showoffzx2

Hello,

Has anyone bought a kit for a front disc brakes with a manual master cylinder rather than a power brake booster?

I love the feel of my drum brakes with a manual master cylinder. I would like to continue this route but change out the front drum brakes to disc. Can you use the same master cylinder that the drum brakes use? My guess is no, but figure to ask. Is everything fairly straight forward with the install?

Truly my drum brakes aren't bad and will stop quickly, my problem is how it pulls horrible. One time it's to the left and next time to the right. I wonder if the proportion valve is going bed and giving different pressures. The drums were adjusted by me and several mechanics and nothing ever went right.

Thanks!!

Gun Jam

Thats a common drum issue.

Do you have dual reservoir Master cylinder now?

If you do there is a very good chance you can run it on your disc brakes with zero issues and it will provide good pedal feel and plenty of stopping force.

How big are your wheels? If you are running 17" or larger you should go with a 13" minimum rotor or you will have stopping issues using big wheels and little disc

11" rotor works well for 14" wheels probably 15s as well.

I have used both SSBC and Global West's wilwood systems up front and both were / are great.. Im in the final stages of dialing in the new wilwood system.

https://mustangforums.com/forum/clas...adventure.html

imp

Way way back, I put discs in front on my original '65 "K" car. Why the hell then I took no pictures, is a good question. I got hold of the steering knuckles, rotors, ball joints, etc., out of a GT-500, and after much matching up of parts dimensionally, got the stuff installed, aligned the wheels, used that factory, tiny, cast iron master cylinder with the screw-on cap, no power assist, no pressure proportioning valve, left the rears alone (for awhile, they got discs later). The combination worked remarkably well! Pedal pressure was not any problem. imp

Starfury

I put the CSRP OE-style front manual disc kit on my '67 and I love it. No problems at all with pedal effort, and no worries about making enough vacuum to run the booster.

showoffzx2

I'm running 17's on the stang. I am really digging Kentucky Mustang right now. I have e-mailed them several times and they are instantly responding. The kit for a manual disk brake setup is $720.95. Very hard to beat anywhere else and the kits come with everything. I will need to check but I want to say I have a dual reservoir on it already. If I can reuse it, that would be great! I know its been replaced, but I want to say in the last 10-15 years.

Maybe that's why I lost so much hair on my head from the drum brakes .

Starfury

You can't use a drum/drum master cylinder on a disc/drum setup. The drum bowl usually has a check valve built in to keep slight pressure on the wheel cylinders to keep the shoes up against the drums (lessens pedal travel). This check valve would prevent calipers from retracting and cause drag on your discs.

imp

This sounds nonsensical, I've never heard of it before, in 60 years of fu@king with Ford brakes, and would really like to hear where you came up with this fact? Ever experience it? I used my original '65 MC, drum/drum, to power my disc/drum set-up, no P.B., worked perfectly.


That check valve would cause drag on drums OR discs. If I'm wrong, and I've been wrong many times, well........imp

fastbackford351

Back in the day, the first upgrade I did to the fastback was to install a set of discs out of a Granada and not knowing any better, kept the stock '67 Mustang master cylinder and it seemed to work just fine for years. When I finally replaced it, I used a manual master cylinder out of a 1976(ish) F100 truck and with the added volume of the F100 setup I did notice it worked a lot better than the smaller stock setup.

Starfury

From old school Ford techs, my ASE shop teachers, several older forum members on a different forum, A1 Cardone, Wilwood, SSBC, CSRP...

Not all drum/drum m/c's have these valves installed, but many of them do. These valves keep about 10psi of pressure on the drum system to keep the wheel cylinders from fully retracting. If you understand how the two different brake systems (drum vs disc) work, you understand why this is necessary.

Wheel cylinders have relatively small bores which require a lot of travel before the shoes fully contact the drums. Drum brake adjustment is hardly precise, so the shoes are almost never right up next to the drums. If you don't keep pressure in the system, the wheel cylinders retract due to force from the brake springs, and the next time you step on the brakes you have more pedal travel to make up for the longer throw of the wheel cylinders. The brakes will still work, but not as quickly.

Disc brakes work entirely different. Caliper pistons with their large bores move very little before the pads contact the rotors. When pressure is released, the square-cut caliper seals retract the pistons just a hair, and any additional clearance needed is made as the rotor wobbles and knocks the pads out of the way. This clearance is measured in thousandths of an inch.

Due to the larger piston area in disc systems, 10psi of residual pressure results in quite a bit of force on the pads (force = psi x piston area). This additional pressure is enough to keep the pads from properly retracting which can cause excessive drag, brake pad wear, and heat checking on the rotors.

The OE-style m/c I got with my CSRP front disc kit didn't have a residual pressure valve installed, so there was one included in the kit that needed to be plumbed inline with the rear brakes.

showoffzx2

I do appreciate all the feedback!

I am in the stages of trying to figure out how much more it will cost to extend my garage to fit the Mustang in. It's currently residing at my mothers garage due to space. Hopefully extending the garage 12ft (sides) and 24ft (back wall) isn't to much.