Brakes: Hydrovac and dual master cylinder

[Kdancy]

Thought I'd start a topic just on this as I can't find one.
Some have changed out their single reservoir MC over to a dual one and still used the hydrovac plumbed to the front brakes.
Anyone reading this have feedback on one they have plumbed that way?

[StudeRich]

That is not the way any Brake Engineer would design a system, or a Car Mfg. would use for obvious reasons, so why even consider such a "backyard" setup? You will have much better results sticking with the Factory single master Cylinder.

[Kdancy]

That is not the way any Brake Engineer would design a system, or a Car Mfg. would use for obvious reasons, so why even consider such a "backyard" setup? You will have much better results sticking with the Factory single master Cylinder.

Ever since running into an apartment complex with a 66 Mustang that had the entire brake system gone thru with all new parts about a month before, I have been extremely leery of driving a car with single reservoir mc. We found that one of the new rear wheel cylinders was defective, and let most of the fluid out in a matter of seconds. I broke the hand brake cable I pulled it out so hard and fast. With a dual mc set up, or Hudson type mechanical back up, I would not have had an accident.

[hausdok]

Hi Kerry,

I had an idea for a workaround the other day. I'd posted the comment below inside of your 58 Packard Hawk Question thread. Maybe you missed it. Maybe not. What do you guys think of this idea for keeping it looking original but working like a dual MC?

Here's the re-post:

I was pondering this whole hydrovac single circuit thing today and wondered why one couldn't simply mount a dual circuit master cylinder with a proportioning valve sideways up under the dash in a custom-made bracket and mate it to a hydraulic slave cylinder like one used for hydraulic clutches.

Push on the brake pedal and the hydrovac activates the slave cylinder and the push-rod on the slave cylinder sends a pushrod into that dual MC and activates the brakes. You could redo the brake lines so that from under the hood, and when you glance underneath the car, they all look original; however, you route the lines up through the floor and beneath the carpet under a sheetmetal chase that protects them and then you join them to the dual MC beneath the dash.

Do it right and you could keep the original brakes all around, keep the hydrovac, even keep the original master bolted to the side of the frame under the car, 'cuz you'd need it to make the hydrovac work. It would look absolutely stock but probably have better braking performance because you'd be able to adjust the PV to balance the brakes front and rear better. Back when I was working on Toyotas in the 70's Toyota used to use some small slave cylinders to activate the clutches on Toy Land Cruisers that would probably be just about a perfect size for this Rube Goldberg idea.

Mike O'Handley
Kenmore, Washington
hausdok@msn.com