Can't get WH brake proportioning valve to center

[betzgb]

Have a new build with a bug I am trying to get figured out. New GM disc brake kit up from from WH, Explorer disc brakes in the back. Hydro boost kit from WH as well. WH proportioning valve. When I press the brake pedal, the brake light comes on. I didn't have a pin in the proportioning valve to keep it centered when I bled the system originally. Other than a moderate left pull when panic braking the pedal is firm and the truck brakes well and feels balanced between front/back brakes. I have tried bleeding all brakes again, hard braking, press and hold to let the valve settle and re-center and can't seem to get it back to center. I have not found any leaks or anything that would cause it to activate. Thoughts?

 

[DirtDonk]

Hey there. Sorry it took so long to get it answer for you. Well, not necessarily an answer, but at least back to the top for others to look at.

What type of proportioning valve do you have? Brass block type, or the adjustable type? Got a pic?
The occasional slight pull may indicate you still have some air in the system. Delaying the application of the opposing side. Probably in the front.
This might also be causing the light to come on sometimes. Or does the light come on every time?
Does it come on and stay on, as long as you put pressure on the pedal? Or does it come on and then go off, even as you are pushing on the pedal?

Just a couple of questions to try to narrow things down. We’ll see if we can dial this out and get you going.

 

[betzgb]

Morning DirtDonk - Brass type valve item 3037. No pictures but I can pop the hood and take some if helpful. The light was coming on every time and staying on as long as the pedal is pressed. Yesterday I tried some hard braking, holding the pedal for 2-3 minutes to see if it would settle, bled the brakes and still no change in behavior. Then this morning I went to try it and no light. I went for a test drive for a few miles and never had the light come on under normal driving or severe braking. The front driver side pull is still there under very heavy braking. Would an air bubble trapped in the valve caused the issue and maybe it has moved to the caliper leaving the value to operate normally but still explain the pull?

 

[73azbronco]

you need to get all the air out of the system, most likely the side that moves the pin the most.

 

[Timmy390]

maybe take the P-valve off, center it, hook up all the lines again and use one of these? Never used one myself however when I convert my 69 Stang to power brakes I plan to.

Tim

 

[DirtDonk]

A brake pull can come from things other than hydraulic issues. You might have a wheel bearing that’s not perfectly adjusted, or a caliper that’s hanging up, or maybe one or two other things. So check everything.

 

[betzgb]

May be separate things. I am going to assume my bleeds yesterday finally nailed the value issue. For the pulling brakes, I am thinking the left front caliper is hanging up. I noticed when I back out of the garage there is a high-ish pitch dragging sound like the pads dragging on the rotor. Like the humming sound that comes from running a wet finger around the rim of a crystal glass. Only when backing slowly, going forward no sound. Looks like good clearance on the knuckle where I had to grind to make room for the caliper. Best I can tell there are no springs to pull the pads back. Sticky piston maybe? Other common causes of a sticking caliper on the GM setup?

 

[73azbronco]

on new brakes, i lift all four corners to check for drag and such.

 

[4xfun]

Double check and make sure that you have plenty of grease for the pins and in the slides for the pads. I personally like sil-glyde, but others products will work. Pad dragging will transfer heat and some products are not as heat tolerant.

 

[nhg2112]

@betzgb did you ever figure out what was going on here? I have the exact same setup as you and exact same issues - drivers pull under panic braking, sound from drivers caliper on reverse...

Just pulled my caliper may try replacing it and see if that helps. FWIW this happened with and without my hydroboost setup so Im fairly certain this isnt a bleeding or prop valve issue. Vacuum booster had a separate prop valve from my wilwood hydro setup.

 

[betzgb]

@nhg2112 sorry to hear you are having the same issue but misery loves company... I haven't had the chance to pull the tire and investigate further. I planned to check the caliper (i.e. pins are lubed, pads are installed properly, piston moves in/out smoothly with a c-clamp, good clearance from steering knuckle, etc. I also read where a defective rubber brake hose can cause fluid to drain back at a slower pace leaving the pad partially engaged lines are all new so hopeful not the case. All else fails, I will swap with a different caliper and see what I get. I will keep you posted when I get back to it.

 

[joshua]

Sorry for the thread jack. But is this the correct tool? I ordered a bunch of stuff from wh and forgot to throw this in. I called um but it already shipped.

PAGOW 1 Pack Proportioning Valve Bleeder Tool, PV2 PV4 Disc/Drum Brake Proportioning Valve Bleeder Tool, for 172-1353 172-1371 with GMs Street Rod Classic Car and Chevys Truck -Blue https://www.amazon.com/dp/B09G68TRKT/?tag=classicbroncos-20

 

[betzgb]

Yes that is the tool you insert into the top of the p-valve when bleeding to keep the pin centered. Once done bleeding, pull it back out and reinstall the center electrical contact.

 

[joshua]

Thank you!

 

[nhg2112]

I just swapped out the calendar and it fixed my issue...just FYI

Looks like the boot had torn and it had a couple rust rings that were holding it up