A small amount of play in the steering system is acceptable, but a noticeable amount can cause concern. Excessive play in the steering system can often be caused by wear in the steering rack.
What Steering Play Actually Means
When you turn your steering wheel gently from side to side when stationary, the amount of movement before you feel any resistance is known as ‘play’. This should be around 25mm to 30mm before you start to feel any resistance and is normal. However, if there is too much play then this can become a safety issue, especially at high speed on a motorway. This excess play creates a ‘dead spot’ where your inputs on the steering wheel will not be transferred to the wheels of your car.
How Wear Inside the Rack Creates Slack
A worn steering rack can cause excessive play in the steering of your car. The steering rack is part of the power steering system on your car and is responsible for converting the turns of the steering wheel into the actual turning of the tires. The steering rack is typically a toothed rack that is meshed with a pinion gear which is attached to the end of the steering column. The pinion gear is supported by a bearing (pinion bearing) which keeps it in place and allows smooth rotation of the gear. As the pinion gear wears, the teeth of the rack and pinion also wear which creates a gap between the teeth. This gap is the amount of play in the steering of your car. A worn pinion bearing can also cause the pinion gear to move slightly from side to side. This also creates excessive play in the steering of your car.
The Role of Tie-Rod Ends
Loose or worn tie-rod ends add to the play. The tie-rod ends are the connections from the steering rack to the wheels. Check the tyres at the 9 o’clock and 3 o’clock positions, then rock them from side to side. If they move then it is likely that the tie-rod ends are worn. See also Car Steering Rack.
Other Symptoms to Watch For
It can be associated with many other symptoms such as vehicle wandering while driving straight, a ‘numb’ or ‘dead’ feel while returning to straight while driving on a bend, and even a clunk or knock when driving over bumps. These types of wear will be to the rack and tie-rod ends as opposed to wear to other parts of the vehicle’s suspension.
When It Becomes an MOT Issue
Play in the steering can become an MOT failure. The MOT criteria for the steering are set out below for reference and will give you an indication of when play in the steering has moved from being a bit of a nuisance to becoming a safety issue and an MOT failure.
Check the steering rack and tie rod ends before play has increased any further.