Hey guys, I am about out of usable room on my '29 Willys roadster build. Wanted to use a booster unit on the brakes but just cant find the extra room. I have a set of Speedway big disc brakes on the front, ford drums on the rear and a duel chamber master cylinder. Can I run this setup without a booster or not??? Please give me your thoughts . thanks
Basically the same setup in my avatar. No issues after many years and many miles and a few panic stops.
I have a 35 chevy pickup. Disc in front ford drums out back no problems. With a heaver car you may have to push a little harder but they'll work.
Just do your homework - Verify your front AND rear piston dia's, then size the master cylinder to suit. I've got disc/disc on one of my cars, no booster and it stops with "very" little effort. My setup works well with a 1.00" master cylinder piston diameter. Mike
same as chopped51-no problems. i am running a pete&jakes set up from the eightys in a 2000lb. car. it stops on a dime...................
I am not entirely sure where the idea comes from that you "must" have a power booster with disc brakes, but I get a lot of calls from guys in your shoes. Just as a couple of others have said, be real careful about master cylinder diameters and go. It was done a million times by the OEM manufactures before the world got so wimpy that power brakes became "necessity". Do make sure your pedal is in 6:1 range or better as far as ratio.
With a light car, there should be no problems. A few years back, I ran 4-wheel disks - 11 inch '71 Maverick rotors with GM callipers on the front and 2000-something Ford Explorer disks in back, using a 79 Lincoln Versailles master cylinder - on an OT V8-powered '74 Pinto - total curb weight about 2470 lbs. with no power booster and it worked great. Pedal travel was normal and, pedal effort was firm, but certainly not excessive or hard. And having that much brake on a sub-2500 lb car was phenomenal - the car would haul down from any speed you cared or dared to go without any brake fade whatsoever and it would stop on the old proverbial "dime...and then give you back 9 cents change, too!! Mart3406 =======
^^^^ as louvers stated: pedal ratio/geometry is huge. No booster needed. very little room in that car, got a 27 sedan, same deal.
My set-up on 39 Chevy is all off a 71 Firebird. That car was non power disc brake car. Just a place to look for the sizing.
Non power on my Galaxie with discs and works fine, you will have to push a little harder. Look for smaller bore master cylinders, I'm using a 1" and have been told a 7/8" would help the pedal feel.
I did that on a '47 Ford Coupe a few years ago.........BIG 12" F100/150 rotor kit from Speedway with BIG GM '71-'76 fullsize calipers on the front......8" Ford with 10"x 1.75 drums on the rear and a '67-'72 Mustang 15/16" bore master cylinder with stock Ford pedal assembly. NO booster and NO proportioning valve.. Very satisfactory results. Nice pedal feel.........great performance with no premature lockup of the rear brakes. Ray
my avatatar has the eci disc kit for a camaro clip up front and standard 10 bolt drums in the rear and runs a non boosted master. it's the corvette 1 inch bore style master. no problems here.
The idea comes from guys that were not around before everything had a booster I think. I got a set of twin piston brakes from an Avanti that didn't have a booster and it gets even better it had a jelly jar from the factory. I used to wrench on a 55 Stude that had Ford discs on the front and an 8" ford with drums on the back, ran for years all over the US with an original master under the floor.
Ditto: My Avatar 55 routinely gets up to 120mph in the quarter mile, and stops - no problem. Manual dual cylinder Corvette master, disc front, Ford drum rear. Cars weighs 3200#
If you still want power brakes there are remote boosters. They can be located anywhere on the car. Hot rod shops sell them. An alternative is the hydroboost system that uses pressure off the power steering pump. OEM starting with GM in the late 70s. Much smaller booster but of course, you have to have a power steering pump.
GM cars had two holes in the brake pedal arm to use with either power assist or manual brakes masters. Simply moved the operating rod closer to the pivot point for manual master to increase leverage. I removed the master on my Austin when I swapped cams in the 327 and didn't have enough vacuum. No way to move the rod, so I simply chopped the arm and lengthened it to gain a little leverage. They work great without the booster, after the mod.
Some of those small hot rod after market boosters seem to do very little anyway. I had a Hillman sedan years ago with factory front disc brakes and no booster and braking was good...
Nice to have those kind of options Rusty. I ran front disks w/o boost and upped the pedal ratio slightly. Seems I recall 6:1 was a typical starting point.
Same here on the Plymouth. I have G.M. calipers all around on 11" discs with a Willwood triple master, balance bar system and two 1" cylinders for the brakes on a 2800 pound car... Life is good!
I build all my cars with no booster. At least 6-1 pedal ratio and a 7/8" piston in the MC. I like having the same pedal feel regardless of engine vacuum and the brakes work just as well with the engine off. You have to get used to pushing the pedal a little harder but it's hard to go back to the over boosted 50's and 60's brake pedal feel once you do.
have a OT '76 Chevy 1/2 ton PU with factory front disc / rear drum and no booster. yep, got to drive like drum/drum but, it works.
Pretty much all the correct info has been stated throughout this thread but allow me to sum it up. I sell hot rod parts for a living and assist in matching brake components every day. 1) Choose the correct bore MC to match caliper fluid requirements. 1" or 15/16" offer greater line pressure with given amount of leg pressure vs. 1.125" bore. Calipers require more fluid than wheel cylinders. 4 wheel disc will need a larger bore MC vs. disc/drum 2) Create a pedal ratio greater than 6:1. I've seen systems up to 7.25:1. 4 wheel disc will benefit from the greater ratio (see #1) 3) Under the floor pedal? Install 1 residual valve, inline, after the prop valve in each circuit front and rear. 2# disc, 10# drum. This will eliminate fluid drain back into your MC and will partially begin to engage your calipers or drums. It will not create drag. It will reduce pedal travel and brake engagement time. 4) Prop valve? Up to you. A combo valve will engage your rear brakes first allowing the car to track straight under panic braking. It will also reduce rear brake line pressure. A prop only valve will just reduce your rear brake line pressure. Dave
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