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Karen51

Master cylinder for 1964 Buick

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I have a full size 1964 Buick and would like to change the single reservoir master cylinder to later model dual, for safety reasons. It has power brakes. I am getting all kinds of answers but not sure what is right. I am wondering if anyone has done this and what parts work ? The most popular answer is to use 1970 Riviera master cylinder and booster but I am not sure if that is right. Any help would be greatly apprecaited. Thanks

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You will need to use on from a car with drum brakes. Be sure and get the brake proportioning valve, if used, on the donor car. You will have to fabricate new brake lines (probably not a bad idea given the age of your car)

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There is no question the dual reservoir master cylinder is much more safe overall than a single reservoir. However in all the years I drove cars before the dual reservoirs came into existence I never had a 100% brake failure which can happen if one of the wheel cylinders completely looses it without notice. But the fact is wheel cylinders often give one a heads up long before that is going to happen. They generally weep fluid long before totally failing and dumping all the fluid in the system. Just one of those things one needs to inspect whether a car has a dual or single reservoir master cylinder.

But if you just have to do a conversion, do it with a whole new setup from one of the companies that make complete systems and avoid modifying with a bunch of salvage yard crap that may make the car less safe than before.

Edited by Jim_Edwards (see edit history)

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I have to agree with Jim. I've had more master cylinders fail unexpectedly than a wheel cylinder. The best thing you can do is check the fluid on a regular basis. If it is dropping, you have a problem somewhere.

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Karen51, this is a common and easy conversion which I did on a 1963 Riviera. Go to the Riviera subforum of the Buick forums on this site and search, you will find a lot of information. Buy a NEW master cylinder designed for drum brakes for a 67 and up Buick and be sure you match the one you have now regarding the depth of the hole in the rear piston for the actuator rod. You do not have to replace the booster if it is working properly but be sure to install the rubber O-ring at the rear of the master to seal the booster vacuum. You will also have to modify the brake lines to match the dual master.

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Perhaps the highest chance of a critical braking loss with a single master cylinder is failure of a line due to rusting. It gives no warning. Suddenly a spot in the line can't take the pressure when brakes are applied and the fluid takes the path of least resistance, out the hole.

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You might also go into the BCA Forums "Post War" section and search for a poster "5563" who had a '63 Buick convertible that he might have done the proposed upgrade to. Once you find one of his posts, you can click on his ID "5563", which will open a drop-down menu with an option for a "Private Message" from the forum to him. He can reply to you with another private message. When you log-on to these forums, look to the upper rh corner of the page where you ID is, then immediately under than for "Private Message" information from others.

I seem to recall some Cadillacs which had dual master cylinders in the earlier 1960s? Or was it Rambler??

All of the factory systems used a "divider block" to allow for a pressure bias between the front and rear systems to turn on a warning light whenever one end of the system lost fluid. You might wire that in with the warning light for the parking brake "ON" light, I believe.

The early blocks might be termed "proportioning valves", but for drum brakes, they did NO proportioning functions, other than to provide the warning light switch. It was disc brakes which needed the proportioning function, not drum brakes. You can find these brass blocks in the repro area or from some of the aftermarket performance upgrade brake parts suppliers. One application I can thing of would be "1969 Chevy pickup" (which was an all drum brake system).

In reality . . . EVERY part of the brake system on an older vehicle can have age and use issues, regardless of whether it's a single our dual master cylinder drum brake system. Wheel cylinders, rubber brake hoses (front AND rear), and line corrosion in climates were road de-icers is regularly used. In ANY case, the offending part (as especially in a wheel cylinder or the master cylinder) might give some warning BEFORE it fails with brake fluid leakage/seepage. This can show up as a curious lowering of the brake fluid level AND/OR a wetness area between the master cylinder and the power brake booster or wetnes on the backside of the repective brake backing plate. A master cylinder brake fluid level check was usually part of an oil change, back then, when the cars were driven much more frequently (as daily!). Now that we don't usually drive the older vehicles as regularly, we sometimes might not remember to check things as we used to.

Check out 5563's information and see what information/mentoring he might be able to provide.

I DO concur with using new parts whenever possible--period--on brake items.

Just some thoughts,

NTX5467

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Most of the first gen Riv guys 63-65, are using a second gen Riv (67 model year) Power Booster and Dual MC for the drum/drum setup. It is a bolt on replacement on the 63-65 Rivs.

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