Why Do My Rear Drum  Brakes Over Adjust?Find Out

If the drum brakes get too far away from the drum, as the brake shoes wear down, for instance, the piston will as a result need more fluid to travel the distance, and your brake pedal may sink nearer to the floor when you press the brakes. It is for this reason that the drum brakes have an automatic adjuster.

Your drum brakes may over-adjust if your brake is not in good condition. Some of the commonest reasons that make your drum brakes over adjust are not unconnected with weak drum brake springs or worn out and damaged brake pads.

There are other causes of drum brake over adjustments, but these are some of the most common.

How do drum brakes work?

Like all other brakes, when you press the brake pedal, the two curved brake shoes that have a friction lining on their outer surfaces, are forced by hydraulic wheel cylinders against the inner surfaces of rotating drums in the wheels of the vehicle.

The effect of this pressurized contact generates a frictional force that enables the vehicle to either slow down or stop entirely.

Trending Searches

• Can Brake Booster Cause Idle? Find Out?
• Do Brake Pads Expire? Find Out Now?
• Why Do Brake Pads Fall Off?
• Why Do They Put Screws In Rotors Fnd Out?

  What causes rear drum brakes to drag?

 Brake dragging is mostly caused by either broken or weak springs on the drum brake. In addition, brake dragging can equally be caused by a corroded or jammed calliper piston or a calliper that has corroded bushings or mounting pins. In another scenario, brake dragging can be caused by frozen emergency brake cables or even an overextended self-adjuster.

How do automatic adjusters work on drum brakes?

Automatic drum adjusters work on drum brakes by using their opposing piston calipers, which are bolted to the knuckle and also have pins that position the pads.

These drum brakes have return springs that will return the brake shoes to a rest position and hardware,  in order to hold the shoes to the backing plate. (Read Also: Can brake drums be powder coated? Find Out)

The shoes can return to a fully retracted or rest position whenever the master cylinder releases its pressure on the wheel cylinder.

In other instances, the master cylinder can contain residual check valves that will prevent air from getting drawn beyond the cylinder wheel cup seals, especially when the shoes are being retracted by the return springs.

Sometimes ago, drum brakes required periodic adjustments, and as the linings wear, the piston in the wheel cylinder would have to move further in order to engage the shoe with the drum friction surface.

In this situation, the return springs would retract the wheel cylinder piston to its rest position. This caused the brake pedal to move nearer to the floorboard whenever the brakes were applied, a process which was commonly called a ‘low pedal’.

When the brakes are adjusted, it will move the brake shoes nearer the drum friction surface and consequently reduce the travel of the wheel piston.

This also needs more fluid in the wheel to apply the brakes. All adjustments were done manually by turning the notched wheel on the adjuster with a brake spoon for the self-energizing type.(Read Also: Can You Mix Brake Pads And Rotors Find Out Now?)

Will rear drum brakes self adjust?

Yes, they do, and very effectively too. When the brakes are applied, the brake pedal cannot move the adjuster screw because the brake is utilized in applying the shoes.

This adjuster lever mechanism must store or memorize the adjustment and equally turn the notched wheel when the brake is released. So, yes, your rear drum brakes can self-adjust in order to enable appropriate brake functions in your vehicle.

Do drum brakes adjust themselves?

Yes, new drum brakes or shoes have to first be manually adjusted, but subsequently, they are capable of self-adjusting themselves.

There are instances when the self adjust may require using the main brakes in a reverse fashion. They can adjust themselves by either going forward or backward.

However, you must always remember that for the self-adjustment to work, you must manually do it first. Essentially, if the shoe brakes have to move too far before they come in contact with the drums, a pulley will spin the adjustment wheel which will, in turn, adjust the shoes a little further.

How to adjust drum brakes after replacing shoes?

In order to adjust drum brakes after replacing brake shoes, first, spin the drum with your hands and feel for any drag. On doing this, the drum should spin freely with very negligible drag.

Should the drag be too much, then back off the star adjuster a little. You should do this in small amounts until the brake is adjusted to where you would like it to be.

Does backing up adjust brakes?

Yes, it does. If the star wheel is located at the base of the brakes and acts as the hinge point for the brake shoes, it means that the adjustment was done by backing up, though the parking brake usually activates this to activate this too.

How do you adjust drum brakes?

Many vehicles are provided with drum brakes, though most times, disc brakes have been used at the front while the drum brakes are used in the rear.

Drum brakes need to be adjusted whenever the brake pedal needs to be pressed down a lot before the brakes become effective.

Any adjustment can only be done on brakes that are in good shape. However, before making any adjustments, confirm that your vehicle has symptoms of a malfunctioning drum brake. (Read Also: Can Brake Drums Be Relined?)

In preparation for this adjustment, get the following items and tools: eye protection, jack, jack stands, rags or paper towels, screwdriver, set of socket and ratchet, torque wrench, and so on. We shall discuss the procedures in three parts, each with its steps.

Part 1

Step 1

First, lift the rear end of the vehicle after making sure that the vehicle is in the park and the parking brake is also on. Place the jack at the correct place and lift one side of the vehicle off the ground. Repeat the process on the other side of the vehicle and support it too.

Step 2

Remove the tires on both sides by unbolting the lug nuts.

Part 2

Step 1

Next, access the drum brake adjustment star wheel. This adjuster is located beneath access in the back of the drum brake and using a screwdriver, gently pry out the rubber gourmet which safeguards the access cover. (Read Also: How Hot Should Brake Rotors Get?)

Step 2

Now, adjust the star wheel, before you turn the star-shaped adjuster a few times. If the star fails to turn due to the part that may hit the drum, proceed to turn the star in the other direction. Spin the drum and feel for any drag.

If there is too much drag, then back off the star adjuster slightly. Continue to do this in small amounts until the brake is adjusted to where you will want it to be. Repeat this procedure on the other side as well.

Part 3

Step 1

Appraise your work at this stage. Once you are satisfied, put the adjuster wheel cover back into its place on the back of the drums.

Step 2

Finally, re-install your tires by putting the wheels back onto the car. Using your ratchet, tighten up the lug nuts in a star pattern until they are snug enough.

Step 3

Lower your vehicle using the jack on a lift point by raising the vehicle until you can remove the jack stand out from beneath the vehicle. Then lower the vehicle.

Step 4

Test drive your vehicle so that you can evaluate your adjustments, but before doing so, pump up your brake first to seat it and ensure that the pedal works perfectly. (Read Also: Can brake pads be too thick?Find Out)

Frequently asked questions(FAQ)

When should I adjust the rear drum brakes?

It is required that you adjust drum brakes whenever you notice that you have to press the brake pedal far down towards the floor before it becomes effective. However, drum brakes can be adjusted effectively only on brakes that are in good shape.

Do brake drums self-adjust installation?

Yes, they do. However, before they do this, you must first manually adjust them, and thereafter they will subsequently be able to adjust themselves. 

Should the drum brakes move too far away from the drum, especially as the shoes wear down, the piston will need more fluid to travel that distance, and the brake pedal is likely to dink nearer to the floor when you apply the brakes. This is the reason why most drum brakes have an automatic adjuster.

When do brakes need to be replaced?

Usually, most brake pads are supplied with a thickness of about 12 mm of friction materials on their surfaces.

Many mechanics recommend that you get them replaced when their thickness reduces to about three or four millimeters.

Your vehicle’s brake pads should be due for replacement long before the brake plates begin to gouge out the brake rotors. This is a complication that is likely to make the job of replacing them more expensive.

Which way do you turn the brake drum adjuster?

The adjuster is found under the wheel cylinder. It uses an adjusting screw and notched wheel and lever in the same way as the Bendix/ Wagner.

Also, a lever( which is part of the parking brake assembly) is usually attached to one of the shoes that will be used to adjust the notched wheel.

You are required to spin the drum clock wisely until you feel any drag. The drum should spin freely with a little drag. If the drag felt is too much, then you should back off the star adjuster slightly. Continue to do this in small increments until the brake is adjusted to exactly where you would like it to be.

What are the disadvantages of drum brakes?

Every coin is said to have two faces, and so, even though drum brakes have monumental advantages, they still have disadvantages as well. Some of these advantages are: 

•  Since drum brakes have an enclosed design, water can collect in them, and when this cavity gets wet due to either rain, floods, or driving through a puddle, the water cannot get out right away.
•  Drum brakes also experience brake fade much faster than other brake systems.
•  Drum brakes get heated up much quicker than other braking systems.

What symptoms show that a drum brake is out of adjustment?

There are really few symptoms that will enable you to know that something is actually off with them. The commonest of these symptoms is a kind of unusual pedal feeling.

Should the drums get unduly worn out, they are likely to cause vibrations that can be felt in the brake pedal. Furthermore, worn-out drums can cause a sort of pulsation or shuddering which is noticeable whenever you apply pressure on the brake pedal.

How do I stop brake drag?

Presently, there is a new product in the aftermarket commonly called the spreader springs, which is a part of an ongoing effort to remove the problem of brake drag.

This reader spring is an accessory to Drag Reduction Technology or DRT for short. They are generally considered ideal solutions from NUCAP that are meant to eliminate the frustrating effect of brake drag. In essence, this new innovation in brake technology will reliably help to stop the problems of brake drag.

Why do my rear drum  brakes over adjust – Conclusion

A drum brake is the latest technology that is basically meant to solve most of the problems associated with disc brakes. Notably, drum brakes are capable of self-adjustments just to make sure that you are provided with the best brake efficiency at all times.

However, to enjoy this facility, you must first adjust them manually before they can subsequently take care of all future adjustments.

To enable you to do this as best as possible, you have been fully treated to how the procedures can be executed with the least possible chances of any mistakes.

The factors that cause brake drag have also been discussed as they should be through telling you its various causes, the symptoms that will notify you of the problem as well as how you should solve the problem when it happens.

You should be likened to a farmer who has all the needed implements for farming and is now also given the land to till.