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MG Midget and Sprite Technical - Clutch Hydraulics

Any midget 1500 Gurus out there?

Here's the story so far-

Last season I had a bit of trouble with the clutch not disengaging properly and difficulty in getting the gears. The fluid level was low in the master cylinder, so I topped it up and all was well. The Master cyl. appeared to be leaking as there was fluid in the footwell and it constantly needed topping up.

Over the winter I fitted a new master cylinder and bled the system through and lo and behold - the clutch wouldn't disengage again.As a result, I had a closer look at the slave cylinder (in situ) and loosened the clamp bolt. With the clamp bolt loosened and the clutch pedal depressed, the slave cylinder moves away from the bell housing, suggesting that if the slave cylinder was pushed farther into the housing and re-clamped it would cure the problem. Is there a shoulder on the cylinder which prevents it from being pushed further in, as I was unable to get any further movement in it?

Dave
Penwithian

Hi Dave

I have had similar symptoms many years ago. I tried pushing the cylinder further foreward and extending the actuator pin. These seemed to work at first but the problem came back. The probem seemed to be a build up of wear in the pivot parts inside the bell housing. I replaced all of these and the problem was solved. I think it can be made worse by the wear on the fingers of the cover plate. I am afraid all this points to an engine out job. Its well worth double checking the bleeding of the system, you should be able to see any air in the clear pipe.

Best of luck Carl
C Bintcliffe

Dave. I don't know for sure if the Spitfire slave cylinder is different from the MG one. You might like to check that out first. I recall hearing that the Spitfire one isn't as long and has a different bore size.

The other thing is that bleeding all the air from the slave cylinder is a real PITA! If you drove the car on some ramps, the rear of the cylinder is facing down and you will not get all the air out of it. The bleeder valve needs to be at the top as well but I'm certain you know that.

I found that by removing the cylinder from the bell housing and angling it so the bleeder valve is at the top worked well.

There is a groove in the cylinder that the securing bolt passes through to secure the cylinder to the bell housing preventing too much forward as well as reverse movement
Clive Reddin 76 Midget

Carl,
Thanks for your comments, I shall have another go at bleeding the system. Having the engine out at this stage of the season (got a run booked on 'Classic Drive it Day' next Sunday) is not to be contemplated.
Strangely though, if the problem is general wear to the clutch internals, there were periods last season when the clutch worked perfectly well. That's why I thought the master cylinder was the main suspect.

Clive,
You answered my question about pushing the slave cylinder further into the bell housing. As you rightly pointed out, the groove in the cylinder through which the clamp bolt passes would result in negligable movement either in or out.
As regards bleeding the system, I have been using an Eezibleed set-up pressured from a spare tyre and would have thought that would purge the air out of the system whatever angle the bleed nipple is at. However, I shall be under the car again tomorrow giving it another go. I'll keep you posted.
Dave
Penwithian

hi folks,
Got into the car today, pumped the clutch pedal a few times and managed to get it into gear with the engine running, took it for a spin and was able to change gear with no problems. There is very little movement in the pedal before the clutch takes up though, so there might have to be a clutch overhaul next winter.
Next problem to solve is the cooling system overheating when standing. The PO fitted an electric fan from an Austin Allegro. The fan is positioned at least five inches forward of the radiator core, so I cant imagine that it is very effective. It switches on and runs for long periods without bringing the temperature down. I might well go back to the belt driven fan for the rest of the season.

Dave
Penwithian

Dave, I use a belt driven pump from a Spitfire and haven't had any over heating problems even in the hottest temperature.

Glad to hear you're running again but perhaps it is time to replace the clutch. Get all new fittings in advance. Will save you looking at the car waiting for parts to arrive.
Clive Reddin 76 Midget

Dave,

Clive's spot on with the bleeding process and whatever you use to push the fluid through you WILL NOT purge all the air from the slave cylinder if the bleed nipple is lower than the highest point of the interior bore. It's worth another go at bleeding before spending a lump of money maybe unnecessarily. If you have the front wheels on ramps, carefully jack up the back until the car is level or even looking 'down hill' a bit, and use axle stands at the back end. It worked for me.

Adam
A. H. Price

I had lots of problems with overheating when I fitted an electric fan along with fuel vapourization in the float bowls, this af course makes the engine run weaker and thus hotter! I reifitted the original fan and hey presto, problem solved. Should be a nice cheap easy fix if it works.

Cheers Carl
C Bintcliffe

Silly question here, but you DO have the clutch slave bleeder in the top port, right? Stating the obvious, I know.

BTW, it took me two attempts at bleeding the thing, using the time-honored pump-the-pedal-and-hold method. I'd just honed the bore on the slave and installed a seal kit; after that second bleeding, it worked fine, and has continued to do so for the last few years.

-:G:-
Gryf Ketcherside

Thanks everyone,
I shall have a bash at bleeding the system again, taking on board the advice to get the car level or even down by the bow slightly.
It's 'Drive it Day' tomorrow so running out of time, I shall live with the dodgy clutch action until I get back home.

Carl,
your experience with overheating and fuel vapourization suits my symptoms to the letter. Not only am I going back to the belt driven fan, but I am also swapping the K&N filters for the original air cleaner plus the intake hoses as fitted to the later 1500s

Dave
Penwithian

Dave,
Another thing worth checking, which on a quick scan of the above I don';t think anyone has mentioned. The Pivot pin on the 1500 clutch lever arm is prone to wear. Either the pin or the bushes. The pin itself can even drop out. The clutch, surprisingly, still works after a fashion because the lever arm continues to pivot on the edge of the bell housing. But not like it should and you get much less clutch movement.

Guy
Guy Weller

This thread was discussed between 13/04/2008 and 19/04/2008

MG Midget and Sprite Technical index

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