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Pelican Technical Article:

BMW E36 3 Series Brake Caliper Rebuild
Jared Fenton
Wayne R. Dempsey

Difficulty Level: 4
Difficulty scale: Adding air to your tires is level one
Rebuilding a BMW Motor is level ten

In this tech article I will go over the steps for rebuilding the E36 front brake calipers.

     The first step is Jack up the front end of the car, put it on jack stands and remove the wheels. Use Wayneís tech article on jacking up the front of the E36 for reference.

     Before we actually take the calipers off, I recommend spraying the whole assembly with a good quality brake cleaner. This will make the job a bit easier and you wont have to worry about crud and grime getting in places where wrenches and sockets will be going. Whenever I am doing brake jobs or anything that will be dirty, I usually head down to the local self-serve car wash, pop off the tires, get a can of brake cleaner and spray everything. Then I simply steam clean it all off.

Once clean, this is how you do it.

     Open the hood and locate the brake fluid reservoir. Take the cap off and place a piece of plastic over the top, use something like saran wrap or cellophane. When you put the cap back on, this will help to create a vacuum and keep the brake fluid from draining out of the lines.

 The next step is to disconnect the brake pad sensor wire from the connector. (Note: the brake pad wear sensor is only on the driverís side, disregard this step on the passenger side) You will now want to loosen the brake line where it threads into the caliper. Iíd use a good penetrant spray to prevent stripping or seizing. Use an open-end wrench to loosen the fitting and then snug it back up. Loosening this fitting now will make removing the brake line much easier later on.

     Now look at the caliper spring clip on the outside of the caliper. This is the brake pad retaining clip. Remove it by carefully prying it off with a screwdriver.

     Next, look at the back of the caliper, you will notice two plastic inserts inside of two rubber grommets. Use a screwdriver to pry the plastic inserts out of the rubber grommets. Directly behind the inserts are two 7mm Allen head bolts. These are the caliper guide bolts. Use a 7mm Allen key and remove these two bolts.

     Now remove the caliper from the rotor assembly, it will simply pull off. Remove the brake pads as well. One brake pad will be pressed into the caliper piston. Simply pull the pad out of the piston.

     You now need to remove the brake line from the caliper. Simply loosen the fitting and pull the brake line out of the caliper. You will need to plug the end of the brake line to keep brake fluid from leaking out as well and keeping dirt and grime from getting into the line. A good way of doing this is to place a small plastic baggie over the end of the line and use a zip tie to hold it tight. Itís also a good idea to have a drip tray or oil pan under the caliper at this time to catch any leaking fluid. Remember, brake fluid will eat paint, so take care not to get it anywhere near the vehicle.

     With that the calipers removed from the vehicle, we can now begin to rebuild them. The first step is to push the pistons out of the caliper. Place a block of wood about Ĺ inch thick between the caliper piston and the outer mounting flange. Now insert an air nozzle in the hole where the brake line goes and using low-pressure compressed air, blow the piston out of the caliper. (Use caution here as the piston will pop out of the caliper with a lot of force, the wood in there acts as a cushion for the piston) Also, be prepared for a lot of brake fluid all over the place, so make sure you dressed in your best shop clothes.

     Now, take a clean pan or tray and fill it with fresh brake fluid. Take the caliper piston and clean it in the fresh fluid. Use a Scotchbrite pad to clean off any dirt or grime. Now look at the outer face of the piston and look for any corrosion or pitting in the face. If you find either of these, the entire caliper must be replaced. You cannot buy the caliper pistons separately. You probably would want to replace the calipers even if you could get just the piston. A pitted or corroded piston means that there will be corrosion and pitting on the inside of the caliper. This is something you cannot fix. 

     Next, remove the outer dust cover on the caliper (it will probably come off when you blow the housing) as well as the inner rubber O-ring that sits in a groove on the inside of the caliper piston bore. Just use a small screwdriver to catch the lip of the O-ring, and then carefully work it out of the bore. Take care not to scratch or gouge the bore with the screwdriver. If you do, the caliper will be shot and youíll need a new one.

     With the seals off, clean the caliper. I would start with the outside. Once again, use a good brake cleaner, a Scotchbrite pad and an old toothbrush. It isnít really necessary to clean the outside, however in my opinion, you might as well as long as itís out. What is critical is cleaning the inside of the caliper. Use the brake cleaner and toothbrush to get inside the bore, and clean everything get that thing looking like new. Once clean, let the caliper and piston air-dry.

     Once dry, you can paint the calipers if you like. Pelican sells a kit to do this. (Please insert link for brake paint here) 

     Now you will need a brake caliper rebuild kit, (available from Pelican of course). This kit will contain two pieces, the inner O-ring for the piston bore and also the outer dust boot.

     Take the inner O-ring and coat it with either brake fluid or caliper rebuild grease, available at any auto parts store. This grease is specifically for rebuilding calipers. Also coat the groove inside the caliper with the grease. Once coated, press the inner O-ring into the groove on the inside of the caliper with your fingers.

     Next, coat the outside of the piston with either brake fluid or caliper grease. Now pull the dust cover over the inside edge of the caliper, with the lip of the dust cover (the lip that goes in the caliper, not the piston) facing away from the piston. The edge of the dust cover that will eventually be seated in the groove on the piston should be facing the piston groove, and the rest of the dust cover should be hanging slightly over the edge of the piston. While holding the piston near the caliper housing, push the lip of the dust cover into its groove in the caliper. Then gently push the piston into the caliper. The piston will hit the inner O-ring and become more difficult to press in. Keeping the piston exactly straight, gently tap it into place using a hammer against a flat piece of metal or wood held against the piston. You can also insert the handle end of a small hammer into the piston and then push the piston into the caliper.

     Now with the caliper re-assembled, you can now re-mount it on the rotor assembly. Re-attach the brake line (donít tighten it yet, just get it snug), insert the brake pads into the caliper, and install the caliper on the rotor assembly. Re-install the caliper guide bolts and torque them to 24 ft/lbs. Now push the plastic inserts back into the rubber grommets, and place the brake pad retaining clip back on the caliper. Now tighten the brake line. On the driverís side, re-connect the brake wear indicator sensor.

     Now we are ready to bleed the calipers. In this instance, we will assume that you have a helper to do this. First, loosen the bleeder screw on the caliper, then quickly snug it back up, we want to just get it loose, not remove it. Next, get a jar and fill it about halfway with fresh brake fluid. Place one end of a clear plastic hose over the bleeder screw and run the other end into the jar.

     Next, open the reservoir cap, remove the cellophane and check the fluid level. Top it up as needed. Leave the cap off, as this will help to draw fluid through the system. Have your helper pump the brakes until pressure begins to build up. Then have your helper step on the brakes to hold the pressure and open the bleeder valve for about 1 second then quickly close again. You will see fluid flow through the hose with a lot of air bubbles in it. Having the hose in a jar of brake fluid prevents air from flowing back into the caliper.

     Again, have the helper again build up pressure on the brakes and hold the pedal down. Open the bleeder valve for about 1 second then quickly close. You will want to repeat this step until there are no more bubbles flowing through the line.  As the air is bled from the lines, it will take less time for the brakes to build up pressure. Check the fluid level in the reservoir while your helper is pumping the brakes to build up pressure. Do not let the reservoir run dry or you will have to bleed all over again.

     Once the lines are bled, clean up the area around the caliper. Use the brake cleaner to get rid of any extra fluid around the area. Once clean, remount the wheels and lower the car.

     Well, there you have it - it's really not too difficult at all.  If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs.  If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one.  Your continued support directly affects the expansion and existence of this site and technical articles like this one.  As always, if you have any questions or comments about this helpful article, please drop us a line.

Comments and Suggestions:
Kikezon Comments: GREAT ARTICLE !
October 14, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts

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