I spent two hours searching the forum for the correct master cylinder to use with 4 wheel discs. I read so many different things that I'm more confused now than before. I even checked the fordmuscle forum and it didn't help. I'm putting 4 wheel discs on my '75. It's not a race car, but I want it to stop on a dime. I know some people are still using the drum/drum and disc/drum master cylinders and they work. I don't want to spend $200 on a Wilwood. I just want to do it the right way. I've read that some people have used 1970's corvette, 1980's dodge truck, 1990's mustang, and even 1970's F-250 master cylinders. I read that the dodge's may have issues with brake line threads matching. I would like to get some feedback on ease of installation and pedal effort. PLEASE HELP!!!!!!
I would find a m/c for 4 wheel discs. Drum brakes require a m/c with a residual check valve that when used with discs it will cause them to drag. Get one for a Lincoln Versailles if you have power brakes and you should be just fine. If the threads don't match up you can get adapters.
I agree with Ramsey... I am going for the 4 wheel power discs and have yet to find the definitive parts to use.
Another member here (RADMAV) pointed me in the ABS POWER BRAKES direction. Look at catalog page 119 under universal master cylinders. I'll probably go with their MC-1373 with my 4 wheel disc set up when the time comes. http://www.abspowerbrake.com/maincatalog_frameset.html
I used a m/c from a 1991 Dodge Dakota pickup. Just change the fittings and short lines, and if you like, put an adjustable prop valve to the rear brakes. No other mods required. I have good firm pedal, good brakes!
http://forums.vintage-mustang.com/mod-custom-forum/575036-maverick-master-cylinder-swap.html i have Disc/Disc and no...R.C.V. or prop. valve...brakes work fine... ......
The bore of the master cylinder has to be the correct diameter for the calipers that you are using. Different caliper bores require different sizes of cylinders.
That's what I was saying, if you DID have the R.C.V. you would have problems but since you don't it should work properly. As far as no prop valve, I would run one myself so you have the proper bias.
For what it's worth... I'm using a master cylinder listed for a '91 Explorer, 1" bore. Maverick power booster. I had to change the flare fittings on the lines to metric. I drive it daily in all conditions and I couldn't be more satisfied with the brakes.
I found this on another site. Does anybody have the knowledge to verify it? This could help a lot of people on making a decision. "Some types have larger reservoirs on the front disc side to supply the void as the pads wear. In most cases it is not because the discs use more fluid to apply. A little math shows a 2.5" caliper piston uses almost exactly the same volume of fluid to apply the typical .050" as a well-adjusted pair of pistons in a 1-1/8" wheel cylinder take to move .125" to apply. Oddly enough, due to the large perceived piston area, folks often think they need a disc MC because they use more fluid to apply. Nope. Drums - if not properly adjusted regularly - consume even more fluid than the discs to apply."
I finally decided to research it and do all of the math. Please feel to correct me if I’m wrong anywhere. I’m not a mathematician. According to the calculations, it appears that a stock Maverick disc/drum master cylinder would be sufficient to meet the volume and pressure requirements. BRAKE VOLUME Front Calipers: 1 Piston Design 2.6" diameter pistons, uses 0.600" thick pads; 1.3" radius x 1.3" radius x 3.14 = 5.306 square inches per piston; 5.3066si x 1 piston caliper = 5.306 square inches per caliper; 5.306 si x 2 front calipers = 10.612 square inches; 10.612 si x 0.600" thick pads = 6.367 cubic inches Rear Calipers: 1 Piston Design 1.88" diameter pistons, uses 0.600" thick pads .94" radius x .94" radius x 3.14 = 2.77 square inches per piston; 2.77 si x 1 piston caliper = 2.77 square inches per caliper; 2.77 si x 2 front calipers = 5.54 square inches; 5.54 si x 0.600" thick pads = 3.324 cubic inches rear TOTAL - 6.367 cubic inches (front) + 3.324 cubic inches (back) = 9.691 cubic inches; Conversion rate 1.8047 cubic inches = 1 oz. Front 6.367 cubic inches ÷ 1.8047 = 3.528 oz. minimum brake fluid required for front reservoir. Rear 3.324 cubic inches ÷ 1.8047 = 1.842 oz. minimum brake fluid required for rear reservoir. ************************************************************************ Front disc brakes typically require at least 1,000 psi of hydraulic pressure to fully actuate (around 800 psi is rock-bottom for disc movement compared to 400 psi for drums). So you need 1000 psi by the master cylinder alone or the combination of a booster/master cylinder. To determine the proper size master cylinder: Figure how much pressure your master cylinder is putting out: C = pedal ratio D = pounds of pressure apply by your foot E = area of you master cylinder F = pounds of pressure out of the master cylinder C X D /(divided by) E = F Example: 15/16" master cylinder, the area equals .46875" x .46875" x 3.14 = 0.69 Square Inches. 100 pounds (foot pressure) X 6.2 (pedal ratio) divided by 0.69 = 898.5 pounds pressure. With a 15/16” master cylinder, it should take about 111 pounds of applied pressure to lock the brakes. 1” master cylinder, the are equals .5” x .5” x 3.14 = .785 Square Inches. 100 pounds (foot pressure) X 6.2 (pedal ratio) divided by 0.785 = 789.8 pounds pressure. With a 1” master cylinder, it should take about 126 pounds of applied pressure to lock the brakes.
that looks good on paper... but is this for the same size tire mass front to rear? 1000 lbs. pressure on a 265x15x10 will stop different than a 205x15x6. when setting up my Disc./Disc. system, there was some testing of different M/Cs. when i got close then i change the...pedal ratio... I have...1150 psi...on my system...firm pressure to pedal...it was hard untill I changed the ...pedal ratio. ...no prop. valve, no R.P. valve...twin piston front...single piston rear. ...what you have outlined is a great place to start... ......
