Mopar Forums - 4 wheel disc master cylinder questions B Body

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4 wheel disc master cylinder questions B Body

I just installed a Right Stuff read disc brake kit on my 70 RR and now need to tackle the master cylinder situation.
I am first going to bleed, then road test to see how it goes then take it from there. I can only assume it will need to be adjusted.
1. Do I install a Wilwood style proportioning valve in-line of the rear hard line? If so, where are you guys installing it?
2. Find a proper 4 wheel disc master cylinder with a possible factory built-in proportioning valve block. Anyone find one that works?
3. Install a 4 wheel master cylinder with a built-in proportioning vale like the one CPP has. Anyone done this?
4. Open to suggestions.

I have a CPP master cylinder from my 67 Camaro I can use but that would obviously need the 4 bolt to 2 bolt adapter, thinking Dr Diff has a nice one.
By the way, the banjo fittings to caliper were leaking and was a pain in the a** to stop leaking, had to replace copper washers with thicker ones. May replace with Stat-O-Seals, any thoughts on that?

Thanks in advance for replies.

I use a 89 ish Dodge Diplomat aluminum master cylinder that has a 1.0325 ish bore for my manual Mark Williams 4 piston - 4 wheel disc brakes. It's a two bolt mount with an adapter plate and the pedal ratio is modified to 7+:1.0 ratio and will put 1200 psi to the brakes with hand controls.

I went ahead and ordered a hydratech kit that Peter Bergman is going to put together for me. I will install it at the same time I replace the factory steering box with a Borgeson kit I am also getting from Bergman. These will tie into each other so installing at the same time will help.
Should be good to go and stop!
What a can of worms I opened doing this rear disc conversion. Also swapped out the 3.23 742 with a 3.91 489 while I had it apart amongst other things.

I just recently changed my proportioning valve with one from Jegs for my disk brake conversion, part #631292. I was shocked at how heavy the thing was, seems very stout. It made an amazing difference, rear calipers went from 500 psi to 900. I did also remove a restriction but most of the increase was from prop valve as fronts only increased 200 psi. One thing to look for is the safety feature of prop valve. What I gathered for information about adjustable prop valves is they do not trip if there is a pressure loss on one side. There are a couple pictures in post 70 of my build thread.
https://moparforums.com/forums/f95/1...tml#post144034