GMC 1989 Light Duty Truck Repair Manual page 103

NOTICE: These fasteners are im p o rtan t attaching parts in that they c o u ld a ffe c t the p e rfo rm an ce o f vital c o m p o ­
nents an d systems, a n d /o r c o u ld resu lt in m ajor re p a ir expense. They m u st be re p laced w ith one o f the sam e part
n u m b e r or with an eq u iv a le n t p a rt if re p la ce m e n t b eco m es necessary. Do n o t use a re p la c e m e n t part o f lesser
quality or substitute design. Torque values m ust be used as sp ecified d uring reassem bly to assure p ro p e r reten tio n
o f these parts.
SUBJECT
Description.................................................................................................................................................................................... 3 B 2 - 1
Saginaw Model 525 .................................................................................................................................................................... 3B 2- 2
Saginaw Model 535 .................................................................................................................................................................... 3 B 2 -
S p e c ific a tio n s ............................................................................................................................................................................. 3B 2-10
A d ju stm ent................................................................................................................................................................................3B 2 -1 0
Fastener Torque.......................................................................................................................................................................3 B 2-10
Special T o o ls ................................................................................................................................................................................3B2-11
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 posi­
tion. The sector teeth are slightly tapered so that a proper
preload may be obtained by moving the pitman shaft end­
ways by means of a preload adjuster screw which extends
through the gear housing side cover. The head of the pre­
load 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.
SECTION 3B2
MANUAL STEERING GEAR
CONTENTS
DESCRIPTION
MANUAL STEERING GEAR 3B2-1
• The model 525 steering gear is used on G and P
model vehicles, (figure 1).
• The model 535 steering gear is used on the CK, 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 wormshaft
measured on the O.D. of the worm thread and a 31.7 mm
(1.25-in.) diameter pitman shaft. The sm aller (525) gear
has a 26.2 mm (1.034-in.) diameter wormshaft and a 28.5
mm (1.125-in.) diameter pitman shaft.
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