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Home >> BMW >> 2022 >> M3 Competition >> Repair and Diagnosis >> Brakes >> Traction Control >> Brakes -- Repair M3 (G80) >> 34 21 Rear Brakes >> 34 21 320 Removing and installing/replacing both rear brake discs (M3 base, M3 Competition, M3 Competition M xDrive, M3 CS) >> Removing rear brake discs

Removing rear brake discs

WARNING: Unintentionally applying the parking brake 
Injury hazard! 
  • On vehicles with "Remote Engine Start" (SA1CR):
  • Starting the engine while working on the braking system is strictly forbidden. When starting the engine via "Remote Engine Start", the parking brake is automatically applied
  • Deactivate the function "Remote Engine Start"
  • Open the hood before working on the braking system. This prevents the engine from being started
WARNING: Vehicle may slip off the vehicle hoist if the vehicle hoist is handled incorrectly 
Danger! Immobilization period-threatening injuries! 
  • Observe safety instructions on raising the vehicle using a vehicle hoist
  • For additional information see: 00... Raise the vehicle using a VEHICLE LIFT
CAUTION: Effects on other persons 
Injury hazard! Risk of damage! 
  • Make sure that no other persons are in or around the vehicle
NOTE: TECHNICAL INFORMATION 
If the front brake pads and the rear brake pads are exchanged together, the parking brake button must be operated 1x and released again after completion of the first exchange (e.g. front brake pads)
If not observed, a fault memory entry will take place
NOTE: TECHNICAL INFORMATION 
Before first working on the DSCi brake (integrated brake), the "DSCi" web-based training must be passed successfully
The "DSCi" web-based training is started in the Learning Management System (TMSi)
NOTE: TECHNICAL INFORMATION 
After a brake pad exchange and before pressing the brake pedal: It is imperative to apply the electromechanical parking brake
If this is not observed, a CC message appears and the brake system switches to the emergency program. The brake booster is no longer active
NOTE: TECHNICAL INFORMATION 
During work on the rear brake, it must be ensured that the button for the electromechanical parking brake cannot be pressed
NOTE: TECHNICAL INFORMATION 
General information on changing the brake pads: 
For vehicles older than 48 months it is recommended to replace the retaining spring or expanding spring
The brake pad wear sensor must be replaced once it has been removed because the brake pad wear sensor loses its retention capability in the brake pad
A CBS reset must be done after every brake pad exchange:
A CBS reset in the vehicle is possible in the event of a partially ground down  brake pad wear sensor. The CBS display in the Central Information Display (CID) is active
In the event of a brake pad wear sensor that is not partially ground down  , a CBS reset is only possible with the diagnostic system. No CBS display in the Central Information Display (CID)
If adhesive bonded brake pads are installed, the brake pads must be replaced after releasing the adhesive bond!
NOTE: TECHNICAL INFORMATION 
To prevent damage to the surface coating: With floating calipers on the brake caliper mounting bracket or with fixed calipers in the brake caliper housing, do not clean the contact surfaces for the brake pads to the extent that it is possible
Clean the contact surfaces with brake cleaner (BMW part number 83 19 2 154 780). Next, apply a thin coat of brake pad paste (BMW part number 83 19 2 158 851 for 3 g) or 83 19 2 158 852 fr 100 g)
Spread brake pad paste on the marked surfaces with a brush
For ADDITIONAL INFORMATION  see: 34 00... brake pad paste

Preliminary work 

NOTE: TECHNICAL INFORMATION 
Note the following for the removal of the brake disc: 
Do not under any circumstances strike the friction ring with tool (e.g. hammer). If required, carefully  tap against the brake disc chamber using a rubber mallet
G14929251Courtesy of BMW OF NORTH AMERICA, INC.