Common Power Steering Issues -Vehicle Darting and Wandering

Welcome to the first of a series of posts discussing common power steering issues, keep your eye out for future posts.

In this post we will discuss 2 real world problem which can be related to a vehicles power steering system, Darting and Wandering.  Each of these problems will be making the vehicle more difficult to drive, increasing driver fatigue and are likely to be increasing wear and tear on the vehicle.

Vehicle Darting

Vehicle Darting, often described as over-steering by drivers, is described as a delay in steering response followed by a sudden response can be a serious challenge for drivers. Think of a driver changing lanes, a appropriate level of right hand lock is applied to the steering wheel, there is no response by the vehicle. The driver increases the amount of right hand lock and suddenly the vehicle responds darting across the road causing the driver to have to work to bring the vehicle back under control.

There are many common causes of vehicle darting, but typically it is due to a partial seizure in the steering system. This can be any part of the steering system including the steering gear, king pins, universal joints and even poorly lubricated turntables.

UV Joints can be cause of darting and wandering problems in commercial vehicles

Check out our article Turntables can be a cause of steering problems for more information on poorly lubricated turntables.

The delay in vehicle response is due to the hydraulic assist up enough force to overcome the seized elements of the steering system. The hydraulic assist is proportional (via the torsion bar) to the difference between the steering wheel position and the road wheel position. I.e. when small movements occur on the steering wheel there is a low level of hydraulic assistance provided.

Vehicle Wander

Vehicles suffering from wander are difficult to hold in a straight line, the driver is continually having to adjust the steering to keep it moving in a straight line. There are many causes of wander, including excessive caster, loose or worn steering linkages and worn steering gears.

Excessive Caster

Excessive caster will cause the steer wheels to aggressively follow the road camber, even to the point of pulling the vehicle down into the depressions caused by traffic on the road. This will cause the vehicle to wander across the road making the driver work hard to control the vehicle.

Worn Steering Linkages and Gears

Worn steering linkages and steering gears will allow the steer axle wheels to change lock of their own accord. As the wheels interact with the road the linkages will be moving around on the clearance which has developed in the linkages and steering gears. The driver will be forced to continually adjust for this wander caused by these random changes in the steering system.