| Fig. 1: Checking worm bearing preload on 1972–81
trucks
|
| Fig. 2: Checking worm bearing preload on 1982–86
trucks
|
| Fig. 3: Using a special tool to tighten the locknut on
the adjuster
|
| Fig. 4: Checking and adjusting backlash
|
NOTE: These adjustments are most accurately made with the steering
gear out of the truck, mounted in a vise. Special tools are required.
- Using an inch pound torque wrench, rotate the wormshaft. Note the torque
required for shaft rotation. Torque should be:
- 1979–81: 5.2–7.8 in. lbs.
- 1978: 7.9–10.4 in. lbs.
- 1976–77: 0.9–3.5 in. lbs.
- 1972–75: 7.9–10.4 in. lbs.
- If not, remove the end cover and correct it by adding or removing shims
under the cover. Shims are available in sizes of 0.050mm, 0.060mm, 0.070mm,
0.075mm, 0.080mm, 0.100mm and 0.200mm.
- Install a spring scale and adapter 49 0180 510B to the wormshaft. Rotating
torque should be 1⁄2 –1
lb.
- If not, loosen the wormshaft locknut and, using spanner 49 UB39 585, turn
the adjuster until preload is within specifications.
- Using wrench 49 1391 580, or equivalent, tighten the locknut to 140 ft.
lbs.
- Set the adjusting screw and shim in the T-groove on the top of the sector
shaft, and measure the axial clearance. Proper clearance should be 0–0.1mm
(0–0.0039 in.).
- If the clearance is excessive, adjust it with different shims. Shims are
available in 0.05mm increments from 1.95–2.10mm for 1982–86 trucks.
- Mount a dial indicator next to the vise, with the pointer on the end of
the Pitman arm. With the gear in what would be the straight ahead position,
backlash should be 0.
- If not, adjust it using the adjusting screw on top of the gear. Hold the
screw with a screwdriver and loosen the locknut. Turn the screw until backlash
is correct. Make sure that the Pitman arm is in the position it would be with
the wheels straight ahead.
- When backlash is correct, hold the screw and tighten the locknut.
