The Stovebolt Site Forums The Shop Area General Truck Talk Dual master cylinder

I've got a 1951 1/2 ton with Patrick's Saginaw 4 speed conversion (Hurst shifter) and have just finished mounting CPP's 6 lug disc brake kit now I am trying to mount CPP's manual dual master cylinder, I cannot for the life of me figure out how to get it to fit in the allotted space. I've looked at web photos and still can't figure it out. The proportioning valve is mounted on the bottom of the master cylinder and the lines going to it interfere with the trans linkage. If I mount the master cylinder with the "L" part of the bracket to the front, the bracket for the proportioning valve hits the gusset on the master cylinder bracket, (I can trim the mount) if I mount the "L" to the rear the cylinder hits the crossmember. Which was is it supposed to be mounted? Should I just take the trans crossmember out and worry about modifying it later?

Not sure how yours work, but I used a Mustang II dual MC with a kit from Fatman's. Bolted right in where the original MC mounted. I didn't need a proportioning valve, even though I've got Mustang II disc in the front.

I'd move the porportioning valve somewhere else. The CPP kit was probably designed for a stock transmission and not the Patricks setup.

Moving the valve will mean a little fabrication to mount and then running some new lines. A minor project compared to modifying the crossmember.

The CPP bracket did not fit on my '54 GMC without modification. I had to cut and re-weld the bracket. Click here then click "front suspension".

Cletis: I found your site very helpful when I was installing the disc brakes. On my install in addition to all the grinding I also had to shim the brackets to get the discs to spin freely. Also found I was missing the steering stop on the drivers side. I'm using a manual master cylinder that has an "L" shaped bracket.

I removed the proportioning valve and I think I can clear the shift linkage. If the bracket is mounted with the short part of the "L" forward it looks like the bolts that will connect it to the frame will not clear the 2 wire clips that hold the lid on. (The master mounting holes are elongated I'll see if it can be moved a hair inboard to clear) If the bracket is mounted with the short "L" to the rear it looks like the master will hit the cab floor. I'll know for sure when I crawl under it today.

OldSub: Do you know if the proportioning valve has to be installed in the same configuration (flat below the cylinder) or can it be turned on it's side and mounted slightly above the master?

Pablos49: Does the Mustang II master have the proportioning valve and residual pressure valves built in? If I ditch the proportioning valve and just add the correct residual pressure valves will it stop correctly or will the rear wheels lock up easily?

As you can probably tell I have just enough mechanical ability to get myself into trouble.

Thanks,
John
Milford, MI

Update.
Two trips to the welding shop and I now have a modified master cylinder bracket with a plate to mount the proprotioning valve. Pictures are buried in this album.

http://s241.photobucket.com/albums/ff93/jal12147/1951%20Chevrolet%20Pick%20up/

I've ordered a brake line kit and plan to use the stock brake line routing. Everything from the tee fitting forward and rearward on the passenger side. I also ordered 2 L fittings so I'll only have to fabricate lines from the master to the proportioning valve and from the valve to the two L fittings on the passenger side of the truck (one connected to the line for the rear and one for the line to the new disc brakes in the front.)
Unfortunately I didn't take any pictures of the bracket before I had it modified but it is from CPP to fit 47-54 Chev trucks and some form of F**d. Some height was added to the side that bolts to the frame so the bolt holes could be relocated 3/4" higher, 5/8" was added to the bottom with with a horizontal plate to mount the proportioning valve.

John
Milford, MI
1951 Chevrolet 3100
1975 Delta 88 convertible