How Steering Parts Are Tested for Play
When checking your steering, the mechanic or MOT tester is looking for play in the steering parts. Play is unwanted movement in the parts that connect your steering wheel to your wheels. Here we take a look at the checks he will have performed to look for play in your vehicle’s steering.
Turning the Wheel by Hand
This check is performed with the vehicle stationary with the engine switched off. The tester then grips the steering wheel and slowly turns it from side to side. The amount of free movement of the wheel before the front wheels start to turn up a straight road is measured. There is a degree of free play in the steering of any vehicle, but there is a point at which this becomes excessive.
Checking From Underneath
The tester then checks the various parts of the steering from underneath the car. This involves giving each track rod end, steering rack and column joint a good hard shake to check for any sign of looseness, such as knocking or clunking. He will also look for any sign of movement from a part that should be rigid.
Measuring Steering Wheel Movement
The free play in a vehicle’s steering can be measured using a simple piece of equipment – a steering play gauge. These usually fit onto the wheel rim and measure the free play in degrees or in millimetres. Department for Transport guidance on vehicle roadworthiness sets the acceptable limits of free play for an MOT tester.
Feeling for Stiffness and Roughness
Play is only one aspect of the check. Also important is the resistance when turning and whether it is even. As a rule, uneven resistance indicates wear to the steering rack or to a column joint.
Watching the Wheel Alignment
Finally the test is conducted on the level with the vehicle pointing in the straight ahead direction. The MOT tester checks if the steering wheel is straight or at an angle to the wheel on the opposite side. Should there be any wear on any of the components it will affect the geometry of the vehicle. If a component were to wear more than the others it would pull the geometry of the vehicle out of alignment.
These are the checks that your mechanic or MOT tester will perform to test the steering for play and find any potential wear and tear. Having an understanding of these checks will help you to better understand what your mechanic is telling you and also be able to check your car yourself for early warning signs of wear and tear.
