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MG MGA - Rebuilding Master Cylinder

Best way to remove seized pistons in an old master cylinder ..?

Have tried to connect my grease gun to the banjo fitting, but cannot get a matching connection.

Also, once I hone the bores, what do you recommend as a lubricator ?

Thanks
A Stojanovic

Try blowing them out with compressed air.
Also have a read of the various section on the mgaguru
http://www.mgaguru.com/mgtech/hydraulics/ht1.htm
Mike Ellsmore

I will probably be shouted down but with my own experience of old master cylinders I would say don't bother, get a new one. Of all the components in these cars, MCs are one of your life lines for keeping you safe on the roads. If the cylinders are seized the bores are likely to be worn and pitted. Honing may not be sufficient so you then have to consider sleeving. I am an advocate of the Caparo MC now widely available on the MGA market. When I fitted mine I cursed myself for not going down that route many years earlier instead of trying to fettle a knackered old unit.

Steve
Steve Gyles

100% agree with Steve. If the pistons are seized, then the bores are almost certainly damaged. Even if honed, they would need to be bored and sleeved first. For the cost and risk involved in that, I would also highly recommend the alternative of an AC Caparo replacement. They bought Lockheed and claim they are produced to the same or higher specifications and are referred to by most retailers as OEM. Same for the slave cylinders.
Neil MG

Best way to get the seized piston out of the M/C is to pitch the whole thing in the bin, and buy a new one.

I agree totally with Steve and Neil. The damage that would be in the bore would require extensive work to fix. New are not that expensive and I personally have never had a bad new one.

...CR
C.R. Tyrell

I agree 100% with the trash and replace opinions. brakes are not worth saving pennies on, and pennies is all you will save with the reconditioning route. Would hate to read of your fate in a darwin award!
dominic clancy

As with the others, I agree with everything Steve G said. I replaced the master in mine around 1990 with a new Lockheed. When I started taking the car apart in 2006, I anticipated a quick hone job, and then refreshing it with new seals.

Wrong... There was deep pitting, and while I was eventually able to hone it out, I don't think I would have ever trusted that cylinder. I bought a new AP "Lockheed" unit and will be using DOT 5 fluid with it, which will hopefully prevent the same thing from happening again.

I only have two minor complaints so far about the AP unit which I got from Moss. First, there was some surface rust on the unit when I received it, and the screws holding the top and front covers were hex bolts, instead of the original type slotted screws. The rust I cleaned off with scotch-brite and etch solution, and I substituted the new slotted screws which I had bought for my attempted rebuild of the other unit. Finally, I clear-coated the unit to prevent it from rusting again.

-Del
D Rawlins

I ask the same question of everyone who want to cheap on the M/C. WHAT IS YOUR LIFE WORTH. I used Dot 5 to prevent water absorption. Remember it is your LIFE.
JEFF BECKER

Might as well stretch this to a third day.

Pits nearly always go deeper than honing ever plumbed.

Get a new one!
Nick and Cherry Scoop

Get a new one, or send yours out to have professionally sleeved. I would also suspect the wheel cyls. As well best to just rebuild the whole brake system thing....cheaper in the long run and you can drive confident...new wheel cyls. And rubber hoses too! Flush out all your lines.

Brian W
ZBMan

This thread was discussed between 01/04/2015 and 18/04/2015

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