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MG MGA - master cylinder rebuild

I remember reading a thread about changing the front cover on a master cylinder while it is in the car. It got me thinking could you rebuild a master cylinder in the car? I have a 1960 MGA with a resleeved master cylinder. brakes work fine but the master cylinder weeps. I would like to freshen it up with a new kit. The car had sat for ten years after being rebuilt with out being driven so I don't think I would need to hone the cylinder. Has anyone done this?
Charles O'Brien

Yup. Done it several times. Remove pushrods and front cover, and pull the pistons out the front. Just be prepared for the spill.

Barney
Barney Gaylord

My experience has been that sitting undriven for an extended period doesn't guarantee that there won't be corrosion in the master and wheel cylinders due I presume to regular brake fluid's tendency to draw water from the atmosphere (unless you're fortunate enoughto have silicone brake fluid). I think you'll want to inspect the master cylinder bores carefully to make sure they are still smooth enough for a good seal.
Tom Heath

I have done this many times. I remove the clevis pins, the front bolt securing the m/c, slacken the rear, tilt the front up, remove the push rods , front cover and pistons. If you are fitting new push rods from Moss, be careful , some are made incorrectly and will bind on corner of the slot wwhen the pedal is depressed. Good Luck, Bill
w.g cook

I've got a weeping master cylinder and intend to put new seals in soon. I will certainly try to do this insitu as dsecribed. Slightly off topic but does anyone know of a reason for not reusing DOT 5 - silicone fluid given its cost?
J H Cole

I have reused Si fluid, but always let it sit for weeks in a clean container, till all air bubbles have settled out, and then decant to remove any foreign matter from the bottom of the bottle, and again leave to sit for a few weeks. If it's clear, and clean, it should be no problem. But it seems to retain bubbles really well, so be careful, and do not reuse immediately after you have bled it.
dominic clancy

Dominic,
If you can set up the fluid in a jar with a nipple on the top, connect a mityvac pump to the nipple and you should be able to pull the air out of solution in a short time.
mike parker

Thanks for the info will try it this weekend. Yes Tom the MC did have silicone brake fluid in it so I don't think corrosion will be a problem.
Charles O'Brien

This thread was discussed between 10/06/2005 and 11/06/2005

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