Q: Every time I go to the neighbourhood tyre shop and am told by the greasy mechanic that I need to align my tyres, I feel like I am being conned. Mr Foreman, please explain a bit about this wheel alignment business. I don’t want to be cheated. Thariq, Kuala Lumpur
A: Dear Thariq,
First of all, it is very unlikely that you will be cheated as we mechanics are usually very honest and upright individuals. Having addressed that, let us move on to the other part of your question.
One of the most common complaints that we get at our shop is that the car is not driving down the road as it used to. If the car is more than three years old, the first suspect is usually wheel alignment. An alignment problem will usually manifest itself in many ways and sometimes it is so subtle you may not realise it. After all, you may naturally compensate for any wear and tear that the car accumulates over the years. The first real sign is abnormal wear on your tyres and you may only notice it when you accidentally catch a view of your worn tyres. Naughty, naughty. you have not been reading this column, have you?
Sometimes, the signs may be more abrupt, like pulling or drifting (no, not like Tengku Djan!) to one side or the steering wheel not centred down a straight road. Or you may notice that the car turns more easily to one side than the other. In any case, even if you do not notice any symptoms, it is wise to check your car’s alignment every six months or so. It will prolong your tyre’s life and provide a more comfortable drive.
WHAT’S WHEEL ALIGNMENT ANYWAY?
Wheel alignment can consist of front wheel, thrust angle or four- wheel alignment. Usually we will go for the four-wheel kind (and not because we can charge more ;-)). Alignment consists of adjusting Camber, Caster and Toe.
Caster is the angle in which the suspension is positioned in reference to the vertical. This is only concerning the front wheels of your car. It has no effect on tyre wear and is usually set in a positive angle to assist in steering and high-speed stability.
Camber is actually noticeable in some cars (especially with the current extreme camber styles,
no comment). It is the tilt of the tyre when viewed from the front.
I bet you went out and took a look, didn’t you?
If it leans inwards, it is set negative camber and outwards is positive camber (very rare, some older Mercedes-Benzes were set like this). The angle can be set in both front and rear wheels. If your tyres are worn on one side or the other abnormally, it is usually a camber problem.
This is the most common adjustment and causes the rapid wear of tyres. If you can imagine a pigeon-toed person, you have understood the concept of toe adjustment. Pigeon-toe is called toe-in and the opposite is, yes, toe-out. You catch on fast. This angle can also be set on both front and rear wheels and is set very close to zero.
THE METHOD OF WHEEL ALIGNMENT
Usually the first order of the day is to go for a test-drive. No, not you, the mechanic will do it. He is looking for symptoms and clues of wear or misalignment. Go with him and get an earful about your bad maintenance habits or the latest gossip, if you must.
Pulling to one side or the other, especially under braking, indicates alignment woes. If it is random, the culprit will be worn suspension parts. A crooked steering wheel indicates the toe angle is misaligned. Shaking or vibration usually points to worn components but sometimes may be caster angle problems.
After the test drive, the car is driven onto the mechanic’s weapon, the Computerised Wheel Alignment Machine. The computer is usually updated regularly with the specifications of all the latest models (and sometimes even old ones, too). Once on the jig, the mechanic will inspect all your suspension components, especially those he suspects are culprits. This is because any wear and tear will have to be addressed before the alignment can be done.
Worn tyres and tired suspension components will need to be replaced before the alignment is performed. This is also the reason why alignment is done after replacing tyres or any suspension components even if there are no alignment problems, as a matter of course.
One oft-neglected check is the ride-height. It is measured from the ground to the bottom of the car and indicates worn-out springs. Of course, those racing springs you bought will change this measurement but your friendly neighbourhood mechanic will have sussed this when you drove in.
The biggest clue your CSI mechanic looks for is the tyres. The shoulders of your tyres and which side it is apparent will indicate which part is worn or what is misaligned. Feathering on the tyre tread is an indication of toe-misadjustment. Cupping on the tyres means caster-angle problems but it may also be worn suspension. Beware of knotted foreheads, raised eyebrows and lots of tut-tutting from the mechanic.
So now he replaces all the worn components and worn tyres and proceeds to measure the specifications of your alignment on his computerised thingamajig. Lots of spanner twirling will commence and lots of peering from underneath the car at the computer screen. Some machines will indicate with colours whether the alignment is spot-on or not. Red is bad, Green is Go.
And once he is satisfied the mechanic will take the car out again for a test drive to verify his work. Be aware that some modern cars require that the steering angle sensor be calibrated after alignment to allow for stability control systems and even adaptive headlamps.
Having your wheels aligned properly will not just get you a better feeling car, it will also save you tyre wear and even improve your fuel consumption. Stay tuned for more next week. See you then and have fun!