either way I hope this helps.

[Doug Liedblad]

Is the slave cylinder outside the bell housing working a clutch release arm or is it an annular inside the bell housing (if any problems pull engine) type?

Given it's an older car it probably has the former. This is what I have and there is some adjustment where the slave cylinder mounts. But then I built the mounting hardware.

It may be the master cylinder. I seem to recall having one that leaked internally so you never saw hydraulic fluid but it would not hold pressure.

The hard to get into first indicates that you may be getting some drag on the clutch causing the input shaft to turn. This could happen if the you are getting pressure loss.

Call or send photos.

Doug

[GWise]

Have you tried double clutching? I wonder about the synchro.

I would agree with doug though - it's probably a matter of it being rebuilt. I could be wrong, but I think you can open up the pedal box (inside the engine compartment) and adjust it from there.

EDIT: is it a cable operated clutch or hydraulic?

[Dave Nichols]

Thanks Doug.

I am even thinking it may be as simple as bleeding the line since pumping the clutch lever helps. Also remember that this car spent a long time sitting before I bought it. Now I drive it every day and keep finding little bugs, many of which are due to lack of lubrication, etc. I just replaced the water pump, put all new seals and gaskets in the car, a new speedo line, fixed a bunch of shorts in the wiring, etc. So far, everything I pull out is dry as a bone, old, cracked and so forth.

That said, it runs like a top and the motor is amazing!

--Dave

[BMWRACER]

If pumping helps. Rule out adjustment or pilot bearing. I'd bleed it first. If that doesnt help it may be a bad master or slave cylinder.

[Dave Nichols]

Thanks guys. I'll start with bleeding it and go from there. It is interesting that there is no problem when the car is cold. It only starts creeping when its hot. Maybe the bubbles work their way up?

[slomove]

I don't understand the symptoms.

When you say "creeping" do you mean "slipping under load"? Or does it mean "not fully disengaging" which would be consistent with the shifting problem?

[Doug Liedblad]

I suspect you will need to rebuild the slave and/or M/C.

The kits are usually inexpensive and it's easy to do.

Unless the cylinders are full of corrosion. Usually more of a problem if they are cast iron.

[Dave Nichols]

I hear ya Doug. If that's the case, and I have to put in a new master and slave, it will be an easy swap (I hope).

Slomove, by creeping, I mean that while in first gear and the clutch is engaged, the car tries to creep forward and would actually move slightly forward if I take my foot off the brake. Because of this, it is also difficult to go from neutral into first gear. This only happens when the car is hot (after driving it for half and hour or longer). If I rev the motor, I can usually get it to pop into first.

On a motorcycle this usually means that the clutch needs adjustment.

[Doug Liedblad]

Dave

Have you fix the clutch hydraulics yet?

Doug

[Ronbo]

I had this exact same problem. Replacing the slave cylinder was the cure.

[Dave Nichols]

I ordered the master cylinder from Ben at Caterham USA. He had me look at the slave and told me it was relatively new (it is one of those blue anodized units) and since it is not leaking, he suspects that changing the master and the hydraulic line to the slave should cure the problem.

Also, it could well be that the clutch was not bled properly since you have to rotate and hold the bleed valve at 12 o'clock to get all the bubbles out.

Anyway, a new master (the current one is a 1976 vintage) and line may cure all ills.

[Doug Liedblad]

Can you get a rebuild kit for the slave?

It should be a simple thing to do and if the MC was gunked up it couldn't hurt.