A break (brake) in time
My Dad always told me when we were shopping for cars, “You can forgive a lot of things in a car if it will start, run cool and stop when you need to.”
We have talked about all three here at Walt’s Workbench, but lately, there have been many questions about brake adjustment on these dear old “flatheads.”
These wonderful cars are heavy and the engineers that designed them allowed for this and made the size and efficiency of these brakes accordingly. However, they do require periodic and proper inspection, maintenance and adjustment at least once a year. Going more so by the calendar than by the odometer, this doesn’t apply if you exceed 5,000 miles in that period of time. However, if you hear strange noises when braking, do it right away.
You should start by putting the car on stands and taking off the wheels. (This is also a good time to rotate your tires and pack the front wheel bearings.) If you installed new linings within the last 1,000 miles, you probably have some “break-in” brake adjustments that need to be made, plus a good cleaning. You will need to remove the drums to do this properly. With compressed air, blow out all accumulated dust. By the way, be sure to wear a painter’s mask while doing this as some of these old linings were made using asbestos.
Now make a visible inspection for signs of leakage of either brake fluids or lubricants. If you find some, it is time for some repairs. Assuming you find none, check the linings for uneven or excessive wear.
Also check for grooves in the linings and/or the drums. If you find these, you should probably have the brakes relined and/or have the drums turned. If you do one front wheel, you need to do the opposite one also and this is true for the rear wheels as well. This does not apply as far as front-to-back goes.
It should be noted at this point that Mother Nature and her laws of physics cause the front brakes to wear and/or need replacement about three times to the rear ones once. This is good, because the engineers made the rear brakes more complicated in proportion, mainly due to the parking brake mechanism.
Your parts store will have brake cleaner in a spray can. Use it generously along with a clean rag. This will also expose any cracks, fractures or faults in the linings or drums.
After cleaning and reassembly, you are ready to start adjusting the brakes. Do each wheel completely, one at a time. Use a brake-adjusting tool to tighten the star wheel until the wheel starts to bind. Then back it off, just until it is free. Take a .010 feeler gauge, insert it into the slot located near the outer edge of the drum and turn the wheel by hand. This will indicate any high spots on the shoes.
If you do have any high spots on the shoes, you will have to adjust the big eccentric at the top inside of the backing plate. To do this, loosen the big nut holding the eccentric just enough to allow a stiff turning of the slotted bolt inside this nut. Rotate the bolt until the feeler gauge no longer binds. Reset the star wheel adjustment again to compensate for your adjustment.
Repeat this cycle as many times as needed to be able to rotate the wheel without finding high spots. Make your final star wheel adjustment after setting the locking nut on the eccentric. Repeat the above on each wheel; however, before doing the rear wheels, be sure to disconnect or loosen the cables to the parking brake until they are free from any pressure on the rear brake shoes. After completing your adjustments, then tighten the parking brake cable to a point just before feeling resistance in turning the rear wheels.
Next, you will want to adjust the brake pedal travel. Adjusting the rod linking the master cylinder to the clevis pin on the pedal mechanism does this. You should have between three-quarters and 1 inch of free pedal travel before resistance against the master cylinder. You must have this free travel to allow the release of fluid at the compensating port. Otherwise, this will cause buildup of brake pedal and/or cause the brake light to stay on while the brake is off.
You are now ready to bleed and flush the brake’s hydraulic system. If you don’t have a pressure bleeder, this is a two-person job. The sequence of bleeding is very important. Start with the wheel farthest from the master cylinder and working to the closest. (On lefthand drive, this will be RR, LR, RF, LF.)
First, make sure the master cylinder is full of new brake fluid. Check it frequently during the process making sure that is always at least half full. Failure to do so will require starting over. The procedure will be the same for all wheels.
You will need a glass jar, a length of clear hose you can fit onto the brake bleeder fitting, and a wrench to open this fitting. Hook the hose and wrench onto the fitting and run the hose into the bottom of the glass jar.
With the bleeder still closed, get your helper to pump the brake pedal to its maximum height and hold pressure on the pedal. Now open the fitting slowly until fluid starts to flow. When your helper tells you the pedal is about to the floor, close the fitting while the pedal is still held down. Have the pedal pumped up again and open the fitting again.
Never have the fitting open if there is no pressure on the pedal. Continue repeating this process until the fluid going into the jar is clear, clean and free of bubbles. Although you need to make sure the master cylinder has enough fluid, do not reuse the fluid you take out. As you finish each wheel, make sure the fitting is left tight. Each wheel will require less fluid than the one before. You are now ready to tour with good brakes.
Of course, the procedure for bleeding is quite different if you have a pressure bleeder, but, if you are skilled enough to have one of these, you are probably smart enough and you don’t need my help.
Time for a brake (er, rather a break) and I’ll see ya next month.