A vehicle that leans to one side is unsightly. Leaning can also affect tire wear, handling and wear to the suspension. Diagnosing the cause of leaning is not difficult, but it requires a structured approach.
The first step in identifying the cause of a leaning vehicle, is to measure the extent of the problem. Tire pressure and size should be carefully checked before proceeding. Make sure all tires are the same size and the air pressure is equal, within one PSI.
A measurement can be taken with a tape measure to learn the amount the vehicle is leaning. The center of the wheel opening to the ground is a good reference.
The height from the four wheel openings to the ground is measured and recorded. This should be carried out on a flat and level surface. Height variations from front to rear are normal on many vehicles. Height differences front to rear are often a part of styling and unless the appearance is unusual, are usually not a problem.
Differences in height, from side to side, should not exceed half an inch (13MM) and the less difference the better. If the vehicle leans more than half an inch in the front or rear, the problem is worth addressing.
The most common causes for a leaning vehicle include:
a binding shock absorber or strut
a bad spring or torsion bar
bent suspension parts
a twisted chassis
A binding shock absorber or strut will normally be felt as a very rough ride. Each corner of the vehicle should travel freely up and down when pushed with hand pressure. If one corner feels much harder than the other three, a binding shock absorber or strut might be suspected.
The shock absorber or strut can be removed for inspection if needed. Struts and shock absorbers are designed to resist motion, but not support weight. The shaft can be pushed in with hand pressure. If not, the shock or strut should be replaced, along with the one on the opposite side of the vehicle. Worn shocks and struts will not cause a vehicle to lean, unless they are also binding.
Many vehicles are equipped with torsion bars and are adjustable. A screw type of mechanism can be adjusted to change the height of the vehicle. Often a proper adjustment of the torsion bars will level the vehicle. Having the wheel alignment set is important, whenever vehicle height is adjusted. Even very slight changes to vehicle height will drastically affect wheel alignment.
Coil springs are generally not adjustable and can also cause a vehicle to lean. Determining if the problem is caused by the front or rear spring can be difficult.
A good way to isolate which spring is at fault is to raise the rear wheels off the ground. The rear of the vehicle should be supported as near the center as possible. This forms a three-point mount, which is self leveling. If the vehicle is now level in the front, the problem is in the rear. The front continuing to lean, suggest the problem is more likely in the front.
Accurately testing springs can be very difficult. Swapping the springs from side to side is an option, when they are the same design. The vehicle leaning in the opposite direction after swapping suggests a bad spring.
Suspension parts and chassis measurement is a specialty, best reserved to a shop equipped to accomplish the task. If the vehicle continues to lean after the above checks, the problem is likely to be in one of these areas. A good frame and alignment shop can measure the vehicle and correct any problem in this area.
Once returned to level and properly aligned, the vehicle will be more stable, ride better and not wear tires. A leaning vehicle does not have to be tolerated. AGCO can set you straight.
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