I'm not quite sure how to interpret those numbers. Every alignment computer is different but the "SAVE THE BEFORE MEASUREMENTS" sounds like a message that appears on one I've used.
Camber and toe readings are always live. Camber actually changes as you turn the wheels. If you watch the left wheel, it will tip out on top when you turn to the left. It's the caster that causes that. To visualize caster, look at the front fork of a bicycle or motorcycle. It doesn't go straight down to the wheel. It goes forward as it goes down. That's why putting your weight on the bike allows you to ride no-handed. Cars are kind of the same way. Caster can not be measured directly. The computer calculates it by comparing the camber readings when you turn a prescribed amount to the left, takes a reading, then to the right, takes another reading, then back to centered. When you get back to center and it finishes taking its last reading, THAT'S when it will automatically save those as the "before" measurements. We call that procedure a "caster sweep". Some mechanics won't bother to do that on front-wheel-drive cars because most of the time it's not adjustable and most of the time it has almost no effect on pull, unlike the big effect it has on older rear-wheel-drive cars. If they don't bother to do that sweep, those "before" numbers don't get saved in memory for the printout, then they have to simply push the button to manually save those numbers. It's just like saving your work periodically in Microsoft Word.
If the mechanic never saves those measurements and doesn't do the sweep, the camber and toe will still always be live and you'll only see those measurements on the printout after the corrections have been made. They might do that to save time but I always saved the "before" readings, then at the end of the alignment I highlighted the ones I adjusted to show the owner what I did for them, then put one copy on the passenger front seat and I saved a copy for myself if I needed it for future reference.
Another reason they might not save the "before" readings is they forgot to adjust something beforehand. First let me explain that there are some computers out there that are REAL fast at getting the initial readings and they use the first technology in the world that does not require the car to be perfectly level, they don't require all four tires to be the same size, and you can even get adapters to align the car with the wheels and tires off. This technology was unheard of and would have been scoffed at ten years ago. Up until then, everything depended on gravity and some type of electronic or mechanical bubble level like in a carpenter's level. That's why the hoist and car had to be perfectly level. These new ones use a mirror attached to each wheel, and cameras that "see" spots on those mirrors. Nothing about anything depends on gravity.
My reason for explaining that is to clarify what I meant by "they might have forgotten to adjust something beforehand". Two common examples come to mind. The last step of the caster sweep is to center the steering wheel absolutely perfectly so on the printout it will show the two toe readings. If those are unequal, that explains why the steering wheel was off-center before. You do that caster sweep by tugging on one tire by hand, then the computer suddenly automatically saves those readings when both tires are equally straight ahead. It doesn't know or care at this point yet where the steering wheel is. I want to be able to show that to my customers so I simply let the computer do its thing; that "save" procedure just takes two or three seconds, then I climb up in the car, put the steering wheel straight which changes both toe readings, then I have to manually press the "save" button again. That puts the new readings into memory as the original "before" readings. Think of it as MS Word does an auto-save every ten minutes, but after one minute you have a lot of changes you don't want to risk losing so you manually click on "save" again, that's all. The point is, the computer saved the "before" readings automatically before you were ready.
The second thing we could forget, at least on the older equipment, was to adjust the tire pressures to make both rear tires exactly equal and both front ones exactly equal. Wrong pressures won't affect caster and toe but it will greatly affect camber. Since camber is always live, once the computer has saved the "before" readings, and I THEN come along and adjust tire pressures, both camber readings will change as one or both corners of the car go up or down. The correct camber readings are found when the tire pressures are correct so if I change pressures after the readings have been saved, I have to re-save them after changing those pressures.
There's a third thing that has a big effect on camber readings. That is holding the driver's door open to center the steering wheel. The weight of the door makes the car lean to the left a little. That might not sound like a lot but these computers are so extremely sensitive, that open door can turn a camber reading red meaning it's out of specs.
I've already found that I forgot to set the hoist down on the fold-down legs so it wasn't level. That's another cause for manually saving the "before" readings after the computer did it automatically.
To add some more confusion to the story, I was the only alignment specialist at a very nice family-owned Chrysler dealership all through the '90s and my computer used an old dot matrix printer, just black and white numbers. I found that real easy to interpret at a glance but you had to be experienced in alignment angles and know what to adjust. Many of these newer computers use a Windows XP program and a color printer that includes colored bar charts along with the numbers. That's so numbskulls with almost no training and no experience can watch an arrow move and it will turn green when they have some adjustment "close enough". That screen can be printed out too and that sounds like what they gave you. I'm not implying your car was aligned by someone with no experience. I'm simply saying they might prefer printing that screen thinking customers will understand bar charts easier than a page full of numbers. My assumption always was customers aren't going to understand the numbers no matter which screen I print; I want them to be able to hand the printout to an alignment specialist at a competitor's shop and have them say, "that guy did a good job for you". I never want to have to defend my shoddy work.
If they did give you a printout with colored bar graphs with arrows over the top, you still have to be careful when drawing conclusions on the quality of the job. Lightly slamming the door closed can settle the suspension and change some numbers. Also, as I mentioned, these computers are extremely precise and detect the slightest change. I started out aligning cars in the late '70s when there were no computers yet. We had light beams that could be read on a metal chart to an accuracy of 1/16 degree and that was plenty good enough for old heavy rear-wheel-drive cars and trucks. The computerized equipment can be set to read to.01 degree. Many front-wheel-drive cars at the dealership needed.06 degrees more camber on the left to offset "road crown", the lean to the right so rain runs off, and there would have been no way to measure that precisely with the old equipment. We used to joke that the computers were so sensitive that the readings would change if we sneezed! That's why you can't assume you got a bad alignment if a few numbers aren't perfectly equal on both sides.
Those bar charts take me a little time to read since most of my experience was with a page full of numbers. As I recall, they show a camber chart for each wheel, and on top of each chart there's a number on the left and another on the right. Those are the limits which that wheel can be adjusted to and still remain within the acceptable range. A third number in the middle, often larger font, lists the actual reading for that wheel at the time the "print" button was pressed. Camber is not adjustable on some cars, (don't get me started on Ford front-wheel-drive cars and their horrendous tire wear problems), and it has to be made adjustable on some cars such as yours. I get the impression you think two "cam bolts" are needed on each front strut to make them adjustable but that's not correct. Only one bolt needs to be replaced to allow a wheel to be adjusted in or out a little. One bolt usually provides a real lot more adjustment than is ever needed.
There are three big things to look at to evaluate the quality of your alignment besides that printout. The first one is when you let go of the steering wheel on the highway, the car should go straight. Mismatched front tire sizes or brands will have different rolling resistances and cause a pull so take that into account if it applies. If you have the same brand and size tires, the car should go straight. All roads are different so if it pulls on one, try it on different roads before you go back and complain. Most mechanics have a regular route they test drive their alignments on and they learn how cars react there when they get few complaints from customers.
The second thing is the steering wheel should be perfectly straight when traveling on a straight road. If the car pulls to one side the steering wheel will be off-center a little as you counteract that pull. Gotta have the car going straight before you can evaluate the steering wheel position.
The third thing takes more time to evaluate. That is tire wear. Camber needs to be just about equal to make the car go straight but if both tires are tipped out too much on top, both will run on their outer edges and scrub that tread off. (That's the huge Ford issue). Camber wear always affects just that one tire, although camber can be set incorrectly on more than one tire.
Incorrect toe will cause the tires to slide a little sideways as they go down the road. That results in a feather-edge that you can feel when rubbing your hand one way around or across the tire tread but you don't feel the raised edges so much the other way. "Total toe" is just the sum of both of the readings. That will be wrong if one wheel is misadjusted AND the steering wheel will be off-center. Total toe will also be wrong if both wheels are misadjusted, but if they're both turned too much toward the center of the car or too much outward, but equally, you'll have that feather-edge wear but the steering wheel could still be straight. Incorrect total toe always causes wear on both tires even if just one wheel is misadjusted. Camber and toe are also measured on the rear of all cars and trucks now, and it can be adjusted on most front-wheel-drive cars. Usually the rear wheels might have to be adjusted once or twice in the life of the car. Caster is never measured on the rear because the wheels don't turn left or right. A few exotic cars are the exception such as the Dodge Viper and Chevy Corvette and they require some really sophisticated equipment.
There's a fourth thing I used to look for that was more subtle. When the front of the car goes up and down over a big bump such as when crossing railroad tracks, the steering wheel should stay straight AND the car should go straight. If you see the steering wheel wobble left and right a little both camber and caster are unequal. This is a big problem mostly on GM front-wheel-drive cars. I won't get into what else needs to be measured and corrected to solve that but many mechanics overlook it or aren't even aware of it. For other brands of front-wheel-drive cars, if you see that steering wheel wobble, there's a good chance something is bent. Even if it's misadjusted as on the GM cars, camber can be readjusted to make both readings appear to be correct, and tire wear will be okay, but that handling problem will still exist.
In looking at your numbers again:
0.5 |0.0 | -0.5 -0.5 | -0.5 | 0.5 degrees
I think we can break these camber numbers down to:
Left front wheel: 0.5 |0.0 | -0.5 the acceptable range is from 0.5 degrees to -0.5 degrees, (which is tipped in on top). You have 0.0 degrees which means that wheel is standing up perfectly straight and it's perfectly in the middle of the acceptable range.
Right wheel has the same acceptable range from plus half a degree to minus half a degree, and they have that one set all the way in on top to -0.5 degrees. While technically that's just in specs, to me that is not nearly close enough. Remember when I said a lot of the Chryslers I aligned went perfectly straight when I set the left camber 0.06 degrees higher? You have eight times that difference. You have 0.5 degrees difference which for most cars is a real lot. The car should be pulling left pretty noticeably. If it is not, either your model is very forgiving or that isn't the actual reading on the right wheel. Perhaps the mechanic left the door open when he pressed the "print" button and you really have closer to 0.2 on each wheel. Some old-school mechanics still put a 100 pound weight on the driver's seat, then adjust camber to what experience tells them is about right. Few people still do that because that is all taken into account with the design of the suspension geometry and when the manufacturer publishes the optimum alignment settings.
"CASTER says really nothing" suggests to me they never did the caster sweep. I would at least want to know caster is correct and equal. It only takes about a minute to do that sweep procedure and you only have to do it once.
I would also tweak both toe adjustments a fuzz:
-0.02 and 0.05 degrees
I'm used to having my computer read toe in inches instead of degrees but that's irrelevant. -0.02 means the left wheel is turned to the left a very tiny amount when the steering wheel was locked perfectly straight. The minus sign means "toe out" or steering away from the center of the car. The right one is positive 0.05 degrees which means it's toed in a small amount so that wheel is also turned to the left. Those numbers would both make the car go to the left, (they're steering to the left as opposed to trying to pull the car to the left which is what camber would do). To overcome the toe issue, you simply bring both wheels back to where they're equal by turning the steering wheel a little to the right. In this case, the top of the steering wheel is going to be to the right by about 1/4" and you're never going to see that. The difference that you have is 0.03 degrees which is just about perfect.
Your total toe specs. When both wheels are added together is:
-0.16 to 0.32 degrees.
-0.08 |-0.02 | 0.16 0.16 | 0.05 | -0.08 degrees
In the '80s a lot of front-wheel-drive cars called for a little toe out meaning the fronts of the tires were further apart than the rears. Tugging on the car to make it go put tension on the steering linkages and pulled the tires ahead a little. That made them perfectly parallel to each other when zipping down the road. Since the late '80s almost all cars, even front-wheel-drive cars call for a little total toe in. The fronts of the tires are closer together like a snowplow going down the road. The rolling resistance pulls the tires back to make them parallel more so than the force of pulling the car forward. I would have liked just a little more total toe in but I think yours is fine.
One final comment has to do with the camber and caster readings on the printout. Most alignment computers can be set up to read to one or to two places after the decimal point. This one is set up to read just one place as in 0.5 degrees. That is done to make the jobs go faster. Especially with those cam bolts you supplied, it's real easy to hit 0.5 degrees. I mentioned a lot of the cars I did needed 0.06 degrees more on the left than on the right, and that was pretty critical. My computer was set up to read to 0.50 degrees. It took more care and time to fine tune those measurements to the hundredth of a degree but in my case, 0.34 degrees would have gotten rounded off by the computer to 0.3 and 0.36 would have been rounded up to 0.4 degrees. The actual 0.02 degree difference wasn't enough to counteract road crown, and the rounded off numbers would have shown 0.1 degree difference which would have been too much and I would have had a tiny pull to the left. It depends on what the mechanic values more, speed or accuracy, and it depends on what has resulted in complaints and happy customers. If he regularly gets good results, there's no reason to whine and snivel about his computer setup.
Saturday, June 16th, 2012 AT 9:50 AM