I have a '66 f100 with a dual master cylinder and booster from from a '78 f150, the booster has gone bad and I was wondering if I could use the master cylinder without the booster.

Also, can I use the brake rod that is currently on the truck? The pedal is sticking up higher than normal.



Thanks.

 

You can run the master cylinder without the booster but the brake rod will have to be modified or replaced. By modifying I mean that you are going to have to measure from the fully extended pedel to the master cylinder plunger socket (use a drill bit to measure the depth of the hole) then grind the rod down and round out the hole. Remeber it is easier to remove less material then having to add some. Just take your time and you will be fine.

 

You have two problems. The first is a bad booster. I think you should replace it. Power brakes are really a safety issue. The second problem and one you have been dealing with prior to the booster failure is touchy brakes caused by an incorrect brake pedal ratio. Someone installed a power booster on a manual system and did not correct the ratio. This is an easy fix and if you plan on replacing the booster post back and I'll help you through the process. If not you have the correct ratio for non power assist.

 

Thanks guys for the info!

 

Why not cover correcting the ratio here?

Scott

 

If the audience knows nothing tell them everything. If they already know everything refresh their memory. The distance between the brake pedal pivot point on the hangar bracket and the point where brake booster rod connects to the brake pedal arm is called the brake ratio. Non power assist have a short ratio, pedal sits up off the floor and allows more leverage. Power assist have a longer ratio and the pedal sits closer to the floor since not much leverage is needed to engage the booster assist. Drilling a new hole for the brake cylinder rod about an inch lower on the brake pedal arm moves the pedal closer to the floor and provides the longer brake pedal ratio for power assist. That said, I use brake pedal arms from power brake equipped trucks to 1979 and the brake pedal bracket from a 66 automatic. I modify the pedal bracket to accomodate the stop light switch. I remove the Ford stoplight switch bracket from the brake pedal arm by drilling two spot welds. I mix and match the plastic bushings until I have a nice tight pivot and the correct power brake pedal ratio. This also gets me the wider power brake pedal and I use a new pedal pad. I use a Ford brake booster rod that is flat, a matching rubber firewall boot (Mustang 45 bucks) and a step bracket to mount the booster to the firewall. This step mount clears the valve cover. Saw off 1 inch from the booster rod at the end that attaches to the brake pedal arm and redrill a new hole. This hole is big 1/2 or 5/8th. Reinstall the eccentric bolt and plastic bushing. This is important so you can fine tune brake pedal height. 100% Ford parts available in the Junk Yard. There is more but this will get you started in the right direction. Do it right, do it once and drive your truck! I know, I'm picky.

 

Ihave decided not to replace the booster. But I do not have an arm that is long enough. I need one that is six and one half inches long. Could I buy one from an auto parts store?

Thank You

 

Nope! You will need one from a truck with disk non power assist. Junk Yard parts