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Adjustable Proportioning Valve Q's
https://slantsix.org/forum/viewtopic.php?t=45679		 Page 1 of 1
Author:  Old Car Scott [ Thu Jul 21, 2011 4:38 pm ]
Post subject:  Adjustable Proportioning Valve Q's
Where do I install the APV on a stock Mopar brake system? Between the master cylinder and the stock PV or on the rear brake line between the stock PV and rear hose?
Author:  Joshie225 [ Thu Jul 21, 2011 6:25 pm ]
Post subject: 
Is this for your '67? Was it originally drum/drum? If so you don't have a proportioning valve. Plumbing an adjustable valve in between the outlet of the master cylinder and the distribution block is easy. In my other race car I put it on the inside of the rocker panel where I could reach it when belted in. In the current race car I left it under the hood.

Image
Author:  SlantSixDan [ Thu Jul 21, 2011 6:29 pm ]
Post subject: 
If you have front disc brakes and you are now encountering rear brake lockup, be advised that disc-brake A-bodies -- even in from-the-factory configuration with factory proportioning valve -- have an endemic tendency to lock the rears prematurely. Everyone griped about it in road tests of the time. Consumer Reports wailed about it. Chrysler did nothing about it, which is dumb because the zero-dollar fix was right on their shelves, see here (and TSB here and MTSC info here). 10" and 11" drum brake wheel cylinders are interchangeable. I routinely swap the 13/16"-bore rear wheel cylinders onto 10" rear drums on cars with 8¾" rear axles, and the ¾"-bore rear wheel cylinders onto 10" rear drums on cars with 7¼" rear axles, and it fixes the problem all the way fixed without having to jack around with an adjustable proportioning valve or otherwise re-engineer the system.

¾" rear wheel cylinder is NAPA 37863 or Raybestos WC-37863 or Bendix
34076 or Wagner WC123412 or Centric 134.67015 or Chrysler 4423 852.

13/16" rear wheel cylinder is NAPA 37696, Raybestos WC37696, Wagner F113704, ACDelco 18E268, Bendix 34064, Chrysler 4313 493, or Centric 134.67013.

(And while you are in there swapping the wheel cylinders, make sure to check carefully for oil-contaminated shoes, which will grab and lock no matter what wheel cylinders you've got)
Author:  Old Car Scott [ Fri Jul 22, 2011 10:15 am ]
Post subject: 
You guys are worth your weight in gold, you know? Can't thank you enough! :D

Josh, it is for my '67, I had assumed that chingus below the old master was a PV, if it's just a distribution block to route the fluid one way or the other I can see why an APV would be necessary.

Dan, I would have never guessed the rear wheel cylinder bores to be too big. Thanks for the links, too.

I already have the APV on hand so I might use that, although I'll check the condition of the rear wheel cylinders as it's a junkyard 8 1/4 axle I swapped into the car.

Thanks again!
Author:  raPoM [ Fri Jul 22, 2011 1:11 pm ]
Post subject: 
What Dan posted is perfect if you have a stock P.V.,but since you already have the adj. P.V I would just run it. I used one on my 67 Dart and it worked perfectly.If you dont already know,tighten the P.V all the way,then back off about 2 1/4 to 2 1/2 turns out as a baseline,should get you almost dead on.
Author:  Old Car Scott [ Fri Jul 22, 2011 2:27 pm ]
Post subject: 
Alright! I'm getting excited! I put the big 11.75 front discs on it because I knew I'd need them driving in the California Bay Area, can't wait to go out and test some "panic" stops! 8)
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