Mechanically speaking, what happens when a cars alignment is off? Why is it designed to misalign to begin with?
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Basically when the wheels get out of alignment it means they aren’t all rolling straight ahead, so the car is harder to steer. It isn’t designed to do that, it’s designed *not* to do that, but cars get jiggled and rattled around an awful lot, especially going over rough roads, so things get loose and have to be readjusted.
What happens when part of your car experiences more force than it can cope with?
Either it bends, or it breaks. If it bends, your wheels can be misaligned and need bent back into place. If it breaks, your car falls apart and your wheels are no longer attached.
Simply, your car wasn’t designed to misalign, but wear and tear on the many parts involved such as wheels, tires, bushings, springs, shocks and struts causes the alignment to need adjustments over time.
Common terms
Caster – the angle of the steering axis
Camber – the inward/outward tilt of the wheel
Toe – the the left/right angle of the wheel (typically thought of as when both front wheels face slightly towards each other or away from each other, think of it like being cross-eyed, this is the most common issue and is the one responsible for pulling to the left or the right while moving straight)
There are also other forms of alignment that are only important if you do it for a living such as having all four wheels parallel with each other but not the body of the car. This causes the car to drive at an angle when going forwards kind of like crab walking.
Angle of thrust is interesting but complicated, I’ll going into it if asked but a Google search is probably more effective.
Now to answer your question, the reason cars need to be aligned is due to components wearing out, also if parts bend or tweak slightly, or if parts need to be replaced the can be a slightly different size.
Many people don’t realize but cars aren’t all built the same, when building anything there is usually a set amount of tolerance to work within. In machining this can be as precise as a .001 inches. In framing this can be as large .5 inches or more, the process of alignment is very precise and it would make manufacturing much more difficult to have the car permanently aligned.
Lastly, though it would be possible to do that, it would run into issues with putting on different sized tires, tire wear, component wear, modification potential, and repairability. I recently had to replace the worn out front suspension on my car and it made the car dangerous to drive as it would try and pull you off the road, after alignment is was fine.
There are lots of ways your wheels can be “out of alignment.” If the wheels are like this / or this / your vehicle’s turning responsiveness can be altered. If they are like / / or your vehicle will drift one way or the other when you want to go straight. The wheels can also be misaligned so that the tops are closer or the bottoms are closer or both wheels tilted the same way. In that case the reduced surface area on the road can reduce your braking or accelerating ability. All of these misalignments can wear your tires more quickly (some more than others).
*Note: some race cars are deliberately “misaligned” to take advantage of the different vehicle performance.
How can this happen? The most common way is when you hit a pothole or curb or something. They aren’t “designed” to misalign. Rather, modern vehicles are quite resistant to misalignment. However, any sophisticated mechanical system operating under the kinds of forces a motor vehicle does will have expected wear that needs a means of correction.
Thanks all for the input.
I assumed (not knowing differently) that the misalignment was a protection mechanism to prevent things from breaking.
One of the few things I can’t, nor have ever done myself, hence not knowing more about it.
I wish there were some self adjustment/recalibration mechanisms in place to at least in a limited fashion straighten it.
Your suspension moves and is subject to wear and tear over time. Then there’s minor damage from from hitting bumps, road debris and rubbing against curbs. Making it adjustable helps to extend the cars life because it can be corrected easily and for cheap.
As to how it effects the car, that’s a bit more complicated. There are three main angles. Caster, camber, and toe. Camber is how the tire leans in or out. Like how lowered or stanced cars have the tires leaned in to tuck up under the fenders, that’s camber. Toe is how the tires are turned in or out, like if you point your feet together or away from each other. Caster is how the two pivot points of the wheel are in relationship to each other. This one is harder to understand, but it’s the same as the rake of motorcycles front forks. It makes the car stable at high speeds. If you think about your bicycle, Caster is why the bike was hard to control when you spun the handle bars so the front wheel is backwards, you changed the Caster to a negative value.
Now toe can help the car drive straight easier. If they are a little pigion footed, the car won’t chase ruts in the road as bad. But if it’s too far away from straight ahead, it will scrub the tires down fast. Kind of like dragging a ball over concrete instead of rolling it. Toe is also what makes the steering wheel center. So if it’s a little crooked, then the toe set even from side to side.
Camber makes the car more stable around corners if it’s slightly leaned inward towards the car. More is not always better here, so too much inward camber makes the car less stable all around. If you have too much inward camber the inside edge of the tire will wear to nothing while the rest of the tire has normal tread. This is due to how the weight of the car is spread across the tire. If it’s too far in that weight is more on the inside and if it’s too far leaned out, the tires outside edge will wear instead. Camber is really a balancing act of handeling and tire wear.
Caster is the only one of these that won’t affect tire wear. Since it’s just a relationship of the two pivot points that allow the front wheels to turn, it doesn’t have any affect on how the tire meets the road. But it is a big performance enhancer. The more rake in that relationship the more stable the car is at speed. If a cop was trying to do the PIT maneuver on your car, Caster is going to make it easy or hard for them. Economy cars are easy to PIT because they have less Caster, like 1-3 degrees. Sport luxury cars like Mercedes have anywhere from 6 to 9 degrees of Caster making them much harder to PIT and it’s what makes them easy to handle at autobahn speeds. There are videos of police chases where they PIT a benz, and their pretty interesting as they often have to pivot the benz around their own car after several hits because they always straighten out pretty easily.
There is a whole lot more than this, but these are the basics of the three angles you will see on a standard alignment.
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