One of the most common comments a repair shop service advisor hears from consumers is, “My car vibrates on the highway, I think I need a wheel alignment.” The advisor will usually respond with something along the lines of, “you probably need your wheels balanced as well…” The consumer inevitably says “no, my buddy told me I just need an alignment, so that’s what I want.
I’ve got news for you – your buddy doesn’t know what he is talking about!
Maybe I am being too harsh here. Truth be told, your buddy is partially correct – you probably DO need a wheel alignment, but, and this is a big one, the alignment will not correct your vibration.
What is a wheel alignment? A wheel alignment is an operation where a technician ensures that all four wheels are pointing in the direction that they are supposed to be pointing as prescribed by the manufacturer. It can be done with a tape measure and a piece of string, but most shops use sophisticated and very expensive machines which utilize computers and lasers to ensure the accuracy of the technician’s adjustments.
Why is wheel alignment important? When most of us see the wheels on a car, we are happy to know that they are straight up and down and pointing forward. The reality is that the manufacturer has designed the vehicle’s suspension, brakes and steering to work properly when the wheels are all pointed in a very specific direction. Alter that direction by even one degree and you can have all sorts of problems, from tire wear to handling and even fuel economy concerns.
How can I tell if I need an alignment? Some of the signs are obvious. Uneven tire wear can be spotted visually or by running a hand across the tire’s surface. Excessive tire noise is another possible indication that tire wear is uneven. A vehicle which will not drive in a straight line on a flat and level highway may have uneven tire pressures or be out of alignment. Hit a big pothole or smacked a curb? You need an alignment.
Wheels that are out of alignment will not, by themselves, cause a vibration. An out of spec alignment can however be the cause of some of the causes of vibration.
A vibration on the highway can be caused by any combination of a wide range of problems, such as:
- Unevenly worn tires
- One or more damaged tires
- One or more tire/wheel combos that are out of balance
- One or more bent wheels
- Damaged or worn brake components
- Damaged or worn suspension components
- An out of balance, worn or damaged drive axle
- Engine hesitation
- Transmission problems
Of the above list, only the first one can directly be attributed to wheel alignment.
So how do I correct a vibration? Any qualified technician will be able to tell you which of the above are causing your shake after a proper test drive and visual inspection. The good news is that most vibrations are caused by wheels/tires which are out of balance. The solution is to balance them, but an alignment at the same time is a good idea to ensure that some tire wear issues aren’t brewing.
If your tires have worn unevenly, sometimes balancing and rotating them (switching their position on the car) will even out the tire wear and make the vibration less noticeable. A wheel alignment will prevent that tire wear from getting worse. If your tires are badly worn, the only solution would be to replace them and do an alignment to ensure the new ones don’t wear too!
Photo credit: Brian Early