Figure 6-12. Steering Gear Rack-Piston Arbor Tool Details

TM 10-3930-623-34

Figure 6-12. Steering Gear Rack-Piston Arbor Tool Details

2. Inspect ball plug (81) in housing (87). If it is

NOTE

leaking or raised above housing surface, drive it in flush,

to 1/16 inch below the surface. Tighten ball by staking

The silver ball size is stamped on the

the housing. If leakage cannot be stopped, housing

rack-piston. If no size is shown it is

must be replaced.

standard ball size number 7. Change

to next larger size silver ball will

3. Inspect all seal surface and retaining ring

increase drag 1 inch-pound or next

grooves for defects. If any defects are found, housing

size smaller will reduce drag by 1

must be replaced.

inch-pound.

4. At initial assembly, the rack-piston nut, worm

5. Inspect ball return guides (64), making sure that

and balls are selected to obtain a preload drag of 1 to 4

the ends where the balls enter and leave the guides are

inch pounds measured on center through an angle of 90

not damaged.

degrees. This preload may drop during service, without

having any noticeable effect on steering.

Upon

6. Inspect lower thrust bearing (68) and races (67).

complaint of loose or hard steering, thrust bearing

adjustment and overcenter adjustment will correct the

7. Inspect rack-piston ball nut (65) teeth for wear

problem if it lies within the steering gear adjustments. If

and chipping. Inspect rack-piston nut surface for scoring

not, check the rack-piston nut and worm assembly for

or burrs.

excessive clearance, lack of drag, and also for

roughness at any point along the worm. If any of these

6-89. RACK-PISTON, WORM ASSEMBLY AND GEAR

conditions is found, disassemble the assembly and

HOUSING ASSEMBLY.

inspect worm and rack-piston nut grooves and all the

balls for excessive wear or scoring. If either worm or

1. Thoroughly clean the parts and lubricate the

rack-piston nut need replacing, both must be replaced as

internal parts with OE-10 engine oil.

a matched assembly.

Drag may be corrected by

replacing the silver balls with a larger or smaller size.

2. Drive new connectors (85 and 86, figure 4-32) in

Black balls need not be replaced unless they are

place with piloted driver.

defective.

in event the black balls cannot be

distinguished from the silver balls, replace with all new

3. Lubricate a new back-up packing (61) with OE-

balls.

10 engine oil. Assemble in piston ring groove on rack-

piston nut (65). Install new piston ring (60) in ring

NOTE

groove over packing by carefully slipping ring over rack-

piston nut.

The ring may be slightly loose after

The black balls are 0.0005 inch

assembly. This is normal. It will tighten when subjected

smaller than the silver balls. The

to the hot oil in the system.

black and silver balls must be

installed alternately into the rack-

piston nut and return guide.

6-22