Chevrolet 1977 10 Series, Repair Manual, Page: 60 / 468

3B-18
OVERHAUL MANUAL
NOTCH IN END CAP MUST FULLY
ENG A G E PIN PROJECTING INTO
VALVE BODY
BACK-UP
O-RING MUST
BE INSTALLED
UNDER PISTON
RING
RACK-PISTON
NUT
Fig. 3 B -4 8 —In s ta llin g S tu b S h a ft A s s e m b ly
Cleaning and Inspection
1. Wash all parts in clean solvent and dry parts with
compressed air.
2. Check pitm an shaft bearing surface in the side cover
for scoring. If badly worn or scored, replace the side cover.
3. Check the sealing and bearing surfaces of the pitm an
shaft for roughness, nicks, etc. If m inor irregularities in
surface cannot be cleaned by use of crocus cloth, replace the
pitm an shaft.
4. Replace pitm an shaft assembly if teeth are damaged
or if the bearing surfaces are pitted or scored.
5. Check pitm an shaft lash adjusting screw. It must be
free to turn with no perceptible end play. If adjusting screw
is loose replace the pitm an shaft assembly.
Assembly
Thread the side cover onto the pitm an shaft adjusting
screw until it bottom s and then turn in one-half turn. Install
a new adjusting screw locknut, but do not tighten.
Rack-Piston
Disassembly
1. Remove tool J-7539 from the rack-piston.
2. Remove the ball return guide clamp, ball guide and
balls.
3. If necessary to replace the teflon oil seal and "O" ring,
remove at this time.
Cleaning and Inspection
1. Wash all parts in clean solvent and dry with
compressed air.
2. Inspect the worm and rack-piston grooves and all the
balls for scoring. If either the worm or rack-piston needs
replacing, both must be replaced as a m atched assembly.
3. Inspect ball return guide halves, making sure that the
ends where the balls enter and leave the guides are not
damaged.
4. Inspect lower thrust bearing and washers for scores
or excessive wear. Check bearing washers to make sure they
are not flat but conical in shape to provide proper bearing
preload adjustm ent when reinstalled in the steering gear. If
any of these conditions are found, replace the thrust bearing
and washers.
5. Inspect rack-piston teeth for scoring or excessive
wear. Inspect the external ground surfaces for wear, scoring
Fig. 3 B -4 9 —In s ta llin g Ring on R ack-Piston
or burrs.
Assembly
1. If the teflon oil seal and "O" ring were removed,
lubricate a new "O" ring and seal with Power Steering Fluid
and install in groove on rack-piston. The teflon ring m ay be
slightly loose after assembly, but will tighten up when
subjected to the hot oil in the system (fig. 3B-49).
2. Slide the worm all the way into the rack-piston. It is
not necessary to have the thrust bearing assembly on the
worm at this time.
3. Turn the worm until the worm groove is aligned with
the lower ball return guide hole (fig. 3B-50).
4. Lubricate the balls with Power Steering Fluid, then
feed 17 balls into the rack-piston, while slowly rotating the
worm counter-clockwise.
5. Alternately install 7 balls into the return guide and
retain with chassis lubricant at each end of guide. Install the
return guide assembly onto the rack-piston. Install the return
guide clamp and tighten the 2 clam p screws to 10 ft. lbs.
6. Insert Bearing R etainer Tool J-7539 into the rack-
Fig. 3B -5 0--ln stalling Balls in Rack-Piston
W O R M
FL A N G E
G U ID E
HALVES
INSTALL BALLS
W H IL E R O T A T IN G W O R M
C O U N T E R C L O C K W IS E