Wheel alignment

The wheel alignment is a method described in the car repair shop , is applied to the wheel geometry of a motor vehicle to check and adjust if necessary.

A mechanic doing the wheel alignment

If the steering wheel of a vehicle is tilted or the car is pulling to the right or to the left, there is often something wrong with the vehicle axis. The angle of the wheel suspension can change over time or through the driving style of the driver. Example: A car with correctly adjusted chassis hits the curb in a sharp left turn. The result: when driving straight ahead, the steering wheel is clearly tilted to the right. Now the workshop is challenged; she has to re-measure and adjust the chassis.

Causes for a shifted wheel geometry can also be accident damage or wear. Worn bearings and loose-vibrated screws can change the installation position of the motor. This in turn affects the position of the transmission , cardan shafts and rear axle center piece in relation to one another. The kink angles can lie outside a defined tolerance margin. Driving noises occur as a result of increased friction between the individual drive train components and, possibly, power losses. In addition, the tires are worn on one side, as indicated by improper tire pressure even or not the vehicle bills to be removed tires is favored. This phenomenon occurs particularly frequently in the commercial vehicle sector , in particular after the load has swayed after insufficient load securing . After all, 70 percent of the complaints about uneven tire tread wear come from there .

Particularly cost-conscious drivers who use inexpensive imported tires need optimal settings for the steering wheel and chassis. Since their tires are often designed for left-hand traffic, they wear out particularly intensively in countries with right -hand traffic . That's because even a road that seems to be perfectly flat isn't. In fact, it usually has a four percent roll. In addition to other factors, this means that tires are worn unevenly and, as a result, driving behavior and driving comfort suffer. Eventually the opposing forces increase. The optimal setting of the steering gear is therefore very important.

Problems with the chassis can arise on the front axle with single and total lane, based on the geometric travel axis, wheel camber , and with wheel offset, based on the left front wheel. If problems occur, caster , spread and track difference angle must also be measured. The track, camber and driving axis angle must be checked on the rear axle. The power steering on the drive axle should not be neglected either.

In the past, wheel alignment, which was carried out with mechanical pendulum devices, often caused great difficulties in workshops because of the lack of precision. Often it was measured subjectively, and empirical values played a major role where there was a lack of objective measurement data. Today, however, measurements are carried out electronically, as quality assurance standards can also be complied with. Often there were also difficulties with the level of the measuring station, usually a lifting platform: The height level right to left has a direct effect on the fall measurement, from front to back on the caster measurement. Today, a wheel alignment station should be exact in order to get a correct result. Therefore, mostly certified headlight parking spaces are used, which are located on measured, level ground or a 4-post lift or scissor lift.

Today, the use of inclination measurement is considered by automotive experts to be the only effective means of correcting wheel alignment. For ten years now, the measurement method has proven itself at well-known vehicle manufacturers . With the inclination measurement, you can also solve warranty cases where tires are worn unevenly and other measurement methods no longer continue. The automotive specialists now use electronic measuring devices, the use of which saves up to 70 percent of workshop time compared to conventional mechanical methods. There are different wheel aligners: optical, CCD and 3D. Such an inclination angle measuring device only needs to be applied to a single measurement point per wheel, i.e. only four measurement points on the entire vehicle. The angle of the wheel suspension is recorded. If this angle is readjusted, the coordination should be optimal again, whereby optical wheel aligners are more prone to errors than more modern CCD and 3D wheel aligners due to the lack of technical adjustment aid. When measuring, adapters are used as required to prevent the measuring sensor from being positioned at an angle and thus incorrect values being determined. In addition to the time savings, a great advantage of these measuring devices is not only their precision , but also the fact that they can save recorded measured values . The car mechanic can then transfer these values to a measuring computer and also document the measurement by printout .

Depending on the design, such hand-held measuring devices can record more than just the angle of the wheel suspension. Several measurement methods are possible with just one device: The chassis level can be recorded - with the help of adapters, the device measures angles both in the direction of travel and across the direction of travel or the articulation angle.

In conjunction with the inclinometer, a steering wheel scale is particularly helpful for wheel alignment. Up to now, spirit levels were common, but the latest models also work electronically. They are equipped with an electronic torque pick-up and allow the chassis to be adjusted to the straight steering wheel. In this way, on the one hand, the lateral drift of a vehicle can be conclusively proven. On the other hand, by fine-tuning the chassis, it is also possible to reduce the forces that act on the driver's arm when steering. The play of the handlebar or the steering wheel must of course also be taken into account. With these electronic steering wheel scales you can even save measured values during a test drive and read them out later via USB . Adapters are usually not necessary here, because better scales are provided with a universal bracket with two stop rollers that fit on every steering wheel.

Web links

Individual evidence

↑ Thomas Vauderwange: wheel alignment , Bird book publishing, Würzburg, 2011