WHEEL ALIGNMENT SPECIALISTS

What is wheel alignment?
Wheel alignment is a maintenance on a vehicle which requires a vehicles suspension angles to be measured and aligned in accordance with the motor manufacturers specifications. This process ensures all 4 wheels on a vehicle point in the same direction when driving. If your tyres are wearing unevenly or your vehicle pulls to the left or right when you drive on a straight, flat road or your steering wheel is crooked or off centre when your vehicle is driving straight then you should get a wheel alignment check as your vehicle may suffer from wheel alignment.

Always have a wheel alignment check on your vehicle when:

• Your vehicle has hit a pothole or curb
• Your tyres are wearing unevenly
• Your vehicle pulls or drifts to one side
• Your steering wheel is off centre when driving in a straight line
• Your steering wheel does not return easily after a turn
• When you put on a new set of tyres and you want them to last
• When you replace suspension or steering components
• Your vehicle has been involved in some sort of accident or collision

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What is a Pre alignment check?
A pre alignment check is very important as it highlights any worn suspension or steering components or worn or illegal tyres, which could potentially be very dangerous and will affect the accuracy of the wheel alignment. If a vehicle has any worn suspension or steering components or tyres then this must be replaced before you perform wheel alignment otherwise it could become more costly later.
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The main purpose of correct wheel alignment is to provide optimum vehicle handling and to maximum the life of tyres. As a benefit, drivers will save money as less tyre replacements are needed also your vehicle will drive smoother with less tyre rolling resistance.
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How are wheels aligned?
Once your vehicle has passed a pre alignment check and all your tyre pressures have been correctly set. We will then check all the 14 angles of your vehicle against your motor manufacturers specifications. The 3 main angles of your vehicle is Camber, Caster and Toe, below we will take a look at all the angles.

Camber
Camber is the angle of lean of the wheel away from the vertical when viewed from the front of the vehicle. If the wheel leans too far, uneven wear will occur.

• Positive camber is when the top of the wheel is leaning away from the car. Too much positive camber causes tyres to wear on the outside edge.
• Negative camber is when the top of the wheel is leaning in towards the car. Too much negative camber causes tyres to wear on the inside edge.

The camber angle is designed and adjusted for each vehicle to optimise the tyre’s behaviour on the straight and during a turn. If there is too much difference between the camber angles of the front wheels, the vehicle will tend to pull to one side.

Caster
The easiest way to understand Caster is to look at a bike (when viewed sideways on).
If you draw a line down from the centre point on the handlebars down the forks to the ground (on a car this would be the suspension strut), this indicates the ‘pivot point’.
Then draw a second line vertical through the centre of the wheel and where this touches the ground shows the ‘tyrecontact point’.
The top angle that has been created is what is known as the Caster Angle.
If this top angle is reduced then stability is less, therefore it is important to get the Caster set to its optimum angle for the best possible control.​

Toe
Toe identifies the direction in which the tyres are pointing relative to the centre line of the vehicle. Toe is usually expressed as the difference in distance between the front of the wheels and the rear of the wheels on the same axle.
Toe settings affect the handling characteristics of the vehicle and its straight line stability.

• Toe-in is when the front of the wheels on an axle are closer together than the rear of the wheels. If there is too much toe-in, the tyre tread will tend to wear more on the outside edges. The tread will also wear in a feathered manner which can be felt by running your hands across the tread of the tyre.
• Toe-out is when the rear of the wheels on an axle are closer together than the front of the wheels. If there is too much toe-out, the tyre tread will tend to wear more on the inner edges. The tread will also wear in a feathered manner which can be felt by running your hands across the tread of the tyre.

​INDIVIDUAL TOE
Individual toe is measured from the vehicle centre line. Individual toe can be thought of as a ‘per wheel’ value.

TOTAL TOE
Total Toe is the sum of two individual toe angle readings added together.

CENTRE LINE
Is literally just that! An imaginary line running down the centre of the car, from the front to the rear and equidistant from the sides.

THRUST ANGLE
Thrust angle is the direction the rear wheels are pointing in relation to the centre line. If the thrust angle is not zero or close to zero the vehicle will ‘crab’ – move sideways from the back!

STEER AHEAD
This is simply to ensure the steering wheel is set straight when the vehicle is travelling along a straight and flat road

CROSS CAMBER
Often overlooked and often resulting in vehicle pull.
Cross camber is the difference in camber from one side to the other, if each wheel is itself correctly in tolerance, but at opposite ends of the scale, then the cross camber will be high and might need attention. Some manufactures now specify this value.
The car will tend, as a general rule, to pull to the side with the least negative or most positive camber.

SAI & INCLUDED ANGLE
Steering Axis Inclination (SAI) is the inward or side to side tilt of the suspension strut top towards the centre of the vehicle, and in all cases is positive.
SAI is not altered in the aftermarket, only returned to the factory setting, perhaps following accident damage. SAI gives driver feel to the steering and assists in unwinding the steering after steering lock has been applied, bringing the steering back to the straight ahead.
The Included Angle is calculated by adding the SAI and Camber Angle together.

SETBACK
Set back is defined, where one of the front wheels is sitting back (relative to the wheel on the other side).

• Negative setback is the left wheel back (relative to the right)
• Positive setback is the right wheel back (relative to the left)

Set back would be identified when measuring the SAI and caster angles as the values would be too low and out of specification. Which side is set back or set forward can be established by reviewing which wheels castor angle is within specification.

RIDE HEIGHT
The height at which the car is from the ground and essentially is measured from the ground to the underside of the car. Although some motor manufacturers ride hide height stipulations vary, eg BMW specify (for some models) from bottom of wheel rim to top of wheel arch.
This is to check there is the same ride height around the car, as set in accordance to the manufacturers specifications and ultimately an accurate alignment measurement.
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WEIGHTING / LOADING – A number of cars need weights to be loaded into the car to meet the car manufactures requirements – e.g. Simulating the average weight of driver and passengers and/or load carried. Weights can also be used to help achieve the specified ride height.