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MG Midget and Sprite Technical - Clutch Slave Cylinder Removal

Can anyone give me some advice on removing the clutch slave cylinder from my '67 1275 Sprite?

Fluid level had dropped and gears were hard to select plus clutch drag making the car creep in 1st so I decided new seals are required.

This one was only meant to take a couple of hours but six hours in and I'm not even half way but I have got a good collection of scrapes, cuts and bruises!

The hydraulic joints all came apart fine. When I took the clevis pin out, out popped the piston and the rest of the fluid - no circlip anywhere to be seen. Could there be a connection with this and the fluid loss? I think a complete cylinder is called for.

The Manual,says' Remove the bolts securing the cylinder to the clutch housing and lift off the slave cylinder assembly'. Yeah, right!

The upper bolt came out fine after a bit of gentle persuasion with an impact socket and light tap on the tommy bar. It's the lower one that's the problem. I just can't get a spanner or socket on the bolt with a good enough grip to allow me to get it started.

I've removed the starter motor to give a bit more room to work. I've released the engine mounts and jacked the engine up but still not enough room (new engine mounts waiting to go in anyway). It's due for a radiator flush so the next thing will be to drain the system and remove the hoses to allow the engine to go up a bit further - unless someone can tell me what I've been doing wrong!

Colin Mee

That's surprising.

The lower bolt is normally easy. The upper one is the awkward one. Usually loosened with a cranked ring spanner over the cylinder and also accessible through the hole in the footwell.
Dave O'Neill2

agreed, the lower one is easy when lying under the car with engine and box in normal position and the top one is best got at via the footwell access hole.
David Smith

Thanks Guys. Of course you're right - I got my uppers and lowers mixed up. I'm a bit out of practice at working upside down and these days it just makes me nausaeous!
I didn't even think of checking for a route via the footwell!
I put it down to tiredness - after 2 1/2 days digging foundations this was meant to be a bit of light relief!

Still, the engine mounts have been waiting to go in since January, so not a total waste of time. I would have changed them anyway as they are so sloppy but did I read somewhere that they are now checked as part of the MOT?
Colin Mee

While your down there you might like to consider fitting a remote bleed. I'm advised for racer types
it is quite common & also recall there was an article in MASACOT.

I had mine done for me at MOT time when I noticed a leak from the Slave. Bleeding from a remote from within the engine bay is now an easy 10 minute job.
Gavin Rowles

I've done this numerous times and agree with all of the above comments. Bottom bolt is easy. Top bolt is got at through footwell access hole and it is just a case of finding the right spanner (I found one particular ring spanner that worked well for me when others did not) and lots of patience as the bolt can only be turned a little at a time. No need to remove starters or jack up the engine but you do need good access to the underside.

Re no circlip, I have yet to find a slave cylinder with a circlip or the necessary groove for the circlip despite references to such in handbooks etc. I too once removed the clevis pin and push rod only to have the piston and fluid all over the floor.

I predict you will have 'fun' bleeding the slave cylinder (unless you are very lucky) but just keep going!

Chris H (1970 Midget 1275)

Colin, when you do get the slave cylinder removed you will find that the bolts that hold it on are far longer than they need to be. Before re-fitting it shorten the two bolts with a hacksaw and also grind the end of the bolts to a cone shape which will make it far easier to locate the bolt and get it started on its thread.
Guy W

Another trick - which I haven't tried - is to cut the upper hole in the slave cylinder, so that it is open. Fit the upper bolt to the gearbox, slide in the slave cylinder, fit the lower bolt and tighten both.
Dave O'Neill2

Dave, Yes I have seen that one too. But if doing it, it is important to cut the lug from the front edge, not from the rear edge. That way when pressure is put on it from repeated operation of the clutch, if the bolt does slacken a bit, it still wont allow the slave to move.
Guy W

It's easy(ish) when you know how! Other things to attend to tonight but couldn't resist trying the footwell route - bolt loose and cylinder ready to remove in less than 5 minutes!

I was beginning to worry about putting it all back together but those suggestions are really helpful - I especially like the slot idea.

As for the bleeding - it looks as though there are some good pieces of advice to consider on another long-running thread and I'll look in to Gavin's remote system.

At least my diversions will mean that I'll have fresh engine mounts in place by the end of this plus I now know that there's negligible wear on the starter ring gear and only moderate wear of the bendix drive - should be good for a few years yet.

Many Thanks

Colin Mee

If you e-mail me via I will dig out the article I wrote for Mascot magazine on remote bleeds and scan a copy to you.
Slot the upper fixing hole vertically.
It is possible to get fixing bolts with a reduced head. Dont ask me where but I have them on my car and they take a 13mm 1/2in spanner.
Alan Anstead

Hello Alan
Thanks for your comment. I tried to reply via but aol wouldn't co-operate!

I think might have already found your article that I came across by trawling the web but I would certainly be grateful for a copy for reference.

Having read about remote bleeding I have had a length of pipe made up and it is ready to install, along with the new cylinder that arrived today. I think the old cylinder is probably usable but the bore is nowhere near as clean as I would like.

Thanks to my roundabout way of doing things, the engine is still jacked up with engine mounting brackets out on the bench with fresh paint drying on them, and the starter motor is still out so there's a reasonable amount of freshly cleaned working space available. I'm going to try to install everything without any cutting or bolt shortening in the first place. If that proves too fiddly I'll think again and try your suggestions.

Many Thanks for your advice

Colin Mee
Colin Mee

When you want to bleed the slave try this. It worked yet again for me only a week or two ago on my 1275 midget.

Connect all the hydralics and let the cylinder hang on the hose with the end rubber cap on the cylinder but no pushrod - remember the only thing holding in the piston is the rubber cap.

Fill the master cylinder with new fluid.

Undo the bleeder on the slave cyl - it is at the top of the "hanging cylinder". Gravity will force the fluid down from the master cylinder to the slave. When the first trickle of fluid comes out of the bleeder, tighten the bleeder.

Top up the master cylinder again & wait 5 mins.

Now release the bleeder again while holding the cylinder at an angle to ensure the bleer takes off any air bubbles from the slave cylinder. You should get a couple of bubbles then clean fluid. Nip up the bleeder. Do not top up the master cylinder.

Now you can remount the cylinder on the gearbox, fit the pushrod - slowly pushing the slave cylinder piston back SLOWLY TO PUSH THE EXCESS FLUID BACK UP TO THE MASTER CYLINDER (this is why you don't top up the master after the 2nd bleed) & dropping the clevis pin in place. Fit the split pin in the clevis.

You can now top up the master if needed.

You should now have a perfect clutch pedal, with no air in the hydraulics.

If the rubber end cap will not retain the cylinder piston when the cylinder is hanging, you need rubbers or re-sleeved cylinder !.

Try my method, it's worked for me first time every time for years.

I do confess to using a pit, which does make the task a whole lot easier, but it can be done with the car on stands as well. I don't bother with the access hole in the footwell.

Getting very frustrated!

By using a combination of most of the suggestions offered, I'm confident that the system is as air-free as I can get it.

As it was still no better, I decided it must be a problem with the master cylinder.

Question 1 - Are there any special tricks for getting at the mounting bolts? While I can get spanners and sockets on them, there's no room to actually work them and I really don't want to round them off, which I have done so often in the past. Would a socket on a u/v joint help me get on the nut on the pedal side?

I have just driven the car round the block. It can cope with three or four gear changes in quick succession before it stops working again. Pumping has no effect. The problem seems to be with the master cylinder not returning to its rest position as fast as it should.

Having been unable to remove the cylinder I have managed to re-seal it in-situ. This meant that I couldn't clean it as thoroughly as I wanted, or inspect it properly.

Question 2 - Is there something that could be obstructing the flow of fluid back into the cylinder? Only the piston and spring emerged when I took it apart and some parts diagrams show a filter or something.

As an aside, I managed to pick up a 60ml syringe FOC from the local vet (High Street chemists seem to stop at 10 or 20ml!). This was very effective for back flushing the system - a 100ml one would have been better. The girl at the vets wasn't at all surprised when I told her what it was for as she has had other classic car owners after them before!
Colin Mee

Can you confirm that you have a dual Master Cylinder?
Alan Anstead

Alan - no, it's separate cylinders. See photo.

It's a '67 Mk IV Sprite. I know that the slave cylinder was replaced in 1993 but have no record of the master cylinder being changed or worked on.

I've bought a couple of hydraulic seal kits that are correct for my year according to the catalogues but don't match the ones I find when I dismantle so I think the cylinders fitted may be later types.

The fluid that came out with the clutch piston was pretty thick and black so I suspect there's a blocked filter stuck in there. I just need to get the cylinder off to check properly but can't undo the lower bolt and I don't want to risk rounding it off. It's already had several dousings with penetrating oil and I'm sure that it will come off easily once it has started.

Colin Mee

Colin, you need to just slacken the nut by using the right combination of ring and open-ended spanners. Once it is loose then a 1/4 inch drive ratchet and socket will get in to undo it the rest of the way.
David Smith

Thanks Dave - I'm great at overlooking the bl*****g obvious! All my sockets, ratchets etc. are clunky half inch. I think I'll go shopping after work to re-equip!
Colin Mee

if you can get yourself any narrowish 5 degree ratchet spanners that are lovely you wont want to use others

and some small, thin, short open-ended and ring spanners

and if you can get both combined in AF let me know

Halfords Advanced Professional do some very nice ones but in metric and only a few will be a good enough fit on AF nuts and bolts

I've bought these as presents (I managed to get one set of imperial for myself before they stopped doing them, gave away two imperial sets before I knew) -

these are sometimes on special offer too -

Nigel Atkins

Good quality AF ratchet spanners are hard to find. I ended up with some good secondhand Snap On's. The new price was just silly.
Bob Beaumont

This thread was discussed between 06/05/2013 and 17/05/2013

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