How To Install Brake Pads or Rotors on an E36 BMW
If you're a first-timer to this procedure, consider doing one wheel at a time from start to finish. That way, if you forget how things go back together you can use the "other side" for reference. Tools or critical dimensions of parts are marked in red.
1. Siphon some (most) of the brake fluid out of the reservoir to prevent overflow.
2. Jack up the car and place is securely on jack stands. Remove the wheels.
3. Remove the spring clips that keep tension on the pads. The flat ends of the spring rest of flat "landings" on the caliper while two retaining tabs (one with one tooth and one with two teeth) closer to the center of the spring fit into two holes in the caliper. The spring can be removed either by pulling with pliers in the center or using a flat bladed screwdriver to lever out the tab with only one tooth from the caliper. I find the screwdriver method easiest.
4. Remove the two plastic dust covers that fit flush over the end of the caliper guide pins. (Located on the back of the caliper.)
5. Using a 7mm Allen wrench or socket, loosen the two caliper guide pins (they do not need to be completely removed).
6. Before removing the caliper, push the piston back into the caliper . You can do this by gently inserting a large screwdriver or pry bar between the pads and rotor and applying steady, even pressure prying them apart. Keep repositioning the pry bar and applying pressure until the piston stops moving.
Alternate Methods: If you've got really strong hands and are worried about damage to the pads or rotors, this can be done without a pry bar by simply twisting the caliper back and forth. You can also push the piston back removing the caliper using a large pair of slip-joint pliers (or special tool), but we've found the "pry bar" method to be the quickest and easiest.
7. Remove the caliper, but do not let it hang by the brake line! You can briefly rest it atop the brake rotor or hang it by a coat hanger from the spring or strut if you cannot reinstall it immediately.
8. Check the fluid in the reservoir again and remove more if necessary to prevent overflow when you push the next piston in.
9. Carefully remove the pad wear
sensor (left front and right rear only) with needle nose pliers and slide the pads out of the caliper.
Steps 10-13 apply only to rotor replacement.
10. Using a 16mm socket, remove two caliper bracket bolts and remove the caliper mounting bracket.
11. Carefully remove rotor set screw. These 6mm Allen head set screws can be difficult to remove. A hand impact driver is a big help in loosening the screw, but be sure the Allen wrench seats fully into the set screw or it will strip. Do not use an air impact gun or the screw may break.
12. Replace the rotor and replace the set screw. (Be sure to clean any cosmoline from the rotor before installing.)
13. Reinstall the caliper mounting bracket and the two 16mm bolts.
Note: If you choose to use an anti-squeal compound on the replacement pads, apply a thin coat only to the surface that mates to the caliper and allow it to fully set up before installing (24 hours isn't too long).
14. If your inboard replacement pads have OEM-style clips to hold them to the piston, install like the original pad and hang the outboard pad on the caliper bracket. If no clips are present, hang both inboard and outboard pads on the bracket.
15. Slip the caliper over the pads.
16. Reinstall the caliper guide pins and replace the dust covers.
17. Replace the tension spring.
18. Replace the wheel and torque the lug bolts.
19. Pump the brake pedal several times (until firm) before driving.
20. Refill the brake fluid reservoir if necessary to proper level.
Be sure to follow pad manufacturer's instructions for proper bed-in procedures. You can greatly prolong pad and rotor life at the track if you do not aggressively use new race pads and new rotors simultaneously until they've both been "seasoned."