BMW AG Motorcycle (R 850 C, R 1200 C). Manual - part 23

34.2

Contents

Page

Removing the ABS unit

 ..............................................................................................................16

Installing the ABS unit

 .................................................................................................................17

Removing and installing ABS relay and relay base 

.................................................18

Removing ABS relay

 ....................................................................................................................18

Installing the ABS relay

 ...............................................................................................................18

Removing ABS relay base

 ........................................................................................................18

Installing the ABS relay base

 ...................................................................................................19

Removing and installing brake lines 

................................................................................20

Removing and installing front brake line

 .............................................................................20

Removing and installing rear brake line

 ..............................................................................21

34.3

34

Technical data

R 850 C

R 1200 C

Brake fluid

DOT 4

Minimum lining thickness

mm (in) 1.5 (0.06)

Wear indicator:
Front brake pads/cutouts in pad material
Rear brake pads/hole in wheel-side brake pad 
backplate enables brake disc to be seen when 
minimum pad thickness is reached.

Front wheel

Brake disc dia.

mm (in) 305 (12.00)

Brake disc thickness

mm (in) 5

± 0.1

(0.20

± 0.004

)

Minimum thickness

mm (in) 4.5 (0.18)

Brake pad surface area

cm

2

(sq in) 100 (15.5)

Piston dia. in brake caliper

mm (in) 32/34 (1.26/1.34)

Piston diameter in handlebar lever cylinder

mm (in) 20 (0.79)

Sensor gap, front

mm (in) 0.45 ... 0.55 (0.020 ... 0.022)

Brake pad

Semi-metallic

Rear wheel

Brake disc dia.

mm (in) 285 (11.22)

Brake disc thickness

mm (in) 5.0 (0.20)

Minimum thickness

mm (in) 4.5 (0.18)

Permissible lateral runout

mm (in) 0.20 (0.008)

Brake pad surface area

cm

2

(sq in) 34 (5.27)

Piston dia. in brake caliper

mm (in) 26/28 (1.02/1.10) with insulating piston

Piston dia. in foot brake cylinder

mm (in) 12 (0.47)

Sensor gap, rear

mm (in) 0.45 … 0.55 (0.020...0.022)

Brake pad

Semi-metallic

34.5

Removing and installing front brake 
caliper

•

Drain fluid from brake system.

•

Detach brake line (1).

e

 Caution:

Do not allow brake fluid to come into contact with 
painted parts of the motorcycle, because brake fluid 
destroys paint.

•

Unscrew the brake caliper.

•

Force back the brake pads/pistons (arrows).

•

Carefully remove the brake caliper.

e

 Caution:

Do not damage brake pads.

•

Install by following the above work instructions in 
the reverse order.

•

Force back the brake pads/pistons.

•

Fill/bleed the brake system. 

e

 Caution:

Use new sealing rings (2).
Do not damage brake pads.

X 

Tightening torque:

Brake caliper at fork slider tube.................... 40 Nm
Brake hose to brake caliper ......................... 15 Nm
Bleed screw at brake caliper  ......................... 7 Nm

RS340021

2

1

RS340050

34.6

Dismantling and assembling front 
brake caliper

e

 Caution:

The brake caliper halves must not be unscrewed!

Dismantling front brake caliper

•

Remove the brake caliper.

•

Remove keeper from retaining pin (1).

•

Drive out the retaining pin (1) from the wheel side.

•

Pull the brake pads out downwards.

•

Seal the bleed screw.

X 

Tightening torque:

Bleed screw at brake caliper .......................... 7 Nm

•

Hold a cloth over the brake caliper.

•

Carefully press out brake pistons (2), using a 
compressed air gun at the brake line connection.

e

 Caution:

Do not allow your fingers to become trapped be-
tween the pistons; risk of injury.

•

Remove the two sealing rings (3,4) from the left/
right brake cylinder bores.

•

Examine the brake caliper pistons for damage.

Assembling front brake caliper

•

Coat new sealing rings (3,4) with brake fluid and 
install. 

•

Coat brake caliper pistons (2) with brake fluid 
and insert.

e

 Caution:

Do not tilt the brake pistons when installing.

•

Using piston resetting tool (5),
BMW No. 34 1 500, press the pistons fully back.

•

Install the brake pads.

RS340070

34 1 500

5

2

3

4

1

34.7

Removing and installing rear brake 
caliper

•

Drain fluid from brake system.

e

 Caution:

Do not allow brake fluid to come into contact with 
painted parts of the motorcycle, because brake fluid 
destroys paint.

•

Detach the brake line from the brake caliper.

•

Unscrew the brake caliper.

•

Install by following the above work instructions in 
the reverse order.

•

Force back the brake pads/pistons.

•

Fill/bleed the brake system.

•

To bleed, release the brake caliper and position 
it with the bleed nipple at the highest point.

e

 Caution:

Renew sealing rings for brake line.
Do not damage brake pads.

X 

Tightening torque:

Brake caliper to rear wheel drive .................. 40 Nm
Brake hose to brake caliper ......................... 15 Nm
Bleed screw at brake caliper .......................... 4 Nm

C330012

34.8

Dismantling and assembling rear 
brake caliper

Dismantling rear brake caliper

•

Remove keeper (1).

•

Drive out retaining pin (2). 

•

Take out brake pads.

•

Seal the bleed screw.

X 

Tightening torque:

Bleed screw at brake caliper .......................... 4 Nm

•

Hold a cloth over the brake caliper piston.

•

Carefully press out brake piston (3) with a com-
pressed air gun applied to the connecting bore; 
work at low air pressure.

e

 Caution:

Keep fingers away from gap between pistons and 
side contact face of brake pads; risk of injury.

•

Remove sealing rings (4) from left/right cylinder.

•

Inspect the brake caliper piston for hairline 
cracks/score-marks/other damage.

Assembling rear brake caliper

•

Coat the new sealing rings with brake fluid and 
insert them into the left/right brake caliper cylin-
ders.

•

Coat both brake caliper pistons with brake fluid 
and install them.

e

 Caution:

Do not tilt the brake pistons when installing.

•

Coat the adapter plate locating pins with 
Shell Retinax A and install the adapter plate.

•

Insert locating plate (5) into brake caliper. 

L

 Note:

The installed position must be correct (arrow point-
ing in forward-travel direction).

•

Insert brake pads and secure with retainers.

GS340140

1

2

3

4

5

34.9

Removing and installing front brake 
disc

•

Degrease brake discs before installing.

L

 Note:

Installed direction (arrow) of brake discs must be 
correct.

X 

Tightening torque:

(clean thread + Loctite 243).......................... 24 Nm

e

 Caution:

Check/adjust the sensor gap.

Sensor gap:............ 0.45...0.55 mm (1.77...2.22 in)

C360020

34.10

Removing/installing rear brake disc 

•

Remove rear wheel.

•

Remove the brake caliper.

•

Heat the brake disc retaining screws to 120 °C 
(248 °F) and remove them.

L

 Note:

Mark the position of the brake disc.
The sensor gap setting remains unchanged.

•

Install by following the above work instructions in 
the reverse order.

•

Degrease the brake disc before installing.

e

 Caution:

[ABS] Check sensor gap and adjust with spacing 
plates if necessary.
[ABS] If the brake disc and therefore the sensor 
wheel are renewed, the disc’s lateral runout must be 
determined/marked.

Sensor gap:............ 0.45...0.55 mm (1.77...2.22 in)

X 

Tightening torque:

Brake disc to rear wheel drive 
(clean thread + Loctite 273).......................... 21 Nm

C330013