Technical Clutch problem

[vale of uscon]

All,

I’ve come to use the car today, get it ready for the MOT etc and I have a clutch problem.
The hydraulic mechanism is working fine, but the operating mechanism to engage the clutch in the housing is not.
I guess it’s ceased up. Strange as it worked last weekend.
So far the car starts inc neutral just as you would expect. Put it in gear and it starts just the same. So definitely stuck in neutral.
Any ideas how I could free it?

Regards
Simon

 

[Skillmaker]

So, you press the clutch pedal...

This extends the shaft from the clutch slave cylinder on the transmission, yes? The shaft on the slave cylinder pushes the arm on the clutch release shaft into the transmission, that rotates the clutch fork inside the transmission to push the throwout bearing against the fingers on the pressure plate, releasing the clutch disk to spin freely, allowing the engine and transmission to rotate seperately (like between gear shifts).

The shaft on the slave cylinder should rest snugly against the arm on the exterior of the transmission attached to the shaft that goes into the bell housing, that is also connected internally to pivot and push the throwout bearing against the clutch pressure plate.

If the hydraulics are working, the clutch slave cylinder shaft extending should cause the arm to pivot the shaft that moves the throwout bearing.

If the shaft moves, but the clutch does not release, then you may have problem inside the bell housing with a clutch fork (the part that moves the throwout bearing) not moving, which could be due to a broken set-bolt or the throwout bearing no longer in contact with the clutch fork.

If the clutch slave cylinder shaft doesn't move, then either the master cylinder and/or slave cylinder is kaput, or the system needs to be bled. OR the shaft for the clutch fork that passes into the bell housing is seized. If that were the case, you probably would not be able to depress the clutch pedal.

Finally, depending on how old the clutch is, and whether there is sufficient movement in the slave cylinder, the nuts on the slave cylinder shaft may need to be adjusted to take up the slack in the system, and move the throwout arm further. This would usually be preceeded by the clutch not disengaging completely and grinding gears a lot.

It is a relatively straightforward system, and if everything is moving, but the clutch doesn't disengage, then the problem is likely inside the bell housing.

 

[vale of uscon]

Skillmaker,

So far everything works externally to the bell housing.
Slave cylinder arm moves about an 11/2”.
I think it’s in the bell housing.
Sounds like nothing I can do but take the gearbox and see.
Time for the garage!

Regards
Simon

 

[Skillmaker]

After rereading your post, I would also need to ask - If it seems like it is stuck in neutral, then the pressure plate is possibly being held in a depressed mode (like you are stepping on the clutch pedal).

Before you remove the transmission, have you tried backing off the two adjusting nuts on the slave cylinder shaft, removing pressure on the arm? This would be allowing the arm to move further away from the engine block, if it were being pressed on by the pressure plate. Could it be a case of bad adjustment and that the release bearing needs to be able to move away from the pressure plate further?

That would be something simple to test first. But if that doesn't do the job, then there is likely a transmission remove/reinstall in your future regardless.

If it was bad adjustment, then you would likely have felt the clutch slipping or gears grinding before a full failure.

 

[Skillmaker]

Any updates on this?

Interested in what the problem turned out to be..

 

[Nello]

How far should the slave cylinder arm move to push the clutch?