BMW E36/E46
Brake Replacement DIY

A DIY brake job is one of the easiest ways to save LOTS of money on maintenance

BMW Balance

Brakes are just one of the ways that contribute to the "balance" of BMW performance. I mean, any idiot can put a big engine in their car and make it go fast in a straight line -- but ask the vehicle to take a turn just as quickly and you need a great suspension to keep up with it. Similarly, once you get a vehicle up to high speed, you need a reliable means to bring it to a stop -- in a hurry if necessary. To borrow a well-worn marketing slogan -- power is nothing without control. BMW brakes give you that control -- provided you replace them when required.

This article aims to communicate the insights gathered while doing my first DIY brake job on my E36. The E46 shares the same basic platform as the E36 (except in the case of my 330, the brakes are just a bit bigger), so the procedures should apply to either model. However, I still recommend you reference a copy of the Bentley repair manual for your specific vehicle to make sure you do the right thing.

Prerequisites

BMW recommends brake fluid be flushed every two years. Every year would be better. If you haven't flushed your fluid in that time and you're about to replace the brakes, it's a good idea to do that while the wheels are off. If you choose to do this you may find my Brake Fluid Flush DIY article helpful.

To perform a brake job, you should have ready access to the following:

Rubber gloves
Brake cleaner (aerosol)
A parts washer or other makeshift wash basin
Permatex Anti-Seize in brush top can (silver is fine, copper is better)
Plastilube high temperature grease (essential -- don't do a BMW brake job without it)
Floor jack (2 ton rating or higher)
2 Jack stands (3 ton rating or higher) on lowest height setting
16mm standard depth socket for caliper carrier bracket
17mm deep socket to remove wheel lug bolts
6mm allen (hex) head socket for rotor retaining screw
7mm allen (hex) head socket for caliper guide bolts
1 or 2 flat blade screwdrivers to aid in removing the retaining clip
24" 1/2" drive breaker bar for removing lug bolts and caliper bracket
Torque wrench(es) capable of 22 and 81 ft*lbs.
One large ("irrigation-type") syringe (optional; depends on the level of fluid in your brake reservoir).
WD-40 (optional, depending on whether the rotors come off the car easily or not)
Appropriate rotors and pads. Include wear sensors if the brake lining warning has illuminated (check realoem.com)
About 2.5 hours per axle if this is your first time, less if you know what you're doing. Book labor is 2 hours per axle.

When you see the red brake wear indicator illuminate, it's time for a brake job! BMW recommends driving for no more than 1000 miles after this illuminates, but due to individual driving style it's not a hard limitation.	The most important thing you can do is read the directions for the specific brake pads you install. These instructions are for the BMW OE units and they explicitly prohibit any "bedding-in" of the pads after installation.	E36 vehicles come with jack pads but they do have a tendency to fall off as the plastic dries out so some people don't realize the car is intended to have them. Pick up a couple if your car doesn't have them installed.
Note that the pads come as a set for each axle. Front pads on the right, rear on the left. Order quantity one (box) for each axle.	Here is a closeup of how the brake wear sensor mates with the inner pad. When the pad wears to the prescribed limit and rubs through the little nub on the sensor, the sensor signals the DME to illuminate the brake pad wear indicator.	Just a picture of the front vented rotors. Contrary to all the marketing BS today, plain rotors like this offer tremendous performance. There is no need for slotted / drilled rotors on a street car.
A closeup of the part numbers for the front rotors for reference. Unlike the pads, these are sold per side, so you'll need quantity two per axle to get the job done.	This is BMW's guide bushing "repair kit". Each package contains two guide bushings, two caps, and an extra cap with a white retaining clip for another application. One package is needed per caliper. Best to replace the bushings every three brake jobs or 100K miles.	The infamous rotor retaining screw. These have a tendency to strip because few people put anti-seize on the threads. While you can reuse the existing screws if they are removed undamaged, you should always have at least one spare per rotor you intend to work on.

Front Brakes

Take a look at the instructions that come with your brake pads. See the highlights for a scanned copy of the instructions that accompanied my BMW OE pads. You may note some statements in these instructions conflict with BMW recommendations. In those cases, always follow BMW's recommendations, since these pads are but one part of a complete system and only the system integrator (BMW) can know what's best for the entire system.
If you don't have air tools at your disposal, break the wheel bolts loose with a breaker bar. Do not remove them. The goal here is to leverage the weight of the vehicle to keep the wheels from turning as you hang on the bar.
Jack up the front of the vehicle and support it on jack stands. I won't detail how to do that here. If you don't know how to jack up a BMW, STOP RIGHT HERE and learn how before your life really depends on it. Free advice that might just save your life: NEVER RELY ON A JACK ALONE TO SUPPORT YOUR VEHICLE!
LOOSEN (but do not remove) the rotor retaining screw on each side. If the screws have been on there a long time, they may be difficult to remove, and unless you can get them off (or feel comfortable drilling them out) there's no point in continuing with this work. Fortunately, mine loosened with a couple of well supported tugs of the ratchet. I say "supported" because the bolts are made of a relatively soft metal and will strip if you get lazy and don't support the wrench and apply the torque properly.
Start on the right side. You can start on either side of the vehicle, but if you've never done a BMW brake job before, I recommend you start on the RIGHT side (as viewed from the driver's seat) first so you don't need to concern yourself with the brake pad wear sensor. It's not that it's a big deal, but it's one less thing to worry about the first time around. Put your key in the ignition and turn it to position 1 to free the steering lock and turn the wheel to the left until it stops. Turn the key back to position 0 (off) so you don't drain your battery. This will give you better access to the caliper on the right side of the vehicle.
Remove the retaining clip. It seems like such a simple thing, but the clip does its job and doesn't want to leave the caliper. The trick is to take a small flat-blade screwdriver and approach each hole in the caliper from the center of the wheel, wedge the tip in and under the clip as close to the hole as possible and pry it up. An additional flat blade screwdriver may come in handy keeping one side of the clip out while you pry the other side.
Remove the protective caps over the caliper guide bolts and then remove the guide bolts. See the Highlights. When you remove these caps, the point is not to grab the "shaft" but the very edge of the cap. The shaft is a flexible rubber sleeve and the cap fits into the end of that. I was able to pry the cap out with gloved fingers, but a small screwdriver may help. With the cap removed, remove the guide bolts. These are only torqued to 22 ft*lbs, so it shouldn't take much effort to remove them unless someone overtorqued them during the last brake job.
Remove the caliper. Once the guide bolts are removed, you'd tend to think the caliper would just pull off, but if the rotors are worn, you'll have to get the pads past the ridge on the outer circumference that forms as the rotor wears because the pads are slightly smaller than the rotors. The problem is the ridge can prevent the inboard pad from pulling away from the rotor, and since the inboard pad is connected to the caliper piston the caliper won't move unless you can compress the piston as required. You can use a c-clamp for this, but note that if you intend to reuse the rotor, be sure to put some kind of shim (wood or otherwise) between the clamp and the rotor face, or else you may damage the rotor surface.
Do yourself a favor at this point and take a look around. Note of how the outer pad sits in the carrier, how the inner pad is fastened to the piston, and the size of the piston. The areas of the pad backing plate that contact the face of the piston and the carrier will need to be lubricated with Plastilube high temperature grease during reassembly. Speaking of pads, the highlights show what remains of the front linings when the brake wear indicator lamp illuminates.
Push the piston back into the caliper. With the caliper removed and the inner pad still connected to the piston, use your C-clamp or other compression tool to push the piston back into the caliper. This is required to get the caliper to fit over the new, thicker pads. On my first time around, I used a compression clamp like woodworkers use, but based on that experience I can tell you that the c-clamp is the way to go simply because it takes a good amount of force to get the piston to fully retract. It's pretty amazing how far out of the caliper body the piston extends. This is one of the reasons why pushing the pistons back into the caliper causes the fluid level in the reservoir to rise so much (about 1/4" per axle). And speaking of reservoir level, here's a tip. If you're bleeding the brakes prior to the brake job (always a wise choice), fill the reservoir only to the minimum mark. That way when you push all four pistons in you'll wind up with the level at or near the maximum and you won't risk overflowing it. Of course, you should always check the reservoir after compressing each piston anyway just to make sure you're not going to make a mess. Brake fluid is corrosive and will gladly remove paint from any surface it touches.
With the caliper removed and supported, remove the caliper carrier from the steering knuckle by loosening the two 16mm bolts. Note that these are torqued to 81 ft*lbs, and may very well require a breaker bar or air tools to remove. My 24" breaker bar made very quick and easy work of this. With the bracket removed, it's a good idea (though certainly not required) at this point to clean up the carrier with some brake cleaner. I took the part over to a plastic storage tub I bought for this purpose and went to work. I got a lot of gunk off of it including a lot of old grease and brake dust.
Remove the rotor. Now the fun part, where we get to look like a pro mechanic. Grab the nearest metal hammer, baby sledge, or (in my case) a dead blow hammer, and hit the rotor once at the 3 o'clock position, then at the 9 o'clock, followed by six, and 12. If you're lucky, the rotor will brake away from the hub after the six o-clock hit. This is the way the BMW techs do it, and it works. Note that using anything but a dead-blow hammer will likely damage the rotor and make it unsuitable for reuse.

If you've gotten this far, congrats. You're half way there. Let's start the reassembly process.

Clean up the hub. Now that the rotor is removed, you're likely to find a lot of old anti-seize compound on the hub. I used brake cleaner combined with a Scotch-Brite pad to remove that and generally clean up the face of the hub and the threads of each bolt hole. Again, this isn't strictly necessary. Wiping it with a towel would probably be sufficient, but I like to be thorough. Once the hub is cleaned, apply a very thin coat of anti-seize to the face of the hub. You don't want to go overboard here...this is simply to aid removal of the rotor at some future date.
Install the new rotor. While grabbing the rotor via the center hole clean both friction surfaces using some break cleaner and paper towels. This will remove any preservative oils or grease and allow the pads to bed in properly. From this point on, try not to touch the friction surface. If you do, simply clean the surface again before continuing. Put a touch of anti-seize on the threads of the rotor retaining bolt and thread it through the rotor into the hub. The torque spec on this screw is 12 ft*lbs, but I didn't bother to use a torque wrench for it. I tightened it until the rotor was fully seated and the bolt head is recessed relative to the face of the rotor hub. The bolt is only there to aid in manufacturing and to retain the rotor if the wheel is removed. As you've probably figured out by now, after a while the rotor binds itself to the hub (yes, even with anti-seize applied), so the bolt serves little purpose in the real world. Whatever you do, do NOT overtorque it or forget to apply anti-seize, or you'll hate life when it comes time to do the next brake job.
Clean the carrier bracket in the wash basin and pay particular attention to the area in which the pad backing plates slide in the carrier. Use a small toothbrush to remove the old bits of grease and pad material before shooting them one last time with brake cleaner and letting them dry. Reinstall the caliper carrier bracket and torque the bolts to 81 ft*lbs, and remember that for the most accurate torque settings, the torque wrench must be "moving" when the click occurs to achieve an accurate result. Do not apply anti-seize to the threads. They're a dry fit.
Apply Plastilube high temperature grease on the lubrication points of the pads. Start with the outer pad first and then insert it into carrier. When ready to install the inner pad, in addition to the lubrication points on the corners, put a bit of grease around the clips in a circular pattern that will contact the caliper piston when installed. Although the pads come with an anti-squeal shim bonded to the inboard side of the backing plate, this grease helps prevent the pad from vibrating against the piston at high frequency and generating that lovely, comforting sound we know as "squealing brakes".
Reinstall the caliper. If you've fully retracted the piston, it should fit over the pads and rotor very easily. Before inserting the guide pins clean them with some brake cleaner and a scotch-brite pad. Do not make the common mistake of applying grease to the guide bolts or anti-seize to the threads. They're a dry fit, and with good reason. If you grease the pins, the stock rubber bushings will swell and cause the caliper to hang up. The result will be excessive outer pad wear. And if you use anti-seize on the threads, you will likely torque them beyond the required 22 ft*lbs. And speaking of torque, one of the pictures demonstrates one of the advantages of buying a torque wrench with a pivoting head. I took advantage of the extra clearance as I tightened the bolts prior to final torque. Just as the bolt started to firm up, I straightened the wrench so I didn't need to do any math to compensate for the offset.
Reinstall the guide bolt caps and the retaining clip.
Take a moment to pat yourself on the back. One down, three more wheels to go.

Repeat the above for the left wheel. The procedure is the same except that you'll need to contend with the brake wear sensor. The connection between the vehicle's wiring and the sensor wiring is contained within a small plastic box at the top of the wheel well. Simply open the door on the box and pull the connector out of the box and disconnect it. You needn't disconnect the sensor from the pad if you're tossing the pads (as I expect you are...otherwise why are you doing this?)

Front Brake Procedure Highlights

A picture looking at the caliper with the wheel turned for better access. The guide bushing caps shown just to the top and bottom of the round center of the caliper must be removed to gain access to the guide bolts.	Here you can follow the wiring of the brake wear sensor from the inner brake pad to the junction box that also houses the connection for the ABS hall-effect sensor used to determine wheel speed.	The junction box is shown open here. It's pretty obvious when you follow the wires, but the wear sensor connector is on the right. Right after this picture was taken, I blew all the dirt and crud out of the box with compressed air.
This picture was taken after installation of the new guide bushings and reassembly of the carrier bracket and caliper. Note that the guide bolts require a relatively light torque, while the carrier bolts (one of which is shown just below the bushing) requires a much higher torque.	A four inch C-clamp easily returns the piston to the caliper bore. I used a piece of cardboard to protect the old brake pad just in case something went wrong and I had to reuse it (always think ahead and don't box yourself into a corner while doing work like this!)	Condition of the inner and outer pads of the left and right front wheel, respectively about 500 miles past the point at which the wear sensor tripped. Definitely still usable for the street, but they won't let you on the track with pads like that...and for good reason.
Retorquing the guide bolts to 22 ft*lbs. I'm taking advantage of the pivot feature only to bring the bolts close to final torque. The final torque is applied with the wrench handle straight, or else a simple calculation must be made to adjust the torque value.	A nice closeup of the new brakes installed. Check out how thick those new pads are, and also take note how the wear sensor is installed on the pad. The little nub on the sensor must face the rotor.	Just before installing the retaining clip. Take a close look at the application of high temperature grease on the outer pad. The goal is to coat the ears and the area of the backing plate that comes into contact with the "ears" of the caliper.

Rear Brakes

The rear brakes follow the same procedure as well except the carrier bracket is torqued to only 50 ft*lbs and you can expect the brake wear sensor to be on the right rear. Also, if your parking brake needs adjustment, now's the time to do it. Mine was fine because I never use it, so I didn't bother with it.

The only snag I had with the entire process came when I tried to remove the right rear rotor. I pounded on the rotor several times but it didn't budge. I then carefully applied a bit of WD-40 to each threaded lug bolt hole and waited a while before rotating the hub and repeating the process. The goal here was not to do a full blast trigger application of WD-40 because the overspray might contaminate the parking brakes. Rather, I used the red tube that comes with the bottle to apply the fluid directly to the seam between the hub and rotor. Ten minutes later, I grabbed the rotor with my hands and it came off. I followed up by cleaning the hub with brake cleaner before applying a fresh coat of anti-seize and installing the new rotor.

Incidentally, the left rear rotor came off very easily, but that was likely because it had been removed recently to replace the wheel bearing. Rear rotors are more likely to get stuck simply because they're typically replaced half as often as the fronts. Remember to apply anti-seize to the hub!

Rear Brake Procedure Highlights

It's certainly nice to have a garage to do the work, but it's not required. What IS required is a stable jacking surface, which explains why I do everything inside.	This is what the rear rotor looks like with the wheel removed. Note all the dissimilar metal corrosion and rust on the rotor hat. If you don't put anti-seize on the face of the hat, the wheels will practically bond to the rotor.	Here I've removed the caliper. Take a peak at the upper right of the picture. The little cylindrical component with teeth on the end is the parking brake adjustment, which is normally accessible from the hole in the rotor / hub.
Taken just after I applied some WD-40 to the lug bolt holes in the rotor to free it from the hub. Note the slight contamination of the parking brake pads. Be careful with the WD-40 so you don't drench the pads with the stuff.	Just a perspective shot of the new rear pad and rotor. This is the left rear, which does not have a wear sensor attached to the pad. As the rear brakes do only about 30% of the work, these will easily last 80K miles or more, depending on driving style.	While I typically replace the rotors with every set of pads for various reasons, they MUST be replaced if they are below the minimum thickness stamped on the rotor hub. This rotor's minimum is 8.4mm.

Test Drive and Break-In

When you're ready to take the car for a test drive, hop in and press the brake pedal several times. The first few times you press the pedal it will feel soft, but will firm up nicely when the pistons are once again pushed out of the calipers and close up the gap between the pads and the rotor. If the pedal continues to feel soft, you may have some air in the system that should be bled before you drive the vehicle. This is much more likely if you have bled the brakes. The average brake job will not introduce any air into the system.

The procedure to break in the brakes varies among pad manufacturer. The instructions that come with the BMW pads strongly advise against aggressive braking or "dragging" the brakes to speed up the bedding process for the first 125 miles. So, contrary to all that you've heard, you don't do anything special to bed in BMW OE brake pads. Just take off slowly, test the brakes to make sure the car will stop, and then go for a normal drive at reasonable (residential) speeds, using the brakes only as required, letting them cool down between uses. The instructions also point out that braking performance will be lower than normal until the pads are fully seasoned. For what it's worth, my technician always told me to take it easy on the brakes for the first 250 miles.

If you replaced the rear rotors and/or the parking brake pads, you'll need to conduct a special procedure to break-in the parking brake, or it won't function as expected. Slow to 25 MPH, depress and hold the parking brake release button, and apply upward pressure to apply the brake. Initially, you will likely find that the brake has little effect, but within a few seconds it should firm up. Apply pressure until the car slows noticeably, or no more than 1200 feet. If after conducting this procedure the brake does not grab while stationary, you will need to adjust the parking brake. I have not conducted the adjustment procedure so I won't document it here, but it is available online.

Conclusion

Most people seem to get 30K out of a set of front brakes and 60K out of the rears. These intervals are highly dependent upon driving style and whether you have equipped the car with larger wheels and tires.

There is no reason to do brakes before the brake lining indicator illuminates, unless you plan to take the car to the track, are planning a long trip, or there is something else wrong with them.

I can't believe I paid other people to do this job for so long. Ask me to rebuild a transmission, and I'll be the first one to bend over and give the dealership my credit card, but with the exception of getting the pads around the ridge on the rotor, I can tell you with confidence that BMW brakes are easy to replace. Of course, like most automotive work it can get a bit messy (be ready to sacrifice an old pair of jeans and a t-shirt to the task), but I think the reward of learning something new, having the knowledge that the job was done right, and saving big bucks on labor is worth the inconvenience.

BMW E36/E46 Brake Replacement DIY