TECHNICAL TIPS

"I have good alignment readings & my truck/car still pulls-what do I do now?"

Application: Pickup Trucks/ Cars

Background: We get this question several times a week from the Tech Line.

By: Jim Berry

Bulletin:
There are several possible problems that can cause a pull. What you must do is to approach the problem logically & eliminate the possible causes one at a time.

1. Did you switch the tires & look for abnormal tire wear from side-to-side? (Even new tires can have a definite pull.)
2. Did you perform a 4-wheel alignment? The 4-wheel or thrust alignment will indicate related problems such as excessive thrust, setback problems.
3. Did you do a toe-out on turns? Look for readings that are not the same from side to side. In a turn the outer tire always steers a smaller angle than the inner tire. There should not be more than one or two degrees difference in similar readings. This would indicate a bent steering arm or some other component.
4. Ask the customer for a little background on the vehicle: Was it ever in an accident? Has it always pulled? Has the pull gotten worse? When? (would indicate a wear-related problem)
5. Look for physical causes such as a bent frame, loose crossmembers (look for rust around the rivet heads), brake drag, loose parts, etc.
6. Remove the tie rods from the steering arms & raise the vehicle.
7. Steer the tires by hand. Look for excessive force needed to turn the tires; "notchy" feel or "catching" while turning; & especially any difference between sides. This would indicate a ball joint or strut bearing problem.
8. Next (for power steering-equipped vehicles) hook up your exhaust hoses & start the vehicle in "neutral". Run the engine up a little (2000-2500 RPM) & look for any movement of the steering box or rack. Movement of the steering indicates a "neutral valve" problem in the rack or box. (On vehicles with a steering box, remove the linkage from the pitman arm for a more accurate indication of the neutral valve condition. You can hook a "fish scale" into the steering arm hole for a more accurate turning force measurement. Chevy or Ford pickups require about 25-30 pounds & Dodge pickups about 30-35 pounds to steer the tire.)
9. If there is still no answer, isolate the brake. If the vehicle is pulling to the right "backset" the left hand caliper & clamp off the hose. Very carefully drive the vehicle to see if the pull is gone. If the car no longer pulls, it is that brake.
10. Do not overlook the rear brakes. A dragging rear brake will have the same effect as a front brake.
11. On the I-beam Ford trucks you may need to increase the caster offset to correct a pull. The older trucks may require up to a 2 degree caster spread to correct a pull.

RDTSB/02/002
Issue Date:
March 15, 2002