GMC 1990 Light Truck Repair Manual page 103

MANUAL STEERING GEAR
SUBJECT
Description .......................................................................
Saginaw Model 525 ........................................................
Saginaw Model 535 ........................................................
Specifications ..................................................................
Adjustment ...................................................................
Fastener Torque ..........................................................
Special Tools....................................................................
DESCRIPTION
The Saginaw steering gear is the recirculating ball
nut and worm type. The worm is located on the lower
end of the steering shaft. The ball nut is mounted on
the worm and the steel balls act as a rolling thread
between the worm and nut to provide a low friction
drive between them.
Teeth on the ball nut engage teeth on the pitman
shaft sector. The teeth on the ball nut are made so that
a tighter fit exists between the ball nut and pitman
shaft sector teeth when the front wheels are in the
straight ahead position. The sector teeth are slightly
tapered so that a proper preload may be obtained by
moving the pitman shaft endways by means of a
preload adjuster screw which extends through the gear
SECTION 3B2
CONTENTS
..................................................................................3B2- 1
................................................................................. 3B2- 2
................................................................................. 3B2- 6
................................................................................. 3B2-10
................................................................................. 3B2-10
..................................................................................3B2-10
..................................................................................3B2-10
housing side cover. The head of the preload adjuster
and a selectively fitted shim fit snugly into a T-slot in
the end of the pitman shaft, so that the screw also
controls the end play of the shaft.
• The model 525 steering gear is used on G model
vehicles, (figure 1).
• The model 535 steering gear is used on the S, T
and M model vehicles, (figure 5).
For visual identification the 535 gear has a four bolt
side cover and the 525 gear has three bolts. The larger
(535) gear has a 28.8 mm (1.137-in.) diameter wor-
mshaft measured on the O.D. of the worm thread and
a 31.7 mm (1.25-in.) diameter pitman shaft. The
smaller (525) gear has a 26.2 mm (1.034-in.) diameter
wormshaft and a 28.5 mm (1.125-in.) diameter pitman
shaft.
MANUAL STEERING 3B2-1
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