Steering - Drift\Looseness Diagnostics and Service

Article No.
94-20-12

10/05/94

^ STEERING - DRIFT - DIAGNOSTIC AND SERVICE PROCEDURE

^ STEERING - LOOSE - DIAGNOSTIC AND SERVICE PROCEDURE

LIGHT TRUCK:
1992-94 ECONOLINE

ISSUE:
A comprehensive diagnostic procedure has been developed to assist technicians in resolving "pull" and "drift" concerns and/or loose steering.





ACTION:
Use the following service procedure to resolve drift concerns where there is a case of steady state (no braking) drift. A diagnostic checklist has been provided to use with this procedure.

NOTE:
THIS TSB ARTICLE SHOULD BE READ COMPLETELY BEFORE PERFORMING DIAGNOSTICS OR REPAIRS.





DETAILED SERVICE PROCEDURE

MISCELLANEOUS CHECKS

Check for loose, damaged or excessively worn parts. Visually inspect the front suspension for loose or worn components (i.e., ball joints, radius arm bushings, alignment attachments, steering linkage, etc.).





NOTE:
IT IS POSSIBLE THAT A VEHICLE MAY HAVE MULTIPLE SYMPTOMS. See ROAD TEST/CAUSE CHART. (illustration)

DIAGNOSTIC PROCEDURE # 1 - TIRE MISMATCH

1. Compare the installed tires and wheels to the certification label. If the tires and wheels match, continue with the diagnostic procedure.

^ If the tires and wheels do not match the certification label, compare tires and wheels to RPO (regular production options) list and set tire to the correct value.

^ If the tires and wheels do not match the certification label or RPO availability, swap known good tires and wheels (as called for by the certification label or RPO list) for the purpose of evaluation only.

^ Set tire pressure to value on certification label.

^ Tire Drift - Swap the front tires from side to side and road test. If the concern is not corrected, continue with the next step.

NOTE:
FOR DRIFT CONCERNS ON VEHICLES WITH REAR LIMITED SLIP AXLES, IT MAY BE NECESSARY TO MEASURE TIRE CIRCUMFERENCE AND PLACE A MATCHED SET OF TIRES ON THE REAR AXLE.

DIAGNOSTIC PROCEDURE # 2 - ALIGNMENT

Refer to Section 04-00 of the Light Truck Service Manual for service details.

Wheel Alignment - Measure the front wheel alignment for out-of-specification vehicles. Align to the "1994 Preferred Alignment Specifications" stated in this article.





1994 PREFERRED ALIGNMENT SPECIFICATIONS

Drive vehicle after alignment is performed.

^ Camber average is defined as the sum of LH + RH caster divided by two (2). Vehicles set to this specification, as measured with the vehicle loaded to normal loading conditions, will result in optimum tire wear.

^ Caster average is defined as LH + RH caster divided by two (2). These are not recommended values for setting. They are only minimum and maximum limitations.

^ CAMBER SPLIT is left camber minus right camber.

^ CASTER SPLIT is left caster minus right caster.

^ Vehicles which exceed the maximum average caster value shown above may result in shimmy concerns.

^ Vehicles operated below the minimum average caster value shown can result in wander and poor steering returnability concerns.

DIAGNOSTIC CHECKLIST

The following checklist should be completed after each step of the diagnostic procedure, where applicable.

DIAGNOSTIC PROCEDURE

1. Tire Mismatch

a. Check tire pressure.

b. Front tires swapped side-to-side.

2. Alignment

a. Toe changed to ___.

b. Caster changed, and split is ___.

c. Camber changed, and split is ___.

3. Miscellaneous








a. Check for loose, damaged or worn parts.

NOTE:
DO NOT REPLACE HEAVY DUTY STEERING GEAR (SPA-EZ OR SPA-FX). THESE HAVE A LARGE SECTOR SHAFT. F4UZ-3504-B WILL NOT FIT.

OTHER APPLICABLE ARTICLES: NONE
WARRANTY STATUS:
Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage

OPERATION DESCRIPTION TIME
942012A Road Test 0.3 Hr.
942012B Diagnostic Procedure # 1 1.9 Hrs.
942012C Diagnostic Procedure # 2 2.2 Hrs.

DEALER CODING
BASIC PART NO. CONDITION CODE
3B440 W6

OASIS CODES: 303000