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73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => Brakes and Braking Systems => Topic started by: KoolerSL2 on January 03, 2009, 01:31:59 pm

Title: Some brake issues
Post by: KoolerSL2 on January 03, 2009, 01:31:59 pm

first let me start off that this problem has existed since ive driven the truck 10+ years.
im having a right side pull issue from the pass side front brake dragging.
now i have replaced every thing i can find which is:
Power booster and new master cylinder, New brake hoses all round, new calipers, brake pads, spindles, bearings, rotors ect..
so technically everything has been replaced but the issue remains.
now with that being said have any of you heard of the portioning valve doing this?
since this is the only brake piece i haven't replaced.
and this truck used to be a manual brake truck i converted if over too power assist with the diesel brakes up front.
if it is the portioning valve do i need to get one for power brakes or are they all the same?

thanks

chris

Title: Re: Some brake issues
Post by: VileZambonie on January 03, 2009, 02:12:47 pm

the combination valve contains a pressure differential switch for the light, a proportioning valve which limits the pressure to the rear brakes to help prevent lock up, and a metering valve which slightly delays the application of the front brakes to give the rear brakes a chance to overcome spring pressure. Now it is possible there is a restriction or blockage somewhere in the system but just because all of your other parts are "new" doesn't mean they can't be the culprit. Try flushing the system and check all of the components. Make sure the pistons return easily, make sure the hose isn't twisted around from when you had the caliper off. Check the rear brakes and take pix of each side if you can for us. Make sure primary and secondary shoes are in the right place. Make sure the shoes are fully seated on the anchor pin. etc

Title: Re: Some brake issues
Post by: KoolerSL2 on January 03, 2009, 02:21:57 pm

see when i redid all of the brakes i thought i might have got a bad caliper or hose and have swapped them out again.
when i bled the system i used my power bleeder and kept on till the fluid coming out was clean and clear.
the brake hoses are routed in factory locations.
the rear brakes work great and have no drag.
just the front pass side is dragging.