Club 80-90 Forums

Hi All. Recently fitted recon engine. 1.9 Waterboxer t25.
Since putting back together clutch doesn.t seem to work properly.
Checked levels and bled system all seems fine.
Taken Gearbox back off clutch plate on right way and again everything seems good.
Lever arm under slave cylinder operating. Slave operating.
No leaks that I can see including under pedals???
Could the Master or Slave cylinder be defective.?? How do I tell?? Cheers.

I've often had to bleed air out of the slave cylinder after replacing a gearbox. I think what's happening is that the spring inside the slave pushes the piston out and results in air getting in past the seal. It's a one way trip for the air and it can't get out again unless you bleed it. Fortunately bleeding is easy. Just make sure the reservoir is full and just slacken the nipple. Bubbles should come out slowly, then just fluid. Tighten up, and it should be OK.

I used the J word there i see. Just slacken the nipple. It may snap off.

Thank you Fox. Have Bled the system but no joy, may do again for longer.

did you fit a new clutch ?
If you did then it maybe wear in the clutch pedal/clevis interface meaning you don't get full operation of the clutch, it would have been okay with a worn one but now the system isn't opening the clutch pressure plate fully
there should only be 1mm free play between the pushrod and the master cylinder, it can be adjusted but it's a bit of mare to do, especially rhd

To illustrate a very worn one: ( you can see where someone had adjusted it previously to take up the wear)

Thanks Aidan and Oldiebut goodie. Not had this mentioned before so will give it a look at.

Also, if you replaced clutch thrust bearing, make sure nothing of the old bearing remains on gearbox input shaft. I once spent a whole day removing and refitting a gearbox to discover that a collar of metal was sitting on input shaft (virtually invisible) resulting in no clutch movement at all once engine and gearbox were bolted together. I'm sure my problem is by no means unique but it is very easily missed, particularly where release bearing has given up entirely.

Had no luck so far with anything mentioned. Thanks for replies though.
Have asked a couple of Clutch garages locally and two of them have mentioned thickness of the Flywheel???
Are there two different thicknesses for a Flywheel for T25 1.9 petrol???

saffron wrote:Since putting back together clutch doesn.t seem to work properly.

Can you describe in more detail what you mean.... is it rough, noisy, not disengaging, not engaging, slipping or what ?

I cant say about flywheel thickness, but in the bell housing there is a cross shaft which throws the thrust bearing. When the fork arms wear down you get a very shallow pedal.
You don't notice this issue until you change the clutch.
thats because a worn clutch assy will give a false high biting point (high pedal). When the replacement clutch goes in the normal release point is restored and the wear on the cross shaft becomes evident as a very low pedal.
Also sometimes the piston goes so far up inside the slave cylinder that the buggers will not bleed.
Try taking the top off of the reservoir, fully depressing the clutch pedal and then FLICK your foot off of the pedal. Observe if air bubbles are released from the master cylinder into the reservoir. If bubbles are released, repeat the action until a full pedal is restored or bleeding the system can be achieved successfully because you have cleared the air-locked system.

hope something here is of value

A few years back I built up the shape of the arms on my clutch fork with a mig welder, then reshaped with an angle grinder - more in desperation at the time as they do indeed wear down over the years. Amazingly, not only did it hold up, its still in excellent fettle and harder metal than before. Good one to try if arm proves difficult to remove or you have no choice but to repair fork ends in situ.

Extra welds onto the shaft is also a good idea, the arms can break away sometimes.

Thanks again for info all!!
In answer to "937 Carrera" . Clutch pedal used to go all way to floor before i put in a recon engine!! Since new engine in pedal stops inch or so off floor and cannot put into gear with engine running. Pedal just stops hard as if cannot travel any further.
Some people have mentioned that the recon engine may have a different size Flywheel than old unit?? Engine supplier says cannot happen??
How can you tell if slave cylinder working ok???. Apart from obvious leaks???
It's as if slave cylinder pushrod needs more travel but seems to be operating to full length??
Cheers again.

Maybe the clutch release bearing hasn't been fitted correctly. When you took the gearbox off for a look did you operate the lever to see if the shaft and bearing were ok.

Right, I suspect the answer is none of the above, but people should be able to help you more now.

Not being able to select a gear with the engine running means that the clutch is not disengaging. The pedal going hard is a sign that there is movement up to a certain point where a physical obstruction exists. Springs flex, solid metal doesn't.

I think I had a similar problem when refitting my gearbox after changing the guide sleeve. I suggest that you make sure that the slave cylinder / actuating arm are properly installed and aligned with each other. Also make sure that the slave cylinder actuating pin is in the retracted position when the pedal is in the up position after bleeding. I can't remember the precise arrangement, or the problem I had and solved after kicking myself, someone with more / recent experience will probably be able to identify the likely problem and help more