No Brakes

[Channeled 91]

Also the rear drums are a PITA to adjust if you dont have the parking brake functioning. This could be another suspect issue to look at.

I have no parking brake.

 

[Chevy-SS]

Your initial description of problem indicates that air in system is absolutely the primary suspect.

Someone already suggested pressure bleeder, and that would be a great next step.

 

[Supercharged111]

Since you have removed the ABS, your brake system is now pretty much like an older square-body,, you've moved backwards.

ABS on these trucks blows, he did not go backwards.

OP is there anything between your master and the booster? Like a metal bracket?

 

[evilunclegrimace]

Well I have finally got my truck running rolling. No the problem is the brakes barely work. I have replaced everything, (master cylinder, proportioning valve, calipers, pads, the whole rear drum brake assembly,lines) and when I pull the truck out of the shop I have to pump and pound on the brake pedal to get her to stop. That is at 5 mph. I bled the master before installing it, bled the proportioning vale, bled the front and rear brakes. I need to get the brakes to work before I take her out for the maiden voyage. Any thoughts?

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Are you saying that the brake pedal is very hard to push and the truck does not stop, or, that when you push the pedal that it is very easy to push the pedal but the truck does not stop unless you pump the pedal?

 

[DerekTheGreat]

Like another has said, be sure your rears are properly adjusted. Did you install the calipers on the right side? Not sure if it's possible on these but a buddy of mine installed the left caliper on the right side and vice versa of a Ford Ranger, this put the bleeders at the bottom, so no matter what he did the pedal was crap yet was getting steady fluid out of the bleeders...

 

[Erik the Awful]

I have no parking brake.

Boom! There is your problem. Pull the rear wheels and drums. If the shoes are good, remove the plug behind the star wheel, adjust the star wheel until you can just barely fit the drums over them. Put the drums on and adjust the wheel with a screwdriver until the drums drag, then back it off a hair. Reinstall the plug to keep dirt out. Re-bleed your brakes.

 

[delta_p]

....and when I pull the truck out of the shop I have to pump and pound on the brake pedal to get her to stop. That is at 5 mph.

I had this when i forgot to plug in the check valve in the brake booster on my C1500 after doing my MPFI swap. So without the booster vacuum I had to stand up on it to stop it backing out of the garage.

Say the pedal has a 5:1 ratio of foot force to booster input out of the pedal linkage, and the booster has 100 in2 of diaphragm area between engine vac and atmosphere sides. 50 pounds of foot force is 250 lbs of booster input force, and with vacuum on the booster is an additional 890 lbs of brake apply force.

 

[Erik the Awful]

So, is everyone ignoring the part where he says he has no parking brake? That's completely separate from the hydraulic system and can cause the symptoms he's having.

Forget troubleshooting hydraulics until you have the mechanical side fixed.

The parking brake specifically operates the rear brakes, which on GMT400s routinely fall out of adjustment.

After you fix that, bleed the brakes thoroughly, and if you still have a problem troubleshoot the hydraulics.