BRAKE SYSTEM


Q:

I have a problem with my 1959 Corvette brake system. I found that my brakes were badly worn, and I decided to overhaul the brake system for next year’s driving season. I did the entire job with no problems until I tried to put the rear drums back on. They won’t fit. It looks like the linings are too thick. I have backed off the adjuster mechanisms, installed new return springs and hold down springs, but the original drums will not go on. I have even had the drums turned. This made them larger, but I still can’t get them on. The problem is the same on both sides. What did I do wrong?



A:

I have to believe that you did a good job on your Corvette brake job, as far as it went. It sounds to me like the parking brake cables may not be fully retracted. Here’s what I mean: Let’s say that, during the life of the brake linings, the parking brake wasn’t working properly. The parking brake handle pulled almost all the way out, and the parking brakes didn’t hold. The owner or technician went under the car to the location near the frame cross member, where the two brake cables meet at the parking brake lever. There, where the threaded rods terminate the brake cables, the nuts were turned on those threaded rods so as to shorten the effective length of the cables. This would have been a satisfactory repair at that time. This shortening of the cables would have caused the brake handle to tighten the brake linings into the drums within the length of the pull of the handle. After this was done, the parking brake would have probably worked satisfactorily.


Now, several years later, when you replace the brake linings with new thicker ones, the cables must be lengthened to allow for the new linings. If you don’t lengthen the cables, the shoes may not be able to return all the way to the anchor pins. This will keep the effective diameter of the brake lining circle larger than the diameter of the drum. This is most probably the reason that the drums won’t go on over the linings. Turn the nuts on the ends of the two brake cables to make the cables longer. (Don’t worry that they may be too long.) This will cause the linings to return all the way to the anchor pins, and allow the drums to fit.


After the brakes have been installed, and adjusted properly to the new diameter of the freshly turned drums, the correct length of the cables must be found. This is done when the brake job is freshly done. It may need to be re done in a few weeks to compensate for the initial wear in the new parts.

After the brakes are installed and adjusted with the star wheel adjuster to yield a good, high pedal; adjust one of the brake cables shorter as you turn the corresponding wheel with your hand. (Car supported off of the ground on safety stands) Find an adjustment that will allow for a free turning wheel when the cable is released, but will stop the wheel when you pull downward about three inches on the cable with your fingers. This is done equally, one side to the other, by comparison under the car. When you find the correct length of the two cables, it will give a good feel to the parking brake handle. That good feel will usually be as follows: When pulling on the parking brake handle, it should tighten the linings into the drums after the handle is pulled out about one third of the total length. This leaves two thirds of the effective length of the pull in reserve for wear.

Best of luck with your Corvette brake job.