Proportioning Valve
- Thread starter GN owner
- Start date
bmackinnon
Active Member
- Joined
- Feb 24, 2005
One end (front or rear) will lock way before the other, and the brake light will be on.....
Vacuum brake conversion
When I quickly apply my brakes like in a panic stop it feels like there is a restriction and there is a resistance to depressing the pedal any faster and then gets easier. I am unable to lock the brakes unless I use both feet. The farther down the brake pedal is depressed it seems like it starts to get harder to press again. If I apply my brakes slowly like in normal street driving the car slows down normally. I've owned an 85 Olds Cutlass in the past and I know how vacuum brakes supposed to feel and react to panic stops. I've converted to vacuum brakes since 2007 and the car has hardly been driven due to the brakes. I bought and installed the vacuum block with a vacuum fitting from Kirbans to insure I had adequate vacuum to the vacuum booster assy. I've replaced the rotors and rebuilt the front calipers. The vacuum booster is a new rebuilt unit from Carquest along with a rebuilt MC also. I've installed the MC and vacuum unit that was working great in my friend's car into my car and the symptoms were the same. I did not notice any problems similar to this before when I had the PowerMaster. The only thing I can figure out might be the proportioning valve since it also has a metering valve which might be stuck in the slightly closed position and thus restricts the hydraulic pressure from going to the brake cylinders unhindered. I hate to just throw parts at the car so I thought I'd post my problem with the brakes in hope that someone might have had similar problems in the past.
When I quickly apply my brakes like in a panic stop it feels like there is a restriction and there is a resistance to depressing the pedal any faster and then gets easier. I am unable to lock the brakes unless I use both feet. The farther down the brake pedal is depressed it seems like it starts to get harder to press again. If I apply my brakes slowly like in normal street driving the car slows down normally. I've owned an 85 Olds Cutlass in the past and I know how vacuum brakes supposed to feel and react to panic stops. I've converted to vacuum brakes since 2007 and the car has hardly been driven due to the brakes. I bought and installed the vacuum block with a vacuum fitting from Kirbans to insure I had adequate vacuum to the vacuum booster assy. I've replaced the rotors and rebuilt the front calipers. The vacuum booster is a new rebuilt unit from Carquest along with a rebuilt MC also. I've installed the MC and vacuum unit that was working great in my friend's car into my car and the symptoms were the same. I did not notice any problems similar to this before when I had the PowerMaster. The only thing I can figure out might be the proportioning valve since it also has a metering valve which might be stuck in the slightly closed position and thus restricts the hydraulic pressure from going to the brake cylinders unhindered. I hate to just throw parts at the car so I thought I'd post my problem with the brakes in hope that someone might have had similar problems in the past.
Can anyone help , I just did hydro boost conversion , having some issues , one of them being , I read you can get a better bleed if you push in plunger ( the one facing front of car ) my plunger looks different as far as theres a pin sticking out that can t be pushed in ? it sticks out , 3/8 of an inch , the pictures I am seeing , they don t have the pin ? it can pull out a bit but not push , any help would be appreciated Thank you
Mine was stuck out and wouldn't center so I removed the brake line entering on top and gently Pryed the shaft back with an awl to manually center the pin. I think when rhat shaft feels uneven pressure it will move the pin to stop flow to the open port but it gets stuck sometimes.
I have the proportioning valve but I have found some other issues , I think because of the high pressure developed by the hydro boost , it will find any problems , first thing I found , I had a guy install line lock , he put it before the proportioning valve its instructions say to put it after , so it could cause trouble , the double flares he did , were not perfect very tiny leak , a leak also sucks air in . with the car running , turned steering wheel very hard ( to the max) found the brand new pressure hose at steering box leaking . I think some of my troubles were from me not taking it serious enough , inexperienced , its a job that you can t leave any stone unturned , nothing left to chance heres my e-mail if I can help kellycameron493@gmail.com
Hi Rich , I had bleeding issues from the get go I had so success finally on the power steering / hydro boost pat of the job , I thought it was a good idea to change my power steering fluid , well that started some work , the brake pedal fell ( because of no fluid) and I had so much air in that hydraulic circuit took for ever to get the air out , but brake pedal has returned almost where it should be , little more turning wheel from limit to limit should be OK . Now the brake hydraulic circuit I had things wrong on the car the line lock had been installed beside the MC , manufacturers instructions say :after the proportioning valve , so I am moving it to correct position , installing new proportioning valve mine was the original cast one . can you give me your input -advice please . I drove my friends t-type with hydr boost and Ifell in love , but this has been a hard one for me thank you
TexasT
Texas, Where are you from
- Joined
- Sep 10, 2002
http://www.kirbanperformance.com/product/432/BRAKE+PROPORTIONING+VALVE+#7189.html
Dennis Kirban sells a brass one.
My car never saw a salty winter so the underside isn't like some I have seen. I know I spent what I thought was an inordinate amount of time bleeding the steering circuit and then the brakes. I used my normal help(daughters 8 and 14 at the time to operate the pedal. I always put a 2x4 under the pedal no matter who I use to do the pedal so they can't over stroke the mc. Then we goofed with the rear bleaders that kept getting clogged with crud. So we had to keep cleaning them out. I bled each wheel until clear brake fluid came out. You must keep topping off the mc to avoid having to start over if you run it dry. I love the brakes though I do notice the pump groans on colder mornings. I am having a blast driving it back n forth to work again like when it was new, except with better brakes.
Dennis Kirban sells a brass one.
My car never saw a salty winter so the underside isn't like some I have seen. I know I spent what I thought was an inordinate amount of time bleeding the steering circuit and then the brakes. I used my normal help(daughters 8 and 14 at the time to operate the pedal. I always put a 2x4 under the pedal no matter who I use to do the pedal so they can't over stroke the mc. Then we goofed with the rear bleaders that kept getting clogged with crud. So we had to keep cleaning them out. I bled each wheel until clear brake fluid came out. You must keep topping off the mc to avoid having to start over if you run it dry. I love the brakes though I do notice the pump groans on colder mornings. I am having a blast driving it back n forth to work again like when it was new, except with better brakes.
I think I mentioned it already above, your proportioning valve pin may not be centered.
TexasT
Texas, Where are you from
- Joined
- Sep 10, 2002
Overstroking just introduces air into the system so you need to start the bleed again at the mc. This time with safety glasses or goggles, and something between the pedal floor board have the helper slowly and steadily depress the pedal and you will see the air bubbles in the reservoir. Repeat until the reservoir produces no bubbles, even the real little ones before moving on to the wheels. Other wise you are putting air into the system.
