Thrust Angle and Vehicle Alignment
A vehicle's thrust angle affects its steering wheel position. The thrust line should line up with the vehicle’s geometric center line. Check this angle if the vehicle has been in a collision. There’s a difference in repair procedures depending on the vehicle's suspension system. A solid axle is checked for axle offset. Independent suspensions are adjustable and require rear toe adjustments to correct an incorrect thrust angle.
Since front wheel drive cars are more prominent than rear wheel drive, four wheel alignments have become the norm. When performing a four wheel alignment, the thrust angle must be checked and corrected before the front end alignment can be performed. Inspect the vehicle for collision damage and rear toe.
Axle offset occurs when the rear axle cocks sideways, causing both rear tires to point in the wrong direction. Like a forklift, if the rear tires point to the left, the vehicle will steer to the right. This condition is typically caused by a broken leaf spring center bolt or problems with the shackle. On vehicle’s with trailing arm suspension, worn or damaged bushings, or a bent arm can cause a noticeable pull in the steering wheel.