Detailed technical characteristics of the brake system (Audi 100 C3)

Table of contents: Front wheel brakes ↓ Rear wheel drum brakes ↓ Rear wheel disc brakes ↓ Brake drive ↓ Brake boosters ↓ Parking brake ↓ Brake fluid ↓ Anti-lock braking system (ABS) ↓ Data for checking high and low… ↓

The service brake system is hydraulically driven and consists of two independent circuits for braking the front and rear wheels diagonally (left front - right rear, right front - left rear).

If one of the circuits of the working brake system fails, the braking efficiency of the front and rear wheels is reduced by half.

The hydraulic drive includes a vacuum booster (on cars with 4-cylinder engines) or power steering (on cars with 5-cylinder engines) and the rear brake pressure regulator.

The mechanical parking brake with cable drive acts on the rear wheels.

On cars with 4-cylinder engines, the front service brakes are disc brakes, the rear ones are drum brakes. On cars with 5-cylinder engines, the front and rear service brakes are disc brakes.

Front wheel brakes

Front brakes of Girling or ATE brand with solid (on cars with 4-cylinder engines) or ventilated (on cars with 5-cylinder engines) discs with floating calipers, single-piston.

Characteristics of the front wheel brake discs

Brake pads

Thickness of the friction lining excluding the backing, mm: 14.

Minimum friction lining thickness (when worn out), mm: 2.

Brand and type of brake pads:

textar solid disc brakes: T 461 or Pagid 511 FF;
brake mechanisms with ventilated discs: Textar T 526 or Juried 526.

Rear wheel drum brakes

The rear wheel brakes are drum-type, with automatic adjustment of the gap between the pads and the drum.

Since July 1987, brake pads with a retaining spring have been installed on the version of the front wheel brake mechanisms with a two-piston caliper. The new model of pads can be used on all vehicles with two-piston brake calipers.

Drum diameter, mm: 230.

Maximum permissible drum diameter, mm: 231.

Axial runout of the working surface of the drum, no more than, mm: 0.20.

Maximum permissible drum ovality, no more than, mm: 0.10.

Friction lining thickness, mm: 5.25.

Minimum thickness of the overlay (when worn out), mm: 2.50.

Brand and type of friction linings: Textar T 062.

Wheel cylinder piston diameter, mm: 17.46.

Since January 1988, brake drums have been installed that are 6 mm higher than the previous ones.

Rear wheel disc brakes

Rear brakes are Girling brand, with solid discs, floating caliper, single-piston.

Brake disc characteristics

Disc diameter, mm: 245.

Disc thickness, mm: 10.

Minimum disc thickness during operation, mm: 8.

Permissible difference in thickness of the working surface of the disc, mm: 0.02.

Axial runout of the working surface of the disk, mm: 0.06.

Brake pad characteristics

Thickness of the friction lining excluding the backing, mm: 12.

Minimum friction lining thickness (when worn out), mm: 2.

Substrate thickness, mm: 7.

Brand and type of brake pads: Juried 237 FF.

Starting with chassis number 44 JN 039013, vehicles with rear disc brakes were fitted with new-style calipers with a piston diameter of 38 mm.

Since January 1988, brake discs have been installed that are 6 mm higher than before.

Brake drive

Master brake cylinder

Master brake cylinder with two coaxial pistons of the Girling or ATE brand.

Diameter of the main brake cylinder, mm:

for brake drive with vacuum booster: 22.20 or 23.81,
for hydraulic brake drive: 23.81.

Brake boosters

Vacuum booster brand Girling or ATE

Piston diameter: 9 inches.

Power steering

The power brake system includes:

common with the power steering high-pressure piston pump. Idle performance, l/min: 0.3;
pressure accumulator with built-in check and safety valves. Pressure created in a new accumulator, kg/cm² at a temperature of 20°C 88-92. Minimum pressure at a temperature of 20°C, kg/cm²: 30.
aTE or Girling brake booster with a piston diameter of 24 mm.

Pressure regulator

The pressure regulator regulates the pressure in the hydraulic drive of the rear wheel brake mechanisms depending on the load on the rear axle of the vehicle.

Data for checking the tightness of the pressure regulator

Brake fluid pressure in the left front brake caliper, kg/cm²: 100.

Permissible drop in brake fluid pressure in 5 s in the wheel cylinder or in the left rear brake caliper, kg/cm²: 10.

Data for checking the regulated pressure

Brake fluid pressure in the left front brake caliper, kg/cm²: 50; brake fluid pressure in the wheel cylinder or caliper of the right rear wheel, kg/cm²: 32.5-42.5.

Brake fluid pressure in the left front brake caliper, kg/cm²: 100; brake fluid pressure in the wheel cylinder or caliper of the right rear wheel, kg/cm²: 50.0-71.5.