Modern brake booster and dual master cylinder for 1958 Buick Special

[harpman]

I am new to this forum. My question may have already been addressed. Apologies in advance if my question is redundant. I want to install modern vacuum operated booster and dual reservoir on my 1959 Buick Special to replace original manual non power brake master cylinder. I want to retain drum brakes on all four wheels. Any ideas or recommendations are appreciated.

[pauldridge]

I have a similar setup on my 1940 Buick.. It has the power brake booster/cylinder from a 1972 Buick Wildcat, was installed by a P.O., who clearly never drove the car.

Initially, the front stock drum brakes would throw you through the window if you even looked at the brake pedal.

The problem is, the 72 master was designed for disc brakes in front, which require considerably more pressure than drum brakes. The stock GM cylinder of that era has a built in pressure balancer attached to the master cylinder, which makes matters even worse by cutting back pressure to the rear drums.

You would be best served to find a unit that was originally designed for 4-wheel drum brakes, (one thought..determine your current master cylinder piston diameter, then try to find a dual master for both sides with similar bore size) and then you shouldn't have any problems.

My solution was to remove that "built in" (well bolted to the side) pressure balancer altogether, then I installed a new, generic pressure balancer (generally used in the REAR brake circuit) into the FRONT brake lines. By adjusting the bias almost to the limit in favor of the rear brakes, my brakes are now pretty well balanced.

Finally, you would need to make sure that you can locate a good sized vacuum source from your manifold or carb, as the boosters generally require a 1/2" hose to vacuum to have sufficient air quantity to consistently power the booster.

Honestly, if it were me, I would forget about the booster idea all together, eliminating a lot of complexity and additional maintenance, and just go for a good non-boosted dual master cylinder, such as one of the Wilwood models. If your car has the master cylinder on the frame under the floor, such a cylinder will be easy to install, and they have versions with remote reservoirs to mount on the firewall so you don't have to go crawling underneath to check brake fluid levels.

I did just that on my '59 Jaguar MK IX, which originally came with a single circuit booster. The booster was leaking fluid, and I really wanted dual circuit for safety, so I just ripped the whole ugly mess out, installed a Wilwood with remote reservoir under the floor. I have never felt like I was missing any significant assist with the booster gone!

Hope this helps
Phil A.
Austin, TX
'40 Buick AND Cadillac, '53 Nash Healey LeMans, amongst others

I am new to this forum. My question may have already been addressed. Apologies in advance if my question is redundant. I want to install modern vacuum operated booster and dual reservoir on my 1959 Buick Special to replace original manual non power brake master cylinder. I want to retain drum brakes on all four wheels. Any ideas or recommendations are appreciated.

[harpman]

Thanks Phil for your recommendations. I understand your logic of going with a non boosted dual master cylinder. The original master cylinder is mounted to an air plenum attached to the firewall. The bore of the original master cylinder is one inch. If I install a dual reservoir master cylinder with a one inch bore for both front and back drum brakes, can I use the original distribution block or must I install some type of adjustable valve distribution block?

[pauldridge]

I'm not sure I understand your question. The "original" distribution block would, of course feed both front and rear brakes, so it will be of no use with a dual circuit system.

With the dual master, there really won't be a distribution block per se.. the front brake line(s) will attach right to the front boss (cylinder) of the master, and the rear brake line attaches to the rear outlet on the master (not that it would matter, but just for the sake of logic).

If it were me, I would hook both front and rear brake lines direct to the respective port on the master. Afterward, if you feel you need less brake bias for the rear (i.e., if the rears lock up before the front), you can always install a bias adjuster inline with the rear line with little modification of what you already have.

Hope this helps.

Phil