Brakes

[alvin stadel]

Well as of this afternoon I took my 57 RHT. off the market. I haven't messed with any of my cars this past spring or summer do to some bad ass health issues. I had the RHT out 3 times and all was well. I had it out today and about messed my knickers because of very weak brakes. I sure wish some of you brake experts lived a little closer to me. I have checked and rechecked everything you have asked about. There are 2 things that may be the issue. One the pins that move the cylinder cups are at a angle, and 2nd, The fact that this 312 has a full race cam, and I can;t get enough vaccume. I have a elctric vaccume pump and it works fine when the RPMS are up' However when in traffic or town driving, there is little brakes and it does get scary. So I think I will get rid of the cam, and get some shorter cylinder pins.  Everything is new and installed correctly, so I am kind of at a loss as of what to do. Thanks in advance for any new info, Alvin

[KULTULZ]

 

There is too much confusion here -

You have a 57 FORD w KH PEDAL ASSIST POWER BRAKES? Did the car come with it or did you do a retro-fit?

You have done a front disc conversion using VERSAILLES disc (I a$$-u-me you used the spindles also?).

What model year MC did you use (DISC/DRUM dualing reservoir), OEM or aftermarket?

Does the MC contain a rear drum residual pressure valve? Do you have a free-standing #10 RPV on the rear circuit? Is there any type of proportioning or combination valve used?

Why such a hot cam on a street car?

What is your manifold vacuum at idle and say 2500 RPM?

Have you put a vacuum gauge on the booster supply line? Does the reservoir tank hold vacuum? Is the check valve operational? Have you checked the vacuum draw of the electric assist pump @ all RPM's?

Did you take photos while performing all of this?

A vacuum booster is not going to be able to see the needed vacuum signal to operate it below 17-18 HG

We need to know all before attempting to diagnose.

[alvin stadel]

No disk brakes, drums all around. It was a power assist brake car. We just updated with new power unit, and dual master cylinder. M/C has 1 1/8 bore. I have been fighting the vaccum issue and thought it was all good until today, when I had to go a little wase at low RPM and this give way to almost no brakes. When I got back on the highway , and higher RPM all worked very well. plenty of stopping power.

[KULTULZ]

No disk brakes, drums all around. It was a power assist brake car. We just updated with new power unit, and dual master cylinder. M/C has 1 1/8 bore. I have been fighting the vaccum issue and thought it was all good until today, when I had to go a little wase at low RPM and this give way to almost no brakes. When I got back on the highway , and higher RPM all worked very well. plenty of stopping power.

Again -

What is your manifold vacuum at idle and say 2500 RPM?

Have you put a vacuum gauge on the booster supply line?

Does the reservoir tank hold vacuum?

Is the check valve operational?

Have you checked the vacuum draw of the electric assist pump @ all RPM's?

You have two choices with that cam,

Either find an electric vacuum pump that works, or

Revert to Manual Brakes (or HYDRO-BOOST).

Do you have a 1957 FORD SHOP MANUAL? There are several adjustments on that unit.

[59meteor]

Do you know the specs on that camshaft? With such a heavy car, and likely tall "highway" gearing, a lumpy cam will not only kill the manifold vacuum, but make the car a dog from a stop, or at low speeds. Not too mention make it gas thirsty. I have never owned a 50s Ford with the "Swift Sure Power Brakes" bellows setup, but I have experienced the big cam/low vacuum syndrome with some of my other cars, kinda a PITA for a driver type car.

[thomasso]

Poor vacuum boost?  Its not going to get any better without repairs.  Simple solution at least for now is an electrific vacuum pump. A good cheap source is a used one from a diesel Range rover. There is one on ebay now for as low as $26.