Torque Steer Diagnostics and Repair Procedure – 2018-2019 Subaru STI

NHTSA ID Number: 10164445

Manufacturer Communication Number: 04-25-19R

Summary

“The primary focus of this bulletin is to provide a procedure to follow when diagnosing a customer concern of Torque Steer, defined as a pulling condition to either the left or right when under full acceleration which requires a somewhat greater than standard correction of steering wheel input from the driver to counteract. As part of this diagnosis, it will be necessary to first eliminate two other conditions a customer may misinterpret as torque steer. These are: Steering Pull and Steering Off-Center. This will prevent incorrect or over-repair, both of which can negatively impact customer satisfaction. This bulletin applies only in cases where the original factory equipment wheels, tires, and all suspension components are currently installed and, the outlined condition is confirmed to be present.

 

2 Affected Products

Vehicle

MAKE	MODEL	YEAR
SUBARU	WRX STI	2018-2019

 

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INTRODUCTION:

The primary focus of this bulletin is to provide a procedure to follow when diagnosing a customer concern of Torque Steer, defined as a pulling condition to either the left or right when under full acceleration which requires a somewhat greater than standard correction of steering wheel input from the driver to counteract.  As part of this diagnosis, it will be necessary to first eliminate two other conditions a customer may misinterpret as torque steer.  These are: Steering Pull and Steering Off-Center.  This will prevent incorrect or over-repair, both of which can negatively impact customer satisfaction.  This bulletin applies only in cases where the original factory equipment wheels, tires, and all suspension components are currently installed and, the outlined condition is confirmed to be present.

 

SERVICE PROCEDURE / DIAGNOSTIC INFORMATION:

Definition of Terms:

• Torque Steer: A pull to either the left or right during full acceleration (high engine torque) which requires a somewhat greater than standard steering wheel input from the driver to counteract and keep the vehicle moving straight ahead.
• Steering “Pull”: A tendency for the vehicle to pull or “drift” to the left or right while at speed (not under acceleration) and holding the steering wheel straight ahead.

Steering wheel position is neutral (straight ahead) but vehicle pulls or drifts to the right (or left).

• Steering Off-Center: The steering wheel must be held at slight angle to keep the vehicle going straight.

Some examples of factors which can contribute to any of these conditions (not a complete list):

• Crowned road (slight slope) toward shoulder
• Remaining cornering force of tire (tire conicity or ply steer)
• Mismatched or unevenly worn tires
• Alignment out of proper adjustment
• Worn / damaged suspension component(s)
• Collision / suspension damage repairs not performed properly or to OEM specification.

 

DIAGNOSTIC PROCEDURE FOR TORQUE-STEER CONCERNS:

 

Step 1-  Confirm the tire pressures are set to specifications; 33 PSI front and 32 PSI rear and verify all tires have no uneven / irregular treadwear or damage which could contribute to a pull or drift condition.

 

Step 2-  Road test the vehicle following a normal driving pattern and confirm if the condition is a result of steering wheel off-center or steering pull as outlined in the Service Procedure section above.

• If steering pull or steering wheel off-center condition is found, address through standard adjustments as found in the applicable Service Manual. The balance of this bulletin does not apply. Additional information on these conditions can be found in TSB 14-19-17.
• If Torque Steer is confirmed, proceed to Step 3 using a roadway as outlined in the NOTE

NOTE:  Before proceeding, identify a SAFE location to perform this testing.  The road surface should be flat and smooth as possible with a minimal (if any) “crown” which could contribute to a steering / vehicle drift toward the shoulder.  The roadway will also need to be lined as shown in the illustration below.  Alternatively, an empty parking lot free of obstacles and lined for parking may also be suitable as the test acceleration distance is relatively short.  The less amount traffic in the selected test area the better.  The lines will be used for measurement reference when necessary.  When using a public or private roadway, at no point should the center line ever be crossed.  Always remain in the lane of travel.  Vehicle control must always be maintained.  Identify markers (e.g. posts, trees or even use traffic cones) to signify a “test zone” 100 meters (330 feet in length).  Keep in mind, there

needs to be enough room prior to entering the zone for the vehicle to accelerate up to 40 MPH in fourth gear and after the zone to safely stop.  SAFETY IS KEY!

 

Step 3- Print out and review a copy of Appendix A found on page 7 of this bulletin.

NOTE: This worksheet is to be use for Torque Steer concerns ONLY.

 

Step 4- Using properly calibrated 4-wheel alignment -capable equipment, perform a complete 4-wheel alignment using the following specifications:

○ Camber:  Identical (no difference between) left and right camber angles

○ Front Toe:  0.13 degrees on each side ○ Rear Toe:  0 degrees on each side.

IMPORTANT:  These specifications are different than those supplied in the 2018 and 2019MY STI Service Manual. Always save a copy of the Before and After alignment print outs as part of the claim documentation.  Examples are provided below.

When complete, road test the vehicle to confirm the repair.

• Has performing a 4-wheel alignment corrected the condition and does the vehicle now operate within the specifications outlined in Step 2?

YES-  Repair procedure is complete.  Proceed to the Warranty / Claim Information section for claim submission information. Save a copy of the Before and After alignment print outs as part of the claim documentation.

NO-  Follow the Step 5 procedures below.

 

Step 5- Complete the Appendix A Torque Steer Evaluation worksheet.

REMINDER: A copy of the completed worksheet, Before and After 4-wheel alignment print outs and a copy of the Repair Order are required to be retained for claim documentation.

• If after performing the alignment 4-wheel using the specifications listed above, the Torque Steer condition remains and exceeds the specifications listed, tires may be ordered through the Subaru Tire Center to correct this condition.
• After completing the worksheet, use the Subaru Tire Center found on Subarunet to order a set of four (4) tires, part number Use the Subaru Tire Center Part Number order field as shown below when making this order.

IMPORTANT:  Only tires ordered through the Subaru Tire Center may be claimed for repair outlined in this bulletin.

• Once the 4 new tires are received and installed, road test the vehicle again using the evaluation process outlined in Step 2.
• If the vehicle is now within the Torque Steer specification, the repair is completed. Proceed to the Warranty / Claim Information section for claim submission information.
• If the Torque Steer condition remains even after tire replacement and confirmation of alignment using que Steer the specifications listed in this bulletin, contact your FSE for further assistance.

 

HANDLING OF REPLACED TIRES CLAIMED TO SOA:

NOTE:  The procedures listed here are specific to this Service Bulletin and not applicable to any other claimed repairs.

All tires replaced and claimed to SOA must have a hole drilled through both sidewalls near the

D.O.T. number.  Retailers may at their option, either hold these tires for normal scrapping or if space is constrained, perform the following procedure:

• Clearly mark each tire near the D.O.T. number with a tire crayon indicating the position it was on the car (LF, LR, RF, and RR).
• Drill at least a ¼ inch hole in both sidewalls of each tire with one of the holes located next to the D.O.T. number and crayon position location lettering.
• Take a photo of each tire showing the D.O.T. number and the drilled hole, and a close-up of the Repair Order showing the RO Number and VIN.
• Print and Save these photos along with the Repair Order hard copy as part of the repair documentation as copies may be requested by the Claims Team.

Appendix A-  Torque Steer Evaluation Worksheet

REMINDER:  This form must be COMPLETED (including ALL before and after measurements).  Copies of the Before AND After printouts are required as part of claim documentation for any tire replacement claimed to SOA.

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NUMBER: 04-25-19R
DATE: 04/25/19
REVISED: 08/28/19

https://www.nhtsa.gov/recalls?nhtsaId=10164445

https://static.nhtsa.gov/odi/tsbs/2019/MC-10164445-0001.pdf

 

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