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MG MGA - Master cylinder

What's a good way to get the pistons out of an old m/c?
Art Pearse

Compressed air -- but stand aside as they can eject at speed! I usually cover the MC with a heavy bagging material to catch the pistons and the residue.
Better and safer to use pedal pressure to clear them and loosen them before removing from the car.
Barry.
Barry Gannon

Art,
A method I like is to find a bolt that will thread into the opening in the piston. Screw it in a few turns and use it to pull the piston out. I've had great success with this method.
Cheers,
GTF
G T Foster

Never done it but a manual grease gun is what I've heard. There is no hi-speed ejection problem that compressed air will give. Plus the pressures to remove the pistons can be much higher.
Chuck Schaefer

GTF - the bolt method worked fine. it was just stuck with gunge, fortunately not rust. Now I have the pistons, what is left of the seals and the return springs out. Now when I look down the bores I see in the brake side, what appears to be a small inverted cup, I guess to centre the spring. But in the clutch side, nothing. the cup seems stuck in place.
Should there not be the same cup on both sides? Does it matter? I can't see the part listed in Moss cat.
looks like the bore will clean up nicely for a rebuild kit. Would these cups be included ?
Art Pearse

There is only 1 brass cup and it should come out.
Here's a very nice step by step pictorial from breakdown to reassembly
http://www.mgaguru.com/guest/mgashop/mcrebuild.htm

Good luck
B Suelzle

That little inverted cup is the "non-return valve" (badly named). This is the bit that allows you to "pump up" the brakes in case of a low pedal condition. It belongs in the brake side only,k There are a couple of rubber bits down there that should be replaced, so keep at it until you can remove the cup and the rubber washer behind it.
Barney Gaylord

This thread was discussed between 07/08/2010 and 10/08/2010

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.