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BMW E30 Rear Disc Brake Replacement

Pelican Technical Article:

BMW E30 Rear Disc Brake Replacement

Jared Fenton


3 hours3 hrs






Lug wrench, floor jack, two jack stands, two wheel chocks, safety glasses, torque wrench, set of metric Allen keys, Liquid Wrench, brake cleaner, large C-clamp, wires or strong bungee cords for hanging brake calipers, metric wrench set and metric socket set, torque wrench, safety glasses

Applicable Models:

BMW E30 3-Series (1984-93)

Parts Required:

Rear disc brake pads and turn rear brake rotors

Performance Gain:

Brakes that stop short, straight and turn with nary a squeak

Complementary Modification:

Replace the rear brake rotors

In this tech article we will discuss replacement of the rear brake pads on the E30 BMW. While this tech article is specific to the E30, it applies to most other BMW models with floating calipers as well.

I had begun to notice that my brakes had started to squeak a bit. Shortly afterwards, I noticed the "brake linings" light come on in the dash. This is a a visual system BMW uses to indicate that the brake pads will soon need replacement. As I did before with the front brakes, this article covers the replacement of the rear brakes.

I started by ordering up new brake pads and brake pad sensor from Pelican, of course and began the process. That said here's how it is done.

First, loosen the lug bolts but do not remove them. Just loosen them, then snug them up. Next, jack up the car in a safe manner.

Once the wheels are removed you will see the disc brake assembly. Look at the backside of the caliper. You'll see an electrical connection coming out of the right rear caliper. This is the wire harness for the rear brake wear sensor. Unplug this sensor where it plugs into the harness, as shown in the photo.

Now look at the rear calipers, you will notice two plastic grommets at the top and the bottom of the caliper. You will need to remove these in order to continue. Once you have them out, use an Allen wrench to remove the two bolts at the top and the bottom of the caliper. Once removed, the caliper should slide off.

Now, take a look at the old brake pads. You can see how worn they are from the pics. Compare these to the new pads. Notice the brake wear sensor on the old pads. This will give you a good idea of how the sensor works. Essentially when the pads wear down to a certain point, it wears away the outside cover of the sensor, eventually wearing it down enough to the point where the metal strip inside contacts the rotor, and completes the electrical circuit, and the light on the dash illuminates. We will be replacing these sensors as well.

The next step is to remove the brake rotors. You need to remove them in order to have them surfaced. Re-surfacing brake rotors is important. Failure to do so can cause the brakes to not seat properly or even overheat. Re-surfacing insures that the new pads will seat properly. Any decent auto parts shop can re-surface your brake rotors for usually around $5 a rotor.

Keep in mind, however that brake rotors, by law, can only be re-surfaced a certain amount of times before you exceed the amount of material that can be removed. This is done for safety reasons. If you have exceeded the amount of material that can be removed, you'll have to purchase new rotors.

In order to remove the brake rotors, remove the Allen head bolt that holds the rotor to the hub. You may have some trouble removing these without stripping the bolt, so I recommend that you soak the bolt in a good penetrant spray for a few hours prior to loosening the bolt. This will help prevent against stripped or damaged threads, and a potential nightmare that will send you screaming over the edge. (Ask me how I know this....)

The next step to remove the rotors is to remove the brake caliper bracket that sits on the back of the hub. You will notice two large bolts holding it to the hub. Remove these two bolts, and remove the caliper bracket. The brake rotor should now come free.

Once you have the brake rotors removed, take them to the auto parts store, machine shop, etc.. and have them re-surfaced. Obviously, take another car to the store, as you'll find your brakes don't work with the brake discs removed from the car.

Now is a good time to clean everything. You'll want to use a good quality brake cleaner to make sure that the calipers and surrounding parts are clean and free of dirt and grime. Grease on the brake discs can cause brake failure.

With the brake discs surfaced, you can now start re-installing the components. Put the surfaced rotors back on the hubs, and make sure to line up the holes, so that the brake disc hold-down Allen bolt will thread in. It's a good idea to put a dab of anti-seize compound on one side of the threads to prevent stripping the next time you remove the brake discs.

Now that the rotors are installed, it's time to compress the caliper pistons. You'll want to do this in order for the new brake pads to fit. As the old brake discs wear, the piston gradually comes more and more out of the caliper, making it impossible for the new pads to fit.

In order to compress the pistons, first remove the brake fluid reservoir cap, this will relieve the pressure on the system, and make it easier for you to push the pistons. Next, use a large C-clamp as shown in the photo, to slowly push the piston back into the caliper. The caliper pistons should slide back with a minimal amount of force.

Now, install the new brake wear sensor in place. Keep in mind that there is only one brake wear sensor on the right rear. The sensor simply clips onto the brake pad as shown in this photo.

Once the calipers are compressed, re-install the caliper bracket on the hub and make sure the bolts are tight. BMW recommends you torque them to 65 ft/lbs.

Next, place the new brake pads on the lower caliper mounting plate as shown.. When they are in place, carefully place the caliper over the pads. You may notice a bit of resistance in doing this because of the new springs that hold the new pads in place. Just use a little force to push the caliper in position, then install the two Allen head bolts and tighten them. Don't forget to put the plastic grommets back in place. These grommets prevent grime and dirt from building up on the bolts, which could eventually cause them to rust and sieze.

Once all this is done, re-check everything. You don't want to take chances with your brakes. Check and then double check that everything is tight.

Now you are ready to put the wheels back on. Once they are re-installed and tightened, take the car out and test the brakes. You should notice that they don't stop very well at first. This is normal. You'll need to seat the brake pads in order for them to work well. Simply drive the car cautiously for roughly 50 or so miles, and the brake pads will seat into the new rotors. It's also a good idea to pump the brake occasionally during this time to get the rotors hot and the pads seated quicker.

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:
okay Comments: This article would be better with pictures, like it claims.
September 1, 2015
  Followup from the Pelican Staff: I agree, photos would be helpful. If we get the chance to take the photos, we will post them. - Nick at Pelican Parts  
Lm Comments: Hello what brake fluid recomend for my 328 is 1998 ?
February 1, 2015
  Followup from the Pelican Staff: Dot 4 will work fine. ?command=show_part_page&please_wait=N&SUPERCAT_FLAG=Y&make=BMW&model=BE30§ion=BRKHYD&page=3&bookmark=8&part_number=81-22-0-142-155-M210 - Nick at Pelican Parts
lti Comments: On my 87 325i convertible
girling brakes in front ATE in the rear .
the 2 caliper anchor bolts were 7mm
September 16, 2014
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
Neil Comments: Hi guys
Just fitted new discs and pads x4 on my 1988 E30 325iC - bled the brakes too. All good, until my first proper drive out today. Returned home and my rear right brake was seriously hot - smoking in fact, and the surface of my Boschbrake pads appear to have almost frayed a little. The other three are fine. Any suggestions?
August 27, 2013
  Followup from the Pelican Staff: Sounds like you have to replace the right rear caliper. It sounds like it's sticking and applying the brakes even though you have took you foot off the brake pedal. You will probably want to replace the hose too. - Kerry at Pelican Parts  
toddnos Comments: what size is the allen or hex wrench needed to remove the calipers on a 1991 bmw e30
January 13, 2013
  Followup from the Pelican Staff: Typically BMW has used 6, 8 or 10 mm for their caliper bolts. Be careful since internal Allen head bolts can be easily stripped. - Nick at Pelican Parts  
Vegas Comments: Is it possible to have disc brakes in the rear of my E30 318i rather than drum brakes? If so how easy would it be to do this conversion? What kind of cost am I looking at and will I be losing anything by doing this?
April 25, 2012
  Followup from the Pelican Staff: We have no idea how much it would cost because we don't know what you are going to pay for used parts? It will involve taking the rear spindle and probably suspension arms out of a newer model than yours and installing them on your car. You may even have to change the whole subframe which believe it on not would be easier. You will also have to change the proportioning valve to direct less brake fluid to the rear so the rear wheels do not lock up under heavy braking. - Kerry at Pelican Parts  
ET Comments: I just wonder is it possible to put a set of E36 M3 rear brake system in my 93 E36 325i ? anything that I need to attention ? thanks!
November 29, 2011
  Followup from the Pelican Staff: It will be trial and error. You will need to replace the master cylinder, lines, etc. - Nick at Pelican Parts  
hash Comments: I have taken all the steps to take the rear rotor out but it seems as if the hand brake shoes holding the rotor back
could this be the case.
April 3, 2011
  Followup from the Pelican Staff: Yes, that could be the case. Make sure that the cable to the shoes is disconnected. Also, you might want to try backing out the adjuster screw - see the article on adjusting the e-brake shoes in our tech article sections. With the shoes off the inside of the brake disc, a big smack with a hammer should make them come off quite easily. - Wayne at Pelican Parts  
Mike Comments: Thanks! a'bfh' got them off. i really had to smack them though!
August 22, 2010
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
Mike Comments: i took out the allen on the rotor and removed the caliper completely, but the rotor seems attached to the hub and wont budge. what's up?
August 21, 2010
  Followup from the Pelican Staff: TGet a big rubber mallet and beat the heck out of it. You won't damage the car by smacking it with a rubber mallet. Smack really, really hard. I had a friend who was at my house doing a brake job and he couldn't get his rotors off either. Turned out he was too timid with the hammer - one big smack from me, and it fell right off. - Wayne at Pelican Parts  
The COB Comments: I'm about to do brakes on my '01 Z3. Can anyone tell me if the rear pad retaining clips are the same as the front?
August 18, 2010
  Followup from the Pelican Staff: I think they are the same, but you typically don't need to replace these when changing pads. - Wayne at Pelican Parts  
Baron Comments: Thanks. My sensors are identical except they don't fit that notch and also don't have that hump facing the disc, wrong sensors? Also my pads have springs where the sensor goes. is it ok to remove the spring from that one pad? Thanks again.
August 4, 2010
  Followup from the Pelican Staff: Hmm, I'm not there, so I can't tell for sure, but I would look at how the old pads and sensors were setup and then install them in the exact same manner. Make sure that the pads and sensors match exactly the ones that you took off the car, and then you should be okay. - Wayne at Pelican Parts  
Baron Comments: Hey folks, I don't know where on the front caliper to put the brake pad wear sensor 1983 318i and my haynes manual doesn't say or show a photo. anybody got a picture of where the sensor goes? even written instructions would be appreciated.
August 2, 2010
  Followup from the Pelican Staff: Hi there. Check out the photos in this article here: - Wayne at Pelican Parts  
KG Comments: You need to apply brake compound to the back of the pads before installing them
July 14, 2010
  Followup from the Pelican Staff: Thanks for the additional Info. We appreciate it.
- Nick at Pelican Parts
country Comments: I changed both back rotors and pads on my 325i but they still squeak whenevr I press on the brakes...any suggestion as to what is going wrong?
January 12, 2010
  Followup from the Pelican Staff: Could it be the front brakes? If the brake parts are new they shouldn't squeak. - Nick at Pelican Parts  

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Page last updated: Tue 3/20/2018 02:03:28 AM