Steering/Suspension - Steady State Left Pull/Drift
Article No.98-5A-46
03/18/98
^ BRAKES - PULL OR DRIFT TO LEFT - NEGATIVE
CASTER SPLIT - RADIUS ARM REPLACEMENT -
4X4 MODELS
^ STEERING - PULL OR DRIFT TO LEFT - NEGATIVE
CASTER SPLIT - RADIUS ARM REPLACEMENT -
4X4 MODELS
LIGHT TRUCK:
1988-96 BRONCO, F-150
ISSUE:
A steady state drift to the left or pull to the left while braking may occur on some vehicles. This may be caused by the negative caster split (caster variation with less caster on the left side versus the right side) being out of specification.
ACTION:
Determine vehicle alignment readings. If negative caster split is out of specification (0 +/- 0.4 degrees), select the appropriate right side radius arm to bring caster split back to specification. Refer to the following Service Procedure for details.
NOTE:
CURRENT PRODUCTION RADIUS ARMS HAVE 1.2 DEGREE (BRONCO) OR 1.5 DEGREE (F-150) CASTER BIAS BUILT INTO THE RIGHT SIDE RADIUS ARM. REPLACEMENT OF THE RADIUS ARMS WILL NOT AFFECT CAMBER.
SERVICE PROCEDURE
1. Determine the amount of caster split the vehicle has by measuring the caster of both front wheels on an alignment machine.
2. Subtract the left front wheel's caster figure from the right front wheel's caster figure to determine caster split. If this figure is positive (left side caster figure is smaller than the right side figure), then the vehicle is exhibiting negative caster split and this procedure will apply to the vehicle. Caster split of +/- 0.4 degrees is within specification.
3. Obtain the paint color marking on the right side radius arm (white or yellow).
^ Yellow paint markings represent a caster bias of 1.2 degrees
^ White paint markings represent a caster bias of 1.5 degrees
4. Subtract the caster split figure obtained in Step 2 from the caster bias figure obtained in Step 3. EXAMPLE : If the result from Step 2 is 0.5 degree, and you have a white striped right side arm (1.5 degrees caster bias), subtract the caster split result of 0.5 degree from the caster biased arm of 1.5 degrees. The final result is 1.0 degree.
5. Select a replacement right side radius arm based on your result of Step 4 from the following chart (choose replacement arm which most closely matches your Step 4 result):
6. Install the new right side radius arm. Refer to the appropriate Bronco/F-1 50 Service Manual, Section 04-01B, for service procedure on right side radius arm replacement.
7. Recheck caster and determine that caster split is within specification.
PART NUMBER PART NAME
F6TZ-3A360-AA Radius Arm - RH (0.25 Degree Bias)
F6TZ-3A360-BA Radius Arm - RH (0.50 Degree Bias)
F6TZ-3A360-CA Radius Arm - RH (0.75 Degree Bias)
F6TZ-3A360-DA Radius Arm - RH (1.00 Degree Bias)
OTHER APPLICABLE ARTICLES: 94-20-13, 98-5A-39
SUPERSEDES: 95-25-9
WARRANTY STATUS: Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage For 1993-96 Model Years, Basic Warranty Coverage For All Other Model Years
OPERATION DESCRIPTION TIME
985A46A Replace Right Radius Arm 1.5 Hrs.
And Check Alignment
DEALER CODING
CONDITION
BASIC PART NO. CODE
3405 W6
OASIS CODES: 301000, 303000