BMW 3 of the E46 series

since 1998 release

Repair and operation of the car

Brake system

Specifications

Separate characteristics are provided also in the text of the Head and in case of obligation of their performance are highlighted in bold type

General parameters
Design	Disk brake mechanisms on lobbies and back wheels. Disks of forward brake mechanisms - ventilated. Disks of back brake mechanisms - ventilated except models 316i and 318i. Electronic and hydraulic system of anti-blocking of brakes of ABS. The braking monitoring system on turns of CBC. Hydraulic system - double-circuit, diagonal. The drum mechanisms of the parking brake on back wheels equipped with the hummock drive
System of anti-blocking of brakes of ABS	dynamic system of stabilization of stability the antiprobuksovochny system (Teves ABS/ASC Mark20ET) which is built in ABS DSC3 on the early E46 models
Thickness of overlays of brake shoes of disk brake mechanisms
wear limit (without back plate)	3 mm
Thickness of overlays of brake shoes of drum brake mechanisms
wear limit	1.5 mm
Brake mechanisms of forward wheels
Minimum admissible thickness of a brake disk	20.4 mm
Diameter of a brake disk
316i, 318i, 320d, 320i, 323i	286 mm
328i, 330d	300 mm
Brake mechanisms of back wheels
Minimum admissible thickness of a brake disk
316i, 318i,	8.4 mm
320d, 320i, 323i, 328i, 330d	17.4 mm
Diameter of a brake disk
316i, 318i	280 mm
320d, 320i, 323i	276 mm
328i, 330d	294 mm
Admissions of the sizes and beating of brake disks:
the maximum amount of processing on the party	0.8 mm
admission of thickness of a brake disk	0.01 mm
maximum lateral beating
it is established	0.2 mm
it is removed	0.04 mm
Parking brake:
diameter of the brake drum	160.0 mm
maximum radial beating of a brake surface	0.1 mm
Brake fluid	1.5 l of DOT 4 of the FMVSS 116 specification
Efforts of a tightening of threaded connections
The moments of an inhaling of fixture are given also in the text of the Head and on some illyustratsiyakh*. * The moments of an inhaling highlighted in the text in bold type are subject to exact observance; the efforts which are not highlighted in bold type are given only approximately
The directing bolts of a brake support of forward wheels	28 N • m
Mudguard, ahead	10 N • m
The lever of the parking brake on a body floor	25 N • m
Brake hose on a support	235 N • m
Bolts of wheels	120 N • m

The brake system consists of the main brake cylinder, the amplifier of a brake and disk brakes of lobbies and back wheels. The brake hydraulic system has two contours: one contour influences forward wheels, another the back. Thanks to it at refusal of one of contours braking of the car is carried out by other contour. Liquid pressure in brake system is created in the dual main brake cylinder when pressing a brake pedal.

The tank with brake fluid is located in a motive compartment on the left side over the main brake cylinder. It provides with liquid all brake system. The amplifier of a brake at the block of cylinders accumulates part of the vacuum created by the engine at absorption. Via the valve the effort of a pedal of a brake if necessary amplifies vacuum. As the diesel engine has not enough vacuum created at absorption, the vacuum is created by the special vacuum pump located on a head of cylinders.

Disk brakes are equipped with supports with one cylinder.

The parking brake is set in motion through hummock drafts and influences back wheels. As the disk brake is inefficient as parking, on back wheels there are in addition two drum brakes which are built in brake disks. Drum brakes are put in action only via the lever of the parking brake.

Work with brake system demands special purity and an order. If necessary experience of such work is absent, it should be seen off on HUNDRED. It is recommended to apply the brake shoes resolved by the manufacturer of the car. At the movement on wet roads it is necessary to press periodically brakes to dump rainfall from brake disks. At the expense of the centrifugal force arising at rotation of wheels, water is removed from brake disks. However on disks there is a thin film of silicone, greasing and pollution which reduce efficiency of action of brakes. And rain flutes lead dirt on brake shoes to formation of zadir on a surface of brake disks. All this promotes decrease in efficiency of braking. When cleaning brake system brake dust is formed. This dust is unhealthy. Therefore when cleaning brake system, watch to inhaling brake dust.

Systems of stabilization of stability of the car on ABS/CBC/ASC Road + T/MSR/DSC

ABS: The anti-blocking system interferes with blocking of wheels at sharp braking of the car. Thanks to it even during braking the car remains operated.

Continuation of ABS is the braking monitoring system on turns of SVS (Cornering Brake Control). SVS on signals of four ABS sensors learns that the car moves on turn. If braking happens on turn, it usually leads to that the car tries, as if to be screwed in turn. This effect is a consequence of the increasing load of a forward axis. The braking monitoring system on turns of SVS regulates increase of brake effort in such a way that it accrues quicker on a forward wheel, external in relation to turn, than on other wheels. Thus, action, the return to the effect stated above is created. SVS works at turns practically as system of electronic distribution of effort. Thanks to it there is possible an impact on back wheels with big brake effort.

ASC (system of automatic stabilization) reduces a torque of both driving wheels by reduction of engine capacity when wheels at dispersal of the car start being turned.

In the presence of the effort monitoring system coupling (+ the T) at start-off of the car from a place brake the turned wheels. As a result of it the torque switches to the "linked" wheels. The considered system practically works as the electronic blocked differential which is disconnected at a speed over 40 km/h. Use of system ASC + T is displayed to the driver by fire of a control lamp.
The system of regulation of the traction moment of MSR is integrated into system ASC + T. This system interferes with blocking of driving wheels on the equal road due to brake operation of the engine when switching on lower transfer or at gas reduction.

At the movement of the car with snow chains in deep snow or at start-off from a place from deep dirt it is expedient to disconnect system ASC + T by means of the switch on the central console. At repeated turning on of the specified switch or at the following start of the engine the system ASC + T again automatically joins.

The system of dynamic control of stabilization of DSC is installed as the additional equipment on model 328 i. The monitor of DSC system carries constantly out comparison of the current parameters of the movement with the parameters of a perfect condition received in the settlement way. If, for example, the car at the movement on turn nedoupravlyatsya too strongly, the power of the car and, therefore, speed of the movement decrease, at the same time the system brakes a back wheel, internal in relation to turn. Thanks to it the turned forward wheels create more lateral direction and the car does not leave turn.

Instructions on systems ABS/CBC/ASC + T/MSR/DSC

The scheme of safety in the electronic control unit watches that with defect, for example, break of a cable, or at too low voltage of the battery (it is lower than 10 V) the system was disconnected. During the normal work after ignition inclusion the control lamp lights up for a short time and then dies away. If the lamp does not die away and in the course of the movement continuously lights up, it indicates malfunction existence. The car can be operated further, but the system of electronic regulation is disconnected.

If in the course of the movement one or several control lamps on a control panel light up, pay attention to the following:

1 Stop the car for a short time, switch off the engine and again start it.
2 Check battery tension. If it less than 10.5 In, charge the battery.

If in a start of motion control lamps light up, and then through short time die away, it specifies that in a start of motion tension of the battery was low, then during the movement the battery was charged from the generator.

3 Check, whether plugs of the battery are tightened and whether there is a reliable contact.
4 Lift and install the car on supports. Remove wheels, check external survey existence of damages of wires of sensors of number of turns of wheels (existence of mastications). More careful inspection of system ABS/CBC/ASC + T/MSR/DSC should be carried out by means of special devices. Address to the Section Diagnostics of Malfunctions. Work it is desirable to carry out HUNDRED in conditions.

Before carrying out electrowelding works it is necessary to rasstykovat the socket of an electronic monitor. Undocking has to be made only at the switched-off ignition. When carrying out painting works it is allowed to subject a monitor to short-term influence of temperature to +95 °C, and it is long-term (no more than the 2nd hour) – up to the temperature of +85 °C.