I hope someone can help me with a problem I have had for some time now. I have attempted to install disc brakes on the front of my 57 F-100 , after finally getting them on correctly (i hope), they bind up on me. Its just like driving with the emergency brake on. The kit I got was purchased from Classic Performance. Also got their proportional valve. I have attempted to get some advise from them, but to no avail. I have run out of ideas, anyone out there got an ansewr for me.?? Roy in Tex.

 

HI. Do you have your proportioning valve hooked up right?the 2 pound goes to the disc and the 10 pound go to the drum.the drum part should have a built in check valve.hope this helps. ART

 

Roy - Welcome to FTE. This is scarey, because I just purchased the disc kit from Classic performance parts. I haven't install the kit yet because I'm still looking for a master cylinder with dual chamber. I'm not sure if the kit comes with the proportioning valve, or did you purchase that separate? According to CPP, you don't need a proportioning valve, however everyone tells me with disc in the front and drums in the rear, you do. It sounds to me that maybe the pistons on the calibers may be sticking and not returning when you let off the pedal, or the pressure is not releasing in the fluid?. Are you running the single chamber master cylinder? and are you running power brake booster? There could be several reasons. That's why I have put off doing my brakes and have the kit sitting on my garage floor.

 

Sure your residual valves and proportioning valve are positioned correctly and not backward?

 

Sounds like your pushrod into the master cylinder is still holding pressure on the system when you are not pushing the pedal down.
I replaced the power booster on my Honda Accord years ago. The manual states you need a special tool to set the proper pushrod length adjustment on them. I didn't have one, so I just installed the rebuilt unit. About 2 miles down the road she did the same exact thing. Just like someone pulled the emergency brake on. I had a tough time even getting it off the street. I used my feet to move the car while backing off on the pushrod once it moved I stopped. I have been driving it for the last 8 years with no problems.

imlowr2: I installed the discs on my 51 F1, and used the residual valves and an adjustable porportioning valve. I went with a 1" master cylinder non-power. It works great I never had a vehicle that I converted turn out so well. If I can be of any assistance e-mail me. Also check out Bonusbuilt.com brake upgrades, and the pictures in the center section on, "how to flip a F1 and walk away from it".

 

Hey thanks for the quick respones to my disc brake problem, they all help. I used a dual master cyclinder from a 73 F-100, and a fixed proportional valve from Classic Performance. It is not adjustable.could be part of my problem. My old ears perked up when master cyclinder rod lenth was mentioned. I am using my orginal master cyclinder rod. Could be that rod lenth is a big part of my problem. Thanks to all, this forum really is great. Roy.

 

I just had probs with the Rod on Booster....I adjusted it and it fixed my probs...Same thing as yours...Brakes were always on....

 

You really have to know what you are buying and how it goes together. If you piece it together yourself, you run the risk of problems. Some master cylinders have a built in combination valve that proportions and provides residual pressure. That is why some vendors say you don't need a prop valve or residual valve. They don't always tell you why. Others have no valve and you can customize your system with an adjustable proportioning valve and individual residual valves for front disc and rear drum or all disc.

I used the ECI front disc kit and a power brake master cylinder from Bob's F100s. I installed an adjustable proportioning valve and the correct residual valves for the front discs and rear drums. The improvement in stopping distance was amazing. I tried several settings of the prop valve until I found the setting I liked to reduce the nose dive. The only other mod I would make is a delay for the front discs so the rears start braking before the fronts. But the system works well as is. Since I installed the brake system I will be swapping in a 9 inch rear axle with bigger rear drum brakes so I will need to adjust the prop valve again when I am done.

 

try backing off the bleeder screw to see how much pressure is on the piston(s), that will tell you if you have a stuck piston or pressure held on the line. good luck

 

I pieced my system together, I followed the brake upgrade tips on www.Bonusbuilt.com, but I was employed as a brake mechanic for 5 years back in the early 70's. Anyhow, I used ford 1/2 ton rotors, 76 Buick Estate Wagon calipers, and 1" manual master cylinder from the same car. I installed the residual valves and adjustable proportioning valve. I started reading stories from people saying a metering valve is needed so the front discs won't come in to soon. I was real concerned because I didn't want to have to change the new brake lines and a metering valve costs around $100.00. I decided to just drive it to see what the brakes would do. I'm glad I did because the brakes work just great, they are every bit as good, or better, that my 87 Accord.

Rod

 

I've heard the term 1" manual master cylinder a few times. What is that? Is that similar to the early Mustang single master cylinder or is that a dual chamber?

 

Hey gang, I just spent the day dismantling my master cyclinder. I removed the push rod and shortened 3/8", and would you believe my brakes appear to be working normally. My rotors are supposed to be off 73 - 78 F-150. calipers off 73 - 87 chev pu. Dont ask me why they chose this combo.?? I will let all of you know for sure about the brakes when I can get it back on the road. Its getting a valve job at present. Thanks people for all the good advise. Roy

 

The 1", 15/16", etc. refers to the diameter of the bore in the master cylinder. A large diameter will move more fluid (obviously), but will require more force from either the pedal or booster to create the required pressure in the brake lines. A smaller diameter will move less fluid but will require less force to get the required pressure. The amount of fluid you need to move to actuate the brakes and the pressure required varies for different brakes. For example, in one application the disc brakes run pressures around 1000 psi on the front while the drum rears only need about 300 psi.

 

Im using your average bolt on mustang II stuff on the front, a master cylinder and booster from a 94 Gt stang, the rear end is an 8.8 with 94GT disc brakes. Im using a wilwood prop valve though. I remeber back in my VW days, that if you had the rod adjusted wrong it would hold the brakes shut. Never had a prob with prop valves though. I would imagine if you had too much pressure it would blow the fluid past the seals on drum brakes, Im using a modified mustang pedal assembly, so I wasnt concerned with the rod geometry, length etc, Makes me wanna take more importance to it now. Now if I can just figure out the E brake cables. Man I love this forum.
Steve

 

I didn't know the Mustang unit would bolt right in place of the stock unit at the time of purchase. I decided to go with a M/C for the Buick Estate Wagon. The same car the calipers went to, the 1" is the bore size. Power and manual cylinders have different bore diameters because of the applied pressure difference. I just went to www.PartsAmerica.com and found a cylinder that the Buick used at the cheapest price $23.00. Figured if it didn't work I wasen't out that much and I could go to another size.