Vauxhall Workshop Service and Repair Manuals

Tandem Master Cylinder, Overhaul

GMF Version

Remove tandem master cylinder.

See operation "Tandem Master Cylinder, Remove and Install".

1   Closure cap (standard version)

2   Closure cap with warning indicator contact

3   Brake fluid reservoir

4   Retaining clamps

5   Seals for brake fluid reservoir

6   Housing of tandem master cylinder

7   Front piston with springs

8   Rear piston

9   Retaining ring

10   Seal ring

11   Brake proportioning valve (GMF version)

Tandem Master Cylinder, Disassemble

Clamp tandem master cylinder in vice.

Lever seal ring out of cylinder bore.

Press piston approx. 10 mm/0.4 in deep into tandem master cylinder using suitable wooden or plastic drift.

To ensure that piston remains in this position, insert a rounded and deburred fitting needle (approx. 3 mm/0.12 in. welding rod) into after-running bore of tandem master cylinder.

Force retaining ring out of master cylinder housing using suitable screwdriver.

Caution: Do not damage piston or cylinder wall.

Note: Retaining ring must not be re-used.

Remove rear piston from housing.

To do this, knock tandem master cylinder against piece of wood until piston can be removed.

Carefully remove front piston from housing using compressed air.

Clean all parts with brake fluid or alcohol.

Do not use any other fluids.

Check housing and piston for wear.

If surface damage (rust) is discovered on cylinder wall, replace tandem master cylinder.

Rubber parts and retaining rings must not be re-used once removed.

Tandem Master Cylinder, Assemble

Thinly coat cylinder bore with Brake Cylinder Paste 19 70 505 (90 295 751).

Clamp tandem master cylinder almost horizontally in vice with bores for brake fluid reservoir facing upwards.

Remove closure plug from assembly sleeve.

Move short part of sleeve to be flush with cylinder.

Continue to insert sleeve in cylinder bore as far as collar of small sleeve.

Carefully insert internal parts of assembly sleeve in cylinder bore until front piston contacts base of cylinder using KM-436.

Use KM-436 to insert rear piston so far into cylinder that deburred assembly needle (arrow) can be inserted in after-running bore.

Insert new retaining ring in groove in cylinder bore. Do not damage cylinder bore.

Press piston into cylinder using suitable wooden or plastic drift and remove assembly needle.

Move pistons backwards and forwards after installation to check for free movement.

Thinly coat seal ring with Brake Cylinder Paste 19 70 505 (90 295 751) and insert in cylinder bore with open side facing outwards until it rests on piston.