chrsgrain
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posted on 14/6/08 at 02:58 PM |
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Hydraulic clutch strangeness...
Hi all,
Good rolling road session the other day, but strange things happened with the clutch - the biting point was moving further and further towards the
floor, on the drive home had to push right into the floor to change gear.
Today, all back to normal.... any ideas what it could be? No change in the reservoir level, so presumably no leak....
Thanks
Chris
Spoing! - the sound of an irony meter breaking...
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jacko
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posted on 14/6/08 at 05:18 PM |
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May be oil getting to the wrong side of the seals in the master cylinder ?
Jacko
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chrsgrain
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posted on 14/6/08 at 05:31 PM |
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quote: Originally posted by jacko
May be oil getting to the wrong side of the seals in the master cylinder ?
Err... don't really understand that... and how can I fix it, a little concerned that if it had gone on much further I would have lost the
clutch...
Chris
Spoing! - the sound of an irony meter breaking...
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chrsgrain
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posted on 14/6/08 at 06:02 PM |
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OK - can someone explain this to me as if I'm a COMPLETE idiot please!!
What is wrong, is it going to get worse, and how can I fix it....!! Please tell me its all the master cylinder, as I have to take the engine out to
get to the slave....
Thanks
Chris
Spoing! - the sound of an irony meter breaking...
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CairB
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posted on 14/6/08 at 07:38 PM |
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Check that when the clutch pedal is up that master cylinder piston seal is past the small hole that allows fluid to refill the working chamber.
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chrsgrain
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posted on 14/6/08 at 10:48 PM |
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Er - I must be being thick here - past in which direction, and I take it I get to this by taking the 'boot' off the activating arm?
Thanks
Chris
Spoing! - the sound of an irony meter breaking...
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CairB
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posted on 15/6/08 at 06:47 AM |
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I think that you should be able to see fluid movement in the reservoir as the pedal approches it fully released position, especially near the hole
mentioned previously.
Have a look at the diagram here, you should be able to see the hole I was referring to.
It allows fluid into the working part of the system then seals off as the pedal is depressed.
If the seal doesn't come passed and open up this hole then any leakage passed the seal will result in the loss of movement of the slave
cylinder.
I have also known brakes to bind due to this problem as fluid needs to be able to move back into the reservoir due to thermal expansion.
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chrsgrain
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posted on 15/6/08 at 12:17 PM |
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Ah - OK I think I get it now! You're saying that its possible that the 'first' seal is leaking, allowing fluid back into the
reservoir instead of pushing the clutch in... and if the second seal is OK you wouldn't see a leak.... is that about right?
Other than rebuilding the cylinder, is there any way of telling if that is the case - it is a pretty much a new cylinder, so I guess it
shouldn't be knackered - which concerns me as then it can really only be the slave - which I really don't want to have to take the engine
out to get at.....
Ta...
Chris
Spoing! - the sound of an irony meter breaking...
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CairB
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posted on 15/6/08 at 01:14 PM |
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Yes, but the problem can be if the main seal doesn't come back far enough to open up the hole.
Then the leaked volume never gets replaced.
Looking into the reservoir you may be able to see if the seal passes the hole, depending how full the reservoir is.
You usually get fluid movement in and out of the hole when the seal passes that you may be able to see.
If you don't see the seal go past then this may be casuing your problem.
This can happen if the piston rod is not adjusted corectly or there is something stopping the pedal from fully retracting.
You could also check that the piston rod is free to reach its end of travel and is not restricted by the pedal.
This could be done by diconnecting the two and checking that the piston rod doesn't want to go further than the pedal allows.
It is only a possibility and may not be relevant to your problem, but its a genuine, non-obvious one that is worth checking.
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NS Dev
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posted on 16/6/08 at 05:56 PM |
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make sure the master cyl is fully returning (so the pushrod is "slack) and then add a clutch pedal return spring to make sure.
If the return spring in the master cyl is a bit poor it can fail to return properly.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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