The steering wheel in your car is not the only part involved in making your vehicle's wheels (and your vehicle) point in the desired direction. There are a number of components working together between the steering wheel in your hands and the tires on the road to make driving possible.
There are a number of different types of steering. In this article we will examine the two most common. Modern passenger vehicles are likely to have rack-and-pinion steering, while older vehicles and some trucks may use recirculating-ball steering. Other components like power steering and suspension also do their part to make steering easier, safer and more efficient. But first, let's see what you have to do turn a car. It's not as simple as you might think!
In order for your car to go round a corner, each wheel must follow a different circle and the wheels actually point at slightly different angles. The inside wheel must turn tighter (and slower) than the faster moving outside wheel. It is the steering linkage that makes the inside wheel turn more sharply than the outside wheel and hence makes steering possible.
Rack-and-pinion steering is the most common type of steering on cars, small trucks and 4WDs. It works via a small gear (pinion) that moves left and right inside a metal tube (rack). The rack is connected to the cars wheels via a rod, called a tie rod.
The main purpose of the rack-and-pinion is to convert what you are doing with the steering wheel inside the cabin into a corresponding movement of the cars wheels. Rack-and-pinion steering makes turning the cars wheels easier by using a reduction gear. It generally takes the driver three to four complete revolutions of the steering wheel to make the wheels turn from left to right.
A vehicle's steering ratio refers to the relationship between turning the steering wheel and the distance the wheels turn. For example, if the driver of the vehicle turns the steering wheel one complete revolution (360 degrees) and car turns 20 degrees, then the steering ratio is 18:1 (360 divided by 20). The higher the ratio the more you will need to turn the steering wheel to get the wheels to turn. The one benefit of a high steering wheel is that the wheels will be easier to turn because a higher gear ration is used.
In practice, cars that are lighter or sports cars will have a lower steering ratio in order to give the steering a quicker response. In trucks where the load makes turning the wheels more difficult, a larger steering ration will generally be used.
Here are a couple of examples that may help to diagnose steering problems. NRMA MotorServe is fully equipped to help you get on top of steering problems, simply call 1300 880 294 to speak with our customer service team.
1. If you have to constantly adjust the steering wheel while trying to drive straight down the road then you most likely have a worn steering components. To pinpoint the problem you will need to raise the vehicle with a suitable jack and stands to check for the loose part. You can do this by turning the wheel back and forth by hand with just a little movement. If you require assistance you can bring the car into NRMA MotorServe and we can take care of it for you.
2. If your vehicle seems to jump or drastically steer to the left or right when you hit a pothole then you may have ball joints that are worn (loose). Note: the following can be dangerous if performed incorrectly, you may want to leave this to a qualified mechanic. To check ball joints jack up the front of one side of the vehicle and use a bar under the tire to move the tire back and forth while someone else watches for play in the joint.
3. If your vehicle suddenly becomes hard to steer requiring additional effort on your behalf, then most likely there is a problem with your power steering. The power steering system may have a leak and be low on fluid or the pump itself may have failed. If the system is just low on fluid try to pinpoint the leak, it may just be a line that can easily be replaced. If there are no leaks, the system is full of fluid but the power steering pump is noisy, then you will most likely need to replace the pump itself.
4. Lastly to help decrease steering problems check your power steering fluid regularly, at least at every oil change. If the steering linkage has grease points make sure you give those some attention at oil change time as well. Don't let a steering problem go for too long, especially if there is play in the steering wheel. NRMA MotorServe performs a visual check and top up of vehicle fluids as part of our 40-point safety check, to book simply call 1300 880 294.