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Brake Pads Replacement
 
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Pelican Technical Article:

Brake Pads Replacement

Nick Czerula

Time:

2 hours2 hrs

Tab:

$100

Talent:

***

Tools:

7mm Allen bit, flathead screwdriver, brake piston compressor, set of sockets

Applicable Models:

BMW Z3 (1996-02)

Parts Required:

Front or rear brake pads, brake pad wear sensors, brake fluid, brake cleaner

Hot Tip:

Stay clear of brake dust

Performance Gain:

Proper brake function

Complementary Modification:

Flush brake fluid. Replace brake rotors

BMW Z3 service brakes consist of hydraulic brake calipers and rotors, one at each wheel. When the brake pedal is pressed, brake fluid is forced out of the brake master cylinder and through the brake lines to each brake caliper. Pistons in the calipers push out and clamp brake pads against the brake rotors (or discs), thus slowing down the vehicle. A vacuum assisted brake booster multiplies the braking force exerted by the driver at the brake pedal.  

The parking or emergency brake uses an entirely separate braking system. A pair of mechanically operated cables attached to the parking brake handle actuates the parking brake shoes inside the rear wheel drums (which are integral with the rear brake rotors). I cover procedures for parking brake cable adjustment and brake shoe replacement in separate tech articles.

The brake pad wear warning system consists of electrical contacts installed in small cutouts in the left front and right rear brake pads. When brake pads wear down to the point that the tip of the contact touches the metal of the brake rotor, a warning light is illuminated on the dashboard. This usually happens when the brake pads are 2 to 3 mm thick (about 1/8 in). Usually, by the time the brake pad warning light illuminates, the driver becomes aware of the problem, and time is found for brake pad replacement. Friction from the brake rotor has worn the top of the wear sensor down so that a new sensor is necessary. In order to avoid the expense of purchasing new brake pad wear sensors, check your brake pads every time you service your BMW Z3 and replace them as soon as they reach 3 mm thickness. As the wear sensor is only located on one brake pad per axle, 3 brake pads on each axle are not monitored by the warning system. This is why periodic inspections are required. 

When replacing your brake pads, always replace both sides of the axle at a time and have a new brake pad wear sensor handy. Even though the sensor may be reused, they become brittle and do not always fit tightly into new pads when reused. 

In this article, I will show you how to replace brake pads on the front axle of your vehicle. Replacing the rear brake pads is similar.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches. 

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability. 

Our vehicle may vary slightly from yours as models do change and evolve, as they grow older. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

With the vehicle on the ground, loosen each wheel stud about 1/2 turn. This will help with removing them once the vehicle is jacked up.

Lift and support axle of vehicle you are replacing brake pads on. See our tech article on jacking up your vehicle.

Remove the wheels on the axle you are replacing brake pads on.

Using a flathead screwdriver, remove brake caliper anti-rattle spring (green arrow) by prying out while securing with hand.
Figure 1

Using a flathead screwdriver, remove brake caliper anti-rattle spring (green arrow) by prying out while securing with hand. The spring can pop off and go flying, be sure to hold it steady.

Open the brake caliper bleeder cover and remove the pad wear sensor (green arrow) wire from the mount.
Figure 2

Open the brake caliper bleeder cover and remove the pad wear sensor (green arrow) wire from the mount.

Pull brake pad wear sensor (green arrow) out of brake pad out of left side brake pad.
Figure 3

Pull brake pad wear sensor (green arrow) out of brake pad out of left side brake pad. Be very careful as sensor tends to break when removed. I like to use a pair of needle nose pliers to pull sensor out.

Using a flathead screwdriver, slowly press brake caliper piston in.
Figure 4

Using a flathead screwdriver, slowly press brake caliper piston in. This allows brake caliper to be pulled off brake rotor easily. I like to pry between the outer brake pad and brake rotor. This way there is less chance of damaging the caliper piston. Forcing the piston back into the caliper will cause the brake fluid in the reservoir to rise. Be prepared to remove some fluid.

Remove rubber plugs from brake caliper mounting fasteners.
Figure 5

Remove rubber plugs from brake caliper mounting fasteners. (green arrows)

Next, using a 7mm Allen bit, remove brake caliper mounting fasteners.
Figure 6

Next, using a 7mm Allen bit, remove brake caliper mounting fasteners. (green arrows)

The last person to service the brakes on my Z3 used a thick grease on the caliper bolts.
Figure 7

The last person to service the brakes on my Z3 used a thick grease on the caliper bolts. It has hardened and made getting them out a little harder. I will have to clean this out of the caliper and off the bolt. Then lubricate the bolts with a silicone brake grease.

Working behind front strut (yellow arrow), open plastic door (green arrow) for brake pad wear sensor electrical connector.
Figure 8

Working behind front strut (yellow arrow), open plastic door (green arrow) for brake pad wear sensor electrical connector.

Disconnect brake pad wear sensor electrical connector by pressing release tab and pulling apart.
Figure 9

Disconnect brake pad wear sensor electrical connector by pressing release tab and pulling apart. Remove brake caliper from mounting bracket. Do not allow brake caliper to hang from brake hose. Secure to vehicle using a piece of a metal coat hanger.

Remove brake pads from brake caliper.
Figure 10

Remove brake pads from brake caliper. Then press piston back into caliper using a brake caliper piston tool. Install new brake pads into caliper and caliper mounting bracket. Install caliper to mounting bracket and tighten fasteners. Then install rubber plugs. Connect pad wear sensor electrical connector and route wiring harness as before. Install brake pad wear sensor into brake pad. Install brake pad anti-rattle clip by pressing into caliper and pushing down to confirm it is properly seated. Once calipers are installed and fasteners are tight, press brake pedal to pump brakes up. Once brake pedal is hard to push, install wheels and check brake operation.

If you are having trouble with a brake pad warning light and the sensors and pads look OK, you will want to test the circuit.
Figure 11

If you are having trouble with a brake pad warning light and the sensors and pads look OK, you will want to test the circuit. Follow the steps previously mentioned in the tech article to unplug the sensor in question. Then jump terminals 1 and 2 (green arrows) together using a fused jumper wire, (photo shows harness side of connector). Turn the ignition ON and OFF, then back ON. If the light goes out the sensor is faulty. If the light doesn't go out, leave the jumper wire in place and perform the same steps on the next sensor. If you jump out both connectors and the light doesn't go out, the problem is likely in the harness. I find most issues are with the harness from the front brake pad sensor up along the body. You will have to test the wires to determine which part of the harness is faulty. You could run new wires to test, which is quickest. Or you can test the wiring using a DVOM measuring Ohms. Once the problem is found, replace the faulty wires or connection.

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Comments and Suggestions:
Jazzer Comments: Thanks for such valuable and comprehensive resource. You are my "go- to" place for all my many jobs on my 1998 roadster 1.9 which is slowly returning to its former glory. Great to have this service.
October 20, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Roger Comments: So far I've looked at and many different things on your site and fond them very helpful and coupled with the pictures feel confident in tackling most basic service jobs on my Z3 which I've only just bought as a project car. Many thanks to you all at Pelican.
August 4, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Steve Comments: Do you recommend any squeak elimination "grease" and if so pls let me know your procedure. thanks.
July 27, 2016
  Followup from the Pelican Staff: No, I do not. That is my personal preference. - Nick at Pelican Parts  
Mel Comments: Complete and detailed. Would be nice if we don't have to click a separate button to view a larger image but still the best instructional I've come across so far.
December 22, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Duke Comments: Thank you for the article. Very useful.
I have a few comments:
- it's be great if you could add torque values for both front and rear. Most people ignore these, and this can have adverse effects.
October 26, 2015
  Followup from the Pelican Staff: Torque specs can be found in repair manuals. That is the best place to get them, in the case they are updated. - Nick at Pelican Parts  
J.W. Comments: That was an excellent " how to " thanks
May 9, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 

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Page last updated: Fri 12/9/2016 02:06:36 AM