HOW TO REPLACE A BRAKE CALIPER
ASE certified mechanics show you the correct way to replace your brake calipers using everyday tools. When doing a brake job its a good idea to replace the changing brake caliper because they can leak brake fluid and stick which causes brake failure and uneven braking characteristics.
BRAKE CALIPER REPLACEMENT COST SUMMARY
- Remove the tire
- Remove caliper mounting bolts
- Remove brake calipers flex line
- Lift the caliper from the brake pads
- Match the old caliper to the new one
- Reinstall caliper onto the brake pads
- Reinstall caliper mounting bolts
- Bleed the system
- Reinstall tire
WHAT GOES WRONG?
A caliper will typical leak between the piston and seal or the piston will seize in the caliper bore causing the brake to lock up and not release. This is caused by the caliper piston developing rust and corrosion near housing seal. Leaks are caused by moister and dirt in the brake fluid which damages the rubber caliper piston seal.
When to replace brake calipers the piston is reset (pushed back inward into the caliper housing) to except the new brake pads it can damage the seal and cause a leak.The seal should be okay for the first or second pad replacement. There are three reasons to replace brake caliper the caliper, the first and most obvious is a fluid leak, the second is to prevent a leak due to age and the thirdis the piston is seized causing irregular braking or pad wear characteristics. A leak will cause the brake system warning light to come on because of the low fluid level in the master cylinder reservoir.
Symptoms of a Bad Brake Caliper:
- Fluid leak
- Overheating brakes
- Car pulls either to the right or left when applying the brakes
- Uneven brake pad wear
Brakes not releasing
HOW DOES IT WORK?
A brake caliper is designed to utilize brake fluid under pressure to transfer hydraulic force from the brake master cylinder to the brake pads. The brake pads then contact the rotating brake rotor to slow the car through friction. A brake caliper is typically mounted to the caliper mount which embodies two caliper slides.
There are two basic designs of brake caliper mounting, fixed and floating. A fixed position brake caliper is bolted to the mount and is not allowed to move. This kind of design is constructed with one piston on either side of the caliper. The floating style of caliper which is more common is mounted to the caliper mounting bracket using slide bolts which allow the caliper to “float“ as the brake pads wear, this design uses pistons on one side of the caliper. Brake calipers can have from 1 to 6 pistons depending on the manufacturer‘s design.
All brake calipers are fitted with a brake fluid bleeder which allows air to escape from the system. If air is allowed in the system it can cause a spongy brake pedal. A brake caliper piston is sealed to the brake caliper housing using a main piston seal. This seal allows the piston to move back and forth without allowing brake fluid to leak and is protected by a dust seal that helps keep debris from contaminating the integrity of the main seal.
HOW MUCH DOES IT COST?
When doing a brake job replacing the brake caliper is the textbook way of doing it. Many repair garage‘s will recommend replacement by makes a judgment call determined by the age and the condition of the brake system. In other words if the car has many miles on it then the caliper has a good chance of leaking, but if the car had low miles they would probably let it slide to save a couple bucks for the customer.
Most replacement brake calipers are rebuilt which cost between $35.00 and $70.00 (US) each, some which include pads. If you are having the job done at a shop expect to pay between $390.00 and $450.00 (US) for two.
HOW LONG DO BRAKE CALIPERS LAST?
Your brake calipers should be replaced anytime your car has over 70,000 to 90,000 miles. If pads are not included get a set of high quality set with rotors to do a complete brake job. They are not that expensive and it‘s the correct way to complete the job.
Before you begin working park your car on level ground with the engine off and the emergency brake on. Raise the car safely using a floor jack and secure it with jack stands. Also, we will be dealing with brake fluid so be sure to wear protective clothing, eyewear and gloves. You will need to remove and reinstall the wheel once this job is done.
Then continue down the guide to pick up on additional tips which is updated regularly.
How to remove brake caliper the Brake Caliper Mounting Bolts: Identify the caliper that is to be replaced. Only replace one caliper at a time. This will help control the brake fluid leakage and confusion while the job is being done.
Using a wrench or socket remove the caliper slide bolts. These bolts can be tight so make sure the tool is squarely on the head of the bolt before applying pressure to loosen. Then grasp the caliper and forcefully and rock it back and fourth. This is to cause a small air gap between the caliper piston and brake pads.
Remove the Brake Line: Once the caliper mounting bolts have been removed. There are two methods of stopping brake fluid from running out of the master cylinder once the brake line has been removed.
The preferred method is to remove the brake flex hose from the frame brake line and use a rubber cap to plug it off. The reason for this is the master cylinder will drain out of fluid once the caliper line is removed which will cause problems bleeding the system. This would be a good time to how to replace brake calipers the brake line as well.
Locate the brake line where it connects to the frame mount. Use a line wrench and loosen the fitting. A line wrench is used because these lines can be tight and if you use a regular wrench on them it could round the fitting causing a problem while trying to remove it.
Once the line has been broken loose you can use a regular wrench and continue removing the fitting which makes the job faster. Brake fluid will start to leak out slowly.
After the line is loose brake fluid will be dripping from it metal tube so be ready with a shop towel to catch it. Now take the rubber cap and install it over the metal brake line to stop the fluid from leaking out. Next use a shop towel to wipe up any excess fluid and then flush with water and soap.
Here is the alternative method to stopping the brake fluid from leaking which we have used in the shop many times. Take two pieces of fuel line and cover the jaws of a pair of needle nose vise grips.
Next, adjust the vise grip to gently pinch the rubber brake hose just enough to stop the fluid from flowing. It‘s important to not over tighten the hold on the rubber line because you don’t want to damage it.
If the brake line has cracks or is leaking brake caliperreplace it along with the caliper. Some mechanics don’t like to use this method because it can sometimes break down the internal lining of the hose if the vise grip is adjusted too tight.
Now it is time to remove the brake line from the caliper. Take a mental note or grab your cell phone and take a picture on how the brake line looks going from the frame to the caliper so you can reassemble it in the same manner. Locate the mounting bolt which is sometimes called a banjo fitting and break it loose with a socket or wrench. A small amount of brake fluid may leak out which is normal.
There will be two sealing washers that are made of copper or aluminum which are on either side of the brake line bulk head fitting. These washers will need to be replaced and should be included with the replacement calipers. If it is too difficult to loosen the fitting then reinstall the caliper onto the mounting bracket which will hold it while undoing the banjo bolt. Grasp the caliper once the line has been undone because it is heavy and can cause injury if it falls.
Remove the Caliper: Hold the caliper and separate it from the mounting bracket and the rubber flex hose. A small amount of fluid may leak out. You are now we are ready to match the old caliper to the new unit.
Clean the Brake Line Mount: Hold the brake line and use a shop towel to clean the end from dirt and corrosion. Both top and bottom must be clean because the sealing washers will leak if these surfaces have obstacles.
Prepare the New Caliper for Installation: Get yourself a top quality rebuilt brake caliper set which helps you do the job right. It is very frustrating when you get the job done and you have a leak or the caliper doesn’t work right because of a cheap rebuild. There are many rebuilders out there so go with a name brand to ensure its quality from Amazon or a local auto parts store. Sometimes a rebuilt caliper will have a core charge involved so don’t throw the old calipers out because they are worth some money. Return the calipers in the box them came in. It‘s a good idea to store them in a plastic bag to help control any brake fluid that may leak out during transportation.
Some calipers will come with new pads and hardware such as sliders which are used to ensure its proper operation. A caliper must be free to move back and forth while bolted to its mounting bracket. This helps the pads to wear evenly and to get the best performance from the car‘s braking action.
The brake fluid port will have a dust cap installed which sometimes holds the new sealing washers which are included in higher quality rebuilt calipers. Use a flat blade (standard) screwdriver to remove the cap and set the washers to the side for installation.
Remove the new slides from the plastic bag supplied with the caliper (some calipers have the slides installed from the rebuilder). These slides are either prelubed or should be installed with a small amount of brake lube. If the slides are installed dry the caliper will stick causing the brakes to pull and the pads to wear unevenly.
Some calipers have a dust boot that must be installed to protect the slides from getting moisture between the pin and the housing which can hinder the caliper‘s performance. Use a hammer and socket to gently push the rubber seal into place. This can take some work so double check them to make sure the seal is completely in place.
Now the caliper is ready to be installed, push the pads into the piston and outer plate. This will help with the installation over the rotor and caliper mounting bracket. Sometimes in shipping the piston will get pushed slightly outward, if so it can be re-insert it by using your hand or large C clamp or channel locks.
Install New Sealing Washers: Clean the banjo bolt thoroughly using a shop towel and brake cleaner. Check the bolt for any cracks or scores in the sealing surface and replace it if needed, this will help avoid leaks.
New mounting hardware which includes the bolts and additional sealing washers are included with most rebuilt calipers. This will complete the installation preparation and give it a professional touch. When reinstalling this hose it‘s recommended that a new copper sealing washer is installed.
Install the New Brake Caliper: While holding the caliper close install the clean banjo bolt with the inner sealing washer still in place. Then push the bolt through the brake line fitting and install the outer sealing ring as now the brake line is ready to be installed.
Thread the bolt inward into the caliper by hand to avoid cross threading. Position the brake line in the correct orientation (with out bends or twists). Tighten the bolt firmly to help seat the sealing washers. Don’t over tighten them because the bolt is hollow and it can break.
While watching the brake flex hose for twists set the caliper into place over the rotor and down onto the mounting bracket. Be mindful of the pads and the rotor to avoid unnecessary contact or force to push the caliper into place. Never use a hammer to install a caliper it should drop into place naturally.
If you have trouble getting caliper all the way down pull the caliper back up and check the slides to make sure they are fully retracted into the housing by repositioning them outward. This will help install the caliper fully.
After the caliper has been set down over the rotor and onto the mounting bracket install the new mounting bolts and thread them in by hand to avoid cross threading (some manufactures use thread lock such as lock-tight). This can take a little jostling to get them started so hand in there. You can also push the rotor onto the bearing hub to help. Continue until both are hand threaded into the bracket.
Use a wrench or socket to tighten the mounting bolts evenly while rechecking the tightness with a torque wrench. Most manufactures will tighten these bolts from 40 to 50 foot pounds.Reinstall the brake line into the fitting and tighten using the boxed end of the wrench.
Remove the brake line locks to allow the brake fluid to start following into the caliper. This rubber line will be pushed back into shape the first time the brakes are applied so don’t worry if there is a small indentation from the clamp. To finish and continue this repair you must bleed the brake system. After the brake bleed is complete check the brake pedal operation and reinstall the wheel. Never drive a car without a good brake pedal. When driving the car listen for abnormal noises and recheck the job if needed.
Tools and Supplies Needed:
- Rebuilt Brake caliper
- Tool set
- Line wrench set
- Brake fluid
- Needle nose vise grips (optional).
- 1/4 Fuel line (optional).
- Brake caliper lube.
- Brake cleaner.
- Vacuum cap assortment.
Brake fluid is corrosive and will damage your vehicle‘s finish. If this fluid comes in contact with a painted surface quickly wipe it with a clean cloth and then wash the area with soap and water and you should be okay. The brake system should always be flushed and bled when brake work is performed to prevent moisture from creating rust. Anytime the brake system is opened a brake system bleed is necessary.
What is a brake caliper rebuilding?
Caliper rebuilding is the replacement of worn or damaged parts. How to change brake calipers typically it involvesreplacement of pressure seals and dust boots that have become brittle from age and/or excessive heat from heavy use, such as racing. Occasionally, pistons may need to be replaced if they have become corroded, pitted, dented, or even melted.
How often should calipers be rebuilt?
There is no hard and fast rule for caliper rebuilding frequency. Some calipers won’t need to be rebuilt during the life of the vehicle. Highpowered race cars may need to have calipers rebuilt several times per season. At each pad change, inspect the calipers carefully. Any of the following conditions call for a caliper rebuild:
- Dust boots are vaporized, cracked, or simply no longer soft and pliable
- Brake pads are dragging, causing them to overheat
- Pistons are difficult or impossible to retract
- Brake fluid is leaking from around one or more pistons
Calipers are being refinished (i.e., stripped and painted or powdercoated).
How do I know what happens when a brake caliper goes bad rebuild parts to purchase?
It‘s critical to determine the piston sizes in your caliper. Many calipers use staggered pistons, in order to hold the pads parallel to the rotor during braking and ensure even pad wear. Do not measure one piston and assume all the others are the same size.
For StopTech calipers, see: How to rebuild a brake caliper Measure StopTech Pistons. For all other calipers, measure piston diameter directly.
- Remove brake pads.
- Disconnect brake lines and unbolt calipers from vehicle.
- Drain fluid from calipers. Remove brake line fittings from the calipers. With the brake line inlet port held ver a container to catch fluid, press the pistons until they are retracted fully. A race caliper spreader tool, like the Girodisc unit shown below, can make short work of this by compressing all pistons simultaneously.
- Clean calipers so brake fluid doesn’t damage finish. Plug the caliper inlet with a rubber stopper or bolt and wash the caliper with gentle car wash soap and water. Dry with a soft microfiber towel and/or compressed air.Do not use strong solvents, such as mineral spirits or “Brake Cleaner.“ These can damage painted, powdercoated, or anodized finishes. Treat the finish on your calipers the same as you would treat the paint on your car.
- Extend pistons. Place a piece of wood or a brake pad into the caliper to prevent any individual piston from ejecting completely. Use an air gun with a rubber tip to apply a jet of compressed air to the inlet until all pistons have extended far enough to be pulled out by hand. Once any individual piston pops out, any additional compressed air is going to flow from that opening and the remaining pistons won’t move. Keep fingers clear, as a piston may eject suddenly and with force. Use eye protection, in case brake fluid sprays when compressed air is used.
- Remove each piston carefully from its bore by hand, keeping it parallel to the bore until free, so that neither piston nor bore is scratched. Any scratch or dent on the sides of the piston will render it unserviceable, and it must be replaced. Otherwise brake fluid will leak past the pressure seal when the piston flaw passes in front of it.
- Remove dust boots by grasping the flexible portion with thumb and forefinger of both hands, applying tension as evenly and over as wide an area as possible. If that doesn’t work, a small flat blade screwdriver may be used to pry them out carefully.
- Remove pressure seals, taking care not to damage the piston bore or seal groove in the caliper body. A thin, flat spatula, a 90-degree bent stylus, or a mechanic‘s pick works well.
- Clean pistons, bores and seal grooves and inspect for scratches, dents, corrosion or other damage. Install new pressure seals. Inspect each seal to ensure it is clean. Lubricate seals with brake caliper ASSEMBLY fluid. (NOTE: This is NOT the same as brake caliper lube, which is used to lubricate sliding, metal parts. Using caliper lube, instead of caliper assembly fluid, may damage your seals and contaminate your brake fluid, leading to failures of ABS and stability control parts. Make sure you use the right stuff!) Insert pressure seals by hand, into the seal groove for its piston bore, making sure the correct size seal is used for each. Check carefully to make sure they aren’t twisted, by running your bare finger across the surface. If it is twisted, remove and reinstall.
- Install dust boots onto each piston, prior to installing piston in the caliper. Make sure you do not get any lube on the dust boots. If you do accidentally get lube on the boots, clean them off with soapy water before continuing. Otherwise the boots may refuse to stay seated and will pop out later.
- Install pistons. Lightly coat the bottom and sides of the pistons with Brake Caliper Assembly Lube. Slide the pistons halfway into the bores. Rock or rotate, if necessary, to ensure they are inserted straight, so as not to damage the piston or seal. Apply even pressure to slide each piston further into the bore. The pistons should go all the way to the bottom of the bore with hand force. If this is not possible, STOP! Remove the piston and inspect the seal to see why it is getting hung up. Debris in the caliper‘s pressure seal groove may be pushing the new seal into the path of the piston. If you force the piston into place, it will tear a chunk off the pressure seal and the caliper will leak.
- Press dust boots into place carefully, ensuring the outer metal ring, molded into the boot, is installed nearly level with the flat area surrounding it. If the boot is pressed unevenly, it is possible to damage the silicone or rubber material inside the metal ring. It may not be possible to push the boots in place with your fingers, in which case a curved piece of wood, plastic or metal may be used. Do not let brake fluid come in contact with the boots, as this will soften them and make them easy to tear.
- Reinstall caliper on the vehicle, using new crush washers for the banjo fitting (if applicable) at the caliper brake line inlet. Reinstall pads. Bleed brakes with fresh fluid and fill the master cylinder reservoir.