He Also Took A Tape Measure And Did The Work Of Four-Wheel Alignment

With regard to the deviation of the vehicle and the abnormal wear of the tires, the first thing we think of is the deviation maintenance of the four-wheel alignment parameters. Wuhan Junge used a tape measure to repair the deviation maintenance of an Iveco daily closed truck a few days ago.
Let’s take a look at this case. This car is a “quasi new car” that has only driven 20000 kilometers. The fault phenomenon is that the vehicle deviates to the left when driving, and the tire wear is serious.

According to the routine, Junge first pulled the toe in of the car, and the toe in value did not exceed the standard range; Then support the front wheel, shake the front wheel, check the clearance between the bearing and the suspension ball joint, and no abnormality was found deviation maintenance.
Because Iveco daily light vehicle adopts torsion bar spring double wishbone suspension, and there are more suspension hinge joints than the overall bridge, the military brother and his partners measured the wheelbase and found the problem: the wheelbase of the wheels on both sides is more than 1cm different.

Lift the car with a lift and check the suspended ball joints, pull rods and swing arms deviation maintenance. It is found that the pull rods of the lower swing arms are not right, the ball head lock nut has been completely separated from the ball head, and there is no abnormality in the appearance of other positions.

The pull rod with abnormal appearance is removed and compared with the standard new part, the length is obviously much longer than the new part. Replace and adjust the length of this tie rod, and adjust the toe in strictly according to the standard, and eliminate the deviation after test run.
For front independent suspension vehicles, the probability of deformation of swing arm tie rod and other parts under the action of external forces such as road impact is much higher than that of integral bridge, so more attention should be paid to driving and daily deviation maintenance.

This is the schematic diagram of the suspension swing arm from the front direction. The hinge points of the steering knuckle (sheep horn shaft) and the swing arm constitute the equivalent steering kingpin of the double wishbone suspension.
From the top view, the ball head of the upper swing arm is inward and backward relative to the ball head of the lower swing arm, which constitutes the inclination angle and caster angle of the kingpin.
The inclination angle of the kingpin is to solve the automatic alignment of the wheel deviation maintenance.From the side, the kingpin is in this position.

After the lower swing arm pull rod becomes longer (green represents the longer pull rod), the lower swing arm with triangular structure will deform, so that the ball head of the lower swing arm will move towards the rear of the vehicle.
From the side view, it will be found that the caster angle of the kingpin decreases, so the automatic return ability is greatly weakened. Therefore, the steering knuckles on both sides connected by the tie rod will be pulled to the other side with normal automatic return.

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