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MG Midget and Sprite Technical - 1500 clutch hydraulics

Hi all,
Collective wisdom saught as ever!

Last night I had the clutch hydraulics fail on me again.
Last time was on the way back from Burghley. Before M50 we replaced the slave as the old one was weaping. We bled the whole lot through with a EasyBleed and all seemed well. We got a good few miles of town driving in and then drove down to M50.
On the way back it started to go and needed bled out again by the AA man (lovely chap, seemed eager to help rather than just relay it. And a spec lift is the ONLY way to raise the back end of the car for clutch bleeding!!) After we bled it, it was fine, drove back no problem and it had been A1 until last night when it rapidly went from fine to nothing.
There's no obvious leaks and it works no problem for some time before failing. Given that the slave and red flexi-hose are new and that full system operation is possible, I'm beginning to wonder if its the master cylinder seals.
As mentioned, we've bled it with the rear of the car raised using an Easy bleed. Is it also necessary to remove the slave and g-clamp it in the 'closed' position?

Any other thoughts?

Cheers,
-Craig

P.S. probably won't make Bo'ness in the midget now - again :-( Beginning to wonder if she's allergic to that event, that's 3 in a row its missed!

C Robertson

Bit of an update.

Had a good look over the system and noticed a bit of play on the master actuator rod (the bit which attaches to the top of the pedal) and a tiny weep on the master behind the big rubber end seal. Neither of these can be helping but didn't seem to be the problem.
Went underneath and found little bobbles of an oil all over the slave cylinder. Pulled it and it seams the large outer seal has come off, presumably affecting the action of the rod. Only reason I can think of for that is that the rod was a bit rough & pulled the seal off. I've rubbed the rod down with wet'n'dry til it was smooth again, reassembled & re-bled the system and it seems good again.

Anyone any ideas as to why this has happened? even without the end seal I'd have expected the system to work OK, at least for a while until grit and stuff wore the piston seal out.

Thoughts?

-Craig
C Robertson

I'd agree that I can't see how the dust cover being slightly errant would affect the actuation - you'll be putting way more grunt in via the pedal and hydraulic ratio to prevent whatever minor resistance the dust cover might provide being a problem.

Your previous question about needing to remove the slave to bleed - not as such, in my experience, though I did find some air hiding in there when I removed it and pushed the slave piston back by hand. So I pumped it out (careful not to push it all the way out) and pushed it back a few times to ensure all air was out of the slave cylinder.

Dave
DH2

Is it still failing?
I don't remove the slave when pressure bleeding and my clutch works well (for now).
BH Harvey

So far so good...
Was at a car show over the weekend and also did a fair amount of stop-start around the town beforehand and it worked perfectly. So with any luck it will be OK now. time will tell as ever!
Cheers,
-craig
C Robertson

This thread was discussed between 09/09/2011 and 19/09/2011

MG Midget and Sprite Technical index

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