C10 brake help needed...step inside

[bigblock73]

Ok, I have a problem with the brakes in my '75 C10.

History:
Last summer I was having an issue with the rear drum brakes being touchy and locking up when applying the brakes at times. In addition to that, I was also experiencing low pedal pressure, and somewhat inconsistent as well...meaning it took different pedal pressures to stop from time to time. With life getting in the way, I parked the truck and began working on our new home we purchased that summer.

Fast forward to July 2014. I took the rear apart, found a leaking drivers a side wheel cylinder, and passenger side axle seal. So, I went ahead and purchased new cylinders, shoes, hardware kit, had the drums turned, and also picked up new wheel bearings and seals. While everything was apart, I had the backing plates, drums and diff cover powder coated...figured might as well make everything back there brand new and not worry about anything for a while...wrong.

Everything has been reassembled, adjusted out and brakes bled, and to my surprise, I have worse pedal pressure and now my idiot brake light is on! I should add, it did not even touch the front brakes, or anything forward of the rear differential.

My inclination is that the master cylinder is bad too, what do you guys think?

What exactly triggers the idiot brake light to come on? Is there a reset for the proportioning valve. I presume the light is tied to the wires going to it. Could the valve be bad?

Looking for knowledgable advice here fellas, please let me know what the heck is going on, pretty frustrated at the moment.

Thanks!

[KQQL IT]

I had to disassemble my proportioning and reset it to get rear brakes to work at all.

[KQQL IT]

Push in thru rear line. And gravity bleed worked for me.

[bluex]

Sometimes you can bleed the front brakes an get the valve to recenter. Bleed the fronts a few times on each side an then go back to the rears again an see if that helps. it can be a pain to get the valve centered again.

[bigblock73]

Thanks guys...I'll bleed the fronts and see if that does it. Never would have thought that would be the problem.

[ElGracho]

I've had this problem before. I even tried resetting the proportioning valve and it didn't work.

The best thing was the solution. I waited until the next day, the valve had unseated and recentered. The light was out and the pedal was nice.

If time doesn't help like it did for me, keep bleeding. Back to front to back and keep going. It will eventually recenter the valve and things will get much better.

Keep us posted.

[bigblock73]

No update yet...out of commission due to a metal particle in my right eye. A trip to urgent care resolved it...hope to have an update on the truck tonight.

Thanks again all.

[TrybalRage]

Hope your eye is doing better.

I recently had very similar symptoms, passenger rear brake was locking up and also had a leaking wheel cylinder there, so took the opportunity to do all the brakes. New cylinders, drums, calipers, and rotors.

My only advice is to bleed the snot out of it. Start with the furthest brake from the master cylinder - the rear passenger. Then go to the drivers rear, then passenger front, then driver front. I did the passenger rear again when I was done to be sure.

[stroker87]

last week end I had this problem so I replaced both rear wheel cylinders I had to go back and forth between both side to get all the air out it was a bit tricky and a P.I.T.A. I might add then once I was done low peddle some one mentioned to me drive in reverse hitting the brakes hard a few times it reset the adjusters I felt them adjust once they did brakes felt much better and the "sticky" drivers rear stopped locking up now just need to put a new booster mind is leaking and you can hear it........

good luck with your eye, hope you feel better soon

[mgchevyparts]

You open a front and a rear at the same time, then bleed and the prop valve should re-center as you now have equal pressure on both sides. The close the bleeders and go back to normal bleed sequence.

[83 Silverado]

If your working by your self, look a the Pneumatic Brake Fluid Bleeder at Harbor freight http://www.harborfreight.com/brake-f...der-92924.html.

I picked one up last year to do the flex line's on my truck, and it save's a ton of time over yelling to or at someone to pump the brakes up. Plus you can flush out all the old brake fluid.