I realize this may have to be posted somewhere else but did not see a brake section. I have completed the 4 wheel disk conversion on a 1959 Fairlane Skyliner. Willowood front , ( Front Brake Kit Part No.: 140-13653 and Inline tube rear with large spin out caliper single piston . SKU: FDBK9XB ) 22 inches vac, 1979 Corvette style master cyl. 1 1/8 inch bore., 8 inch dual diaphragm power booster, new 3/16 nickle lines, pressure bled system after installing everything and bench bleeding master. I have hard pedal about 1.5 inches from floor, car will not panic stop or hard stop for that matter, definitely would not drive. No proportioning valve. Any ideas?
Put the drum brakes back on it? Since there is a lot of pedal travel, you probably can't use a smaller bore master cylinder. Can you fit a larger booster in the car? But hopefully someone else will have a useful answer. I don't like 4 wheel disc brakes on old cars. Maybe you could just put the drum brakes back on the rear.
Air? I use a vacuum setup to bleed, then do another bleed manually to get any remaining air out. I have good pedal on my manual four wheel disc setup using the same master but, it's 1" bore.
Are you using a Disc/Disc master cylinder. All a booster does reduce the leg pressure when braking. The only difference a booster will make to pedal travel if you have not got the right gap between the booster rod and the master cylinder piston.
Too bad you’re having problems. The Wilwood kit front 4 piston and stock rear 9” work great together using their MC with or without a booster. Only the diameter of the MC is different. Their prop valve works as intended. You might want to go over to the Ford group here under social forums under brands. There is a lot of information on brake conversations there up to the 59’s
System was bleed using a power bleeder, forcing fluid through the master cylinder to each caliper , catching fluid coming out in a jar until all lines stopped showing air bubles, then closed off.
Trying to reply in order, only about 1.5 total travel. Booster has no gap between master and firewall, fact is I had to push the piston in about 1/4 inch to mount it. Adjusted pedal travel both ways, up, and down, first upward to compinsate for having to pushing piston back, that put the pedal all the way to floor, no stoping at all, then downward until where I am at, I still have another 1/2 inch adjustment, but pedal is high now and it will stop, just not quickly, so I doubt that will help, it like not enough pressure to activate the calipers all the way. Pedal travel has been customized to go a little or a lot, depending on adjustment,
I am not clear on this. Do you mean to say that the pushrod from the brake pedal had to push into the booster in order to mount the booster on the firewall? Do you have a parking brake lever, or pedal attached?
Think you miss understood what i meant by Booster/M/C gap. https://techtalk.mpbrakes.com/how-t...forget-the-booster-pin-to-master-cylinder-gap
No, on booster mounting. it was fine using an adapter kit, the master cylinder piston had to be pushed in in order to mount it to booster, but it did not cause brake drag. Yes I do have parking brakes, but have not hooked up the cables yet. My mistake on pedal travel, ment to say master cylinder piston rod or rod from booster to master cylinder can be adjusted, pedal is fixed and stock. That rod is pushing the piston about 3/4 inch into the master cylinder at present, it is the only way I could get a higher pedal and not bottom out on floor and still no stoping at all, now it will stop, and pedal is higher and fine until it stops travel about 1.5 inch from floor then it gets realy hard to push about another 1/2 inch and slow stoping. Talked to Willowood Tech, we are trying to get in touch with inline tube to find out the rear piston size and pressure required to fully engage it, he thinks it is possible it is drawing all the fluid pressure and starving the rest of the system. It's all new to me, to far in to go back. thee has to be a way to get it all to work properly, we will see.
I have a '59 Ford with manual discs up front, stock drums out back. The car stops great, dual master is from a '72-ish Mustang. I run a simple CCP Brakes distribution block. My guess is that you have a lot of parts that do not play well together. I'm no fan of the cheesy Corvette style masters that are all over the place.
7/8” no booster, by Wilwood tech. Also replaced rear drum wheels cylinders with smaller size. Also for non power. 2 suppliers told me to do that. When I was talking to the Wilwood tech he said that was a good idea. I also used F-150 11x2-1/4” drums for a better match up to the original Fords on my 56. I’d bet if I went to a 3/4” MC pedal pressure would be less but it’s great now..
If you had to push the M/C piston in to get it to fit to the booster then you have got a problem right from the start. You need the gap as in the mpbrakes article for a start.
squirrel is right 4 wheel disc brakes do not work real well with old cars. it can be done with a lot of work and engineering and to me the benifit is not the effort. the results are that much better than disc fronts and drum rears. Remember 4 wheel disc are designed for anti lock systems. Tom
Ok, thanks for all the input. Lots of work, lots of engineering on pedal travel, and push rod length, Tons of patience, and MOST OF ALL, CORECT MASTER CYLINDER, 1.25 Bore, and now stopping on a dime as well as my new Ram pick up.
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