What have I done? Clutch Master goes 'pop'!
Discussion
Hi,
A couple of months back I rebuilt the clutch master cylinder. Having driven the car 200 miles-ish since the rebuild I had decided that the biting point was a bit lower than it used to be. I considered this to be due to trapped air so today I went to bleed the system using a gunson easi-bleed.
I set the system up at 20psi, tested it for leaks then filled up the brake fluid container and opened the bleed nipple. After checking the fluid was bleeding OK I jumped into the car and pounded the clutch peddle half a dozen times. With this done I slipped back under the car and tightened the bleed nipple. It was whilst I was crawling out from under the car that I heard a sudden release of air. It was at this point that I found a quantity of clutch fluid in the drivers footwell with piston and spring assembly from the master cylinder sitting in the middle of it.
So my question is, what went wrong? I have found the circlip that holds the pushrod into the master cylinder and it looks fine. Does the circlip need to be fitted into the master cylinder a certain way round (e.g. compressible tabs at the bottom)? Does the pushrod need to be screwed into the peddle only a certain distance? Or was this simply a case of being over-vigourous on the peddle?
Your thoughts would be appreciated.
Thanks,
Ralph.
A couple of months back I rebuilt the clutch master cylinder. Having driven the car 200 miles-ish since the rebuild I had decided that the biting point was a bit lower than it used to be. I considered this to be due to trapped air so today I went to bleed the system using a gunson easi-bleed.
I set the system up at 20psi, tested it for leaks then filled up the brake fluid container and opened the bleed nipple. After checking the fluid was bleeding OK I jumped into the car and pounded the clutch peddle half a dozen times. With this done I slipped back under the car and tightened the bleed nipple. It was whilst I was crawling out from under the car that I heard a sudden release of air. It was at this point that I found a quantity of clutch fluid in the drivers footwell with piston and spring assembly from the master cylinder sitting in the middle of it.
So my question is, what went wrong? I have found the circlip that holds the pushrod into the master cylinder and it looks fine. Does the circlip need to be fitted into the master cylinder a certain way round (e.g. compressible tabs at the bottom)? Does the pushrod need to be screwed into the peddle only a certain distance? Or was this simply a case of being over-vigourous on the peddle?
Your thoughts would be appreciated.
Thanks,
Ralph.
I guess the pressure was too much for the circlip to hold back. I think the circlip is only intended to stop the assembly popping out and to keep it together. Its never under any pressure other than from the small internal spring.
I have never found the need to use a pressurised gadget for bleeding my clutch as its so small and simple a circuit. I would suggest putting it back together and checking the circlip is in decent condition, bleed normally and its should be ok.
I have never found the need to use a pressurised gadget for bleeding my clutch as its so small and simple a circuit. I would suggest putting it back together and checking the circlip is in decent condition, bleed normally and its should be ok.
Thanks for the responses. Last night I jammed myself in the footwell and learnt a couple of things...
Previously, when I re-attached the master cylinder onto the car after its rebuild I had left the clevis pin on the pedal. When I screwed the pushrod into the clevis pin I assumed that the hole in the clevis pin was blank and that the push rod would only go in so far. After last nights investigations I now know that the pushrod can go right through the clevis pin and contact the back of the pedal. This had obviously happened because there was some scoring on the end of the pushrod. I think the jarring motion of the pedal rubbing on the end of the pushrod must have caused the circlip to be ripped out of its groove. Maybe in combination with the pressure from the bleeding kit.
Now I've put the system back togther and bleed it through. Drove the car 10 miles this morning with no issues. Fingers crossed it is all sorted now. Biting point still feels quite close to the floor though. I can't decide if I'm too used to the daily driver or if something else is going on
Previously, when I re-attached the master cylinder onto the car after its rebuild I had left the clevis pin on the pedal. When I screwed the pushrod into the clevis pin I assumed that the hole in the clevis pin was blank and that the push rod would only go in so far. After last nights investigations I now know that the pushrod can go right through the clevis pin and contact the back of the pedal. This had obviously happened because there was some scoring on the end of the pushrod. I think the jarring motion of the pedal rubbing on the end of the pushrod must have caused the circlip to be ripped out of its groove. Maybe in combination with the pressure from the bleeding kit.
Now I've put the system back togther and bleed it through. Drove the car 10 miles this morning with no issues. Fingers crossed it is all sorted now. Biting point still feels quite close to the floor though. I can't decide if I'm too used to the daily driver or if something else is going on
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