Bad proportion valve? Just cant win

[davek]

70 Bee new MC,new hoses,new calipers went to bleed the lines and nothing going to the back. Unhooked back hose and nothing. I just cant win with my Bee. I have always had a hard pedal so Im thinking I have been only using the front brakes. I sprayed the proportion valve with PB and hoping it will breaks free. My plan is disconnect back line from pv and pump brakes fluid should come out.

 

[pnora]

Did you fully bench bleed both halves of the master. They can fool you and you may only be bleeding 1/2 of it. Requires a lot of push on the piston to bleed the second half. Have someone hold the pedal down and crack the rear line at the master and see what it does.

 

[BeepBeepRR]

Can you reset the valve? If you are not getting fluid to the rear brakes it seems the valve has shut down the rear brakes.

Bad proportioning valve?

hi All, I just redid my front brakes to disk with ‘the right stuff’ kit on the 68 charger, installed new brake lines too. When I’m bleeding the brakes I get nothing coming out of my rear brakes at all, then a crap ton of pressure bleeding only from my passenger front side. Nothing comes from...

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[davek]

Did you fully bench bleed both halves of the master. They can fool you and you may only be bleeding 1/2 of it. Requires a lot of push on the piston to bleed the second half. Have someone hold the pedal down and crack the rear line at the master and see what it does.

yep fully bled the MC, I disconnected the brake hose on the rearend and no fluid.

 

[pnora]

yep fully bled the MC, I disconnected the brake hose on the rearend and no fluid.

Did you do what I suggested. If not you need to. Or you can continue to replace parts and spend money.

 

[yella71]

As was said, start at the master cyl and crack open the lines while pushing the brake peddle. continue down the line to see where the fluid stops flowing. the rear brake hose is far back. you may have an issue closer to the front of your system, maybe not. you could have a collapsed brake hose. did you open the line BEFORE the hose? there is a right way to diagnose your issue. let us know what you find

 

[dan juhasz]

just buy an adjustable rear metering valve from jegs or summit they are inexpensive and easy to plumb in and are thumbwheel adjustable

 

[davek]

Did you fully bench bleed both halves of the master. They can fool you and you may only be bleeding 1/2 of it. Requires a lot of push on the piston to bleed the second half. Have someone hold the pedal down and crack the rear line at the master and see what it does.

yes I cracked open the rear line before the PV and I get fluid.

 

[Ron H]

Check the T-block on top of the axle housing?

 

[Sixpactogo]

If you have no fluid at the rear brakes and you bench bled the master properly, your problem is going to be in the proportioning valve. Post 3 explains it well. I don't have that plastic tool but probably should buy one. I have had this happen more than once and thought it was a bad proportioning valve. When it happened the first time, I called the Right Stuff tech guy. He told me to stomp on the brake pedal hard a couple times to get the valve to reset itself. Didn't work. I bought another with the same outcome. I finally took the thing apart and manually moved the switch. If I would have had that damn tool back then I would have saved myself a big headache.

 

[Sixpactogo]

yes I cracked open the rear line before the PV and I get fluid.

crack it open after the PV and see what you get. More than likely nothing.

 

[davek]

well I got it off and yes it was the problem. Back line was blocked off on valve. Found a guy that sells the rebuild kits. I might clean it and see if it works.

 

[davek]

 

[BeepBeepRR]

well I got it off and yes it was the problem. Back line was blocked off on valve. Found a guy that sells the rebuild kits. I might clean it and see if it works. View attachment 1484503

Any chance you hit the brakes with the line off or leaking wheel cylinder? If so either one would cause it to shift the piston to close off the rear brakes.

 

[davek]

NO clue if its been this way for years,always hard pedal.

 

[BeepBeepRR]

NO clue if its been this way for years,always hard pedal.

Well at least you got it figured out. Forgot to add if the reservoir for the rear brakes was ever empty at one time and no fluid would also cause it to push that piston. It designed to keep pressure equal to front and rear and if the pressure is lost on one side or the other it shifts that piston so as to at least give you some sort of brakes.

 

[davek]

Reservoir was never empty as long as Ive owned it .

 

[davek]

update blew out the back lines and very little came out.Sprayed brake cleaner through to lines, cleaned the PV and I can now blow air threw all openings. Next is put it back together and see if it works.

 

[BeepBeepRR]

The Road Runner rubber line at the rear of the car on the axle had a bad bad bad blockage. Took a coat hanger and ran it through it. It was like Tar inside the hose. Bought another hose and put it back together. Been fine since until that crappy Right Stuff booster went bad On the car a year with less than 100 miles on it.... Got a new pirate jack booster and master and its good stuff now.

 

[threewood]

View attachment 1484504

I rebuilt my valve with their rebuild kit. Original was gunky. No issues in 6 years.