Wheel alignment angles — basic information (BMW 3 Series E46)

Definitions

1. The suspension and steering setup is characterized by four geometric parameters. All angle values are expressed in degrees (wheel alignment can also be expressed as a linear dimension). The pivot axis is an imaginary line that passes through the suspension strut and, if necessary, continues until it intersects with the vehicle's support surface.

2. Camber is the angle between the line running through the center of the wheel and its contact patch with the ground and the vertical when looking at the wheel from the front or rear. "Negative camber" means that the top points of the wheels are tilted inward from the vertical, while "positive camber" means that the top points of the wheels are tilted outward from the vertical.

3. The front camber angle is not adjustable and is provided for reference. The rear camber angle is adjustable and can be measured using a special indicator.

4. Kingpin caster is the angle between the steering axis and the vertical line passing through the center of the wheel and its contact patch with the ground, when viewed from the side of the vehicle. With "positive kingpin caster," the steering axis is tilted so that it intersects the ground in front of the wheel, and with "negative kingpin caster," the steering axis intersects the ground behind the wheel.

5. The caster angle of the front wheels is not adjustable. This angle can be measured using an indicator. If the angle value differs greatly from that specified in the Technical Data, it is necessary to contact a service station, as this can only be caused by severe wear or damage to the suspension components.



6. Wheel toe-in is defined as the deviation of the plane of the wheel from the longitudinal axis of the car, when looking at the car from above. With positive toe-in, the wheels at the front are turned inward - towards each other. With negative toe-in, the wheels at the front are turned outward - away from each other.

7. Front wheel alignment is adjusted by screwing(or unscrewing) right tie rod end.

8. The toe-in of the rear wheels is also adjustable. The adjustment is achieved by loosening the bolts securing the trailing arm bracket and moving this arm.

Control and regulation

Setting the front wheel alignment

9. To check the toe-in, you need a special device, so the easiest way is to go to a service station. However, you can buy this device in most auto parts stores.

10. To check the toe-in, you first need to purchase a suitable device. There are two types of such devices. The first type of device is designed to measure the distance between the extreme points located on the inner surface of the wheel in its front and rear parts (for a stationary vehicle in accordance with the description above). The second type of device is designed to control the actual position of the wheel contact surface in relation to the road surface (for a moving vehicle). This is done in the following way. The moving tire drags a plate lying on the ground. The plate's movement is recorded on a scale. Both types of devices have their advantages and disadvantages, but when used correctly, each of them gives reliable results.



11. When taking measurements, the steering wheel must be in a position corresponding to straight-line movement.

12. To make the adjustment, apply the parking brake, then raise the front of the vehicle and support it on supports (see "Lifting and supporting the vehicle on supports").

13. First of all, clean the threaded areas on the ends of the steering rods. If they are rusty, etch them with a special compound. Loosen the outer clamps of the boots, wrap the boots and put fresh grease in them. Now the boots will not twist or tighten when turning the steering rods.

14. Hold the steering rod with a wrench and loosen the lock nut on its end. Change the length of the steering rod by turning it. Shortening the steering rod (screwing into the tip) reduces positive wheel alignment.

15. After completing the adjustment, hold the rod and tighten the lock nut to the required torque. If after adjustment the steering wheel spokes are not horizontal while the wheels are in the straight-ahead position, remove the steering wheel and reinstall it (see paragraph 17).

16. After lowering the vehicle to the ground, recheck the toe-in and, if necessary, readjust. Make sure that the boots are not twisted or stretched. If necessary, install new boot clamps (see paragraph 24).

Rear wheel alignment adjustment

Note: Before you begin checking the toe-in, measure the camber angle of the wheels.

17. The procedure for checking wheel alignment is similar to the check for the front wheels (see item 10).

18. If adjustment is necessary, loosen the bolts securing the trailing arm bracket and move the bracket to the desired side. After completing the adjustment, tighten the bolts securing the bracket to the required torque.

Setting the rear wheel camber angle

19. Checking and adjusting the rear wheel camber angle should be done at a specialized service station. However, you can buy suitable equipment at many auto parts stores. For reference, we inform you that the camber is adjusted by loosening the bolts that attach the lower arms to the trailing arms and rotating the eccentric washers. After completing the adjustment, tighten the bolts to the required torque.