Individual characteristics are also given in the text of the Chapter and, if their implementation is mandatory, are highlighted in bold
| General parameters | |
Design | Disc brakes on the front and rear wheels. Front brake discs - ventilated. Rear brake discs - ventilated except for 316i and 318i models. Electronic-hydraulic anti-lock brake system ABS. Cornering braking control system CBC. Hydraulic system - dual-circuit, diagonal. Drum parking brake mechanisms on the rear wheels, equipped with a cable drive |
ABS anti-lock brake system | dynamic Stability Control built into ABS DSC3 on early E46 models Traction Control (Teves ABS/ASC Mark20ET) |
Thickness of brake pad linings for disc brake mechanisms | |
| wear limit (without back plate) | 3 mm |
| Thickness of brake shoe linings of drum brake mechanisms | |
| wear limit | 1.5 mm |
| Front wheel brakes | |
| Minimum permissible brake disc thickness | 20.4 mm |
| Brake disc diameter | |
| 316i, 318i, 320d, 320i, 323i | 286 mm |
| 328i, 330d | 300 mm |
| Rear wheel brakes | |
| Minimum permissible brake disc thickness | |
| 316i, 318i, | 8.4 mm |
| 320d, 320i, 323i, 328i, 330d | 17.4 mm |
| Brake disc diameter | |
| 316i, 318i | 280 mm |
| 320d, 320i, 323i | 276 mm |
| 328i, 330d | 294 mm |
| Tolerances of dimensions and runout of brake discs: | |
| maximum processing size per side | 0.8 mm |
| brake disc thickness tolerance | 0.01 mm |
| maximum lateral runout | |
| installed | 0.2 mm |
| removed | 0.04 mm |
| Parking brake: | |
| brake drum diameter | 160.0 mm |
| maximum radial runout of the braking surface | 0.1 mm |
| Brake fluid | 1.5L DOT 4 FMVSS 116 spec |
| Tightening forces of threaded connections | |
| Tightening torques for fasteners are also given in the text of the Chapter and in some illustrations*. *Tightening torques highlighted in bold in the text must be strictly observed; efforts not in bold are only approximate | |
| Front Brake Caliper Guide Bolts | 28 Nm |
| Mudguard, front | 10 Nm |
| Parking brake lever on the body floor | 25 Nm |
| Brake hose on the caliper | 235 Nm |
| Wheel bolts | 120 Nm |
The brake system consists of a master brake cylinder, a 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 wheels. Due to this, if one circuit fails, the car is braked by the other circuit. The fluid pressure in the brake system is created in the dual master brake cylinder when the brake pedal is pressed.
The brake fluid reservoir is located in the engine compartment on the left side above the master brake cylinder. It supplies the entire brake system with fluid. 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 is increased by vacuum if necessary. Since the diesel engine does not have enough vacuum created by suction, the vacuum is created by a special vacuum pump located on the cylinder head.
The disc brakes are equipped with single-cylinder calipers.
The parking brake is operated via cables and acts on the rear wheels. Since the disc brake is ineffective as a parking brake, there are two additional drum brakes on the rear wheels, which are integrated into the brake discs. The drum brakes are operated exclusively via the parking brake lever.
- Working with the brake system requires special cleanliness and order. If the necessary experience of such work is absent, it should be carried out at a service station.
- It is recommended to use brake pads approved by the vehicle manufacturer.
- When driving on wet roads, you need to periodically press the brakes to remove sediment 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 cause 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 formed. 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 car brakes sharply. Thanks to this, even during braking, the car remains controllable.
An extension of ABS is the SVS cornering braking control system (Cornering Brake Control). The CBC detects from the four ABS sensors that the vehicle is cornering. If braking occurs on a corner, this usually results in the vehicle attempting to turn into the corner. This effect is a consequence of the increasing load on the front axle. The CBC Cornering Brake Control system adjusts the build-up of braking force so that it builds up faster on the outer front wheel than on the other wheels. This creates an effect that is the opposite of the above effect. SVS when cornering, it works almost like an electronic force distribution system. This makes it possible to apply greater braking force to the rear wheels.
ASC (automatic stabilization system) reduces the torque of both drive wheels by reducing engine power when the wheels begin to spin during vehicle acceleration.
If there is a clutch effort control system (+T) when the car starts moving, the spinning wheels are braked. As a result, the torque is switched to the "gripping" wheels. The system in question practically acts as an electronic locking differential, which is switched off at speeds above 40 km/h. The use of the ASC + T system is indicated to the driver by the lighting of a control lamp.
The ASC+T system integrates a traction torque control system MSR. This system prevents the drive wheels from locking on level roads by using the engine's braking effect when downshifting or when releasing the accelerator.
When driving the vehicle with snow chains in deep snow or when starting off in deep mud, it is advisable to switch off the ASC + T system using the switch on the centre console. When the switch is switched on again or the engine is started again, the ASC + T system is automatically switched on again.
Dynamic Stability Control System DSC is installed as an optional extra on the 328 i model. The DSC control unit constantly compares the current driving parameters with the calculated ideal state parameters. If, for example, the vehicle is understeered too much when cornering, the vehicle's power and therefore its speed are reduced, while the system simultaneously brakes the rear wheel on the inside of the corner. As a result, the turned front wheels create more lateral guidance and the vehicle does not exit the corner.
Notes on ABS/CBC/ASC + T/MSR/DSC systems
A safety circuit in the electronic control unit ensures that if there is a defect, such as a broken cable or if the battery voltage is too low (below 10 V), the system is switched off. During normal operation, after the ignition is switched on, the indicator lamp lights up briefly and then goes out. If the lamp does not go out and lights up continuously while driving, this indicates a malfunction. The vehicle can be continued to be used, but the electronic control system is switched off.
If one or more indicator lights 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 the battery voltage. If it is less than 10.5 V, charge the battery.
If the indicator lights come on at the start of the movement and then go out after a short time, this indicates that the battery voltage was low at the start of the movement, then during the movement the battery was charged by the generator.
3. Check that the battery terminals are tight and that there is good contact.
4. Raise and place the car on stands. Remove the wheels, check the wheel speed sensor wires for damage by visual inspection (presence of chafing). A more thorough check of the ABS/CBC/ASC + T/MSR/DSC system should be carried out using special devices. Refer to Section Troubleshooting. It is advisable to carry out the work in a service station.
Before performing electrical welding operations, the connector of the electronic control device must be undocked. Undocking should only be performed when the ignition is switched off. When carrying out painting works, it is allowed to expose the control device to a short-term temperature of up to +95°C, and long-term (no more than 2 hours) – up to a temperature of +85°C.
(The original article is available on the website: BMWMAN.ru)