Mercedes W124

since 1985-1995 of release

Repair and car operation

W124 Mercedes
+ Governing bodies and control devices
+ 2. Maintenance (diesel engines)
+ 4. Repair of 6-cylinder petrol SOHC engines
+ 5. Repair of 6-cylinder petrol DOHC engines
+ 6. Repair of the diesel engine established in the car
+ 7. Major maintenance of engines
+ 10. System of injection of BOSCH CIS-E fuel (KE-JETRONIC)
+ 11. System of injection of BOSCH HFM fuel
+ 12. Fuel system of diesel engines
+ 13. Fuel system of diesel engines
+ 15. System of ignition of 4-cylinder petrol engines
+ 16. System of ignition of four-cylinder petrol engines
+ 19. Mechanical transmission
+ 20. Automatic transmission
   22.2. General information
   22.3. Pumping of hydraulic brake system
   22.4. Brake pipelines and hoses
   + 22.5. Replacement of forward brake shoes
   22.6. Replacement of back brake shoes
   22.7. Forward brake disk
   22.8. Back brake disk
   22.9. Forward brake support
   + 22.10. Support repair
   22.11. Back brake support
   22.12. Main brake cylinder
   22.13. Vacuum amplifier of brakes
   22.14. Unilateral valve of the vacuum amplifier of brakes
   22.15. Adjustment of the parking brake
   22.16. Brake shoes of the parking brake
   22.17. Pedal of the parking brake
   22.18. Cables of the parking brake
   22.19. Stoplight switch
   22.20. Anti-blocking system (ABS)
   + 22.21. Elements of anti-blocking system
   22.22. The vacuum pump on models with diesel engines

22.11. Back brake support



The brake liquid used in hydraulic system of coupling is poisonous, therefore at its hit on skin it is necessary to wash out immediately this place a plentiful quantity of water. If liquid got to eyes or in an organism, it is necessary to address immediately to the doctor. Some liquids have property easily to ignite and can light up even from contact to hot knots of the car. Besides, the liquid used in hydraulic system of coupling, dissolves paint and plastic therefore at liquid hit on a paint and varnish covering of the car wash out it a plentiful quantity of water. Also this liquid is hygroscopic, i.e. absorbs moisture from air and therefore the liquid, being stored in open ware, it is not recommended to use a long time.

At work of brake shoes the brake dust which contains asbestos, unhealthy forms. Therefore when cleaning brake shoes do not use the compressed air and do not inhale a dust.


At installation of a back brake support it is necessary to use new bolts of fastening.

1. Lift a back part of the car and fix on supports. Remove the corresponding back wheel.
2. For reduction of losses of brake liquid uncover a popolnitelny tank of brake system, close a tank mouth polyethylene and again screw a cover. It is necessary in order that the cover tightly closed a popolnitelny tank. Alternatively, using a clip, press the brake hose going to a support.
3. Clear area round the connecting coupling of a brake hose and a support. Weaken the connecting coupling, fixing a brake hose to a support.
4. Remove brake shoes.
5. Unscrew bolts of fastening of a support, then screw together a support from a brake hose and take it from under the car.

Support repair

Piston arrangement in a back brake support


2–measuring template;


4–brake disk

1. Being careful, clear a support of a brake dust and dirt.
2. Note an arrangement of pistons in a support in order that it was possible to establish them correctly on the places.
3. Take pistons from a support for what it is possible to use air under the low pressure submitted to the brake cylinder through an opening for a brake hose. Thus instead of brake shoes establish wooden whetstone. Remove from pistons dustproof covers.
4. Using a small screw-driver, take sealing rings from flutes in support openings.
5. Wash out all details in methyl alcohol or pure brake liquid and wipe them. For pro-cleaning of tubes and openings use the compressed air.
6. Check a condition of all details of a support and replace the worn-out or damaged details.
7. Special attention turn on the cylinder and the piston. In the presence of scratches, рисок, wear or dot corrosion it is necessary to replace the piston and the cylinder, and it means that it is necessary to replace a support assembled.
8. Irrespective of a condition, replace all rubber consolidations.
9. At installation check that all details pure and dry, and that each piston is established in the opening.
10. Dip pistons and new sealing rings of pistons into brake liquid and apply a thin film brake liquid on openings for pistons in a support.
11. Establish sealing rings in support openings.
12. Before piston installation in a support turn it in such situation that the ledge on a flange of the piston was from above. For check of correctness of installation of the piston in a support of Mercedes-Benz recommends to use a special template (see drawing). Such arrange scientific research institute of the piston excludes squeal at work of brakes.


1. Using the corresponding tap, clear openings for bolts of fastening of a support.
2. Screw a support on the coupling of a brake hose.
3. Establish a support on a place and fix bolts, having tightened them the demanded moment.
4. Tighten the coupling of fastening of a brake hose to a support the demanded moment.
5. Establish brake shoes and remove air from hydraulic brake system. If at work with hydraulic brake system all precautions were observed, it is enough to pump over only the corresponding back brake.
6. Establish a wheel, then lower the car on the earth and tighten bolts of fastening of a wheel the demanded moment. Check level of brake liquid.