Drum Brake Self Adjuster Not Working? The 192 Top Answers

” ” Figure 6. Adjustment Mechanism

For drum brakes to work properly, the brake shoes must stay close to the drum without touching it. If they move too far from the drum (e.g. if shoes wear out), the piston needs more fluid to travel that distance and your brake pedal will sink closer to the floor when you apply the brakes. For this reason, most drum brakes have an automatic adjustment.

Now let’s add the parts of the adjustment mechanism. The adjuster uses the self-actuating principle discussed above.

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As the lining wears out, more space forms between the shoe and the drum. Every time the car stops in reverse, the shoe is pulled tight against the drum. When the gap becomes large enough, the adjustment lever swings enough to advance the adjustment gear one tooth. The adjuster is threaded like a screw so when you turn it it loosens a bit and lengthens to fill the gap. As the brake shoes wear a little more, the adjuster can advance again, keeping the shoes close to the drum at all times.

Some cars have an adjuster that operates when the emergency brake is applied. This type of adjuster can become misaligned if the emergency brake is not used for a long period of time. So if you have such an adjuster, you should apply your emergency brake at least once a week.

Causes of the brake locking

The brakes on your vehicle are certainly one of the most important safety features. So if they apply or ban themselves when you need them most, it can be both dangerous and heart-pounding. Here’s why some brakes lock up and what to do when it happens to you.

Why brakes lock up

There is a long list of reasons why one or all of the brakes on your vehicle could lock up. These can include an overheated brake system, using the wrong brake fluid, damaged or defective parts (calipers, brake pads, pistons, rotors, etc.), a defective ABS component, a defective parking brake and more.

While diagnosing a brake problem is important, once you’re dealing with a lockup, nothing else matters. When your brakes lock up, it often boils down to two scenarios: lock up when you least expect it (and haven’t put pressure on the brake pedal) or when you hit the brakes hard.

We call the first scenario braking resistance or self-applying. Even though you may not have applied the brakes, residual hydraulic pressure can cause the brake calipers to activate and lock up. Today, this is the most common form of bridging in road traffic. Do not ignore this problem as it can quickly lead to mechanical failure of other parts of your braking system.

The second type can be called brake lock-up. This can happen if you both brake hard to avoid a crash, or brake gently to come to a stop. Essentially, the force of braking (even lightly) can activate the full stopping power of your brakes – bringing you to an abrupt and less secure stop. You might even slip. If this is the case, you can expect to find steering and controlling your vehicle extremely difficult.

For more information on these types of systems, see our complete guide to disc brakes and drum brakes and our brake service FAQ.

How to react with a lock-up

Whether you experience brake drag or brake lock-up, get to your local Les Schwab as soon as possible. Our technicians will ask which wheel or wheels appear to be locked and when. Any information you can provide will help diagnose and repair.

But if you’re driving and you hit a blockage, you have three options that could help you avoid an accident.

Put pressure on the brakes and try to gain as much control as possible. If your vehicle has anti-lock braking system (ABS), you will feel some feedback in the pedal and you may hear a mechanical noise when your vehicle stops. The feedback is the ABS, which prevents the wheels from locking and stops you from skidding. Take your foot off the brake pedal to give your wheels enough traction to potentially unlock temporarily. Then, if necessary, apply pressure to the brake again. Repeatedly (and rapidly) squeeze the brakes over and over until the brakes either release or bring you to a safe stop.

Les Schwab knows about brakes and safety

If you are having brake problems or simply want to have your brakes professionally checked or repaired, contact your local Les Schwab. Our technicians understand both disc and drum brakes and how all the interconnected components work together to keep you safe. Make an appointment or just stop by and we’ll help you get back on the road safely.

Find your store

Many vehicles are equipped with drum brakes. For many years, disc brakes have been used at the front of vehicles while drum brakes are used at the rear.

Drum brakes can last a very long time if properly maintained. Regularly adjusting the drum brakes ensures that the brakes do not drag while driving, as this can sap power from the vehicle and cause the brakes to wear out much faster.

Drum brakes usually need adjustment when the brake pedal has to be depressed heavily before the brakes engage. Adjustments can only be made on brakes that are in good condition. Keep in mind that not all drum brakes are adjustable. To ensure your brakes are in good condition before you adjust them, inspect your vehicle for signs of a bad or failed drum brake.

This article covers the adjustment procedure for star wheel type drum brakes.

Part 1 of 3: Prepare to adjust the drum brakes

Materials needed

Step 1: Raise the rear end of the vehicle. Make sure the vehicle is in park and the parking brake is on.

At the rear of the vehicle, place the jack in a secure location under the vehicle and raise one side of the vehicle off the ground. Place a jack under the raised side.

Repeat this process on the other side as well. For safety reasons, leave the jack in place to provide extra support for your vehicle.

Warning: Improper lifting of a vehicle can result in serious injury or even death. Always follow the manufacturer’s lifting instructions and only work on level ground. Only lift the vehicle using the lifting points recommended in your owner’s manual.

Step 2: Remove the tire. With the vehicle safely raised and secured, it is time to remove the tires.

Remove the tires on both sides by loosening the wheel nuts. Keep the nuts in a safe place so you can find them easily. Remove the tires and set them aside for some time.

Part 2 of 3: Adjusting the drum brake

Step 1: Access the drum brake adjustment star wheel. The drum brake adjuster is located under an access panel on the rear of the drum brake.

Use the screwdriver to gently pry the rubber grommet that protects this access panel.

Step 2: Adjust the tail wheel. Turn the setting star a few times. If it doesn’t stop spinning because the pads are hitting the drum, spin the star the other way.

After the pads hit the drum, back off the star wheel one click.

Spin the drum with your hand and feel if you pull. The drum should rotate freely with very minimal resistance.

If there is too much resistance, turn the star adjuster back slightly. Do this in small increments until the brake is adjusted the way you want it.

Repeat this process on the other side of the vehicle.

Part 3 of 3: Check your work

Step 1: Check your work. Once the brakes are adjusted to your satisfaction, put the dial cover back into place on the back of the drums.

Look at your work and confirm that everything is in place.

Step 2: Install the tires. Put the wheels back on the car. Using the ratchet or tire lever, tighten the lug nuts in a star pattern until snug.

Be sure to tighten the wheels according to the manufacturer’s specifications. Also, perform the torque procedure in a star pattern.

Step 3: Lower the vehicle. Using the jack on a lifting point, raise the vehicle far enough to slide the jack stand out from under the vehicle. Once the jack is out of the way, lower the vehicle to the ground on that side.

Repeat this process on the other side of the vehicle as well.

Step 4: Test drive your vehicle. Take the vehicle for a road test to confirm the brake adjustment.

Before riding, step on the brake pedal a few times to apply the brakes and make sure the pedal is working properly.

Drive the vehicle in a safe place and make sure the brakes are working properly.

Adjusting your drum brakes will make them last much longer and prevent brake drag. If the brakes are dragging, this can lead to a loss of power and reduce the vehicle’s fuel consumption.

If you are uncomfortable performing this process on your own, you can hire a Vermin Club experienced technician to adjust the drum brakes for you. If necessary, the certified professionals from Vermin-Club will even replace the drum brake for you.

Over-adjusted drum brakes

Drum brakes are adjusted to compensate for normal wear and tear. If set too hard, the brakes can lock up or activate with very little pressure on the brake pedal. The brake shoe adjuster readjusts the distance between the drum and shoe during normal driving. If there is a problem with the adjuster, it may over-regulate.

Table of Contents

symptoms

lock the brakes

The brakes can lock up if adjusted too hard. The brake shoe will have an initial starting point closer to the drum. If it’s too close, the two can touch and slow down the wheel.

causes

Defective brake shoe adjuster

The brake shoe adjuster pushes the shoe outward as the brake pad wears. The adjuster normally works when the vehicle is in reverse. If the adjuster is broken, it can adjust the shoe when not needed and push the shoe closer to the drum.

Shoes adjusted too much when installing

When installing new brake shoes, they must be adjusted to the correct point. If the shoe is too close to the drum when installed, the vehicle will not have a chance to correct the error. The shoe stays in a closer home position and moves even closer to the drum as it is adjusted by the shoe adjuster.

Wedge Adjuster Turning the square pin clockwise drives a wedge between two pistons and forces the shoes apart.

A typical braking system uses disc brakes at the front of the car and drum brakes at the rear. Normally, the handbrake acts on the rear shoes by means of a mechanical connection – a cable and some levers and pivots. The wheels are always lifted – and in many cases removed – to make brake adjustments. Raise the car at the jack point closest to the wheel to be trimmed and support it on an axle stand. Disc brake pads automatically adjust to wear, regardless of whether the car has disc brakes on only the front wheels or on all four.

Automatic adjuster Automatic adjusters work with the hand or foot brake. Each time the brake is applied, a lever turns a ratchet wheel and adjusts the brake shoes. The adjuster has a device to prevent over-adjustment.

On some vehicles with rear drum brakes, the brake shoes are automatically adjusted as the pads wear, keeping the contact area of ​​the brake shoes close to the drum and reducing brake pedal travel. Where the drum system is not self-adjusting, you can move the shoes closer to the inner surface of the drum as the liner material wears. They must be adjusted if the brake pedal travel increases before the brakes engage. Drum brake shoes are adjusted so that each shoe almost touches the inside of the drum. A touch of the brake pedal causes each shoe to immediately press against its drum. As the brake pads wear, the foot brake pedal travel increases, increasing your braking time. The brake pedal travel is too long if the pedal hits the ground before the brakes lock and you need to pump the pedal to restore full braking power. Most manually adjusted drum brakes have a single adjuster, but some – especially if they are on the front wheels – have two. Look at the brake backing plate behind the wheel and drum. If there are two brake lines or a bridge line across the backplate, it has two hydraulic wheel cylinders and may have two adjusters.

Cam Adjuster An adjustment pin through the brake backplate rotates a worm cam against a pin on the brake shoe.

Often the end of the adjuster is a square-ended rod coming out of the backplate, and the adjuster may be of the wedge or worm cam type. Some may have a hexagonal end. The ends are often partially recessed or otherwise hidden, making them difficult to adjust with an open-end wrench. Always use the correct brake wrench for the vehicle to avoid damaging the adjuster.

Star Adjuster A star adjuster rotates on a threaded rod that pushes the brake shoes apart.

The adjuster can also be a star wheel accessed through a hole in the back plate or front of the brake drum. You may have to remove the wheel to reach it. The adjusters are exposed to weather and dirt and tend to seize. Lubricate them with penetrating oil an hour or two before starting work and just before turning them. Disc brake pads always have light contact with the discs. This can be felt or heard if you spin the front wheel while the vehicle is jacked up. As the friction material wears, the piston or pistons in the caliper move toward the disc, thereby picking up wear on the pads or disc, or both. No customization is possible. But such a system is not always perfect. Part or all of the piston can become stuck in the brake caliper, preventing it from easily pressing the brake pad against the brake disc when the foot brake is applied. If the piston is partially stuck, it can jerk off with full pedal pressure. During deceleration, uneven braking can cause the vehicle to skid or skid, especially on slippery surfaces, if moderate braking is applied.

Adjusting a tail wheel

Remove the plug in the back plate to access the star wheel adjuster.

If you need to remove the wheel to access the adjustment hole, loosen the wheel nuts before lifting the car to the nearest jack point and resting it on an axle stand. If the access hole is on this side, remove the plug in the backplate and use the tip of a large flat head screwdriver to turn the star wheel.

Use a large screwdriver to turn the star wheel.

Check your car’s manual for the direction to turn the adjuster. Otherwise, move it several teeth. This should be enough for the brake shoes to clamp against the drum and prevent further movement. If the brake does not bind, move the tail wheel in the opposite direction. Decrease a click or two or until the wheel just spins freely.

Resetting an automatic adjuster

Turn the hex head screws on the back plate to loosen the shoes from the drum.

Automatic adjusters will always keep the brakes properly adjusted, but if you need to remove the brake drum for any reason, you may want to back off the adjustment a bit to make the job easier. Some cars, notably Vauxhalls, take this into account.

The brake drum can then be removed to reveal the shoes and automatic adjuster mechanism.

With the car raised and supported on jack stands and the wheel removed, turn two hex head screws on the back of the back plate. The bolts are turned toward each other, pushing the shoes away from the drum. Only a small adjustment is necessary. After assembly, only the foot and hand brakes need to be operated to restore the correct brake setting.

Setting a snail camera

Turn each adjuster clockwise a small amount at a time to bring the shoes closer to the drum.

Press the foot brake firmly several times to center the brake shoes in the drum. Raise the car at the nearest jack point and support it on an axle stand. Lubricate the adjuster with light oil. To bring the shoes closer to the drum, turn the adjuster clockwise as viewed from the back of the backplate. (This is the usual direction but may not apply to every type – consult your vehicle handbook.) Spin until you feel resistance and then try to spin the wheel. It should be locked. Back off the adjuster one click at a time until you can turn the wheel freely; a slight noise when the shoes touch a high point inside the drum is permissible. Remember that the driven wheels have some resistance due to the gearbox. Spin the wheel before making the adjustment so you can see the drag. If necessary, repeat the adjustment on the other wheel or wheels of the vehicle to ensure brake balance.

Turning a wedge adjuster

When adjusting, turn the wheel until it clicks, then adjust gradually until the wheel spins freely.

Spline adjusters are similar to the snail cam type in that a square shaft protrudes from the backplate. Within the barrel, the wedge adjuster has a tapered inner end. When screwing or unscrewing, he moves the shoes further apart or closes them. To adjust, raise the affected wheel and support the vehicle on an axle stand. Adjust with a brake wrench. The direction of rotation can be clockwise or counterclockwise. On the front wheel, turn the adjuster in the direction of rotation of the forward wheel. Spin a rear wheel in the direction specified by the manufacturer in the vehicle manual or a service manual. The turning effort required is usually very small. Lubricate exposed portion of adjuster shaft with light oil. Spin the shaft while spinning the wheel. If the wheel locks, back off the adjuster until you can hear the shoes just touch and the wheel spins freely.

Loosening a disc brake piston

In a fixed-caliper disc brake, two cylinders on each side of the disc actuate the pads.

Pick up the suspicious wheel and spin it by hand. If it spins freely with no resistance (except maybe from the final drive), ask a helper to lightly depress the foot brake pedal. The wheel should stop almost immediately when the pedal is touched. If it doesn’t, remove the wheel and look at the brake pads. If you see a gap between one or both pads and the disc surface, the piston is stuck. The piston can also stick in the “on” position, holding the pads tight to the disc. This leads to drag on that wheel, uneven braking, rapid pad wear and increased fuel consumption. To check for locking, apply and release the footbrake and try to spin the wheel. After a slight binding for part of a turn, it should spin freely. If it doesn’t, the brake is stuck in the on position. The only remedy for a stuck piston is to disassemble and clean the unit. A job best left to a garage. Often, the seizure is caused by excessive wear, corrosion, or scoring on the piston and internals, or both, and a new caliper assembly is required.

The floating caliper system has a cylinder with two pistons. One piston applies one pad and the other works the second pad through a sliding fork.