How to Fix Seized Brakes

by Jody L. Campbell

Fixing seized brakes can only be successfully completed if you can determine what caused them to seize. A sticking or stuck caliper piston, a pad stuck in a caliper anchor, a clogged brake hose or a frozen slide can cause seizure in disc brakes. Over adjusted shoes, an improperly functioning parking brake system, a frozen wheel cylinder bore or a broken or dislodged component wedged between the shoe and drum can all be leading causes to drum brake seizure.

Lift the vehicle (in neutral gear) on a vehicle lift to allow the wheels to suspend. Test each wheel to determine which wheel or wheels has drag or will not turn by hand. Remove the hubcap, and then remove the wheel nuts with an impact gun and socket. Remove the wheel.

Inspect the caliper on disc brakes first. Remove the caliper bolts and pry the caliper off the rotor and pads using a pry bar. If the caliper comes off hard without the brakes being applied, a caliper piston is most likely to blame. To check the piston, secure the caliper to the vehicle with a caliper hook. Remove the pads if they are clipped to the caliper. Inspect the pads. A clear indication of stuck brakes is premature wear of brake pads. Compress the piston of the caliper with a caliper piston tool. A large C-clamp would work as well. If the caliper piston does not retract back into the bore, it has seized and needs to be replaced. Replace the caliper and bleed the hydraulic braking system.

Inspect the caliper slides if the piston retracted properly. Caliper slides can also become contaminated or the protective rubber boots may crack and allow water, rust, sand and other corrosive elements to seize the caliper slides. If you're able to remove the slides (it will be somewhat difficult), you can clean them off thoroughly with the die grinder (or a bench grinder with a wire brush wheel works well) and reapply brake lubricant to them. Reinstall them, replace the compromised protective rubber boots and retest the caliper after replacement.

Pry the pads out of the caliper anchor for vehicles that use pads not clipped to the caliper. When pads are installed, a high temperature brake lubricant is applied to the contact points of the anchor. This allows the pads to move back and forth when the caliper piston is applied and released. Because the brakes are exposed to the elements of adverse weather conditions, it is common that the lubricant washes away and rust and corrosion set in. This can cause the tabs of the pads backing plates to seize inside the caliper anchors. Remove the anchors and the pads. Clean the contact points of rust and corrosive build-up with an angled die grinder and a reconditioning disc or a wire brush. Remove the rattle clips and clean the caliper points beneath the clips. Apply brake lubricant under and on the rattle clips. Replace the pads, replace the anchor and then replace the caliper. Retest.

Inspect the adjustment of the rear brakes. Remove the rubber plug (if available) from the backing plate of the drum brakes. Insert a brake-adjusting tool into the porthole along with a screwdriver to push the adjuster retainer away. Turn the internal star wheel to back off the rear shoe adjuster and try to turn the wheel. If you're able to, continue to readjust the star wheel until you can easily remove the drum and inspect the adjuster mechanism. These can be removed easily. Clean the threads of the adjuster, apply a liberal amount of lubricant or anti-seize compound and reassemble.

Inspect the rear brakes, once the drum has been removed. If a component falls out of the drum or from the drum brakes when the drum is extracted, the seizure of the brakes could have been caused by this part being wedged between the drum and a shoe. Check the drum for scoring and the shoe for damage. Replace the component; replace the shoes if necessary. Machine the drum or replace the drum, if needed.

Press the bores of the wheel cylinder inward (1 at a time) with a screwdriver to determine if the bores are stuck. The hydraulic pressure in the braking system should allow the bore to expand back outward to contact the horn of the shoe. If you compress the bore and it does not return or you cannot compress the bore, then the wheel cylinder has failed and needs to be replaced. Replace the wheel cylinder and bleed the braking system.

Check the flow of brake fluid to the bleeder screws of the seized wheel. This will determine if the hydraulic brake fluid is properly functioning. Have someone pump the brake pedal 4 times and open the bleeder screw with a hand wrench. If no fluid comes out of the bleeder screw, remove it. Have the helper step on the brake pedal again. If fluid comes out, replace the bleeder screw or unclog it. If fluid still does not come out, replace the bleeder screw and disconnect the brake hose. Press the pedal again. If fluid does not come out or barely trickles out, the brake hose should be replaced. Bleed the brake system any time you replace a hydraulic brake component.

Inspect the master cylinder and power brake booster. To determine a bad master cylinder, place a brake line lock on each brake hose at all 4 wheels. Have someone step on the brake pedal and remove 1 line lock at a time. The pedal should remain high and hard until the lines are removed and then slight pressure will release off each line lock removed. If the pedal drops to the floor during the removal of 1 line lock, there's a hydraulic problem with that particular wheel. If the pedal remains high and hard once all the line locks are removed, the master cylinder may be the problem. Check the vacuum line for the brake booster. Replace the master cylinder and bleed the system.

Items you will need

About the Author

Jody L. Campbell spent over 15 years as both a manager and an under-car specialist in the automotive repair industry. Prior to that, he managed two different restaurants for over 15 years. Campbell began his professional writing career in 2004 with the publication of his first book.