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Over the years, the parking brake on your BMW may become unadjusted and fail to perform properly. The adjustment of the brake shoes is an easy process, and shouldn't take you more than an hour to accomplish.
The first step is to raise the rear of the car and remove the two road wheels. This will allow you access to the rear calipers. Make sure that the parking brake lever is released. Using a screwdriver, push back slightly on the brake pads until the brake disc is allowed to turn freely on its spindle. Be careful to check the fluid level in the master cylinder reservoir, as pushing the pads back will make the fluid level rise and may cause it to overflow.
Once the brake disc can be moved easily, move to the cockpit of the car, lift up the handbrake boot, and loosen the two nuts that attach the handbrake cable to the inside of the brake mechanism (Figure 1 and Figure 2). If there is any pretension on these cables, then it will be difficult to adjust the handbrake. The adjustment of the parking brake shoes is accomplished by turning a small gear or sprocket with a screwdriver. Unfortunately, this sprocket can only be reached through one of the lug nut holes in the brake disc.
Rotate the brake disc until you can see the small adjusting sprocket through the lug nut hole (Figure 3). You may need a flashlight for this procedure. Reaching in through the hole, use a screwdriver to rotate the cog until the parking brake shoe is tight and the rotor can no longer be rotated. A glimpse of what the cog looks like with the brake rotor removed is shown in Figure 4. If you are working on the right side of the car, you need to turn the cog towards the front of the car to tighten the brake shoes. If you are working on the left side of the car, you need to rotate the cog to the rear of the car to expand the shoes. If you are turning the sprocket a lot, and the brake disc isn't tightening up, then you are probably turning it the in the wrong direction. Repeat this procedure for the opposite side of the car. After you have the sprockets adjusted so that the brake shoes have just pressed up against the inside of the disc, and you can no longer turn the disc, back them off until the disc can spin.
Now move back to the cockpit of the car, and pull up on the hand brake several times to help seat the cables. Finally, pull up on the hand brake so that the ratchet clicks through four notches. Now, tighten up the cables using the nuts at the bottom of the handbrake lever (Figure 5). Tighten each of these nuts to the point where there is just a bit of slight resistance each respective wheel. Now, release the lever and verify that the wheels turn freely. The brake discs should be free to rotate with the handle in the down position, but fully locked by the time that the handbrake is pulled up a few notches past the four clicks.
When you are finished, recheck the master cylinder reservoir, and also step on the brake pedal a few times in order to make sure that the pistons have repositioned themselves properly against the brake pads. Also verify that the parking brake lamp on the dashboard illuminates as soon as the handle is pulled up.
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.
Palle Bo Madsen adds the following tip:
Due to the fact that everybody only uses the emergency brake as a parking brake, the brakedrum gets rusty inside, at least in the wet and cold season/climate.When You then try to adjust or brake it in, the rust becomes a glassy layer on the inside of the drum and on the brake shoes. This glass like layer has very little friction, so You can't stop the car with the emergency brake, but only use it as a parking brake.
Remedy: The BMW workshop changes the disc, the brakeshoes and the brakepads...
I use sanding paper either by a rotating machine or by hand to remove the rusty and or glass like layer from the inside of the drum and the brake shoes. Then I put it back together, adjust it with the cogwheel as You have described it and then run the emergency brake in. Now it is working as it should...