Separate characteristics are also given in the text of the Chapter and, if they are mandatory, are highlighted in bold
| Common parameters | |
Design | Disc brakes on front and rear wheels. The front brake discs are ventilated. Rear brake discs - ventilated except models 316i and 318i. Electronic-hydraulic system of antiblocking brakes ABS. Cornering Brake Control CBC. Hydraulic system - double-circuit, diagonal. Drum mechanisms of the parking brake on the rear wheels, equipped with a cable drive |
ABS anti-lock brake system | dynamic stability control system built into ABS DSC3 on early E46 models traction control (Teves ABS/ASC Mark20ET) |
Thickness of linings of brake shoes of disk brake mechanisms | |
| wear limit (without back plate) | 3 mm |
| Thickness of linings of brake shoes of drum brake mechanisms | |
| wear limit | 1.5mm |
| Front wheel brakes | |
| Minimum allowable brake disc thickness | 20.4mm |
| Brake disc diameter | |
| 316i, 318i, 320d, 320i, 323i | 286 mm |
| 328i, 330d | 300 mm |
| Rear wheel brakes | |
| Minimum allowable brake disc thickness | |
| 316i, 318i, | 8.4mm |
| 320d, 320i, 323i, 328i, 330d | 17.4mm |
| Brake disc diameter | |
| 316i, 318i | 280 mm |
| 320d, 320i, 323i | 276 mm |
| 328i, 330d | 294 mm |
| Dimensional tolerances and runout of brake discs: | |
| maximum processing size per side | 0.8mm |
| brake disc thickness tolerance | 0.01mm |
| maximum lateral runout | |
| installed | 0.2 mm |
| withdrawn | 0.04mm |
| Parking brake: | |
| brake drum diameter | 160.0 mm |
| maximum radial runout of braking surface | 0.1mm |
| Brake fluid | 1.5 L DOT 4 specification FMVSS 116 |
| Tightening torques for threaded connections | |
| Fastener tightening torques are also given in the text of the Chapter and in some illustrations*. *The tightening torques in bold type are subject to exact observance; Efforts not in bold are indicative only | |
| Front wheel brake caliper guide bolts | 28 Nm |
| Mudguard, front | 10 Nm |
| Parking brake lever on body floor | 25 Nm |
| Brake hose on caliper | 235 Nm |
| Wheel bolts | 120 Nm |
The brake system consists of the main brake cylinder, brake booster and disc brakes on the front and rear wheels. The brake hydraulic system has two circuits: one circuit acts on the front wheels, the other on the rear. Due to this, if one of the circuits fails, the braking of the car is carried out by another circuit. The fluid pressure in the brake system is created in the dual brake master cylinder when the brake pedal is depressed.
The brake fluid reservoir is located in the engine compartment on the left side above the brake master cylinder. It provides fluid to the entire brake system. The brake booster at the cylinder block accumulates part of the vacuum created by the engine during suction. Through the valve, the force of the brake pedal, if necessary, is enhanced by vacuum. Since the diesel engine does not have enough vacuum created during suction, the vacuum is created by a special vacuum pump located on the cylinder head.
Disc brakes are equipped with single cylinder calipers.
The parking brake is actuated via cables and acts on the rear wheels. Since the disc brake is ineffective as a parking brake, the rear wheels have an additional two drum brakes built into the brake discs. The drum brakes are operated exclusively through the parking brake lever.
- Working with the brake system requires special cleanliness and order. If the necessary experience of such work is not available, it should be carried out at the service station.
- It is recommended to use brake pads approved by the vehicle manufacturer.
- When driving on wet roads, it is necessary to periodically apply the brakes to release precipitation from the brake discs. Due to the centrifugal force that occurs when the wheels rotate, water is removed from the brake discs. However, a thin film of silicone, grease and dirt remains on the discs, which reduces the effectiveness of the brakes.
- Dirt on the brake pads and rain grooves lead to scuffing on the surface of the brake discs. All this contributes to a decrease in braking efficiency.
- When cleaning the brake system, brake dust is generated. This dust is harmful to health. Therefore, when cleaning the brake system, be careful not to inhale brake dust.
Vehicle stability control systems ABS/CBC/ASC + T/MSR/DSC
ABS: The anti-lock braking system prevents the wheels from locking when the vehicle is braked hard. Thanks to this, even during braking, the car remains steerable.
A continuation of ABS is the CBC cornering braking control system (Cornering Brake Control). The CBC learns from four ABS sensors that the vehicle is moving around a curve. If braking occurs on a corner, this usually results in the car trying to roll into the corner. This effect is a consequence of the increasing load on the front axle. The CBC Cornering Brake Control system regulates the build-up of braking force so that it builds up faster on the outer front wheel than on the other wheels. Thus, an action is created that is the opposite of the effect indicated above. SHS cornering works almost like an electronic force distribution system. This makes it possible to act on the rear wheels with a large braking force.
ASC (automatic stabilization system) reduces the torque of both drive wheels by reducing engine power when the wheels start to turn during acceleration of the car.
With clutch force control system (+T) when starting the car, the spinning wheels are braked. As a result, the torque is switched to "mating" wheels. The system in question practically acts as an electronic locking differential that disengages at speeds above 40 km/h. The use of the ASC + T system is indicated to the driver by the warning light coming on.
Traction control is integrated into the ASC + T system MSR. This system prevents the drive wheels from locking up on level ground by braking the engine when downshifting or downshifting.
When driving with snow chains in deep snow or when pulling away from deep mud, it is advisable to deactivate the ASC + T system using the switch in the center console. When the indicated switch is turned on again or the next time the engine is started, the ASC + T system is automatically turned on again.
Dynamic Stabilization Control System DSC installed as an option on the 328 i. The DSC control unit continuously compares the current driving data with the calculated ideal state. If, for example, the vehicle is understeered too much when cornering, the vehicle's power and thus the driving speed is reduced, while the system simultaneously brakes the rear wheel that is inboard of the corner. Thanks to this, the turned front wheels create more lateral direction and the car does not go out of the corner.
Notes on ABS/CBC/ASC + T/MSR/DSC systems
A safety circuit in the electronic control unit ensures that in the event of a defect, such as a broken cable, or if the battery voltage is too low, (below 10 V) the system turned off. During normal operation, after the ignition is switched on, the control lamp lights up for a short time and then goes out. If the lamp does not go out and lights up continuously while driving, this indicates a malfunction. The vehicle can continue to be driven, but the electronic control system is deactivated.
If one or more warning lamps on the instrument panel come on while driving, pay attention to the following:
1. Stop the car for a short time, turn off the engine and start it again.
2. Check battery voltage. If it is less than 10.5V, charge the battery.
If at the beginning of the movement the control lamps light up and then go out after a short time, this indicates that the battery voltage was low at the beginning of the movement, then during the movement the battery was charged by the generator.
3. Check if the battery terminals are tight and there is good contact.
4. Raise and place the vehicle on stands. Remove the wheels, visually check for damage to the wires of the wheel speed sensors (the presence of chafing). A more thorough check of the ABS / CBC / ASC + T / MSR / DSC system should be carried out using special instruments. Refer to Section Troubleshooting. It is desirable to carry out work in the conditions of a service station.
Before carrying out electric welding work, it is necessary to disconnect the connector of the electronic control device. Uncoupling should only be done with the ignition off. When carrying out painting work, it is allowed to expose the control unit to short-term exposure to temperatures up to +95°C, and for a long time (no more than 2 hours) – up to a temperature of +85°C.