The parking brake is designed to hold the vehicle in place when the vehicle is at rest. If the parking brake is not holding the vehicle, then the vehicle could roll or even damage the transmission if it is automatic.
Most vehicles have disk brakes on the front and drum brakes on the rear. The rear brakes usually have two functions, stopping the vehicle and holding the vehicle still at rest. If the linings on the rear brakes are worn enough to not stop the vehicle, then the parking brake will not hold the vehicle at rest.
Vehicles can be equipped with rear drum brakes that stop and use as a parking brake, rear disk brakes with integrated parking brakes, or rear disk brakes with drums brakes for the parking brake.
If the parking brakes won’t hold the car, then you need to check the following:
- Parking brake lever/pedal out of adjustment or stuck
- Parking brake cable stretched
- Rear brake shoes/pads worn out
Part 1 of 3: Diagnosing the parking lever or pedal for adjustment or stuck condition
Preparing the vehicle to check the parking brake lever or pedal
Materials Needed
- Channel locks
- Flashlight
- Safety glasses
- Wheel chocks
Step 1: Park your vehicle on a flat, hard surface. Make sure that the transmission is in park (for automatics) or in first gear (for manuals).
Step 2: Place wheel chocks around the rear tires that will be remaining on the ground. Engage the parking brake to the lock the rear tires from moving.
Checking the condition of the parking brake lever or pedal
Step 1: Put on your safety glasses and grab your flashlight Locate the parking brake lever or pedal.
Step 2: Check to see if the lever or pedal is stuck. If the lever or pedal is frozen in place, it may be from rust on the hinge locations or the pins are broken.
Step 3: The the back of the lever or pedal for the parking brake cable attachment. Check to see if the cable is broken or frayed. If you have a cable with a bolt attached, check to see if the nut came loose.
Step 4: Try to set and reset the parking lever or pedal. Check for tension as you set the parking brake. Also, check to see if there is an adjuster on the lever. If there is, check to see if it can be turned. If the lever adjuster cannot be turned by hand, you can put a pair of channel locks onto the adjuster and try to free it up. Sometime overtime the adjuster becomes rusty and the threads get frozen.
Cleaning up after performing the diagnosis
Step 1: Collect all tools and place them out of the way. Remove the wheel chocks from the rear wheels and put the aside.
If need to perform a repair of the parking brake lever or pedal that's out of adjustment or stuck, contact a professional mechanic.
Part 2 of 3: Diagnose the parking brake cable if it is stretched
Preparing the vehicle to check the parking brake cable
Materials Needed
- Flashlight
- Jack
- Jack stands
- Safety glasses
- Wheel chocks
Step 1: Park your vehicle on a flat, hard surface. Make sure that the transmission is in park (for automatics) or in first gear (for manuals).
Step 2: Place wheel chocks around the rear tires that will be remaining on the ground. Engage the parking brake to the lock the rear tires from moving.
Step 3: Raise the vehicle. Using a floor jack that is recommended for the weight of the vehicle, lift under the vehicle at its specified jacking points until the wheels are completely off the ground.
Step 4: Place the jack stands. The jack stands should go under the jacking point locations. Then lower the vehicle onto the jack stands. For most modern cars, the jacking points for jack stands will be on the pinch weld just under the doors along the bottom of the car.
Checking the condition of the parking brake cable
Step 1: Put on your safety glasses and grab your flashlight Locate the parking brake cable in the cab of the vehicle.
Step 2: Check to see if the cable is stretched. If you have a cable with a bolt attached, check to see if the nut came loose.
Step 3: Go under the vehicle and check the cable along the undercarriage of the vehicle. Use your flashlight and check to see if the cable has any mounts that have came loose or broke off.
Step 4: Look at the connections. Examine the connections to see where the parking brake cable attaches to the rear brakes. Check to see if the cable is stretched where it attaches to the rear brakes.
Lowering the vehicle after performing the diagnosis
Step 1: Collect all tools and your creeper and place them out of the way.
Step 2: Raise the vehicle. Using a floor jack that is recommended for the weight of the vehicle, lift under the vehicle at its specified jacking points until the wheels are completely off the ground.
Step 3: Remove the jack stands and keep them far away from the vehicle.
Step 4: Lower the vehicle to where all four wheels are on the ground. Pull out the jack and put it aside.
Step 5: Remove the wheel chocks from the rear wheels and put the aside.
Have the parking brake cable replaced by a professional mechanic if necessary.
Part 3 of 3: Diagnose the condition of the parking brake shoes or pads
Preparing the vehicle to check the parking brake shoes or pads
Materials Needed
- Flashlight
- Flat tip screwdriver
- Jack
- Jack stands
- SAE/metric socket set
- SAE/metric wrench set
- Safety glasses
- Sledge hammer 10 pounds
- Tire iron
- Torque wrench
- Wheel chocks
Step 1: Park your vehicle on a flat, hard surface. Make sure that the transmission is in park (for automatics) or in first gear (for manuals).
Step 2: Place wheel chocks around the rear tires that will be remaining on the ground. Engage the parking brake to the lock the rear tires from moving.
Step 3: Use a tire iron to loosen the lug nuts on the rear wheels.
- Note: Do not remove the lug nuts until the wheels are off the ground
Step 4: Raise the vehicle. Using a floor jack that is recommended for the weight of the vehicle, lift under the vehicle at its specified jacking points until the wheels are completely off the ground.
Step 5: Place the jack stands. The jack stands should go under the jacking point locations. Then lower the vehicle onto the jack stands. For most modern cars, the jacking points for jack stands will be on the pinch weld just under the doors along the bottom of the car.
Checking the condition of the parking brake shoes or pads
Step 1: Put on your safety glasses and grab your flashlight Go to the rear wheels and remove the lug nuts. Take off the rear wheels.
- Note: If your vehicle has a hub cap, you will need to remove it first before removing the wheels. Most hub caps can be removed by a large flat tip screwdriver where others need to be removed by the tire iron.
Step 2: If your vehicle has drum brakes, grab a sledge hammer. Hit the side of the drum to free it up from the wheel studs and centering hub.
- Warning: Do not hit the wheel studs. If you do, you will need replace damaged wheel studs, which can take some time.
Step 3: Remove the drums. If you cannot remove the drums, you may need to use your large screwdriver to loosen the rear brake shoes.
- Note: Do not pry off the drums for you can damage the backing plate.
Step 4: When the drums are off, check the condition of the rear brake shoes. If the brake shoes are broken, you will need to take repairing action at this point. If the brake shoes are worn out, but there is still linings left to help stop the vehicle then take a tape measure and measure the amount of linings that are left. The minimum amount of linings should not be any thinner than 2.5 millimeters or 1/16 of an inch.
If you have rear disk brakes, then you will need to remove the wheels and check the pads for wear. Pads cannot be any thinner than 2.5 millimeters or 1/16 of an inch. If you have disk rear brakes but have a drum parking brake, then you will need to remove the disk brakes and rotor. Some rotors have hubs in them, so you will need to remove the hub locking nut or cotter pin and lock nut to take the hub off. When you are done inspecting the drum brakes, then you can put the rotor back on and reassemble the rear disk brakes.
- Note: When you have the rotor off and it has a hub in it, you will want to check the bearings for wear and condition and it is suggested to replace the wheel seal before putting the rotor back on the vehicle.
Step 5: When you are done diagnosing the vehicle, if you plan on working on the rear brakes later, you will need to put the drums back on. Adjust the brake shoes tighter if you had to back them off. Put on the drum and wheel. Put on the lug nut and tighten them up with the tire iron.
- Warning: Do not attempt to operate a vehicle to where the rear brakes do not operate correctly. If the brake linings or pads are below threshold, then the vehicle will not be able to stop in mannerly time.
Lowering the vehicle after performing the diagnosis
Step 1: collect all tools and your creeper and place them out of the way.
Step 2: Raise the vehicle. Using a floor jack that is recommended for the weight of the vehicle, lift under the vehicle at its specified jacking points until the wheels are completely off the ground.
Step 3: Remove the jack stands and keep them far away from the vehicle.
Step 4: Lower the vehicle to where all four wheels are on the ground. Pull out the jack and put it aside.
Step 5: Get a torque wrench and torque the lug nuts. Make sure that you use a star pattern to ensure that wheels are torqued properly with no runout or wobble effect. Put on the hubcap. Make sure that the valve stem is visible and free from contacting the hubcap.
Wheel lug nut torque values
- 4 cylinder and V6 engine vehicles 80 to 90 foot pounds
- V8 engines on cars and vans 90 to 110 foot pounds
- Large vans, trucks, and trailers 100 to 120 foot pounds
- One ton and 3/4 ton vehicles 120 to 135 foot pounds
Step 5: Remove the wheel chocks from the rear wheels and put the aside.
Replace the parking brake shoes if they're failing.
Fixing the parking brake that won’t engage can help improve the braking of the vehicle and prevent any damage to the brake system and transmission.
