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This job takes about 30 minutes of actual work (once you have the car off the ground and wheels off). This is pretty easy but requires attention and a lot of soap afterwards. If you are not comfortable or competent with working on your brakes, leave it to a professional!
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  • Your front wheels must be off the ground to change brake pads. See Getting car up on jack stands DIY.
  • I assume that your car is already up on a lift or on jack stands and the wheels are off.

Step 1: Getting the required items together

This job requires:
  • A lift or some other method of getting the front wheels off the ground.
  • 7mm Allen Head Socket
  • Socket Wrench
  • Torque wrench (recommended)
  • 6" or larger "C" clamp
  • Large flat screwdriver
  • Small flat screwdriver
  • Disk brake anti-squeal compound
  • Brake cleaner
  • Something to rest calipers on (Cardboard box, spare jack stand, etc - something about as tall as bottom of the caliper).
  • A BMW M3 (E46).
  • About 30 minutes of free time.

M3 Front Disk Brake

Step 2: Start on Driver's Side - Free Things Up

  • Note: Pop the hood (no this has nothing to do with the caliper but you will need to get in there in a bit and might as well do it before you're covered with brake dust and grease).
  • You will need to pop the brake line out of its retaining bracket (bottom grommet) (see image).
  • You will also need to pop the brake wear sensor wire out of the same bracket (top most grommet) (see image).
  • Just use your fingers to push the grommets out of the bracket. Push away from the strut, toward the center of the car.

Brake Line/Wear Sensor Wire Retaining Bracket

Line/Sensor Wire Released From Retaining Bracket

Step 3: Freeing Things Up Part II

  • There is a small plastic clip that clips into a hole toward the lower end of the strut (on its back side) that harnesses the ABS wire and the wear sensor wire - gently pull it out. (see first image)
  • There is one more bracket that holds the wear sensor wire in place - its on body of the car, right by wear the brake line goes into the engine compartment - just follow wire to the bracket and pop the grommet out of the bracket. (see second image).
  • NOTE: The wear sensor is only on the driver's side on the front brakes. You still have to release the brake line on the passenger side just like above but you will not have to worry about the wear sensor at all on the front passenger side.

Retaining Clip (view from behind the strut)

Upper Bracket

Step 4: Removing the Brake Pad Anti-Rattle Clip

  • Use your flat head screwdriver to pry under one of the arms of the clip and to push the arm away from the rotor toward yourself (see image).
  • This can take a little doing and may require a little imagination (some claim this can be done with your hands - I like my fingers in one piece).
  • When the clip releases it may pop off with a little zest do watch your face, etc. and don't get blinded by a flying anti-rattle clip.

Anti-Rattle Clip

Anti-Rattle Clip Removed

Step 5: Taking Yet More Stuff Off

  • A short and simple step - there are two plastic caps that protect the bolts used to retain the calipers.
  • These are located on the back side of the caliper (see image) - just pull them out with your fingers.

Plastic Caps

7mm Retaining Bolts Exposed

Step 6: Giving Things a Squeeze (Compressing the Piston)

  • You need to compress the brake piston. This can be done on the car (easier) or once the caliper is off the car (harder).
  • There is a special tool to do this via BMW but since you don't have one (I'm willing to bet on that) we will use our own special tool - a garden variety 6" or larger "C" clamp.
  • Open the clamp and place the end on the back of the brake piston housing (see second image).
  • Place the other end on the outside brake pad (see first image).
  • Gently compress till you meet resistance. Depending on the condition of you brake pads you will see the outside brake pad move in about a 1/4" from its starting position.
  • CAUTION: Watch brake fluid level in the brake fluid reservoir as you compress the piston. You're compressing the system with the clamp and forcing fluid out of the caliper - make sure the fluid reservoir does not over flow - there is nothing worse than brake fluid for paint - if the reservoir gets close to overflowing, use a turkey baster, etc. to siphon off a little fluid. Do not siphon off any more than required to keep it from overflowing. Make sure to replace what ever fluid you siphon off with NEW fluid after you're done.
  • Remove the clamp.

Clamp Location From Front

Clamp Location From Back

Clamp Location From Rear

Brake Fluid Reservoir

Step 7: Preparing to Remove the Caliper

  • You will need something to set the caliper on after its released or it will hang down by the brake line - not the world's brightest idea. A cardboard box about the same height as the caliper works well.
  • Using the 7mm Allen bit, loosen the two caliper retaining bolts. These are both accessed from the back of the caliper (these are the bolts that were covered by the plastic caps you removed in Step 5).
  • You don't have to pull these all the way out but its probably easier just to do so.

All the Stuff Taken Off So Far

Step 8: Removing the Caliper

  • Carefully pull the caliper directly back toward the back of the car - mind the fact that the wear sensor and brake line are still attached to the unit!
  • Once released, set the caliper on what ever you are using for a support.
  • Your outside brake pad will stay on the brake pad carrier, just lift it out and set it aside (don't toss it yet!).

Pulling Caliper Off

Removed Caliper

Step 9: Releasing the Inboard Pad

  • The inboard brake pad is clipped into the piston (see image).
  • Gently push the pad toward the center of the caliper to release - keep in mind that the wear sensor is still attached.

Releasing the Inboard Pad

Step 10: Removing the Wear Sensor

  • The wear sensor sits at the top end of the inboard driver's side brake pad.
  • Use a small screw driver to gently pop it upwards and out of the pad's recess.
  • Set the inboard pad aside (don't toss it yet!).

Brake Wear Sensor

Step 11: Cleaning Up

  • Use brake cleaner to thoroughly clean both the runners on brake pad retaining bracket and the caliper (particularly the piston and the outboard arms).
  • Wipe clean.

Brake Pad Carrier Bracket


Step 12: Preparing the New Pads for Installation

  • Examine your old pads and note the areas of the pad that contact the piston and the caliper.
  • Apply a liberal amount of anti-squeal compound to the new pads in the area where they will contact the caliper and piston (use the old pads as a template).
  • Too much is better than too little here and this is a place where its OK to be messy.
  • Don't worry about being able to see the anti-squeal compound once the brakes are installed - after a couple of days, whatever color the compound you used will be turned into a nice shade of brake pad dust gray.

Inboard Pads
Old Pad, top
New Pad, bottom

New Outboard Pad

Step 13: Installing the Inboard Brake Pad

  • Set the new, anti-squeal coated inboard brake pad into the piston inside the caliper (see image).
  • The clip on the back of the inboard pad will snap into the piston itself and snap in securely.

New Inboard Pad in Caliper

Step 14: Installing the Outboard Brake Pad

  • Set the new, anti-squeal coated outboard brake pad into the brake pad carrier (see image).
  • The pad will just loosely sit in place until the caliper is installed.

New Outboard Pad in Carrier

Step 15: Installing the Caliper

  • Slide the caliper back on making sure that the outboard pad stays on the brake pad carrier.
  • Reinstall the two retaining blots to hold the caliper in place and torque them down to 22 ft lbs.
  • Reinstall the two plastic caps you removed in Step 5. (they just pop back in by hand)

Step 16: Reinstall the Brake Wear Sensor

  • The brake wear sensor will snap back into the inboard brake pad.
  • You will be able to see the recess in the inboard pad through the back of the caliper (see image)
  • Gently snap the sensor back in and check to make sure its seated.

Brake Wear Sensor

Step 17: Reinstall the Anti-Rattle Clip

  • The anti-rattle clip just snaps back on the caliper.
  • Slide the clip in from the front of the caliper until it snaps back into place.

Anti-Rattle Clip In Place

Step 18: Finishing Up

  • You're almost done - just need to secure the brake wear sensor wire and the brake line and then you're all set.
  • Reverse Steps 2 & 3 to secure the wire and line.
  • Reinstall the wheel and torque the lugs to 88 ft lbs.
  • Repeat for passenger side - you will be skipping everything to do with the brake wear sensor on the passenger side since there isn't one there.

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