The Stovebolt Site Forums The Shop Area The HiPo Shop How to adjust proportioning valve?

Hello, I have floor mount dual resevoir,7" power booster And disc/drum combo. 2# residual to disc and 10# residual to rear. Adjustable proportioning valve to rear. Just don't know how to properly adjust proportioning valve. Have read all the internet info but just can't seem to get it right. My brakes do not lock up. Please help.
Al V.

I have a very similar setup with the same problem. I attended the NSRA's "Nat South" over last weekend and spoke to the owner of "Fatmans Fabrication" about this problem. He suggested that anyone running disc front and drum rears not hookup the rear brakes to the proporting valve. He said it just robs pressure off the front discs. He also said a one time he put the adjustable proportioning valve on the front system but later learned to removed it as he always ended up with the valve wide open. I'm in the process of re-plumbing my system to see if it works.

Thanks for the respond. I've installed them on other street rods and always had good brakes. I sure don't want to replumb at this stage. I really never adjusted the valve. Had no need to.
Thank you,
Al

To adjust mine, ( in the rear line), I went to a open parking lot and did a bunch of 30 mph stops. Start with it wide open, mine would lock the rear wheels pretty easy. I kept closing the valve with each hard stop till the tires just slightly skidded but not leaving black marks. I figured 30 mph was a good test speed, I have also tried it at 50 mph and it still stopped straight with no problems or skidding with a heavy quick brake application.

I think its a good idea for everyone to do a couple of quick stops, you need to know what the truck is going to do in case you really need to panic stop. In my case, its going to go where I point it, and not come around on me with tires smoking!

Joe

Thank you Joe. I'll give that a try as soon as I put my drive shaft back in. I've got it out to plug the yoke weep hole.
Al

Can't I just run with it wide open? I really don't want to replum
at this time.

This is what I learned after tearing my hair out for 3 days. It was very difficult to get all the air out of the rear lines. I found and old timers trick on the internet. Take a canning jar and drill a hole in the top to push clear plastic tubbing to the bottom, leave about 18" hang out of the jar, drill a smaller hole in the top for the air to release. Fill the bottom of the jar enough to cover the bottom of the tubing in the jar. Now push the tubing over the bleeder after placing box wrench over the bleeder.Loop the tubing above the bleeder . This allows the air to escape but keeps fluid above the bleeder. Now open bleeder and remove master cover and start pumping slowly as to not splash fuid over everything. Keep a bottle of fluid at the master to keep the well full as to not pump it dry. Keep checking the tube above the bleeder to make sure the fluid is above the bleeder. The brake lines are not under pressure when you are not pumping, so no need close bleeder until all the air is removed from line. Now close off bleeder and move to next rear drivers side. This was a very slow procedure but it worked for me. I pumped for hours to get all the air out. Keep a light near your master to see if you're getting any air bubbles out of the master. You're not done until all bubbles are gone from master and fluid is above the bleeder. Repeat this as needed. If you have a adjustable proportioning valve to rear be sure that it is turned all the way closed putting full pressure to rears. You won't know if you got all the air out until you put it down and see if you can lock the rears up on gravel. Then proceed to tune your proportioning valve as to not not lock up the rears in a panic stop.I normally don't chat this much but I thought it was a good way for other to bleed and change fluid.
Al