Chevrolet 1977 10 Series, Руководство по ремонту, Страница: 174 / 468

5-8 OVERHAUL MANUAL
BENDIX TANDEM POWER BRAKE UNIT
UNIT REPAIR
Disassembly
1. Scribe a line across the front and rear housings to
facilitate reassembly.
2. Carefully remove hydraulic push rod and seal and
slide seal from rod.
3. Remove vacuum check valve and grommet.
4. Remove dust boot and silencer from operating valve
rod.
5. Remove dust guard retainer, dust guard and silencers
from rear plate hub with an awl. Then, reinstall steel retainer
on hub.
6. Squirt denatured alcohol down the operating valve
rod to lubricate rubber grom m et in the valve plunger.
7. Position two small blocks of wood on either side of
air valve rod and install end of air valve rod in vise, leaving
just enough clearance to position two (2) open end wrenches
between the vise and retainer on hub of rear plate.
8. Using the wrench nearest the vise as a pry, force the
air valve off the ball end of the rod. DO N O T damage the
plastic hub or allow vacuum cylinder to fall to the floor (fig.
5-IB and 5-2B).
9. The edge of the rear housing contains twelve (12)
lances. F our (4) of these lances (one in each quadrant) are
deeper than the other lances. The metal that forms the four
(4) deep lances m ust be partially straightened so that the
lances will clear the cutouts in the front housing. If the metal
tabs that form the deep lances break during straightening, the
housing m ust be replaced (fig. 5-3B).
10. Remove the hydraulic push rod and vacuum seal
from the front housing.
11. A ttach base of Holding Fixture J-22805 to front
housing with nuts and washers and draw down tight to
eliminate bending or damage to studs.
12. Place power unit with Holding Fixture J-22805 in
an arbor press with rear housing up and secure to plate of
press by a suitable means of holding Tool J-22805 (fig. 5-4B).
By using a 1-1/2" open end wrench on Tool J-22805 and
allowing unit to turn against back of arbor press, press will
hold unit from turning.
13. Place Spanner W rench J-9504 over studs on rear
shell (fig. 5-4B). Use three washers and nuts to attach wrench
to housing. Use a suitable piece of pipe of approximately two
inches I.D. and approxim ately three inches in length. Place
over plastic diaphragm plate hub. Place a piece of flat stock
steel over end of pipe and press rear housing down far enough
to relieve tension of diaphragm rubber lip and spring.
14. R otate spanner bar counterclockwise until the lances
in the edge of the rear housing are aligned with the cut-outs
in the front housing. Considerable effort may be required to
rotate the front housing.
W A RNING : The diaphragm return spring is
compressed in the power section and
expands as the pressure on the housings
is removed. If the housings do not separate
when the screw has been turned slightly
to reduce the pressure, tap the housings
w ith a rubber hammer to break the bond.
15. Slowly release press to perm it the two housings to
separate.
16. Continue to release press until diaphragm spring
tension has been removed.
17. Remove the front housing and return spring.
18. Remove three nuts and washers from Spanner
W rench and separate wrench and rear housing.
19. Remove Holding Fixture J-22805 from front
housing.
20. W ork edges of front diaphragm from under lances
of rear housing and remove complete vacuum assembly from
Fig. 5-1 B-Rem oving A ir Valve Rod
Fig. 5-2B--Air Valve Rod Assem bly