My '63 Valiant's master cylinder (the round kind with the bolt that goes through the middle of the top) does not have a gasket. Should there be one? If so....any idea where I could get one (or something I could use to improvise one)?

Thanks again for all your help

You definitely need a gasket there. You may find one at a restoration place like www.laysons.com or www.yearone.com. I made one long ago from 1/8" neoprene rubber sheet (can get at some hdware stores or building/plumbing supply). Don't use regular rubber because the brake fluid will eat it up.

Lou

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Home of Slant6-powered fun machines since 1988

If the gasket has been missing for a while it may be a good idea to flush out the out brake fluid. Brake fluid is hygroscopic (readily absorbs water). Without a gasket, the fluid is not sealed from the air and could have absorbed water vapor. This will rapidly deteriorate your brake hydraulics. Pump out the old, refill and bleed all four brakes.

Cecil

You could also switch to silicone fluid which does not absorb water.

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Chuck Rivers, Webmaster

Cecil[/quote]
You could also switch to silicone fluid which does not absorb water.[/quote]
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Aahhh; Yes one could do that, but it would involve a full systems flush using something akin to brake/contact cleaner, then allowing it to dry out before refilling and doing a full bleed on everything.

Don't get me wrong, though. The effort is ultimately worth it. Higher fluid boiling point, silicone-based, non-hygroscopic, longer life from your brake components. It's just not a one-afternoon job.

Roger

I know that theoretically the silicone brake fluid is better. But I've never really had good luck with the stuff. I ve tried all kinds of things to help it, but it either gave me a spongier pedal, or leaked, or both. It's very expensive, and not every shop has it on the shelf.

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'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
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I went to a Wagner Brake seminar one time, and the stated they had a lot of problems with H-D motorcycles with aluminum master cylenders, and silicone fluid. Also maybe Dennis can give some input on this. I used to do in house lift truck repairs. We had 110 Crown lift trucks. They all had silicone brake fluid in them from the factory. We had a lot of problems with leakage. We finally changed to normal fluid and, cured the problem.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

A lot of show car guys use silicone only because it doesn't damage paint like normal fluid.

Cecil

As Charlie said, some lift trucks use D0T 5 and it was really expensive to stock all our service vans with some just to cover a very limited market. The Hyster factory did some extensive testing and concluded that there is no harm in mixing DOT 3, DOT 4, and DOT 5 fluids. It will not mix well and will look like crap, but it will still work and will not damage any components.

As for the leaking, I have worked on Schaeff trucks that would empty the M/C with DOT 5. I would refill them with DOT 3 and never have another problem.

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