Thread: Hard brake pedal/pressure

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Brake extremely hard to press down Has 4 wheel power disc sbc no cam good vac in 37 Ford coupe with 20 on rear and 18 on front does not pull or shudder when stopping just a very hard pedal that will move 1 to 1/12 in from top when stopping
What suggestion on whereto look to correct the problem
Thanks in advan

Talk about deja vu!! Take a look at Navy's thread and the problems he's going through trying to sort out his brakes on a new build - Brake troubles You might read through that, and then the first step is to accurately list all of the components in your brake system starting at the pedal ratio and going through the MC, valving, booster, calipers and rotors, unless one of the others has a quick fix idea for you.

You need to provide a lot more info about the brake calipers, size of master cylinder bore, size of power booster and whether it's a single or dual diaphragm. The pedal leverage ratio is also a must.

As an example, my car has a 3.8/1 pedal ratio. With a single diaphragm booster, 1" master cylinder bore and Wilwood discs, the pedal pressure was higher than I wanted. A change to a dual diaphragm booster increased the pressure and reduced the pedal force by about 27%, which was better, but still not overwhelming. I've just reassembled the chassis (for the last time) and installed both an 8" dual diaphragm booster and the 7/8" bore master cylinder, that should increase pressure and reduce pedal pressure by over 50%.

I called Wilwood and got a recommendation of a minimum 8" dual diaphragm booster, with a 1" bore master cylinder, so I went one step further, adding the smaller bore master cylinder. I will be a few months before I get to try it out.

A manual brake system from Wilwood has a 7/1 pedal ratio, that they claim will make the brakes operate as easily as many boosted setups. It does require more pedal travel, with that ratio.

Yep, too many folks believe that a larger bore MC is always better. T'aint always so, McGee . . .

Originally Posted by Henry Rifle

Yep, too many folks believe that a larger bore MC is always better. T'aint always so, McGee . . .

I agree with you. As an example,my T-bucket has a 7/8" bore on the front and a 13/16 bore on the rear. They are operated by a balance bar. This is with drum brakes front and rear.

My current project will most likely wind up with 3/4" bores front and rear on a balance bar. Might use a 5/8" if I need to get the pressure I want. This car will have discs all the way around.

Both cars are manual brakes. On the new car, I'm shooting for a fairly low pedal effort (around 100 lbs) so my wife can drive it easily.