People love their cars. We couldn’t do without them. But have you ever thought about how cars go where you want them to go? The whole system of steering is officially called the Steering Linkage Mechanism / System. But here in South Africa we simply call it the Steering Rack.
Most cars have 4 wheels, plus a spare wheel and more often than not, a steering wheel too. (Believe it or not, we have seen cars without a steering wheel.)
The Steering Rack: A Simple Concept
Steering a car is a simple concept. Turn the steering wheel and the car goes in that direction. Simple for us, but beneath your foot pedals is a marvelous array of intricate little links, connections, bobbles and bits that make it possible for you to take your car (and yourself) wherever you want to go.
The steering system is what makes it all possible. Your steering mechanism consists of an array of linkages and gears that ultimately connect the driver to the wheels. Most vehicles only have a steering system designed for the front wheels to turn in response to the steering wheel, while the back wheels just “go with the flow”.
The genius in the steering system is that when you turn, the front wheels have to turn at a different angle because one wheel is closer to the direction you’re turning in than the other one is. To think all of this was invented more than a century ago.
Time for some maths: what’s the steering ratio? The steering ratio is defined as the difference between how far you turn your steering wheel and how far the wheels of your vehicle turn during one rotation of the steering wheel. Yes, that’s a mouthful, but it’s an important concept to remember.
Calculating Steering Ratios
As you turn the steering wheel, the wheels should turn too, when they don’t, that indicates a high steering ratio. The longer it takes the wheel to respond, the higher the steering ratio. To calculate the steering ratio, you divide a complete rotation of the steering wheel (360 degrees) by the total degrees the wheels turn.
In most cars the steering ratio varies between 12 and 20:1. That means when the wheels turn 20 degrees during one rotation of the steering wheel, the steering ratio would be 18:1 (360 divided by 20).
The steering linkage is made up of all the parts of the steering infrastructure that couple the steering wheel to the front wheels. It’s the glue the binds everything together, except it’s not glue. It’s an amazing configuration of bits and screws and bobbles.
When you turn your steering wheel, the steering linkage causes your front wheels to react by moving in the proper direction.
The components of the Steering Linkage Mechanism (aka Steering Rack)
The main parts of the steering linkage system are the tie rod ends, ball joints, and control arms.
The tie rod ends are sort of a ball socket joint assembly situated where the steering linkage is joined to the wheels. As the two parts of the linkage grind against each other, grease in the tie rod ends shields them from wear. The grease keeps the parts moving fluently and prevents rubbing against each other that would wear them away.
The steering linkage system connects to the wheels, which are held in place by a metal pivot pin that goes through the wheel and is attached to one or two control arms (aka steering arms) which allow the wheels to turn in any direction. To keep things moving smoothly, ball joints are located in areas where movement takes place.
Ball joints are probably the most important parts of the steering systems on vehicles of all types.
A ball joint is a ball socket assembly that attaches the steering knuckle to the suspension system. The ball joint allows for pivoting and rotating movements of the wheel as it moves up and down and is steered left to right.
Steering Rack Service Tip
Some steering system components are packed with grease to reduce friction and keep the parts they insulate from wearing away too early. In earlier times, these parts needed grease replenished regularly. Almost all of today’s vehicles (some Trucks and SUV’s excluded) have lifetime lubrication systems intended to operate for the life of the vehicle, removing the need for extra lubrication.
At Driveshafts Centre we don’t brag about it much, but we’re boffins when if comes to sorting out steering linkage mechanism problems. If you have a funny rattle on the front end of your car it could be one of the components of your steering mechanism. Or, maybe your steering ratio seems too high (loose or lots of play) or too low (absolutely no play).
Simply give us a shout and we’ll sort out the problem for you.