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MG MGB Technical - Clutch Slave

Just changed clutch slave.
Lot of C''p came out of the bleed when getting the air out. Clutch now bits early. ? The master cylinder looks ancient but shows no sign of a leak, should I change it?
New to this site so rgds Bob
R. C. Elwell

Welcome to the BBS.

It is not a bad idea to change the master cylinder and the flexible hose so that you have a whole new system.

The fact that there is dirt in the fluid suggests it has been neglected and whilst the cylinder may look good on the outside, inside it may be corroded and the rubber seals perished.
Chris at Octarine Services

R.C. If you do as Chris suggests and replace the system, you will be starting with a know good system. Then, change and flush the hydraulic fluid at least every two years and it should hold up well. Regular brake fluid attracts mosisture and allows rusting to take place internally. More of a problem where you live than where I live. But, regular flushing and replacement with fresh fluid is a good idea with both the clutch and brake systems. Les
Les Bengtson

Helicoil the new clutch master body and you'll make your life a lot easier. Tightening the bottom bolt is a b*tch.
Mike MaGee

One more thing. Replace the metal line too as rust developes inside and can ruin all the seals. It just happened to a buddy of mine w/his 2 year old master.
Mike MaGee

And when refilling the system do so from the slave bleed nipple rather than the master, and you shouldn't need to bleed it :o) I used a gunsons EeziBleed (because I already had one) on very low pressure but any kind of pump will do.
Paul Hunt

Thanks Will order a new master tomorrow. The dirt in the fluid looked like bits of black rust so will replace the lot.
As the clutch bits a bit early ie near the floor which it did not before I guess some fluid id now leaking past the master piston even tough no sign of a leak.
rgds Bob
R. C. Elwell

Hi,
I too changed a leaking clutch slave, bled it, it bit early yesterday but worked, today had to pump it to firm it up enough to get in gear. Fluid hadn't gone down, and master looks fine - I don't really want to replace it unless really necessary. How can you tell difference between air still in system and dodgy master cylinder?

Cheers,
Chris
Chris

second Paul's suggestion....before I got a MityVac I used an old fashioned pump style oil can or "oiler" and attached some clear plastic tubing then attached to the nipple...at the end, hold down handle and tighten/close the nipple. No bubbles.
J.T. Bamford

R.C.,

If your clutch bites near the floor, you probably have some wear in the linkage. Check where the clutch pedal connects to the master cylinder. Got wear in the hole in the clutch pedal, the pin or the push rod? Also check down at the slave cylinder for wear in the pin, push rod and clutch lever.
Matt Kulka

Matt,

Unless the wear in the master cylinder linkage/pedal results in the piston resting against the retaining circlip it will have no effect on the clutch operation as the hydraulics are self adjusting up to that point.
Chris at Octarine Services

Chris,

I think that's exactly what happened in my case. I had wear at almost every component in the linkage. The holes in the push rod were oval, the hole in my clutch pedal was very oval, and both pins needed replacing. The one up at the pedal was worn literally halfway through. I think the master cylinder piston simply couldn't back out far enough to take up all of that slack.

It was a wonderful thrill replacing all of the pieces at once and having the clutch take up with the pedal 1/3 through its throw, instead of right off the floor. So much so, that it was the deciding factor to say the MGB was ready as the stick shift training vehicle for my oldest daughter.
Matt Kulka

All New now and fine. Feels a bit different but now bites 2/3 from the floor.
Had to cut off bottom flex new braded one now on. Hope it lasts another 25 yrs.
R. C. Elwell

This thread was discussed between 10/07/2004 and 17/07/2004

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