Hi All,

Had the car running great and clutch has gone to floor. No leaking fluid anywhere to be found. Had fixed leaking slave cylinder and put new hose and kit on a month or so ago and got clutch working perfectly.

When I press the clutch pedal, get a squelchy fluid sound from the master cylinder. Have removed it from car and taken circlip off and plunger out, after draing fluid (bit of dark gunk in the bottom).

How do I dis-assemble the rest of it? It is the early tin Cooper S Lockheed master cylinder. Guess it needs a kit but don't want to wreck it by taking it apart the wrong way.

Any help would be greatly appreciated.

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Cooper S Mk2
Cooper S Mk1
ex Cooper S Mk2, various Morris 1100s, 1300s, 1500s, Leyland Sherpa!

If the piston, spring and cup is stuck up in the bore I usually do one of 3 things.
Tap it on the bench or use compressed air down the outlet or poke a thin screwdriver down the outlet hole.
It is a very basic system so don't worry if you mix things up. I can post a picture up for you.
Also clean up the base of the bore to assist the piston to come out.
If you use compressed air just be aware that air will fill up the reservoir so don't blast it with to much air or leave the cap off.

Thanks GTO,

A pic would be great. Can't find anything on the net showing the internals.

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Cooper S Mk2
Cooper S Mk1
ex Cooper S Mk2, various Morris 1100s, 1300s, 1500s, Leyland Sherpa!

There is a breakdown here that you can use. It shows which way the o-ring and cup goes.
http://www.theminiforum.co.uk/forums/to ... -cylinder/

Sometimes you may have to use a bit of wet and dry around the base of the bore as the rust and crud has made it rough. You only need to do the first 1/2 inch or so.

There are 2 styles. One with a groove around the outside base of the bore. It uses 2 o-ring seals. The other has no groove and uses 1 o-ring and 1 cup.

Thanks,

Main part wouldn't come out with 90 psi, so cleaned where it stopped and pushed it in and let it spring out and after a few times, came out. Needed the compressed air for the spring and cup part.

I am sure this will also help others in the future.

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Cooper S Mk2
Cooper S Mk1
ex Cooper S Mk2, various Morris 1100s, 1300s, 1500s, Leyland Sherpa!

You can also use a bent bit of wire to hook the spring out.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Does the one way valve come out? Last piece that came out was the spring.....

Also, I have the original type in the diagram and the white plastic part that sits in the other end of the spring has cracked...doesn't come with kit. The cup and ring rubbers look fine, so could this cracked plastic part cause the cup to deform and let fluid through?

Thanks again.....

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Cooper S Mk2
Cooper S Mk1
ex Cooper S Mk2, various Morris 1100s, 1300s, 1500s, Leyland Sherpa!

There is no one way valve in a clutch master cylinder. The pic is for brake master cylinder

http://i41.tinypic.com/2u8yw5w.jpg


Pic of clutch master cylinder

Thanks,

Thought I had lost something

So, it is the "spring retainer" that is broken.....

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Cooper S Mk2
Cooper S Mk1
ex Cooper S Mk2, various Morris 1100s, 1300s, 1500s, Leyland Sherpa!

Yes i suppose it could. I would replace the cup.
Also look down the bore with a torch can you see any pitting marks scratches.

Is so you may need a resleeve or hone if you are lucky.

I have never had much luck just replacing the cup.

I've just rebuilt the same cylinders. One of my "spring retainers' was also cracked.
I don't think that retainer is large enough to help flare the cup outwards against the bore. I think it is to stop the end of the spring wearing a hole through the rubber cup.
I didn't get a new one in either kit I bought - found an old one.
A few months ago, DrMini on this forum pointed out that the slave cylinder kits now don't have the cup filler or spreader which IS needed to support the cup skirt - otherwise fluid just flows around the cup.

Thanks,

Will order a kit, hone the bore and see how it goes....

I managed to do this with my slave cylinder which fixed it right proper!

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Cooper S Mk2
Cooper S Mk1
ex Cooper S Mk2, various Morris 1100s, 1300s, 1500s, Leyland Sherpa!

Just put new upgrade version master cylinder kit in and tried it out........after much work, got a great clutch pedal pressure so thought all good. Last job was to put clutch pedal clevis pin split pin in........and found brake fluid dripping down onto pedal and carpet.......

So, quickly removed MC and checked all internals and refilled with fluid-pumped and still leaking fluid.....so put old original piston, seals etc in and no leaks, but no pressure also.

Guess I just need the original old style MC kit? Only logical solution I can think of.

Any thoughts?

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Cooper S Mk2
Cooper S Mk1
ex Cooper S Mk2, various Morris 1100s, 1300s, 1500s, Leyland Sherpa!

Make sure you have the 0.75" kit to suit your 0.75" bore.
Clutch masters are usually 0.75" and brake masters are usually 0.70"
I try and make sure that I use the Cup and O-ring Piston inside the non groove body, and use the 2 x O-ring piston inside the grooved body.