!@##$ brakes!
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Junior User
Joined: Oct 2006
Posts: 63
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From: jasper,GA
!@##$ brakes!
88 f-150, 2wd. I am losing a brake battle and its driving me mad. I replaced booster, master cylinder, new pads and shoes and new wheel cylinders in the back and the brakes still dont feel good and if i am going slow the left rear wheel locks up everytime. kinda scary when it rains and one wheel locks up going into a turn! i have bled and rebled the brakes and no air. the rears are adjusted correctly. is this the hydraulic abs unit going bad? the pedal kinda sinks when u r sitting at a red light.please help.
Posting Guru
Joined: Jul 2009
Posts: 1,069
Likes: 1
From: Toledo, Ohio
Mine does it too. Im having a brain fart right now but there is a valve in the driver frame rail that the brake lines run to. It controls the brake pressure to the rear wheels. replace it. That should fix your problem.
[Edit] Proportioning Valve
[Edit] Proportioning Valve
Thread Starter
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Junior User
Joined: Oct 2006
Posts: 63
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From: jasper,GA
thanks but at $200 , i was hoping it was something cheaper. I have heard just bypass the rabs with a peice of new brake line. someone also said there is a spring on the inside of rabs u can take out . heard any of these?
Post Fiend
Joined: Jan 2005
Posts: 8,402
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The sinking pedal does sound like a bad RABS valve module (on inside of left side frame rail).
You can bypass it with a short length of hard brake pipe as many have done. However for your problem if you look at the end of the module you will see a large hex bung. Unscrew this bung (against spring pressure all the way), take the spring out and replace the bung. No fluid will come out. Pump the pedal a few times to fill the chamber and see if the sinking pedal problem is solved. If not you can replace the spring and look else where.
However that will not solve the locking brake problem, neither will a fully working RABS system. Check that the shoe retraction springs are good. To eliminate an out of round drum you could swap drums and see if the problem swaps with them.
You can bypass it with a short length of hard brake pipe as many have done. However for your problem if you look at the end of the module you will see a large hex bung. Unscrew this bung (against spring pressure all the way), take the spring out and replace the bung. No fluid will come out. Pump the pedal a few times to fill the chamber and see if the sinking pedal problem is solved. If not you can replace the spring and look else where.
However that will not solve the locking brake problem, neither will a fully working RABS system. Check that the shoe retraction springs are good. To eliminate an out of round drum you could swap drums and see if the problem swaps with them.
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Junior User
Joined: Oct 2006
Posts: 63
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From: jasper,GA
thanks i will try taking the spring out. I dont think its a drum being out of round cause i have had them turned. also... whern you hit the brakes and it locks up it also sticks. it takes a sec after you let off the pedal to release. the springs seemed fine to me when i replaced the shoes. if i just disconnect the rabs(unplug it) will that help or will i still have to get a new brakeline? thanks guys!
