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Brake Maintenance

When we mention brake repair we normally think of replacing the brake shoes but much more can be involved in a brake job. The brake shoe pushing against the brake drum is what brings the car to a stop but the pressure comes from the hydraulic wheel cylinder that is expanded with brake fluid that is pumped through a series of metal lines and finally a rubber line. The fluid starts its course at the master cylinder which is just a hydraulic pump attached to the brake pedal. Of course there must be brake fluid in the reservoir, the brake drum must be free of grease and the brake shoes adjusted correctly. So if the master cylinder is pumping, the metal lines are not rusted out, and the rubber hoses are not swollen shut with age (which they often are) we can concentrate on replacing the shoes and the wheel cylinders. To remove the brake shoes we first have to remove the brake drum. In the rear it is held on with a 36mm (1 3/16) nut that is tightened to about 250 ft. lb. when it is installed and usually takes a lot more to get it loose. If you don't have an impact wrench you can lock the wheel with a piece of angle iron drilled to fit a couple of the lug bolts. Then use a steel pipe over a breaker bar for leverage. A ¾" drive bar works best.

They also make a tool sometimes called a slug wrench
Or you can invest in a Torque Miester (from Kymco Motorsport) which always works.
The front drum is much easier. Refer to our article on front wheel bearing maintenance.
With the drum off you can access the shoes.
They are held against the backing plate with a spring with a cap that can be removed by twisting it to allow the pin to slip through the slot in the top.
Now remove the brake springs. The one nearest the adjuster is the weakest and easiest to remove with pliers.
With this one removed you can spread the shoes to remove them from the adjusters and then bring the ends together and release most of the tension on the other spring making it easy to remove.
The ends of the shoes just slip into the slots in the adjusters and the wheel cylinders. If there is grease on the shoes you will need to replace the grease seals which is a topic for another tech article. The shoes could be wet with brake fluid from a leaking wheel cylinder.
Since the new shoes can be ruined by a leaking wheel cylinder I like to replace them at the same time as the shoes. They are only held on with one bolt at the back of the plate.
Then unthread the brake line from it. Now is also a good time to replace the rubber brake lines if they have been there for several years. They are usually the cause of brakes pulling to one side.
On the rear shoes you will need to unhook the emergency brake cable.
The arm is held to the shoe with a horse shoe clip. This will need to be removed and installed on the new shoes.
The rear will also have a spacer bar under the stronger spring that has a clip that is pushed on from the rear. Be sure to notice the notches in the end that line up with the emergency brake arm. (Note: The bar will look upside down on one side of the car).
While the shoes are off the adjusters can be removed and cleaned and greased. They just slip into the socket in the backing plate but can become corroded and stuck. They may have to be chiseled out and replaced.
They should be reinstalled in their shortest adjustment. If the groove is an angle the widest part goes toward the center of the drum.
With the adjusters installed and wheel cylinders replaced we reverse the procedure by installing the strong spring (and spacer bar if rear) and slide the ends into the grooves in the wheel cylinder. Then slide the other end into the groove in the adjusters and install the other spring.
Now install the retainers by slipping the cap over the spring and pin and push and twist to lock in place.
Now is time to replace the drum. In most cases the drum will need to be either turned on a drum lathe to make the surface perfectly flat again or if it is already too worn or scarred it will need to be replaced.

 

Reinstall and torque the rear to at least 250 ft./lb. and renew the cotter pin. Adjust the brakes by turning the adjusters all the way out until the drum sticks and the back off just until it moves again.

If you have replaced the wheel cylinders and hoses you will need to bleed the air out of the system. Be sure to keep fluid in the reservoir while you have someone pump the brake while you open the bleeder on the wheel cylinder. Have your helper hold the pedal down as you open and close the bleeder. Start with the wheel farthest from the master cylinder.
Once you have cleared out the air you are ready for a test drive. The pedal may feel a little softer at first and after a few hundred miles or less you may need to readjust the brakes. Hope this helps to "stop you in your tracks" You can see this done in detail in our Vol.4 Brake Maintenance video available from Bug Me Video

Rick Higgins and Crew
Bug Me Video, Inc
.

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