The V8 Owners Forum -

Hi
I'm desperate.
I have a Replica Cobra with a Rover V8 engine and LT77 gearbox. The pair came out of an SD1 . I built the car around 30 years ago and all has been fine until I recently had to change the engine ( That's another story !). It seemed a sensible time to renew the clutch slave cylinder so I fitted a replacement. Clutch would not disengage and there seemed to be too much free movement on the pedal . The new slave cylinder had come with its own pushrod which I had not fitted because I couldn't see how so I refitted the original slave. This worked and I had a clutch - this made me assume that there was some difference in the new slave that meant I had to use the new pushrod and I hadn't done that, hence the lack of success.
About a week later - no clutch ! On investigation I found the fluid had disappeared . The reinstalled old slave had obviously not liked the cleaning I had given and it was leaking fluid badly . I checked the new slave against the old one and they looked virtually identical so I reasoned it should be fine with the original pushrod. The new slave was re-installed and the system bled. The pedal still had a bit more free travel than i liked but it felt as though the clutch should be disengaging - but it wasn't
My manual warns that when changing the slave cylinder the clutch release arm is easily dislodged - I have been careful during all these changes but I just can't see why my clutch is not working now. Have I dislodged the release arm? And , how can I tell? The pushrod is poking out of the gearbox just as it was before the cylinder change .
I'd really appreciate any hints or guidance - Many thanks
Baggy

Did you make any other changes such as changing the clutch pressure and/or friction plate?

If the new slave didn't work but replacing with the old one did that would indicate that there is no problem with the release arm (maybe!).
If I remember correctly the slave mounts to the front of the bell-housing on these so the dimension of interest is from the mount face to the location face for the pushrod with the slave a maximum extension. Has this beem measured carefully?

The reason I put 'maybe' above it I do wonder if there is a problem with the release arm which meant the new slave didn't work at all but allowed the old one to work but possibly at a greater extension than previously, this could have allowed the piston to come out of the bore or enter a corroded area of the cylinder either of which could cause it to leak.

PIctures would help.

Is the clutch standard? I ask because I bent the release arm on my Landie which caused the clutch to not work any longer.

Chris.

Thank you Chris and DG Cobra for your responses. I currently have a clutch ! I've fitted new master cylinder, slave cylinder and hose. The problem seems to have been with the bleeding .I've spent days under the car up to my elbows in brake fluid with my wife pumping the pedal as requested. The process isn't helped by the fact that the new MGB master cylinder has a reservoir about the size of an eggcup meaning every couple of pumps it needs topping up and / or it's easily emptied letting air into the system and having to start all over again.
I finally got some success by adapting a master cylinder top so that I could connect a larger reservoir and then I connected a vacuum pump to the bleed nipple and sucked the fluid through. There is still more free play than I would like and my guess is there is still some air in the system but at least its drivable . I might take it to a professional with a proper lift and bleeding equipment rather than lie under it any more
Cheers
Baggy

Baggy wrote: ↑Fri Sep 13, 2024 4:54 pm Thank you Chris and DG Cobra for your responses. I currently have a clutch ! I've fitted new master cylinder, slave cylinder and hose. The problem seems to have been with the bleeding .I've spent days under the car up to my elbows in brake fluid with my wife pumping the pedal as requested. The process isn't helped by the fact that the new MGB master cylinder has a reservoir about the size of an eggcup meaning every couple of pumps it needs topping up and / or it's easily emptied letting air into the system and having to start all over again.
I finally got some success by adapting a master cylinder top so that I could connect a larger reservoir and then I connected a vacuum pump to the bleed nipple and sucked the fluid through. There is still more free play than I would like and my guess is there is still some air in the system but at least its drivable . I might take it to a professional with a proper lift and bleeding equipment rather than lie under it any more
Cheers
Baggy

Good to hear you're on the way to a fix. I must admit I'm a bit spoilt as I have a lift in my garage which helps a lot with these kind of jobs and I'm also able to split the hydraulic circuits on my Cobra so I can bleed the upper and lower sections independently.
One thing I've done in the past is disconnect the slave and clamp over it this way you know if you've got the air out as your pedal will be solid.