Proportioning Valve

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71DartGuy

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Got a question for yall. I'm almost finished installing disk brakes on my 71 dart. Car was originally manual drums all the way around and now has the 73 and up disks and I added a booster too. The question is, does the prop valve need to be changed to match the disk brakes? I bought the one that came with the master and booster and went to install it this weekend and found that it looked exactly like the one that is already on the car. Are they different internally or are they the same valve. It looks like kind of a pain in the *** and I dont want to change it if I dont have to. Thanks, Mike
 
You should, I would just get an adjustable one like the mopar unit if I were you. Then you can adjust it to the proper specs of the front locking just before the rears. and get the pedal feel that works best for the car.
 
71DartGuy said:
Got a question for yall. I'm almost finished installing disk brakes on my 71 dart. Car was originally manual drums all the way around and now has the 73 and up disks and I added a booster too. The question is, does the prop valve need to be changed to match the disk brakes? I bought the one that came with the master and booster and went to install it this weekend and found that it looked exactly like the one that is already on the car. Are they different internally or are they the same valve. It looks like kind of a pain in the *** and I dont want to change it if I dont have to. Thanks, Mike
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I didn't change mine and it stops just fine. I did however run new line off the prop valve to the calipers hoses. It was not a fun job.
 
Cool. I may just leave it alone and see how it does. Any idea where I can get some new hard lines from the master to the prop valve? I kind of had to bend mine to get them to line up after putting the booster on- looks like a hack job and its driving me nuts!
 
I replaced the front brake hard lines a few years ago and used stuff from Year One. Went together pretty painlessly. What you call a prop valve is just a distribution block with an internal pressure switch. You should be good to go with the old one.
 
Thanks don. I kind of figured YearOne would be the way to go. I'll give them a call this week. Thanks for the input
 
71DartGuy said:
Cool. I may just leave it alone and see how it does. Any idea where I can get some new hard lines from the master to the prop valve? I kind of had to bend mine to get them to line up after putting the booster on- looks like a hack job and its driving me nuts!
Click to expand...

I bought a tubing bender at Advance Auto and it helped me not kink the line and also gave the line a nice clean bend to it. I measured each line and bought straight line that they have hanging in the back and then you have to bend it to fit. Just make sure you get the right fitting on each end of the line. I had to buy a 60" line and then add a 18" line in order to do the right wheel brake line done. That's the longest they had. If a line is to long bend a nice loop in it and then you can stretch it to fit just right and it looks stock. You probably won't have to do this but I used the old line and bent the new line just like the old line laying on the floor. It helped out a bunch.
 
On all drums it is just a dist block, but with disc you should have a proportiing valve. The pressures are much diff and you need to compensate for best stoping. If not, on a panic stop you will most likely lock the rears up much earlier and nit get the full benifit of disc on the fronts. About 60-65% of you stopping is with the front brakes.
 
djwhog said:
On all drums it is just a dist block, but with disc you should have a proportiing valve. The pressures are much diff and you need to compensate for best stoping. If not, on a panic stop you will most likely lock the rears up much earlier and nit get the full benifit of disc on the fronts. About 60-65% of you stopping is with the front brakes.
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Exactly
 
djwhog said:
On all drums it is just a dist block, but with disc you should have a proportiing valve. The pressures are much diff and you need to compensate for best stoping. If not, on a panic stop you will most likely lock the rears up much earlier and nit get the full benifit of disc on the fronts. About 60-65% of you stopping is with the front brakes.
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OK I'm not sure about where to mount it if I decide to install one. Do you install it on the line going to the rear brakes?
 
yes. get the adjustable one and plumb it in after the dist. block. adjust it so the fronts lock up first. you might need to find a wet parking lot.
 
Am I mistaken, or should you use a double flare tool to install fittings on brake hard lines?

Jerry
 
Some pretty hefty hydraulic pressure is exerted on those fittings when you stand on the brake pedal. Don't want them blowing off at the wrong moment.

Jerry
 
mild steel needs to be double flared since it has a seam, stainless doesn't have a seam.
 
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