Front Disc Conversion-Proportioning Valve and Master Cylinder

[Stihl011]

I have purchased an SSB-W153 front brake conversion kit, and was busy reading the instructions, and found out I need a different master cylinder and a proportioning valve.

After digging into it appears to me that someone before me has already replaced the master cylinder with the one needed for disc brakes. According to a youtube video I saw, a drum brake car would have had a "double hump" master cylinder, and the one I have looks like a after-market cylinder of the type used on the disc brake cars. Am I correct on this?

The proportioning valve I'm less sure of. I'm not actually sure if I have one already or it's just a distribution block (which I assume)

It looks like I could get an after-market adjustable one, but would have to find a place to mount it on the frame. There is also the PV6070MOP style that I can buy, which I think is both a distribution block and a proportioning valve, that will mount in the distribution block's location, but will need some changes to the tubing. I am concerned whether or not it will fit my car. The link below does not have a 68 barracuda listed.

PV6070MOP - O.E.M. Mopar Proportioning Valve - | Disc Brake Kit

As always, thank you for any information you can provide

 

[72Dart6pack]

Go to the Doctor Diff website & email Cass. He can answer all your questions.

 

[Mike Herlinger]

I have purchased an SSB-W153 front brake conversion kit, and was busy reading the instructions, and found out I need a different master cylinder and a proportioning valve.

After digging into it appears to me that someone before me has already replaced the master cylinder with the one needed for disc brakes. According to a youtube video I saw, a drum brake car would have had a "double hump" master cylinder, and the one I have looks like a after-market cylinder of the type used on the disc brake cars. Am I correct on this?

The proportioning valve I'm less sure of. I'm not actually sure if I have one already or it's just a distribution block (which I assume)

It looks like I could get an after-market adjustable one, but would have to find a place to mount it on the frame. There is also the PV6070MOP style that I can buy, which I think is both a distribution block and a proportioning valve, that will mount in the distribution block's location, but will need some changes to the tubing. I am concerned whether or not it will fit my car. The link below does not have a 68 barracuda listed.

PV6070MOP - O.E.M. Mopar Proportioning Valve - | Disc Brake Kit

As always, thank you for any information you can provide

View attachment 1715216021

View attachment 1715216022

Where did you end up mounting your prop valve.. im in the same boat.. not sure where I want that thing.

 

[Stihl011]

I’m ashamed to admit I haven’t done it yet, I got busy and/or drunk. Hopefully in the next few weeks and I’ll post.

 

[72Dart6pack]

At least your honest.

 

[DesertRat]

I converted my car to disc/drums. Bought a stock disc drum MC and a factory proportioning valve from somewhere-probably from someone here.
I mounted the proportioning valve in the factory distribution block location after installing a rebuild kit in it. I just built new lines as needed to make it work.
It isn't the recommended method to rebuild the prop valve but they make a kit with good instruction and my car stops on a dime.

 

[Peter Bates]

I bought my prop valve from MBM boosters but I'd assume that doc diff is the same thing. Looks like you have the proper master cylinder

 

[Stihl011]

At least your honest.

I've started the kit, not yet mounted the prop valve, but ran into an issue with the brake discs rubbing on the lower ball joint mounting nuts. Tech support has been responsive but unable to help me out with it yet, saying they don't have problems with the kit typically and that I was putting the bolts in from the wrong side (true on the top bracket which wasn't rubbing, not true on the ball joint mounts, they only will go in one way).

Did you get this far? How much clearance do you have between the nuts and the disc?
(link goes to video on my google drive)

 

[383Scampman]

Go to NAPA , ask for a master cylinder for a 73-76 Valiant/Dart with disc/drum non-power if you are going manual . Same but ask for power if you power brakes . About $38.00 with core . As for the valve there are several ways to go here . Classic Industries/Year one have them , as well as others . Or you can go with a Wilwood valve . Either way it's easy/peasy. Don't forget to bench bleed the master or you'll be in deep doo doo .

 

[Stihl011]

At least your honest.

So I finally got it done. I ended up mounting the valve facing down inside of the frame behind the front driver side wheel well. This is right after the distribution block/brake warning light switch.

I made myself a simple L bracket out of some 2" wide steel and drilled two holes to mount the valve on one leg of the mounting bracket, then drilled a hole in the center of the other leg, so that I lined up with a hold that was already in the frame. I then attached the bracket and valve assembly with a self-tapping screw.

I had to shorten the rear brake line by about 4 inches, and re-flare the end, as well as make a short brake line from the dist. block to the valve.

 

[72Dart6pack]

Nice work.