I am working on an O/T car (65 Galaxie). I have hung a 67 Galaxie dual chamber master cylinder. I am rebuilding all 4 drum assemblies. My boss was saying he thinks I need a proportioning valve in the system. Any brake gurus want to offer up advice?
getting ready to do this to my 61 Falcon gasser with a 67 Mustang mastercyl. From everything i know (which is more than alot, but less than more) I will need a prop valve. and i'm not sure why, but i've heard you plumb the front reservoir to the rear brakes Edit: just remembered that the rears go to the front reservoir when your doing disc/drum. so i guess it doesn't matter which goes where for drum/drum? anyone confirm this? i will do front to rear though so the plumbing doesn't need reworked if i go disc later.
Wasn't until the early 70s discs were standard. You just need the junction block the two lines feed into after they leave the master. Proportion valve is for disc front/drum rear, as noted.
I was told that you need the proportioning valve on drum/drum setups to keep the rear brakes from locking up before the fronts do. Was I given some bad information?
Thanks, 31 Vicky. The car is a '59 Ford convt. with drums all around. The last "real" brake job it had was 22 years ago when it was first built. At that time, everything in the system was replaced, and a '64 Ford "jar lid" master was installed. I am now in the process of replacing rubber hoses, wheel cyls, etc., and changing over to a dual master. The master is for a '67 Ford, full size, with factory standard brakes and drums all around. The port to the rear was plugged at the block, and I am using a Summit adjustable proportioning valve, in the line to rear brakes, to create the bias you spoke of. Anyhow, a tech at Summit recommend the valve to use in this setup. Hopefully, I'll get this finished today, and get to see how well it works.
My master cyclinder was ordered as a drum/drum system. Both chambers are the same size. So you are saying that you are running the whole system of of the front chamber?
My '61 Tbird and O/T '68 Malibu are Drum/Drum and neither has a proportioning valve. (The 'bird is a single M/C and the Malibu is a Dual M/C.) Disc/Drum will have a prop valve. I've looked into changing my '61 Tbird over to Disc/Drum,and when I do i will need a prop valve. I think it's Wilwood that makes an adjustable prop valve to "fine tune" the Disc/Drum conversions.
In the mid 60s I worked in a station for a couple of years when Colo still had the "Safety inspection, brake and light" We sold a lot of brake shoes! The brake jobs were all on drum/drum systems and all that I remember had more brake shoe area on the front shoes than on the rears to compensat for that. It was part of the drill to make sure the front shoes went on the front.....................as far back as my '31 chivvy and as late as a '66 'satng I owned the front shoes had more lining area than the rears. I would guess that the manufacturer's knew what they were doing Of course there might be exceptions to that and my memory could be clouded, but if somebody has information to the contrary, I'm all ears.
Prop valve Not necessary on drum/drum (balanced OEM)systems where the rear drums and the front drums are from the same vehicle and simply going from a single MC to a dual MC, by any stretch of the imiganition, unless you are a proportioning valve salesman. Proportioning valve for a mix-matched Disc/drum system (shade tree) where the drums on the front are replaced with disc with some replacement selected at random and the original drums are used on the back. In these cases it's known that without proportioning valve which are simply a (band-aid to correct for no engineering) Without prop valve the rears are likely to lock up before the fronts due to using mix-matched components. I would suggest that I would look high and low for a complete system rather than mix-match components. If building a car from scratch, there is simply no logic to mix-match. Even If I were going to replace all the lines and fittings I would take the entire plumbing system from a donor car and make sure I duplicated it using all the components. On my custom truck I used complete system from a jap pickup truck, disc front, boosted MC, drum rear, and all the lines, and there is no proportioning valve in that system. Proportioning valve might be needed if you mis-match front/rear brakes drum/drum where fronts are from different manufacturer/weight of vehicle than on the rear, but as I said before, I'd look high and low before considering doing that.
No, front brakes off rear chamber to original block. Plugged outlet in the original block that fed the rear brakes. Installed Summit adjustable proportioning valve in line from front chamber on master to rear brakes. This was done to try and control premature rear brake lockup. Still bleeding the air out...hope it works right!
Guru? Not. You are coming off a single OEM MC. Select a dual MC with same size bore, as somebody has already said, both front and rear same size, can't use a Disc/drum MC. No Proportioning valve needed.
29NASH has some excellent advice. As well as the front shoes being wider, the front wheel cylinders utilise a larger bore so as to push with more force on the brake shoes. Also, be sure you check to see that both ports on the master cylinder have residual pressure check valves - they're located behind the brass seats. These residual pressure valves prevent air from seeping into the hydraulic systen at the wheel cylinder cups while the brakes are in the released position.
Triplex, get a dual chamber drum/drum master cylinder of the same bore size as the original, check that it has residual pressure valves behind the seats, and screw it on the car . Make sure you use the correct end of the m/c for the correct end of the car and you'll be fine. On a Ford m/c of the vintage you are talking about USUALLY, but not always, the smaller of the outlet fittings fed the front brakes, but do some research to be sure because it does make a difference, that's why there are two different size fittings, keeps the $80.00 an hour guy on the assembly line from hooking them up backwards. There was nothing in the way of a proportioning valve between the m/c and the T fitting that split the system before, so you don't need one now. Remove the T and connect the system, leave everything else alone, and quit trying to make things more complicated than they are!
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