Here I am driving the truck back home from Home Depot using the side streets and enjoying the drive as the engine has finally been tamed and is quite and smooth as silk. Stop at the stop light and then go another 3 blocks to a 4 way stop and... no brakes as the pedal goes all the way to the floor. Nobody in my lane as I run right through the sign. Throw the truck into neutral and use the emergency brake to bring it to a stop. Get out and look at all 4 wheels for leaks... none. Look at the master cylinder... full. Now what?

One mile to home so I decided to go for it using neutral and the emergency brake. Fortunately it is almost flat till I hit my driveway where I coast up. Later with my wife at the brakes I notice, while looking into the master cylinder, that the piston doesn't move when she pushed down on the pedal. What the heck? Guess I will have to remove it from the firewall to see what happened as nothing is visibly wrong from the cab point of view.

 

Mike look for something broken. It has been my experence that brake problems were gradual even if fast. To have one change like a traffic light is uncommon. IMHO.

The system is even made so there is nothing pulling, it is all push.

Your issue would make me want to upgrade to power disc if you haven't already.

John

 

Power disk are not immune to failure. I blew out a rear wheel cylinder on my '83 and had to limp home on the emergency brake.

 

I agree, but their stopping ability is much greater than 4 wheel drum. IMHO

John

 

Single outlet master cylinders are deathtraps. At least upgrade to a dual outlet master. You should always have at least half your braking that way.

 

I agree with ddavid here. I lost my single master and switched to a dual for just that reason. I have since completed my power disc brake conversion and would highly reccomend it to everyone.
I had to tow home my sons girl friends car yesterday, a 3400 pound car on a dolly. Towed it from Oakland to Modesto up over the Alamont and thru some major traffic and the brakes performed perfectly. The truck also pulled every hill with little effort. I would have never attempted this without the disc brakes.

 

Pop the cap off the master and have your wife pump the brkes slowly. Most likely the piston seal gave out in the bore and is allowing fluid to be pushed back into the reservoir. You'll see what looks like a current or rushing of fluid at the surface. For less then $50 you can install a dual master with the new line and three tee fittings. One for the inline brake light pressure switch, one to the rear brakes, and one for the front brakes. If you do a complete rebuild with the soft lines that will help, if you haven't done that already will add an extra $90 or so dollars. New cylinders vary between stores though. For my disc brake conversion I went a little wild with new everything. Total with all the parts, new steel lines, stainless steel braided front caliper hoses, brake proportioning valve, corvette master cylinder, big GM calipers, rotors, ECI brackets, bearings, wheel cylinders, rear axle hose, chrome 7" dual diaphram booster, mounting brackets, and attatching hardware, ran me $470.

 

Well disc brakes are a long way off if at all. Would have to do the research to see what is needed, where to get it and how much to pay for it. Switching to a dual cylinder is a possibility but would again call for some research in how to do the lines and then make them. Done a lot of things on cars but have never made brake lines and that would be brake lines that seal. So to get the truck back on the road I simply have to take a closer look at the master cylinder and see what happened and then correct it. Of course that would need to be during the day so it will have to wait till the end of October when I get back from the Philippines.

 

Mike believe it or not you can make the brake lines. They are pretty easy to make with a double flare tool kit from any parts store. The kits are usually less then $40. I can type you through the whole procedure. Start off by making some practice flares. The most important aspect is starting with a clean straight tubing end. To do this use a mini pipe cutter and a small round file to clean up the inner diameter of the tube. Once the inner diameter is smooth take the die that fits inside the tube without having to be pressed in. There are two sides to the die. One has the piece that goes in and the other has a concave seat. Placement of the tube in the holder is measured by the shoulder of the die. With the concave facing the holder, set the amount of the tube sticking out of the holder, slide the tube until it just contacts the shoulder of the die. This will ensure you have enough tube to "squish" for the flare. Tighten down the holder with the two nuts. Then take the die and insert it into the tube. Put the u-clamp on with the cone seated in the concave part of the die. Screw the u-clamp tight until the die is flush with the holder. Take the u-clamp and die off. Put the u-clamp on again with out the die and tighten is again to create the seat. Take the tube out of the holder and compare it to the line you took off. Do this until you see the same patern with both lines. Once you get the hang of it you'll laugh at yourself how easy it is.

Now here are somethings to keep in mind. Don't try to use brake line from a prebent kit. Usually the tubing is just small enough that the holding fixture wont be able to clamp it in place. It will just keep on sliding out. There is straight tubing that can be purchased with the correct flare nuts on it for the master cylinder. Just match up the fitting with the master at the parts store. Nothing looks tackier then adapter nuts on the master cylinder for your brake lines.

 

Thanks, I'll keep track of this till I get back and can do some work on the brakes. A double master cylinder while nice would not have made much difference here since the problem lies with the master cylinder rod itself. If the problem doesn't straightened out with a simple solution then I'll go your route and then learn how and where new lines go given that the current distribution block would be bypassed?

 

Correct. If you follow the line coming out of the master to the frame rail you'll see it bolted to the frame rail. The pushrod can have two things wrong with it. One the bolt that holds it on the prake pedal lossened and fell off. Two the pushrod fell out of the back of the master cylinder because the pedal bump stop under the dash wore out.