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Autopapyrus · Mercedes-Benz A-Class W176
https://autopapyrus.com/guides/mercedes-benz/a-class/rear-brake-disc-replacement/
Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.

Mercedes-Benz A-Class W176: Rear Brake Disc Replacement

On the Mercedes-Benz A-Class W176 (2013, M270 1.6 engine), the rear brake discs are replaced together with the pads every 60-80 thousand km (37,000-50,000 miles), depending on driving conditions. The procedure requires putting the electronic parking brake into service mode in order to retract the caliper pistons.

Difficulty: Medium Time: 1.5-2 hours Steps: 16 Tools: Jack and jack stands, lug wrench, socket set (E12, 17 mm), torque wrench, Torx T30 screwdriver, pry bar or C-clamp for pushing back the piston, diagnostic scan tool or access to the instrument cluster menu, WD-40 or penetrating lubricant, wire brush

Part

  • 🔩 Rear brake discs 276x9 mm (OE or aftermarket such as Bosch, Brembo, TRW), rear brake pads (must be replaced whenever the discs are replaced), DOT 4 brake fluid, copper anti-seize grease for the guide pins
There's a full repair manual for this car Every system, wiring diagrams and torque specs — not just this job. Haynes and 7 more. See manuals →

Step by step

16 steps
  1. Park the car on a level surface, shift to neutral, loosen the rear wheel bolts, raise the rear axle with a jack, place jack stands, and remove the wheels.
  2. Activate the electronic parking brake service mode: turn the ignition on (without starting the engine), then on the instrument cluster press and hold the phone button and the OK button on the steering wheel at the same time for about 5 seconds, enter the service menu, select Brake Pad Replacement or a similar item, and confirm the operation. The caliper pistons will retract to their home position.
  3. Remove the two caliper carrier bolts (17 mm socket, reassembly torque 130 N·m (96 lb-ft)) and take off the caliper together with the carrier. Hang it from the body with wire or a cord so that its weight does not pull on the brake hose.
  4. Remove the protective bracket from the guide pins, if fitted, and take out the old brake pads.
  5. Remove the Torx T30 screw that secures the brake disc to the hub (reassembly torque 10 N·m (7 lb-ft)). If the disc is seized, tap around its circumference with a rubber mallet and use WD-40.
  6. Remove the old disc, clean the hub with a wire brush to remove rust and dirt, and check the wheel bearing for play (rock the hub by hand; there should be no play).
  7. Fit the new brake disc onto the hub, aligning the holes, and tighten the Torx T30 screw to 10 N·m (7 lb-ft).
  8. Push the caliper piston back into the housing with a C-clamp or pry bar (if the electronics did not retract it fully). Turn the piston clockwise while pressing it in, and watch the brake fluid level in the reservoir (it may rise; remove the excess with a syringe).
  9. Lubricate the caliper guide pins with copper grease, install the new brake pads in the caliper, and check the condition of the rubber guide pin boots.
  10. Install the caliper with its carrier and tighten the carrier bolts to 130 N·m (96 lb-ft).
  11. Repeat the procedure on the other rear wheel.
  12. Install the wheels, lower the car, and tighten the wheel bolts in a crisscross pattern to 110-130 N·m (81-96 lb-ft).
  13. Turn the ignition on and press the brake pedal firmly to the floor several times (5-7 presses) so that the pistons seat against the new pads and the pedal feels firm.
  14. Exit the parking brake service mode: enter the service menu on the instrument cluster again and complete the pad replacement procedure, or turn the engine off and restart it. The system will perform an automatic calibration.
  15. Check the brake fluid level in the expansion reservoir and top it up to the MAX mark if necessary.
  16. Bed in the brakes: for the first 200-300 km (125-185 miles), avoid hard braking and make gentle stops so the pads and discs wear in properly.

Common mistakes and warnings

  • Do not skip the electronic parking brake service mode. Trying to push the pistons back without deactivating the EPB can damage the caliper's electric actuator. Always replace the discs as a pair (both rear discs), otherwise braking will be uneven. Do not let grease get on the working surfaces of the discs and pads. If the pedal is soft or sinks to the floor after the replacement, bleed the brake system to remove air. If the disc thickness is below the minimum specification of 2.5 mm, replacement is mandatory.
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