05-19-2009, 09:33 AM
Drives: '09 135i
Join Date: Sep 2008
DIY - Brake Pad Replacement
**Disclaimer - I am a novice, amateur mechanic. The DIY below is based solely on my first experience with changing the brake pads on the 135**
This is a basic DIY for changing the brake pads on the 135. Here is the DIY in 2 parts. The pictures are from the Edmunds.com suspension walk-around as I forgot to bring my camera with me.
*With the car lifted (jack stands, lift, etc) and wheels removed. Tools required are highlighted in red.
Rear Pads (simple):
The rear pads are easy because you don’t have to remove the calipers.
1. Open the brake fluid reservoir under the hood.
2. With you hands on the weights, pull/squeeze the brake pads away from each other and away from the rotor to give yourself more room to work with.
3. Using either a very small screwdriver or a punch, hammer out the retaining pins from the outside of the caliper towards the inside. All you have to do is get them past the initial notch and they should pull right out.
Note that there is a retaining spring that pushes against these pins and against the pads. You may have to push the spring back with your finger in order to remove the pins completely. Once one pin is removed, you will be able to remove the spring (or it will fall out) and easily remove the other pin.
4. The pads will now pull right out of the caliper.
5. The right rear brake set has a pad wear sensor (the left rear does not) on the inside brake pad. To remove the sensor, just pull it straight out of the pad. No tools are necessary. The pads that I used (Carbotech AX6) did not have cut-outs for the sensor, so I just taped the sensor back over itself with electrical tape, and made sure it was behind the caliper and out of the way of the wheel.
6. Backing Plates: All of the stock pads on the 135 have very thin, metal shims/backing plates on them. I believe that these are used to hold the pad in place in the caliper. Both the Hawk and Carbotech aftermarket pads were modeled after the stock pads including these plates, therefore, the aftermarket pads are actually thicker than the stock pads. If you put the stock backing plates onto the aftermarket pads they will be too thick to fit into the calipers. EDIT: Hawk and other have since produced correctly sized pads which will accept the stock backing plates.
I mention this, because there is a consequence to not putting the backing plates on the aftermarket pads (see end of post).
7. Now you can put the replacement pads back into the caliper and reverse the steps you took to get the stock pads out. Push the pins through from the inside of the caliper to the outside (opposite direction from removal). Note that you will have to use that punch again to get the retaining pins fully back into their original position. Make sure that they make it all the way through the caliper and stick out as shown in the pictures.
Last edited by Ruffan; 04-14-2011 at 12:15 PM.