GMC 1989 Light Duty Truck, Repair Manual, Page: 103 / 998

MANUAL STEERING GEAR 3B2-1
SECTION 3B2
MANUAL STEERING GEAR
NO TIC E: These fasteners are im p o rta n t atta c h in g parts in that they c o u ld a ffe c t the p e rfo rm a n c e o f vital c o m p o ­
n ents an d systems, a n d /o r c o u ld resu lt in m a jo r re p a ir e xp ense. They m u st b e re p la c e d w ith o ne o f the sam e p art
n u m b e r o r with an e q u iv a le n t p a rt if re p la c e m e n t b e c o m e s necessary. D o n o t use a re p la c e m e n t p art o f lesser
q uality or su bstitu te design. Torque values m u st be u sed as s p e c ifie d d urin g reassem b ly to assure p ro p e r re te n tio n
o f these parts.
CONTENTS
SUBJECT PAGE
Description.................................................................................................................................................................................... 3 B 2 - 1
Saginaw Model 525 .................................................................................................................................................................... 3 B 2 - 2
Saginaw Model 535 .................................................................................................................................................................... 3 B 2 -
6
S p e c ific a tio n s ............................................................................................................................................................................. 3 B 2 -1 0
A d ju stm ent................................................................................................................................................................................3 B 2 -1 0
Fastener T o rq u e.......................................................................................................................................................................3 B 2 -1 0
Special T o o ls ................................................................................................................................................................................3B2-11
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 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.
• 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 worm shaft
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 worm shaft and a 28.5
mm (1.125-in.) diameter pitman shaft.