Never go to a shop for an alignment again. Never mess with alignment strings again. The first of this two-part series will show you how to take charge of your alignment settings for $60. This first part will be about checking toe with a laser level. We’ll get to camber later, but for now let’s deal with setting toe with a laser level.
If you have been using strings, you’ll find the laser level method much easier. After a couple iterations, armed with only masking tape and a laser level, you’ll be able to check your toe at all four corners in two minutes flat. If you can’t get it done in two minutes, put the beer down and use both hands.
My Harbor Freight laser level shoots a beam 18 mm from the level’s edge. So if your wheel set up is square, meaning equal tire width, and your toe is neutral, the pictured Harbor Freight laser level pressed against your rear tire will shoot a beam forward that passes 18 mm outboard of your front tire. If you use a different level, measure that same distance. If your wheel set up is not square, be prepared to adjust your numbers a little.
Put some tape on your rear wheels. Put it on the center of the wheels so the location of any marks you may make on the tape will be relatively insensitive to small changes in the wheel’s toe. It doesn’t have to be elegant, it just needs to stay put.
Put tape on center of wheel. The charm of attaching the tape to the center of the wheel is that fixing toe problems later won’t noticeably change the position of the tape. Your tape solution doesn’t need to be pretty. Just make it solid enough that it won’t move around and thereby change the location of the marks you’ll be making on it.
You’ll first need to make some reference marks. Since the Harbor Freight laser level’s beam is 18 mm from the level’s edge, find something about 18 mm wide, lay it across your tires and use it to make marks on your tape. You will want these “neutral toe reference marks” at each corner. In the picture below, I used the width of a tape measure to help me put a neutral toe reference mark, circled in red, on the tape.
If you use a different laser level, make your neutral toe reference marks at an appropriate distance. If, for example, your laser beam is 12 mm from the level’s edge, then your neutral toe reference marks would be at 12 mm from the tire.
To get an accurate measurement, mark the blue tape with 18mm neutral toe reference mark circled in red. 18 mm was the distance between the laser and the edge of the Harbor Freight laser level. I used a tape measure to set the reference marks because its width turned out to be conveniently close to 18 mm.
Don’t be Obsessed by Measuring all of This Closely
Because you’re shooting the laser at a distant target, any toe problem at one wheel will make the laser dot miss your reference mark on the tape on the other wheel by a large margin. This exaggeration of any toe problem makes spotting and fixing the problem child’s play. In fact, although I’m using numbers in this article to make explanations more clear, when I set my toe all I do is glance at the strike of the laser — I don’t measure anything.
The exaggeration of any problem also makes setting toe very precise. You will find that you get 1 mm precision fairly easily
From its position on the left front tire, the laser is shooting rearward to center the steering wheel.
Putting a Number on “Exaggeration of the toe Problem.”
Your tire’s toe sets the angle of the laser beam that strikes the tape on the distant wheel. Unless you want to obsess over the details, assume 1:6. That is to say, a 1 mm rear toe problem causes your laser to miss your reference point by 6 mm.
If you do want to obsess over numbers, measure the distance from rear axle to front, 101” on an SpecE30, for example. Put your laser level on a wheel/tire and note where the level actually touches the tire, about 18” on an E30. 101/18 = 5.6. Personally, I just call it 1:6.
A shop’s fancy alignment rack measures toe at the wheel, not at the tire. If you choose to “imagineer” a solution that allows you to press your laser level to your wheel rim instead of your tire, it will change the ratio a bit. In the end it won’t matter, though. For any reasonable toe setting, if you decide to obsess over getting the ratio exactly right and then work out the difference at the wheel of using a 1:5 ratio vs. a 1:7 ratio, the miniscule difference you end up with will make you feel ridiculous.
For example, if you wanted 2 mm of rear toe out, the laser shooting forward from the front tire would angle outboard 12 mm relative to the front wheel tape’s neutral toe mark. This is why you can get huge accuracy with very little effort — if you are off by a millimeter or two, it just won’t matter. A 2 mm problem at the distant tape, because of 1:6, is only a 0.33 mm problem at the rear tire. If a person wanted to be obsessive, they could note that the problem is even smaller if it was measured at the wheel, like a shop’s fancy machine would do.
As a caveat, it’s important to note that some cars have a wider track at front or rear so you need to identify that. The BMW E30, for example, is 8 mm wider at front. Because of the 6:1 rule for E30s, the 4 mm delta on the distant tape would result in a front/rear toe out of 0.67 mm (4mm/6). Certainly you can rigorously account for the 4 mm difference if you want to. When I was younger and more obsessive, I would have done so. However, now that I’m older and less of a nutjob, I’d be inclined to mitigate 0.67 mm of toe-out problem with a few beers.
Also, don’t worry about your garage floor being perfectly flat for setting toe. Toe doesn’t change much in compression. If the floor looks reasonably flat to your uncalibrated eyeball, that’s good enough.
Here you can see the laser dot on rear wheel tape. As mentioned, the Harbor Freight laser level’s laser is 18 mm from the edge of the level, so neutral front toe would result in a laser dot 18 mm outboard of the rear tire. If you had some front toe out, the laser dot would hit the tape inboard a bit. Caveat: The obsessive will note that due to the E30’s front being a little wider, with neutral front toe, the laser beam would actually pass 22 mm from the rear tire. However, that 4 mm difference doesn’t amount to much when the laser is shooting at a distant target. Imagine if the laser was pointing to a target 100 meters away. How much would 4 mm matter? It doesn’t matter much when the target is one wheelbase away, either.
Hold the laser level against your left front wheel with one hand, watch where the laser dot is striking the rear wheel’s tape, and reach your other hand into the driver’s window to adjust the steering wheel.
If your front toe is neutral, a centered steering wheel should put the laser dot on the neutral toe reference marks on the tape on left and right rear wheels. If you don’t want neutral front toe, using the 1:6 rule, mark where you want the laser dot to be, and adjust your tie rod(s) to get you there, if necessary. A little front toe out will move the laser dot inboard from the neutral toe reference mark on the distant tape.
If your centered steering wheel results in the laser dots on the rear tapes being asymmetrical, like perhaps one dot is on the neutral reference mark, but the other dot is off by 12 mm, then adjust one or both tie rods to fix your centering, while retaining any front toe that you might want. Also, consider putting something slippery under your front tires to help them turn. A half dozen sheets of magazine paper, or folded-over plastic garbage bags, for example. A tie rod that is a little bent is no big deal, that’s why they’re adjustable.
If you use toe plates to check front toe, you can’t tell which tie rod should be adjusted to fix a toe problem. If you use a laser level, however, the laser dot on the rear tape will clearly indicate which tie rod needs adjusting.
You can avoid repeatedly lifting and dropping your car to change and then inspect toe, by making a “drooping toe mark” on the other wheel’s tape.
Knowing how much you want to change front or rear toe, lift the car and with the tires drooping down, use the laser level to make another mark on the distant tape. We’ll call that the drooping toe mark. Now adjust your toe and, without dropping the car, shoot another beam from your drooping tire towards the drooping toe mark on the distant tape. If you didn’t get the 4 mm you wanted, adjust again. Once the laser and the drooping tire mark indicate that you might now be good, drop the car and shoot another beam to confirm.
This drooping tire mark business almost always works and it means that I don’t have to serially lower/lift the car over and over again trying to fix a problem that can only be measured with the car on the ground.
Toe plates don’t work well in the rear because they only measure “relative” toe. If, for example, both of your rear wheels pointed a bit left, which would cause your car to crab left, toe plates wouldn’t identify any problem. Similarly, if you have a rear toe problem only on one side, toe plates won’t indicate which rear wheel is the problem. In contrast, a laser level indicates “absolute” toe. So no matter the nature of your rear toe problem, the fall of the laser dot will clearly show what is going on.
Put tape on the center of your front wheels and draw the 18 mm neutral toe reference marks on them.
Put the laser level on a rear tire and shoot the beam forward toward the neutral reference mark on your front wheel’s tape. Mark on the tape where the laser spot fell and decide if the delta between this mark and the neutral reference mark is worth dealing with. If you like a bit of rear toe in, say 1 mm, then the E30 1:6 rule would have the laser spot 6 mm inboard from the front tire neutral reference mark.
For example, 18 mm of problem on the front tape marks means 3 mm of genuine problem at the rear wheel—probably worth fixing, but not a crisis. This is an example of how a small problem at the wheel is presented as a glaringly obvious problem on the distant tape marks. That’s why you don’t have to touch your tape measure.
When working on rear toe, spot check to see that your steering hasn’t moved. As you raise and lower the car adjusting rear toe, occasionally put the laser level on a front wheel and shoot a beam rearward to confirm your front wheels are still pointed straight.