What causes alignment to go out of spec?

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I know that wheel alignment goes out of spec after bushings, tie-rods, ball joints and other suspension components wear out and they have more and more play in them but what I am wondering is what causes the alignment to change after hitting a pothole? If nothing is bent, the adjustement of the tie rod doesn't actually move after hitting the pot hole right? So if the tie rods stay locked to the previous position when the wheel alignment was fine, what causes it to change after hitting a pothole?
 
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If nothing is bent, broken, jarred loose, or knocked out of adjustment then nothing would change after hitting a pot hole. In other words in order for the alignment to go out, something in the front end has to change.
 
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Sometimes a bushing can be bound up after and alignment and when you hit the pot hole it gets knocked loose. This is more common on alignment settings at the far end of specs but can happen to any unit. Alternatively, you can hit a pot hole hard enough that the bushing temporarily deforms and then becomes bound up. Bolts will also slip a bit with the high point loads from pot holes and other factors.
 
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Originally Posted By: demarpaint
If nothing is bent, broken, jarred loose, or knocked out of adjustment then nothing would change after hitting a pot hole. In other words in order for the alignment to go out, something in the front end has to change.
...or the back end.
 
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Originally Posted By: johnnyh55
I know that wheel alignment goes out of spec after bushings, tie-rods, ball joints and other suspension components wear out and they have more and more play in them but what I am wondering is what causes the alignment to change after hitting a pothole? If nothing is bent, the adjustement of the tie rod doesn't actually move after hitting the pot hole right? So if the tie rods stay locked to the previous position when the wheel alignment was fine, what causes it to change after hitting a pothole?
How would you know that "nothing is bent?" Slightly bent components are difficult to detect., except with alignment rigs. There can also be measurement errors caused by the tech setting up the equipment that could be causing the change.
 

johnnyh55

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Originally Posted By: jjjxlr8
How would you know that "nothing is bent?" Slightly bent components are difficult to detect., except with alignment rigs. There can also be measurement errors caused by the tech setting up the equipment that could be causing the change.
Well if the tech at the alignment shop says the alignment is out so it needs to be aligned but he doesn't mention any components needing to be replaced, wouldn't that mean nothing is bent? Or that would mean something is bent but he can get it back to spec without changing whatever componnent that is bent? So the alignment will be in spec with a bent componenent.
 
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We were on our honeymoon, 4yrs after getting married. "66 Bug. In Utah on I 80 we hit a dollop of asphalt about 3" high going 60. It bent <span style="font-style: italic">something</span> and knocked the toe out. Badly enough to see shreds of rubber when we stopped for gas. It was re-aligned by adjusting the tie rods. Between the 4 ends, there is wide range of adjustment.
 
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Just a new car "settling" in from welding stresses can go out. It can constantly pop in and out if it was not jigged right. Many mac struts don't have brake reaction rods so, you can slam on a brake and put the toe out of spec. The lower swing arm bushings can be very compliant. Garbage mac strut bolted to floppy sheet metal. Ackermann steering geo is not great, IMO.
 
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On a Renault Megane, I had a shorter distance between front and rear wheels on one side of the vehicle. I don’t know if it was a pothole or the rear-ended crash I’ve been involved in, but after changing 4 corners arms, it stayed the same. Bent body?
 
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Originally Posted By: Cujet
I've discovered that alignment issues suddenly occur after lending my cars out.
You too? eek
 
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Originally Posted By: johnnyh55
Originally Posted By: jjjxlr8
How would you know that "nothing is bent?" Slightly bent components are difficult to detect., except with alignment rigs. There can also be measurement errors caused by the tech setting up the equipment that could be causing the change.
Well if the tech at the alignment shop says the alignment is out so it needs to be aligned but he doesn't mention any components needing to be replaced, wouldn't that mean nothing is bent? Or that would mean something is bent but he can get it back to spec without changing whatever componnent that is bent? So the alignment will be in spec with a bent componenent.
No, the tech won't be able to tell if some component is 'tweaked' slightly. Yes, it is possible to get the alignment back with slightly bent components. Yes, the alignment that is measured on the alignment rigs can be adjusted to be in spec with slightly bent components. Sometimes new cars come with out of spec alignments. I've seen "non-adjustable" rear suspensions that are out of spec on a new vehicle. Camber bolts or other suspension kits are required to get them back in spec in those situations. Assuming that the car was built with non-bent components, it might have been just a stack up of tolerances during manufacturing or just a defect. It doesn't take much to change the alignment!
 
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I personally would get an alignment every 6 months. At least around here the roads suck, and it can make a huge difference in tire wear and handling, especially on the highway.
 

Nick1994

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If your alignment has changed then something is either worn out or bent. Getting an alignment will mask the problem. It can be almost impossible to see a bent part, so sometimes an alignment is all you can do. Hitting a pot hole isn't going to turn the adjusting collars on your tie rods.
 
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Originally Posted By: jjjxlr8
Originally Posted By: demarpaint
If nothing is bent, broken, jarred loose, or knocked out of adjustment then nothing would change after hitting a pot hole. In other words in order for the alignment to go out, something in the front end has to change.
...or the back end.
Good point. thumbsup
 
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