Chevrolet 1980 Light Duty Truck Repair Manual page 154

5-18 BRAKES
locations 180° apart (fig. 5-13C). D o not break studs loose
in rear housing or put pressure on power piston tube when
locking housings.
7. Push felt silencer over push rod to seat against end
o f power piston tube. Snap ring retainer is now placed on
push rod so it can hold silencer against power piston tube.
Plastic boot is now pushed to seat against rear housing.
Raised tabs on side o f boot will locate in holes in center o f
brackets. The jam nut and clevis can now be reassembled
to push rod.
G aging of Pow er B rake U nit
The following gaging operation is necessary only when
a major structural part such as front or rear housing, power
BENDIX SINGLE D IA P H R A G M POWER BRAKE UNIT
Disassembly (Figs. 5-1D and 5-2D)
1. Scribe a line across front and rear housings to
facilitate reassembly.
2. R em ove the front housing seal (fig. 5-2D); pulling
the piston rod from the front housing will also remove the
seal assembly. Rem ove the piston rod.
3. A ttach base o f H olding Fixture J-22805 to front
housing with nuts and washers and draw down tight to
elim inate bending or damage to studs. Clamp base in bench
vise with power section up (fig. 5-1 A).
O V E R H A U L M A N U A L
piston assembly, master cylinder piston or master cylinder
assembly is replaced with a new part. The gage measures
how far the m aster cylinder push-rod projects from front
housing. This dim ension must be correct to insure proper
clearance in master cylinder between primary cup and
com pensating port.
M ake check as follows:
1. Place T ool J-22647 over piston rod in a position
w hich will allow gage to be slipped to left or right without
contacting studs.
The center section o f gage has tw o levels. The piston
rod end should always touch the longer section o f gage
which extends into front housing. The piston rod end should
never
touch the shorter section o f gage (fig. 5-14C).
2. A ny variation beyond these tw o lim its m ust be
com pensated for by obtaining the service adjustable piston
rod, and adjusting the screw in end to m atch height o f gage.
UNIT REPAIR
C A U T IO N : Be sure to align tool so th a t
th e check valve in th e fro n t housing is not
dam aged.
4. Loosen locknut and rem ove push rod clevis and
locknut, if so equipped.
5. R em ove the m ounting bracket from the rear
housing, if so equipped.
6. R em ove the dust boot retainer, dust boot and
silencer from the diaphragm plate extension.