Steering/Suspension - Pull Or Drift Diagnostic Info
Date: November 21, 2011
DIAGNOSIS OF VEHICLE PULL (DRIFT) AND STEERING WHEEL OFF CENTER
The General Procedures linked if you are using a internet copy of this bulletin has been amended. Please discard previous versions of these General Procedures.
APPLIED VEHICLES: All Nissan - except GT-R
If a customers reports their "vehicle pulls" or the "steering wheel" is off-center, use the Diagnostic Flow Chart above and the other information in this bulletin to diagnose and correct the issue
Determine if the vehicle has a pull or steering wheel off-center issue that requires repair.
If the vehicle has any tire issues, such as:
Tires that are different sizes (except when specified from the factory)
Significant difference in the amount of wear between any of the tires
Any other tire irregularity or damage to any tire
Replace the tire(s) or use known good tires from another vehicle for all road tests and diagnostics in this bulletin.
Make sure tire pressure is set to the correct specification.
1. Install the following measuring tools on the vehicle:
Steering Wheel Offset Gauge
Road Crown Gauge
Refer above for a description of these tools and an explanation of their use.
2. Obtain a watch with a second hand (preferably a stopwatch) to use during the road test.
3. Take the vehicle for a road test and confirm the customers concern.
Select a flat road where the vehicle can be driven in a straight line at a preferred speed of 60 mph.
During the road test make sure the vehicle is pointing straight. Don't worry about steering wheel position during the road test.
If you adjusted the tire pressure or changed the tires before the road test, the issue may have been resolved.
If there are cross winds strong enough to affect the vehicle's straight line movement, then diagnosis cannot be performed.
4. Determine the vehicles issue - refer to the definitions of "Pull" and "Steering Wheel Off-center".
5. When the road test is completed, remove the Road Crown Gauge, leave the Steering Wheel Off-Set Gauge in place until the Service Procedure is complete.
6. Refer to the Flow Chart for the next step.
Other Service Information
Customers may report that their vehicle's steering wheel is "off-center" because the steering wheel spokes are tilted to the left or right when the vehicle continues straight ahead on a straight flat road (see example in Figure 1).
If a vehicle's steering wheel spokes are slightly off center while driving straight, it may be the normal result of road crown. Most roads in the United States are built with a "crown" to help rain water drain from the road surface. The slope of the road crown varies from place to place.
Vehicles have a natural tendency to drift to the low side of the crown. The greater the slope of the crown, the faster the vehicle will drift in that direction.
Tires and vehicles are designed to counteract the effect of typical road crown, but may not fully counteract the effect of a highly crowned road.
Some freeways slope to both the left and right from the center. When driving on a freeway that slopes in both directions, a vehicle may exhibit a small amount of drift to the left when driving in the left lane and a small amount of drift to the right when driving in the right lane.
This bulletin does not address road crown issues because they are not vehicle related, although the customer may incorrectly perceive them to be.
Description/Definition of Steering Wheel "Off-center" Condition
The steering wheel spokes are tilted to the left or right more than allowable (see example in Figure 2) when driving straight ahead on a straight flat road.
Allowable specification for steering wheel off-center
All Nissan (except NV1500, 2500, and 3500): 2 mm or less.
NV1500, 2500, and 3500: 4 mm or less.
When driving straight on a highly crowned road, the steering wheel may be turned (off-center) to counteract the affect of the road crown. When road testing for an off-center condition, the vehicle should be driven on a straight flat road.
Although the vehicle does not pull in either direction, the customer may perceive that the vehicle pulls because it will respond if he or she tries to bring the steering wheel back to center. This condition can occur if the tie rod length is uneven (not adjusted correctly) from side to side.
Description/Definition of a Vehicle "Pull" Condition
The vehicle consistently drifts to one side while driving at a constant speed on a straight, flat road.
A vehicle is said to "pull" if it completes a lane change in less than 7 seconds (with no steering correction from the driver) when driving at 60 MPH on a road with less than 2 degrees of road crown slope. All four wheels must pass into the other lane during this time (7 seconds).