Dan Ferrell writes about do-it-yourself car maintenance and repair. He has certifications in automation and control technology.
Is Replacing a Brake Caliper Hard?
Replacing a brake caliper on most vehicle models is pretty much a straightforward repair. You can do this project at home using some common tools. Still, specially if your car comes with an ABS system, you need to take certain precautions. But don't worry. This guide tells you how to approach this project at home, and, whether your car has a conventional or ABS system, the steps you need to follow for a smooth brake caliper repair.
Steps to Replace Your Brake Caliper
- Locate the brake caliper.
- Minimize brake fluid loss.
- Remove the old brake caliper.
- Install the new brake caliper.
- How to bleed the brake line.
- Strategies and pro tips for a successful brake caliper replacement.
Each of these steps is described in detail below.
|Tools You'll Need for This Project|
Piece of clean plastic sheet
2 jack stands
Small drain pan
Brake parts cleaner
Ratchet, extension and six-point sockets
New brake fluid
Piece of clear rubber hose
12oz plastic container
AND, IF NECESSARY :
Torx bit or Allen wrench
Rotary brush and drill
C-clamp or retracting tool
How to Locate and Replace the Brake Caliper
On fairly new vehicle models, check your car owner's manual before you start this repair. For better performance, some models offer energy brakes that self-activate. On these models, your owner's manual or vehicle repair manual should tell you how to deactivate the brakes.
With ABS systems, take precautions to prevent air from entering the brake system. Purging some of these systems requires special equipment, and your dealer or shop may be your only option for the procedure.
How to Minimize Brake Fluid Loss
- Pop the hood open and use a shop rag to thoroughly clean the brake master cylinder. The master cylinder attaches to the brake booster--a drum-like component mounted on the driver's side of the firewall.
- Unscrew the master cylinder reservoir cap and place a piece of clean plastic sheet on top of the opening.
- Then, replace the cap on top of the plastic sheet and tighten the cap. This will create a vacuum and help prevent much fluid loss when you detach the brake line from the brake caliper.
How to Remove the Brake Caliper
- Engage the parking brake (unless you are replacing a rear caliper) and use two pieces of wood to chock the front or rear wheels (the side you won't be working on). This prevents the car from rolling while you work on it.
- Loosen the wheel lugs on one or both front or rear wheels. NOTE: If you are not familiar with the caliper assembly, it's a good idea remove both wheels so that you can use the other assembly as a reference point when installing the new caliper.
- Raise both wheels using a floor jack.
- Place the vehicle on jack stands and finish removing the wheels.
- Place a small drain pan under the caliper to catch any brake fluid that might drain out of the brake hose.
- Disconnect the parking brake cable, if you are working on a rear caliper. Consult your car repair manual, if you need help.
- On some vehicles you'll need to remove a brake pad wear sensor, usually located on one of the brake pads. Carefully remove the sensor (WARNING, this sensor is fragile) using a pair of nose pliers. If necessary, consult the repair manual for your car make and model.
- Locate the brake hose connected to the brake caliper (usually on the upper, back side of the caliper).
- Thoroughly clean the brake hose end, bolt, and fitting on the brake caliper using a shop rag and brake parts cleaner to prevent contaminating the brake system. If the brake assembly is covered in dust, don't blow it out; only use brake parts cleaner spray to remove it.
- Using a line wrench or ratchet, extension and a six-point socket, loosen and tighten back the brake hose snugly, just enough to prevent brake fluid loss. Avoid using a regular wrench here to prevent rounding off the head of the bolt securing the hose.
- Then, loosen and remove the caliper mounting bolts. Some calipers have a mounting bolt on each bottom end, which allows to completely remove the caliper off the mounting bracket; other models use a bolt on one end that you can remove to swing the caliper upwards. Depending on your car model, you'll need a Torx bit, Allen wrench, or regular wrench or socket and ratchet to unscrew the caliper mounting bolts or pins.
- Once you remove the mounting bolt(s), carefully work the caliper off the rotor, or swing the caliper upwards. NOTE: Some caliper mounting bolts have a set of tabs at the end. On this, you need to squeeze these tabs with a pair of needle pliers while prying the bolt head at the other end to slide the bolt off the caliper.
- Take note of the position of any caliper hardware you may need to remove so that you can install it on the replacement caliper (clips, pad support, springs, anti-rattle clips, shims).
- Some brake pads mount on the caliper itself; others mount on the caliper mounting bracket. If the brake pads are mounted on the caliper itself, you may need to pry off the outer pad using a screwdriver. The inner pad may mount to the piston with a clip that attaches to the pad back plate, so you'll need to carefully pull the pad off the caliper piston.
- Use a wire hanger to secure the caliper to a suitable suspension component to prevent the caliper from hanging by the brake hose; otherwise you'll damage the hose.
How to Install the New Brake Caliper
- Clean the brake assembly using brake parts cleaner and remove rust from the assembly, specially those parts on the mounting bracket that come in contact with the caliper. This is critical on sliding calipers, which provide grooves for the caliper to slide on. Rust may cause the new caliper to get stuck and freeze during operation. Use a wire brush or a rotary brush and a drill to remove rust off the wheel assembly surface and bracket.
- Before installing your new brake caliper, carefully read the instructions that come with it. Your caliper may come with special grease already applied or in a small package that you need to apply. Make sure to use this grease following the manufacturer instructions.
- Transfer the brake pads to the new brake caliper or have them ready on the caliper mounting bracket, depending on your specific model. If possible, replace the mounting hardware, like springs, clips, and anti-rattle clip.
- The new caliper should have the piston fully retracted, ready to install. If not, you can use a C-clamp to retract the piston slowly into its bore when working on a front caliper. Place the clamp over the caliper and position the inner pad on the piston. Rotate the clamp large screw to push against the inner pad to retract the piston. On rear calipers you probably need a special retracting tool you can barrow from your local auto parts store. Consult your vehicle repair manual, if necessary.
- On some models, you need to apply a layer of high-temperature grease to the steering knuckle where it contacts the brake caliper. If necessary, consult your vehicle repair manual.
- When ready, place the caliper in position. Add a layer of silicone grease to the caliper mounting bolts (pins) and to the insulators (where you need to insert the bolts), if you have a single piston caliper and the mounting bolts allow caliper movement. Then install the caliper mounting bolts by hand and tighten the bolts to the manufacturer's suggested torque, using a torque wrench. You can find the recommended torque in the repair manual (or aftermarket manual) for your particular vehicle make and model.
- Remove the bleeder screw using a wrench. Apply Teflon tape to the screw threads (around three turns) and reinstall the screw. Start the screw by hand first and then tighten the screw snugly with the line wrench. Don't tighten the screw completely until after you bleed the caliper later.
- Now, have the new copper washers ready for the brake hose and the line wrench. When ready, disconnect the brake hose from the old caliper and connect the hose to the new brake caliper. Tighten the bolt just enough to prevent brake fluid from leaking.
- Use a shop rag to wipe clean any brake fluid you may have spilled during the transfer of the brake hose.
- Remove the plastic sheet from the brake master cylinder.
- Bleed the brake line. If you don't have an assistant to help you bleed the line, you can do it yourself using a hand-held vacuum pump in about one minute. Check out the instructions in the article "Brake Bleeding With a Hand Held Vacuum Pump" to bleed the brake line, or the whole system if you have to. Otherwise, follow the steps described in the next section.
How to Bleed the Brake Line
After replacing the brake caliper, this next procedure helps you bleed any air from the brake caliper or brake line attached to it, even if you are working on an ABS system.
However, if you think air has got into the brake master cylinder, or hydraulic control unit (HCU), and your car has an ABS system, you may need to take your vehicle to the dealer or shop and have them bleed the system with special equipment. Consult your vehicle repair manual, if necessary.
- Without starting the engine, depress the brake pedal at normal stopping pressure about five times to remove any residual vacuum out of the brake booster.
- Check the brake master cylinder reservoir. Add new brake fluid to bring the level up to the MAX mark, if necessary, and replace the reservoir cap.
- Place one end of a length of clear rubber hose over the bleeder screw on the new brake caliper. The hose should fit snugly over the bleeder screw. You can find clear hose in a craft supply store.
- Insert the other end of the clear hose into a plastic container and add some brake fluid to the container, just enough to submerge the end of the hose in it.
- Ask an assistant to depress the brake pedal five times and then firmly hold the pedal depressed.
- Then, loosen the bleeder screw about 1/4 or 1/2 a turn, just enough to let brake fluid to flow through the clear hose for about 2 seconds and then tighten the bleeder screw again. Watch for air bubbles flowing into the brake fluid in the container.
- Ask your assistant to release the brake pedal.
- Repeat steps 5 through 7 until you see no more air bubbles flowing into the brake fluid in the container. During the bleeding procedure, be sure to maintain the level above the MIN mark on the brake master cylinder reservoir.
- Properly tighten the bleeder screw after you finish bleeding the caliper or brake line.
- Add brake fluid to the master cylinder reservoir, if necessary.
- Verify the brake pedal feels firm, and test drive the vehicle around the block. Drive at a slow speed to make sure the brakes slow down and stop your car as they should.
- Back in your garage, check the brake hose and the bleeding screw on the new caliper for leaks. And during the following week keep checking for leaks.
Tips and Strategies for a Successful Brake Caliper Replacement
Whether this is your first time working on the brake system of your car, or you are already familiar with it, check these tips. They'll help you make a smoother repair job.
- Never blow out dust when cleaning a brake assembly, it may contain asbestos. Use a brake parts cleaner.
- When disassembling a wheel brake assembly, keep parts organized and use the opposite assembly as reference, in case you forget how to put things back together.
- Replace the brake pads as well as the caliper if the thinnest side of the lining is as thick or thinner than the backing plate.
- If you haven't replaced the brake hoses in the past 10 years, consider replacing them now. Old hoses begin to peel from the inside, block proper brake fluid flow, and may cause the caliper to seize.
- Replace brake calipers in pairs (front or rear) if they have 100,000 miles or more of use. This will help maintain brake system quality performance.
- Install new mounting hardware if possible - heat weakens hardware material after miles of work and may cause the new brake caliper and pads to rattle or squeal.
- If your brake assembly configuration differs somehow from the one described here, consult the repair manual for your particular vehicle make and model.
Replacing a brake caliper is not a common repair unless excessive wear, damage to the piston bore or housing, or sticking brakes (some cases), or brake fluid leak appears. Still, this project is not difficult and often a better alternative to rebuilding a brake caliper.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
Dan Ferrell (author) on June 29, 2020:
If you want to replace the calipers, it's better to take it to a shop. You need to access the control valves inside the ABS module to bleed the brakes once the calipers are installed, so you need a scan tool. Hope this helps.
terry fielding on June 29, 2020:
how model to fit new brake calipers on b m w x5 2004