Opel 1900 1973 Service Manual page 266

cylinder to brake booster and torque nuts to 14 Ib.ft.
on the GT and 12 lb.ft. on the Opel 1900 and Manta.
2. Position assembly into brake booster bracket and,
on the GT only, thread piston push rod onto the
thrust rod.
3. Install brake booster to support attaching washers
and nuts and tighten to 11 lb.ft. of torque.
4. On the GT install master cylinder support to inner
fender skirt bolts.
5. Connect vacuum hose to brake booster.
6. By turning the piston push rod on the thrust rod,
(GT only) adjust until the brake pedal free travel is
7. Connect brake pipes to master cylinder and bleed
brakes.
MASTER CYLINDER OVERHAUL. GT
Removal of Master Cylinder
1. Disconnect the two brake pipes from the master
cylinder.
2. Remove the front support to skirt attaching bolts,
the cylinder to booster retaining nuts and lift out
master cylinder.
Disassembly
1. Prior to brake master cylinder disassembly, pour
brake fluid out of brake fluid reservoir, remove reser-
voir from master cylinder and take sealing plugs out
of housing.
2. Screw static pressure valve(s) out of housing.
3. To facilitate disassembly, push piston somewhat
into cylinder and insert a rounded off piece of weld-
ing rod approx. .12 in. thick into feed port to retain
piston in this position.
4. Remove stop screw and snap ring out of housing
and take out both pistons together with springs.
5. Remove stop screw from piston for rear brake
circuit and remove all component parts. Remove
also all component parts from intermediate piston of
front brake circuit.
Cleaning and Checking
1. Clean parts with genuine brake fluid, Delco Su-
preme No. 11, or equivalent. Do not use any other
cleaning solvents. Dry with compressed air. Free up
compensating and feed ports.
POWER BRAKE BOOSTER AND MASTER CYLINDER
2. Polish cylinder bore of housing with crocus cloth.
If lapping scores and rust spots are still noticeable,
replace brake master cylinder assembly.
3. Check
if required. The rubber seals and static pressure valve
always have to be replaced.
Assembly
1. Assemble front and rear brake circuit pistons.
Prior to assembly coat rubber seals with brake fluid.
2. Coat cylinder bore, piston sliding surfaces and
seals with brake fluid.
3. Insert preassembled intermediate piston for front
brake circuit together with thrust spring and spring
seat into clyinder bore. The smaller diameter of the
tapered thrust spring must face piston.
4. With a drift, push piston (against spring pres-
sure) into housing and insert a piece of welding rod
into feed port of front brake circuit to retain piston.
5. Install stop screw with new seal ring into housing
and tighten.
6. Insert preassembled piston for rear brake circuit
into cylinder bore and install snap ring into groove
in housing.
7. Check piston fof free movement by moving it to
and fro. If required, place washers under the head of
the stop screw.
8. Lightly push piston into housing and remove
piece of welding rod out of feed port of front brake
circuit.
9. With a rounded off piece of welding rod (.020 -
11. Coat new sealing plugs with brake fluid and in-
sert them into housing. Push twin brake fluid con-
tainer into sealing plugs and install screen and cover
with seal ring.
Installation
1. Install master cylinder onto brake booster with
washers and nuts. Torque to 14 lb.ft.
2. Attach the front mounting bracket.
3. Install brake lines on master cylinder, and bleed
brakes.
inner components for damage and replace,