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MG MGA - M/C gasket

Making a new gasket for the front cover of the twin-bore master cylinder. Should I use the cover as a guide or does the bore area need to be clear (so the piston can retract as far as the cover plate itself?
Art Pearse

Art

That gasket is to prevent dirt contamination from the outside, not prevent weeps from the inside. The problem with that plate and its 2 fixing bolts is that, if used with a thick gasket and the bolts are tightened to much, the plate can distort - as mine did on my old MC.

I believe that the consensus is that if you are having problems with the brake piston clearing the fluid return hole, then make the gasket holes large enough to accept the piston. However, as the gasket should only be 1/64" thick, we are talking only a minute additional piston movement, although you could of course fit a thicker paper but run the risk of cover plate distortion.

I think Barney has previously queried the need for this gasket, provided that the MC face and the cover plate are both flat.

Incidently, I managed to true up my cover plate by rubbing it on a flat sheet of glass, using valve grinding paste.

Steve
Steve Gyles

Use the end cap as a cutting template, and make holes large enough for the push rods to go through with a little wiggle room (as original). We only cut the inside holes as large as the cylinder bores if there is trouble with the piston not returning far enough to clear the fluid holes at bottom of reservoir.
Barney Gaylord

OK Thanks. My cover plate also has the slight bow in it. I am flattening it with sandpaper.
Art Pearse

This thread was discussed between 10/11/2010 and 11/11/2010

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