The Steering System in Your Car: Common Malfunctions and Maintenance

So far, this module has discussed the vehicle systems responsible for providing power to your car. Now, it is time to learn about the maintenance and operation of two other essential systems, which allow you to control the vehicle’s direction of travel and connection with the roadway. The car’s steering and suspension are two distinct but closely related systems, which are often referred to together.

The steering system connects the steering wheel in the passenger compartment with the front wheels of the vehicle. The rotational force you exert on the steering wheel inside the car is transferred down the steering column and converts into a swiveling motion, which pivots the vehicle’s wheels to the left or right, directing the vehicle across the roadway. The suspension system includes tires, springs, shock absorbers and linkages, which work together to maintain a strong connection between the wheels and the road. It also allows for relative movement between the vehicle and the wheels, to ensure a smoother driving experience.

Let’s delve a little deeper into the component parts of the steering and suspension systems, to find out how they work together to keep you in control of your vehicle.

The steering column

Your vehicle’s steering wheel is connected to the front axle of the car, via a long metal shaft called the steering column. In early road vehicles, the steering column was essentially a solid metal pole. If a vehicle with a single-piece steering column is involved in a head-on collision, the driver may be impaled on the steering column. For this reason, modern vehicles are built with telescopic steering columns that collapse in on themselves (like a telescope) in the event of a head-on impact.

The steering column itself is resistant to wear and damage, though issues can occur with the gears and bearings housed within the steering column, or in the mechanism connecting the column to the forward axle. Unusual sounds and resistance when turning the steering wheel are both common indications of a problem within the steering column.

The steering gearbox

A gear mechanism connects the base of the steering column to the vehicle’s front axle. The rack and pinion gear system is most commonly used in small to medium-sized cars, though other steering gearbox designs may be found in older, or larger vehicles. The gear mechanism’s job is to convert the rotational movement of the steering wheel into lateral movement in the axle, to pivot the wheels. It also reduces the amount of steering wheel movement necessary to turn the wheels to the desired angle. Before such systems existed, cars had extremely large steering wheels that connected directly to the front axle and required a great deal of effort to turn.

In the rack and pinion system, a circular pinion gear lined with teeth is fixed to the base of the steering column. The teeth on the pinion gear lock into a row of teeth on a horizontal rack, which connects to the front wheels at either end. When the steering wheel turns, the pinion moves the rack laterally, pivoting the front wheels toward the left or right.

Power steering

All new vehicles (and most modern cars built over the past couple of decades) feature a power steering system. The power steering system includes a hydraulic piston and motor, powered by the vehicle’s engine, which supplies the brunt of the energy required to turn the car’s wheels. Power steering reduces the driver’s physical workload, allowing for easy direction changes with small, gentle turns of the steering wheel. Prior to power steering, turning the steering wheel in heavier vehicles demanded considerable physical strength.

Your vehicle’s power steering hydraulic pump relies on fluid to operate. If a leak in the system causes power steering fluid levels to drop, your steering may become heavier and less responsive. Most vehicles require a power steering fluid replacement approximately every four years, or every 30,000 miles traveled. You can find the recommended replacement frequency for your car in the vehicle owner’s handbook. Power steering fluid replacements should only be handled by a qualified mechanic, as it is important the process is carried out correctly.

Suspension

The vehicle’s front wheel suspension system is directly connected to the steering system. The two mechanisms must work in harmony, for the driver to maintain control of the vehicle. While the steering system is responsible for directing the vehicle, the suspension’s three main jobs are:

• Supporting the vehicle
• Absorbing the force of impact from potholes, bumps and uneven roadway surfaces
• Allowing the steering system to respond appropriately to the driver’s input, namely by maintaining traction between the tires and the roadway

Most modern vehicles feature a strut suspension system which is comprised of two components: springs and shock absorbers. Other suspension systems also use springs and shock absorbers, though they are positioned separately. In a strut suspension system, a cylindrical shock absorber runs down the center of a spiral-shaped spring, which connects the wheel rack to the body of the vehicle, beside each wheel. The spring’s job is to support the weight of the vehicle while ensuring it moves smoothly over large bumps and dips in the roadway. The shock absorber serves to cancel out vibrations that would otherwise be transmitted to the passenger compartment, and prevent the vehicle from bouncing on its springs following bumps in the road.

While most of the “action” in your car’s suspension occurs in the springs and shock absorbers, the system also includes the wheels and tires, plus various joints, bearings and linkages which connect it to the steering rack. Over time, these components will be subject to wear and will eventually need to be replaced.

Steering malfunctions

If you notice any irregularities with your vehicle’s handling, it could be that one of the steering or suspension’s component parts is wearing out, or malfunctioning. You may be able to figure out what is amiss based on these common malfunction symptoms:

1. 1

   The steering wheel feels stiff.
   This may indicate low power steering fluid levels.

2. 2

   The steering wheel feels loose.
   This could be the result of wear to your steering gear system.

3. 3

   Erratic steering response.
   This warrants immediate servicing by a qualified mechanic. Erratic steering generally indicates a serious problem, which may originate anywhere in the steering and suspension system.

4. 4

   Squealing noise when you start the car.
   Most commonly, this indicates something amiss with the power steering belt.

Steering and suspension maintenance

Most major steering and suspension maintenance tasks must be carried out by a mechanic. Your vehicle owner’s manual will detail a recommended frequency for each service activity. Typically, this includes:

1. 1

   Checking wheel alignment.
   This should be carried out approximately every two years, or every 30,000 miles driven. Wheel realignment may be required more often if you spend a lot of time driving on bumpy or unevenly surfaced roads, as this increases the impact to your steering and suspension system.

2. 2

   Inspecting shock absorbers, bearings and joints.
   Whenever you take your vehicle in for a service, the mechanic should routinely check these components for damage and signs of wear.

3. 3

   Checking the power steering belt and hydraulic fluid.
   This routine maintenance task should be carried out by a mechanic roughly every 5,000 miles. The fluid typically needs a complete replacement every 30,000 miles – your owner’s manual can advise you.

In addition to the tasks listed here, you can help keep your steering and suspension system in safe working order by looking after the vehicle’s tires. Maintaining proper tire pressure and replacing tires when the tread wears down is essential. Otherwise, all other aspects of the steering and suspension system will not be able to work effectively, and the vehicle may become unsafe to drive.