Hey I just looked back and I never mentioned that I went ahead and put a new master cylinder on it last saturday. It's better, but I still have the low pedal for the first few pumps after it sits a couple days. I really like the new master cylinder. Screw cap type, way better than the old set up. As as added bonus, this one has enough power to engage the pressure activated switch that works the brake lights. Now we're gettin somewhere!

 

To clarify a few things... The pedal dropping after sitting a few days seems more like a master cylinder problem. There is a return spring on the piston that pushes it back to a "ready" position. If the master has never been rebuilt then it is a good chance that spring inside the bore is fatigued. Also there should be a return spring on your brake pedal arm to put it back in a "ready" position.

itsmywifestruck the only way the brake fluid would need the same length tubing is if the system is an "open air" type. Being that it is completely sealed fluid will travel at the same speed and flow the same reguardless of tubing length. The only way it wont is if there is air trapped in the lines. Fluid does not compress like gas does. The coils of extra tubing under the master cylinder is for frame flex and cab shifting. The more excess tubing the less strain the tubing will experiance from vibrating around or shifting.

 

The master cylinder is a reman, and I think a little air gets in the lines at the right rear if it sits.

 

Ok- have a little money to spend if I can narrow this problem down. The right rear looks like it has a bad wheel cylinder on the right rear as it is alittle moist on backing plate. I have lost no fluid at all since the new master cylinder was put on and all brakes were bled well. I have no braking action until the pedal is about 2-3 inches off of the floor. When you use the brakes, you have to use the toe of your foot to pull the pedal back up. Again, no fluid is lost. The brake lights, activated by the pressure sensitive switch, only work when they want to. I am going to attemt to get out later today to get this and several other things done. Just thought I'd jump on here to see if anyone has any other ideas for me on these brakes.

 

If the adjustment at the wheels is too loose the brake pedal will be very low and require pumping to get any good braking. That might account for the no lights also, there is not enough pressure in the lines until the shoes contact the drums to activate the pressure type switch. BTW, I prefer the mechanical switch like used in later trucks, then the lights work even if the brake hydraulics fails.
Most reman masters come with plugs for the outlet ports to bleed the master before installing, did you bench bleed the master? You should be able to plug the outlet and bleed all the air out of the master which will result in a solid piston, it won't move more than about 1/16" when pushed. If you can't get that to happen you have a faulty master.

 

You know it dawned on me that you're using the pressure brake light switch. I have heard that the diaphram will break down and leak. I would replace it since they are dirt cheap. It would rule out a leak and fix your intermitant light problem at the same time.

 

The switch is pretty much a pipe plug in the front of the master cylinder, so a leak there would be pretty obvious.

Yes, I did bench bleed the master cylinder.

I bled the brakes at every wheel extensively.

I checked and readjusted all four brakes.

I'm just not seeing that it's losing fluid and stating that the right rear is moist would be a stretch. It's obvious that the wheel cylinder has leaked before, and I have replaced them all once.

 

Check under the dash. You may have to pull the boot away to see it. The reman masters are sometimes honed oversize and the o-rings don't seal correctly. That is where I found my leak before I did the system conversion.

 

Ok- I started my list of things to do to the truck by getting my cab back up off of the driver's side cab mount from where it had rotted and collapsed around the rubber bushing. Lo and behold- no more steering binding, truck shifts better (three on the tree), and my clutch has magically adjusted itself (can you hear the sarcasm?). So-that's three problems addressed by fixing one thing. The truck repair gods are smiling upon me today. As I am working on the cab mount I hear the telltale creak of the front left brake slowly backing off (remember I had mentioned that the brakes were hanging up?). So I finish my cab mount fix, replace the steering rag joint (again), and decide that this would be the best brake to inspect first. I pulled the drum off and immediately saw the long shoe on the front. Ok, well, this ain't right. Disassemble and reassemble correctly, adjust, and move to the other side. Shoes are on correctly- cool- less work for me! Adjusted it to a slight drag, just like the other side. Drove around the block to see how it acted with the fronts being correct now and it is perfect. Pedal might go down an inch maybe before I get good hard solid pedal, and no matter how hard you push, it never goes down to where it used to engage. And, it is now not hanging at all, pedal returns and truck rolls freely. Best brakes the truck has had since I've owned it! Steering, clutch, brakes, and shifting apparatus all function smoothly, and she is now a dream to drive again.

Here's what I am not comprehending. Why would one pair of shoes being flopped cause such a low pedal, and why would this cause it to hang up? I know that they were not too far out of adjustment as I have done that in the last month.

Anyway, thanks for all the input and ideas from you guys. Another successful fix thanks to all the guys on FTE. Alright what's next?