34 21 200 Removing and installing/replacing both brake pads of rear disc brakes
Special tools required:
- Brake pad wear sensor: After removal it must be replaced (brake pad wear sensor loses its retention capability in the break pad).
- Retaining pins and expanding spring: for vehicles older than 48 months it is recommended to replace the retaining spring.
So as not to damage the surface coating, do not mechanically clean the guide surfaces for the brake pads on the caliper mounting bracket, if possible.
Instead, clean with brake cleaner, part number 83 19 2 154 780, and apply a thin coating of break pad paste, part number 83 19 2 158 851 (3g) or 83 19 2 158 852 (100g).
Spread brake pad paste onto the marked surfaces using a brush.
Observe GUIDELINE FOR APPLYING BRAKE PAD PASTE ON BRAKE PADS AND BRAKE ANCHOR PLATE .
Necessary preliminary tasks:
- Remove WHEELS .
- Remove BRAKE PAD WEAR SENSOR
Both guide bolts must be released and then the brake caliper detached towards the rear.
The springs may be bent when only one bolt is released and the brake caliper is folded up.
Unscrew guide bolts (1).
If necessary, grip at hexagon head (2).
Installation note:
Replace guide bolts.
Tightening torque 34 21 3AZ .
Mark any worn brake pads.
In the event of one-sided brake pad wear, do not change brake pads round.
Remove brake pads (1) in direction of arrow from caliper carrier.
Observe MINIMUM THICKNESS OF BRAKE PADS .
Clean brake pads.
Do not apply grease to brake lining backplate.
Check minimum brake disc thickness:
- Position special tool 34 1 280 at three measuring points in area (1) and measure.
- Compare measurement result and lowest value with SETPOINT VALUE .
New brake pads may only be installed if the brake disk thickness is greater than the MINIMUM BRAKE DISC THICKNESS .
If new brake pads are mounted on a brake disc, the following must be observed:
- Bevel edges in the area (1) slightly (dimension A must not exceed maximum 1 mm).
These procedures applies for all the following described brake systems.
When pressing piston back, note brake fluid level in expansion tank.
Overflowing brake fluid will damage the paintwork.
Screw brake piston with special tools 34 6 309 , 34 6 306 , 34 6 307 , 34 6 308 into brake caliper.
Dust boot must not come into contact with brake pad paste as this may cause the dust boot to swell.
Check dust boot for damage and replace if necessary.
Clean contact surface (1) of brake piston with brake cleaner and apply a thin coating of brake pad paste.
Clean contact surface (1) of brake caliper with brake cleaner and apply a thin coating of brake pad paste.
So as not to damage the surface coating, do not mechanically clean the guide surfaces for the brake pads on the caliper mounting bracket, if possible.
Instead, clean guide surfaces with brake cleaner and apply a thin coating of brake pad paste.
Apply a thin coating of brake pad paste to both sides of T-head of brake pad in area (1).
After completing work:
- When installing new brake pads at front and rear axles, brake fluid level must be brought up to "MAX" mark.
- Read and comply with notes on BREAKING IN NEW BRAKE DISCS/BRAKE PADS .
- Fully depress brake pedal several times so that brake pads contact brake discs.
- If necessary, when replacing brake pads, reset CBS display as per factory specification.
Replacement:
Remove lining springs (1) and replace.
Installation note:
So as not to damage the surface coating, do not mechanically clean the guide surfaces for the brake pads on the caliper mounting bracket, if possible.
Instead, clean guide surfaces with brake cleaner and apply a thin coating of brake pad paste.