PROPORTIONING VALVE -- 4-WHEEL DISCS

[MOPAR MITCH]

Hopefully someone can help. I've recently installed a Dr Diff 10.7" rear disc setup onto my "72 Challenger. Fronts are Cordoba 11.75" rotors and factory rebuilt new stock calipers; steel braided lines. The dash brake light stays on. I spoke with Dr Diff (Cass) and he told me the factory proportioning valve body needs to be gutted empty.. or else a replacement drum-drum proportioning valve needs to be installed (along with newly shaped lines to the master cylinder... I'm using an aluminum Mopar unit that was installed many years ago).

Basically, the rear discs are not working until I get the prop valve modified as above (gutted or replaced).

Does anyone know IF this particular factory cast iron prop valve body can be gutted? Its the later-style rounded design (possibly used late 72 through 73-74 on E-bodies). Dr Diff/Cass isn't sure if it can be modified/gutted. He can sell me a drum-drum new prop valve... along with the newly shaped brake lines... would take brief time for this to be done.

[Burdar]

...

[Mrbill426]

Yes it can, as Burdar has shown.  There is a vendor the sells the seals and some hard parts for those.

Scott Hollenbeck
Muscle Car Research LLC
https://www.musclecarresearch.com/
(571) 262-1612

[7212Mopar]

Dr Diff also sells a distribution block and you need to add a manual adjusting brake bias valve for the rear. The only problem I have is the brake warning light is on no matter how much I bleed the brakes. Otherwise it is working great.

[MOPAR MITCH]

T/Anks so very much to all of you for the help and information.  I will let you know what I decide and how it works out.

[MOPAR MITCH]

WANTED:  I'd like to buy and gut an extra distribution block same as this one from my '72 Challenger (was F disc, R drum)... so that I could just do a quick simple swap...

Would anyone happen to have one (I believe it's '72 and up).

[Burdar]

Make sure the one that you buy still has brake fluid in it.  It's best if the lines are still attached.(but snipped off)  If these valves sit with no fluid in them, they will rust up and you'll never get them apart.  I had to buy another one to use for parts.  My original one was rusted up inside.  I found a guy that had a lot of them.  I think he gave me 6 or 7 of them to try.  Most were rusted up inside too.  Finally I found one that I could get apart.

They used a similar valve into the 80s.  You might be able to find a replacement from an early 80's Mirada/Cordoba.

[MOPAR MITCH]

Update... I found and bought an identical unit (old and cruddy) while at the recent Mopar Nats.... have been able to gut most of it except for the two long internal brass valves.. tried with a screw puller, penetrating oil, etc ... won't come out.   The bottom brass valve is needed as its a face-seal for the brake line fitting.    Now, I'm considering to drill it out, but... would still need a replacement bras unit to re-install.  Any leads on such a part?   I've contacted Scott at Musclecarresearch... waiting for his response IF he may have the part.

I could also pull and try gutting my good current on-car unit... maybe that unit would be more easy to gut apart.

[MOPAR MITCH]

Update -- I was able to purchase a replacement internal brass valve (used) from Scott at www.musclecarresearch.com   should have it in a few days... then hopefully finish the rebuild/gutting of the distribution block.

[Mrbill426]

Excellent... keep us posted 

Update -- I was able to purchase a replacement internal brass valve (used) from Scott at www.musclecarresearch.com   should have it in a few days... then hopefully finish the rebuild/gutting of the distribution block.