Brake system — specifications (Opel Ascona C)

System type.- Four-wheel dual hydraulic circuit (diagonally divided). Discs in front, drums in the rear, with servo unit. The rear brakes have pressure regulating valves. The handbrake on the rear brakes is controlled by a floor-mounted lever.

Brake fluid type/specification. — Hydraulic fluid SAE J1703F or DOT 4 (Duckhams— Universal Brake/Clutch Fluid).

Brake discs.

Diameter - 236.0 mm (9.29 in).

Thickness (new):

• 1.3 and 1.6 - 12.7 mm (0.50 in).
• 1.8 (ventilated) — 20.0 mm (0.79 in).

Minimum thickness (after processing*):

• 1.3 and 1.6 - 10.7 mm (0.42 in).
• 1.8 - 18.0 mm (0.71 in).

Maximum wear is 0.1 mm (0.004 d).

* Once these dimensions have been reached, only one more set of brake pads may be used, after which the discs must be replaced. Disc pads.

Total thickness including plate - from 15.5 to 15.9 mm (from 0.61 to 0.63 d).

Wear limit (including the record) — 7.0 mm (0.28 in).

Caliper.

Piston diameter:

• 1.3 and 1.6 - 48.0 mm (1.89 in).
• 1.8—52.0 mm (2.04 in).

Brake drums.

Inner diameter:

• "salon" and "hatchback" - 200.0 mm (7.87 in).
• "station wagon" - 230.0 mm (9.06 in).

Maximum internal diameter after processing:

• "salon" and "hatchback" - 201.0 mm (7.91 in).
• "station wagon" - 231.0 mm (9.09 in).

The maximum permissible deviation from roundness is 0.1 mm (0.004 d).

Brake shoes.

Dimensions: Width.

• "salon" and "hatchback" - 52.0 mm (2.05 in).
• "station wagon" - 58.5 mm (2.30 in).

Wear limit (above the rivet head) — 0.5 mm (0.02 d).

Rear cylinder.

Piston dimensions (minimum acceptable):

• "salon" and "hatchback" - 17.39 mm (0.685 d).
• "station wagon" - 18.98 mm (0.748 in).

Cylinder barrel (maximum permissible):

• "salon" and "hatchback" - 17.53 mm (0.690 in).
• "station wagon" - 19.12 mm (0.753 in).

Nominal diameter:

• "salon" and "hatchback" - 17.46 mm (0.687 in).
• "station wagon" - 19.05 mm (0.750 in).

Master cylinder.

Piston diameter (minimum acceptable):

• GMF — 20.58 mm (0.810 in).
• ATE - 20.49 mm (0.807 in).

Cylinder barrel (nominal) — 20.64 mm (0.813 in).

Servo unit.

Type - Vacuum, with one diaphragm.

Manufacturer: GMF or ATE.

Size - 178, 203 or 227 mm (7.0, 8.0 or 9.0 d) depending on the model and year of manufacture.

Free supply of foot and hand brake.

Foot brake - from 6 to 9 mm (from 0.2 to 0.4 d).

Handbrake - Braking should begin with the second click.

Torque values. — (Nm/lbf·ft).

• Master cylinder lock bolt. — 6/4.
• Vacuum Servo Assembly - 18/13 Support Bracket.
• Road wheel bolts - 90/66.
• Blow-off screw - 9/7.
• Banjo caliper coupling hollow bolt - 25/18.
• Brake Pedal Support Bracket - Bulkhead - 20/15.
• Cross Pedal Shaft Nut - 18/13.
• Rear cylinder - rear plate - 9/7.
• Master cylinder mounting nuts - 18/13.
• Vacuum servo nut - manifold - 15/11.
• Hydraulic tube connecting coupling nuts - 11/8.
• Handbrake cable lock nut - 20/15.
• Mudguard plate for disc - steering knuckle - 4/3.
• Brake drum screw - hub - 4/3.
• Handbrake lever - floor - 20/15.