Tensioning of the parking brake in the BMW 1 Series and 3 Series

In this post, instructions as provided by the brand are given for correctly tensioning the parking brake in the 1 series and 3 series BMW.
This process affects the following bodies:

1 Series: E81, E82, E87 and E88.
3 Series: E90, E91, E92 and E93.


Note:

The hand brake must be adjusted if:
• The parking brake shoes or other parts in the assembly are replaced.
• The brake discs are replaced.
• Excessive travel (10 teeth).
• Renewal of the parking brake Bowden cables.

Tensioning process

First, detach the hand brake lever bellows. It is recommended to use plastic levers so as not to damage the vehicle's interior.
Lever the points indicated in the images to disengage the bellows and extract them over the lever.

After extracting the bellows, the adjustment unit should be locked. To set this unit, the parking brake lever must be actuated to its stop.

Then, exert pressure with a screwdriver on the unit and release the hand brake lever while keeping the adjustment spring stop pressed back. Continue releasing the lever and maintain the pressure until the retention hook engages in the stop.

Then, fully unscrew the bolt from the respective wheels and rotate the wheel until the adjustment screw is visible in the threaded hole.

Turn the adjustment screw with a screwdriver until the wheel cannot be turned by hand and then release the adjustment screw in accordance with the following specifications:
• 185 mm diameter duo-servo brake: 8 slots.
• 160 mm diameter duo-servo brake: 9 slots.

WARNING! A basic setting of less than 8 slots could cause damage to the shoes, as they would be in permanent contact with the disc.

After carrying out the adjustment on both wheels, tighten the wheel bolts to the indicated torque (120 N). Once the wheel nuts are tightened, the adjustment unit must be unlocked. To do this, move the retaining hook outward using the screwdriver as a lever.

Once the tensioning is complete, replace the hand brake lever bellows and operate the lever at least 5 times with medium force to adjust the parking brake Bowden cables.


Check the basic tensioning setting with the following table:

- 0 teeth (hand brake released): There is no braking force.
- If there is a brake tester available, place the gear level in the "N" position and measure:

• Without self-locking differential ≤ 150 N
• With self-locking differential ≤ 200 N

- 1st tooth: No increase in force with respect to the previous one. The control lamp may come on.
- 2nd tooth: The control lamp should come on
- 3rd tooth: Increase of braking force.
- 5th tooth: High braking force should be apparent. If available, the brake tester should reach a value of ≥ 400 N.

Initial braking of the parking brake

If there is a reduction of the braking effect after the replacement of the disc or brake shoes, carry out the following adjustment:

On the brake test bench (brake tester):
- Operate the hand brake lever until the wheel force is 800 N.
- Lock the hand brake lever on the bottom tooth and keep it in this position for a maximum of 2 minutes.
- Unlock the hand brake lever and check that the basic setting is uniform over its entire travel.

On the road (if possible, on the company's site or on a street with no traffic):
- When travelling slowly (maximum 40 km/h), operate the parking brake lever until a braking effect is felt.
- Pull up the hand brake lever to the next slot and continue travelling for approximately 400 metres (at a maximum speed of 40 km/h).
- Unlock the parking brake lever and check that the basic setting is uniform over its entire travel.


If necessary, repeat the process after leaving the brake to cool for a few minutes.