F 350 4WD Pickup V8-7.3L DSL (1988)
Technical Service Bulletin # 901110
Date: 900523
Steering/Suspension - Shimmy
Article No. 90-11-10
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STEERING-SHIMMY-DIAGNOSTIC PROCEDURE-4X2 UNITS ONLY
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SUSPENSION-SHIMMY-DIAGNOSTIC PROCEDURE- 4X2 UNITS ONLY
LIGHT TRUCK:
1987-89 F-350
ISSUE:
Front end shimmy may occur at various driving speeds or when hitting bumps in the road. There are several vehicle conditions sometimes
described by customers as shimmy which may not actually be "shimmy". Shimmy, as observed by the driver, is defined as large amplitude,
rotational oscillations of the steering wheel resulting from large, side to side tire/wheel movements.
ACTION:
Inspect the truck and perform the following diagnosis to determine the shimmy's causal factors. Be aware of the following points:
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Shimmy is not always confirmed during road testing.
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It is very important to check all systems that can cause shimmy.
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After a general review of the front suspension/steering systems, make the necessary adjustments and replacements as noted.
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Check bolt and nut torques to be sure they are tightened to the specified torque specifications.
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Check the front end alignment. Look for excessively worn tires and out of balance wheel and tire assemblies.
Shimmy should not be confused with steering wheel nibble and vibration concerns.
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Steering wheel nibble is a condition resulting from the tire interaction with various road surfaces. It is observed by the driver as small amplitude,
rotational oscillations of the steering wheel.
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Various suspension/steering vibrations are sometimes confused as shimmy. They appear as steering column shake and wheel/tire imbalance. They
induce a vertical motion in the steering wheel/column.
Refer to the appropriate model year Light Truck Shop Manual, Sections 18-01, 11-01 and 12-01 for NVH conditions other than shimmy.
Steering Linkage Inspection:
1.
With the weight on the front wheels, check the linkage joints while someone else turns the steering wheel from side to side.
Figure 1
a.
For rubber ball socket (RBS) joints, see if the ball stud makes contact with the window opening in the socket bowl while on the truck, Figure
