GMC 1989 Light Duty Truck, Repair Manual, Page: 32 / 998

1B1-14 A-6 AIR CONDITIONING COMPRESSOR
Figure 30— In s ta llin g the P iston d u rin g the
G aging O peration
Im portant
9.
10
.
11 .
12
.
13.
14.
15.
• Do not install th e shoe discs (35) on the
re ar of th e piston (32).
Rotate the shaft and axial plate (39) until the high
point of the axial plate is over the No. 1 piston
cylinder bore.
Lift the axial shaft assem b ly (39) up a little out of
front cylinder half (29).
• Hold the front thrust races and b earing (“ ze ro ”
race, race b earing , “ z e ro ” race) ag ain st the
axial plate hub.
Position the No. 1 piston (32) over the No. 1 cylinder
bore (notched end of th e piston being on the bottom
and the piston straddling the axial plate) and lower
the shaft to allow No. 1 piston to drop into its bore
(figure 30).
R e p e at step 11 for pistons Nos. 2 and 3.
Install the rear cylinder half (42) on the pistons,
aligning the cylin der with th e d isch arge cross-over
tu be hole in the front cylinder.
• Tap the piston into p la ce using a plastic m allet
or p iece of clean wood and a h a m m e r (figure
31).
Position th e d is c h a rg e cross-over tu b e o p e n in g
betw een a pair of co m pressing fixture bolts to perm it
access for the fee le r g ag e.
Install the top plate to J 9397.
Tighten
Nuts to 20 N m (15 ft. lbs.).
GAGING PROCEDURE
Tools R equired:
J 8001 Dial Indicator Set
J 9 3 9 7 C om p ressin g Fixture
J 9 4 0 2 Piston A ssem b ly Tray
J 9661-01 F eeler Tension G a g e Set
Two gag in g procedures provide th e running tolerances.
T h e first p ro ced u re d eterm in e s the size shoe discs to
p r o v id e a t e a c h p is to n a 0 . 0 4 1 - 0 . 0 6 1 m m
(0 .0 0 1 6 -0 .0 0 2 4 -in c h ) total preload b etw ee n th e seats and
th e axial plate at the tightest p lace through the 3 6 0
d e g re e rotation of the axial plate. T h e b ro nze shoe discs
are availab le in 0.013 mm (0.0005-in ch ) variations.
T h e second procedure, p erfo rm ed at th e rear shaft
thrust b earing and race pack, provides a 0 .0 6 4 -0 .0 7 7 mm
(0 .0 0 2 5 -0 .0 0 3 0 -in c h ) preload b etw een th e hub su rfaces of
the axial plate, and the front and rear hubs of the cylinder.
Fourteen steel thrust races, including a basic “ z e ro ” race,
are availab le in 0.013 mm (0.00 05 -in ch ) increm ents. Use
J 9661-01 for gag in g the shoe disc size. U se J 8001 to
d eterm in e the thrust race size.
1. M e a s u re the c le ara n c e b etw een the rear ball of the
No. 1 piston and axial plate in th e following m anner:
a. S e le c t a c o m b in a tio n of oiled fe e le r gag e
leaves to fit snugly b etw een th e ball and axial
plate.
b. A tta c h J 9 6 6 1 -0 1 to th e f e e le r g a g e . A
distributor point ch eckin g scale m ay be used.
c. Pull on the spring scale to slide the feeler
g ag e stock out from b etw een the ball and axial
plate. Note the reading on spring scale as the