JHM Butt & Co Ltd Station Yard, Bawtry, Doncaster, South Yorks DN10 6QD Tel: 01302 710868 Email: info@buttsofbawtry.com www.buttsofbawtry.com
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Training QuickTrak Wheel Alignment Ltd offers certificated training courses for those customers new to wheel alignment or the advanced programmes for the more capable technician. This type of training is ideal for businesses such as accident repair centres, car manufacturers, insurance companies, colleges, fast fit centres and general garages. Training is available for group courses or on a one to one basis. These are held either at our purpose designed training rooms or at your premises. Course subjects cover product training or wheel alignment theory. These course are not just limited to QuickTrak customers, we offer an independent service to all those who wish to develop their understanding of the subject. In house training offers uninterrupted time allowing full concentration. Wheel Alignment a quick guide Wheel alignment, sometimes referred to as Tracking (Europe) or Breaking (North America), is part of standard automobile maintenance. The procedure consists of adjusting the geometric angles of the vehicles road wheels so that they are set to the car maker's specification. These geometric angles (Toe, Camber & Castor) move out of Manufactures tolerance ratings through normal wear and tear & steering component replacement. Wheel alignment should be measured using QuickTrak alignment gauges at least once a year as preventative maintenance. The purpose of these adjustments is primarily to reduce excessive/premature tyre wear; and to ensure that the vehicle s road wheels travel in a straight and true manner. Service QuickTrak has a dedicated service department to support their customers in the field. They have specialist engineers in fully equipped service vans. Maintenance contracts are available to take away the worry of service and repair, leaving customers free to concentrate on their business. QuickTrak constantly monitors customers equipment making sure it is running at optimum efficiency. Primary angles Primary Angle(s) is the basic overall alignment of the road wheels in relation to each other and to the cars body/chassis. Primary Angles are: TOE CAMBER CASTER (Note: On some cars, not all of these angles are adjustable on every wheel. Caster is for steer wheels only) 14 3
Secondary angles The secondary angles include numerous other adjustments, such as: SAI (Steering Axis Inclination) (left & right) Included angle (left & right) Toe out on turns (left & right) Maximum Turns (left & right) Toe curve change (left & right) Track width difference Wheelbase difference Rear Toe Adjustments Place the turn plates under the REAR wheels and place the flags on the front wheels. Make sure the front wheels are in the straight ahead position. Place the measuring heads on the rear wheels, ensuring that the toe scales are at the rear. Front scale readings must be equal, if not use the rear wheel track adjusters to make them equal. Front ride height (left & right) Rear ride height (left & right) Frame angle When the scales are equal add both toe scales to find the total toe. If this amount is between 0mm and 2mm then generally the axle can be said to be correct. Setback (front & rear) Setback is the difference between right side and left side wheelbase length. It can also be measured as an angle. Setback less than the manufacturer specified tolerance (for example about 6mm) does not affect car handling. That's because, when the vehicle is turning, one wheel is ahead of the other by several centimetres and therefore the setback is negligible. There are even some car models with different factory setting for right and left side wheelbase length, for various design reasons. An off-spec setback may occur because of a collision or a difference between right and left caster.[2][3] NB: Toe readings are reversed when the measuring heads are on the rear wheels i.e. Toe in = Toe out and vice versa 4 13
Rear Toe Angle Rear wheel toe, either in or out, is always an individual measurement. Front wheel toe can be measured as a total, using a toe gauge, because the steering system will allow unequal adjustments on either side, to self-centre. With rear wheel toe however, each wheel can affect the steering as there is no compensating steering wheel for the rear axle. It is the rear wheel axle alignment that controls the steering wheel position. When adjusting rear wheels for toe-in or toe-out, each angle must be exactly equal on both sides, if not the vehicle will be steered away from its centre line by the inaccurate wheel. The rule of thumb, when making rear wheel adjustments, is to increase or decrease them to the manufacturer s settings. The vast majority of modern vehicles have a toe-in or toe-out of no more than 1mm per wheel. Over that tyre wear occurs to unacceptable levels. Wheel Alignment Wheel alignment is a geometrical setting relating to the amount that the rear axle is out of align to the front axle. If the rear is not aligned it may be steering the vehicle from the rear, which will result in what is known as crabbing. When a problem similar to the one shown in the drawing occurs, the vehicle will steer to the left, resulting in the steering wheel having to be turned to the right to counteract the rear steering force. At the same time the front wheel position adopts a set-back situation with respect of the vehicle s centre line. Should the front axle now be measured from the front only, this set-back situation will not be noticed. So to offer a full alignment service a vehicles thrust angle must be checked. So basically, rear wheel toe must be kept equal to the centre line and correctly toed in or out in order for the vehicle to handle correctly. With the onset of the front wheel drive vehicle, rear wheel toe adjustments have become more common place. It is easier to build an average tolerance body shell and trim the rear wheel alignment to suit, as opposed to tying yourself down to close tolerance body, which would give acceptable tyre wear and steering capability. 12 5
Front Wheel Alignment Rear Wheel Alignment Drive the vehicle onto the turn plates provided NEVER attempt to carry out a wheel alignment without positioning the vehicle correctly on the turn plates. Place the turn plates under the REAR wheels and place the flags on the front wheels. Make sure the front wheels are in the straight-ahead position. Step Four Turn the steering wheel to the straight-ahead position and lock it into the driver s seat with the spring loaded wheel clamp. Hang the rear assemblies onto the top of the rear tyres so that the horizontal bar is sitting at approximately the centre of the wheel and touching the tyre at both points. Use the spirit level on top of the gauge to achieve the 90 degree position. Place the measuring heads on the rear wheels ensuring the toe scales are at the rear. Note the front wheel reads; Example: left front wheel reads 1, right front wheel reads 4. The difference is 3 remember this figure (3 lines to the right). Take your laser measuring head and mount on the front wheel. The black locking hand screw on the assembly allows the hanger to be shortened or lengthened to suit different wheel sizes. Set the hand screw so that the hanger sits on top of the tyre and the three 40mm buttons touch the wheel rim. Check the spirit level is in the correct position and the toe scale is to the front of the vehicle. Transfer the measuring heads to the front wheels and the flags to the rear wheels. Adjust the track rod equally to give a rear scale indication of 3 lines to the right, i.e. 1.5 lines on either scale. The steering wheel is now set to the vehicle thrust line. Step Five Switch on each control panel so that the laser hits the rear scale. Check the number on each scale then add the readings together and divide by 2. For example, nearside reads 3, offside reads 5 so the reading for each side in this example needs to be 4 Adjust each track rod end to achieve required reading. Step Six When both rear scales are equal front wheels are aligned. 6 11
Front Wheel Set-back Measurement Drive the vehicle onto the turn plates provided. Front Toe Toe angle, also referred to as tracking, relates to the way in which the actual width of the wheel track varies between the front edges when compared to the rear edges of an axle s wheels. Turn the steering wheel to the straight-ahead position and lock it into the driver s seat with the spring loaded wheel clamp. Take your laser measuring head and mount on the front wheels Check the spirit level is in the correct position and the toe scale is to the front of the vehicle. Step Four Using the bottom scale labelled SETBACK you can record the readings for near and offside of the vehicle a reading of above 10mm will require further investigation. As viewed from above, the front road wheels will either be pointing towards the centre line or away from it. If the wheels point away from the centre line, they are said to be toed-out (also called a negative toe); in specification books this will be represented by a number preceded by a minus sign. Wheels pointing towards the centre line, (as shown in the diagram) are toed-in (positive toe). In this simple front only situation, the steering wheel position is shown set at right angles to the centre line, and each front wheel equally set toed in to centre line, with the rear wheels parallel. Toe angle is built into vehicle geometry to reduce the tyre wear to a minimum and to counteract any tension built in by the other angles. Ideally once the vehicle starts moving forward, forces in the suspension and drive should pull the wheels almost parallel. However most vehicles today will be set to have slight toe-in or toe-out, this is a result of vehicle designers compromising; for example, setting the wheels to toe-in provides better straight-line stability whereas setting to toe-out offers a quicker steering response. 10 7
Front Toe Adjustment Front Wheel Set-back Each toe scale is made up of two colours, green for toe-in and red for toe-out. When the laser hits the toe scale if both colours are the same then add the readings together; Example: 2 green and 1 red means the axle is 3mm toe-in, 2 red and 1 green means 3mm toe-out. If the readings are different colours then subtract the lower from the higher; Example: 2 green and 1 red means the axle is 1mm toe-in. After calculating the total toe and obtaining your reading adjust each track rod end by looking at the rear scale, making sure that the rear scale readings remain equal; Example: Each rear scale reading is 4, your total toe scales is 1mm toe-in and you require total toe to be 3mm toe-in. Adjust each track rod increasing the rear scales to 4.5 or 5 on each side until you arrive at the desired toe on the scale. You must keep the readings on the rear scales the same at all times. If you require less toe on the axle then reduce the numbers on the rear scales, keeping them both equal. Front wheel set-back is a check used to determine the position of the front wheels with reference to a line placed perpendicular to the vehicle s centre line. Ideally the left hand wheel should be located directly opposite the right hand wheel. However, a tolerance of 5mm is allowed on all new cars, it s acceptable on older cars to have a set-back of 10mm. Whilst conducting a routine toe check on vehicles, noting any excessive set back provides a good indicator, which suggests closer inspection is required as collision damage or suspension problems may be present. Please note: most alignment equipment does not tell you which wheel is at fault, just that there is a difference across the centre line. However positive set-back indicates that the right hand wheel is set-back further than the left. Negative set-back indicates that the left hand wheel is set-back further than the right. If the vehicle has power steering then run the engine at this point, then lock up the track rod ends. 8 9