My f100 manual brakes won't stay pumped. I have to keep pumping the brakes, cuz if I keep the brake pedal pushed down it fairly quickly goes all the way to the floor. I checked the single master cylinder and it was full of brake fluid.

The truck has original brake system including hoses. If I want to put in a dual cylinder with power booster, what are my options? I tried to do some searches for after-market brake parts, but so far I haven't gotten very far.

Was really surprised it hadn't lost any brake fluid. Figure it has air in the line or mushy brake hoses or ???. I'm not too experienced on manual brakes.

Any thoughts would be most appreciated.

 

The master cylinder is most likely shot. It is bypassing internally instead of forcing the fluid to the wheel cylinders.
I'm afraid I can't help on the upgrade options for your year truck, but I know someone will have an answer soon!

 

https://www.ford-trucks.com/article/...ough_1964.html
Theres some info in that tech article that should help get you started.

Alot of brake questions have been asked in this forum - do a search.

Keep in mind, there are alot of differences between the 61-64 and 65-66 slicks.

 

I recently put a dual M/C in my '64. I got a remanufactured one at the parts house for a 68 Mustang (drum/drum). It bolted right in w/ no mods. I also replaced all of the steel and flexible brake lines. There is a lot of discussion in this forum about whether to use a proportioning valve or not. I did not install one and have had no problems. You'll also have to come up with a different method to actuate your brake light and there is plenty of instruction on the forum for that. I ended up installing a "T" at the M/C for the switch... it's not pretty but it worked.

 

I used a big block 68 Mustang drum/drum m/c on one of my early adventures in braking.....the m/c bolts right up without the proportioning valve on stock 64 F100 drum brakes. This unit had a built-in residual valve that kept the rear shoes in the correct position.

The guys are right about evaluating all the hoses and lines....40 years of life for brake parts is stretching it a bit. I rebuilt everything from wheel cylinders, lines, shoes and drums and still was not happy with the braking results. Adding a power booster to the mustang drum/drum cylinder didn't make the brakes comparitable to todays standards. Even with the Mustang dual cylinder it will take a strong leg to achieve marginal braking. Check out 911brakes.com for some good info on brake modifications and you might find you would be money ahead to go straight to discs on the front with a Mustang disc/drum master cylinder. Adding power booster to discs is another story altogether and requires quite a bit of fabrication.

As the brake light switch I found it easier to mount a simple push button switch on a bracket that was activated by the brake pedal. Lights activated faster and the switch was a radio shack stock item.

 

Thanks for all the good info! I'll keep you posted how everything turns out!