The car is about 98% done and I have done virtually all the work on this build. However I have some concerns with the braking. Used hydraulic drums front and rear. Adjustable bias valve installed to balance system pressures,adjusted brakes and fully bled system. Problem is that I have a high pedal but it takes a "lots" of foot pressure to safely stop the beast. Installed power brakes on the 34 build but wondering if this is normal in this set up. Do the shoes need to be seated? Bias valve adjustment wrong? Any advice is appreciated.
What year and what brake system? Did you check the fit of the shoes in the drums before you installed everything? Did you make sure the shorter primary shoe was toward the front on the vehicle? Is the master cylinder a match to the original brake system? Did you rebuild or replace the wheel cylinders? Sent from my iPad using Tapatalk
I don’t recall any drum brake system using a bias valve...the master cylinder provided the balance between front and rear and the differential in the size of the friction material between front and rear provided the rest of the balance...65% front...35% rear...on average. Sent from my iPad using Tapatalk
Why did you add an adjustable bias valve? I've been working on old Ford's for 52 years and have never heard of that
Shoes and drums are matched sets . Standard Ford new master cylinder. Pedals from a mid Forties Ford. Think I had a brain freeze..... bias valve most likely the culprit. Stupid of me.... always over designing the wheel. Simple rerouting of brake lines. Guess I’m not quite there. Sent from my iPhone using The H.A.M.B. mobile app
Yes, if the brakes are over 40 years old. But residuals are good for any drum brake, regardless of age.
Two, or three things... "Standard Ford master cylinder" Don't think there is any such thing. What is the wheel cylinder bore size? What is the master cylinder bore size? Or, what was the original application for the master cyl & wheel cyl? -Dave
Another example of poor information on brakes, the master cylinder does not provide balance between front and rear, it simply moves fluid, have a look at pascals law...and YES residual valves are required as V8bob said, unless the wheel cylinders have cup expanders, still will not hurt to have them. Sent from my iPhone using H.A.M.B.
Guess I was thinking of a dual master...plus the residual valves are built in to the ports of a drum brake master... Sent from my iPad using Tapatalk
Provided you are using a drum brake master to start with...., we don’t have nearly enough information to guess on his problem, need master cylinder and wheel cylinder dimensions as well as pedal ratio etc. Sent from my iPhone using H.A.M.B.
Since no one has asked yet, do you have any pedal free play? do you have the adjustable master push rod/eye bolt arrangement? Chappy
I have free play at top of the pedal and the push rod is adjustable. Front wheel cylinder bore is 1.125 and rears are 1.065 inch bore Master cylinder bore is 1.625 inch bore. All are new pieces. I removed the residual valves and bias valve today ,re-routed fluid lines and bled the system. Pedals are unmolested 39-40 pedals. Frankly not much difference in braking. Need a "brake" from climbing under the car about now! Suggestions appreciated.
What kind and year drum brakes are they? Are you sure about the 1.625 master cylinder bore? That's a very large bore, and would definitely require a booster.
That master cyl bore sure sounds large to me. I would ditch the adjustable bias valve and just go with the stock Ford components. I used 39 pedals and master cyl and stock Ford wheel cyls for late forties backing plates plumbed with 1/4 inch brake lines. Stops great, couldn't ask for better performance from drums.
Brake problem update....pulled the the drums from the car and this is what I found. Appears the shoes had high spots and that has limited shoe drum contact. Had high spots removed, readjusted the brakes and re bled the system. After much rain and some stupid spring snow here finally took the car out. Braking is remarkably better!!!!! Sometimes the simplest things are hardest to see. Thanks all for the input.
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