Ctrp 1204 Determining Wheel Alignment String Your Car 004

Sometimes it's just hard to beat the old-fashioned way of doing things. This can definitely be true when it comes to squaring your car, or checking the alignment of all four wheels. Manufacturers have come up with lots of different solutions involving elaborate rigging systems, lasers, jigs, and other contraptions, and many of these devices work really well. But they can also be expensive, time consuming and finicky to use.

On the other hand, racers have been achieving the same results for decades with nothing more than a ball of string, four jackstands, a tape measure, and a plumb bob. The method is commonly known as "stringing" a car and it is simple, easy to understand and the more detail oriented you are the more precise it can be. Different racers have developed different methods of stringing a race car, but we're going to show you the simplest and most popular method. After properly stringing your car, you'll be able to determine the car's wheelbase on both the left and right sides, the individual toe on the left and right side (which is not the same as the total amount of toe-in or toe-out), whether the car is rolling true or crabbing and the tread width front to rear.

Begin by placing your car in a level area of your shop with the suspension set up so that it is sitting at ride height. You also need to have mounted up a set of relative new tires on unbent rims.

Now you're ready to run your strings. Tie a length of string a few feet longer than the wheelbase of your car to two jackstands. Technically, what you tie your string to doesn't have to be a jackstand, but they are the best height and weight and extras are almost always lying around in every race shop. Whatever you use, just make sure they are stable, heavy enough to keep good tension on the string yet light enough to move around relatively easily.

Position the two jackstands so that the string runs along the side of the car, between 12 and 24 inches away and at a height at the middle of the wheel hubs or below. Whether you begin on the right or left side of the car doesn't really matter, but the height of the string does a bit. If you think about it, the only part of the tire that actually matters is the portion coming in contact with the track. The tech guy at the track may measure at the hubs, but the race car doesn't ride on the hubs. Camber changes can also change your track width, so placing the string lower on the tire can often give you a better idea of what the contact patch is doing.

Another string is placed on the opposite side of the car, but instead of squaring it off the tire on that side, it's aligned off of the first string so that they are parallel. This way, if the rearend is bent or has some toe built in, it won't throw off your measurements. Check out the full process in the photos.

  • Ctrp 1204 Determining Wheel Alignment String Your Car 006
    1 Begin by running a string between two jackstands and stretching it down the side of the car. Begin at the rear wheel and move the jackstand until the measurement is the same at both sides of the same wheel. As you can probably tell by now, this is really a two-person job because getting the string perfectly parallel to the wheel can be a bit of a tedious task.
    1 Begin by running a string between two jackstands and stretching it down the side of the
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    2 If you have a new set of rims, measure from the string to the rims, or you can measure from the sidewall of the tire—just avoid any lettering, obviously. Set the string height at the center point of the wheel or slightly below. Just don’t go too low because you need to measure across the width of the wheel where it’s still fairly wide to make getting the string parallel to the entire length of the car as accurate as possible.
    2 If you have a new set of rims, measure from the string to the rims, or you can measure
  • Ctrp 1204 Determining Wheel Alignment String Your Car 007
    3 How far away you place the string from the car is really up to you. Davis (pictured here) and Wallace prefer to keep the string far enough away that they can comfortably work on the suspension if necessary. Just make sure you don’t get the string so far away that the tape measure bends on you.
    3 How far away you place the string from the car is really up to you. Davis (pictured her
  • Ctrp 1204 Determining Wheel Alignment String Your Car 009
    4 Before moving to the front end, you need to make sure the steering is centered as precisely as possible. One method to do this is simply to eyeball the pitman arm and make sure it is pointed straight back. You can also turn the steering wheel from lock to lock and then halve that to find the approximate center. Or you can take an X-measurement between the pivot points on the pitman arm to the drag link. If the two measurements are the same, the steering should be centered.
    4 Before moving to the front end, you need to make sure the steering is centered as preci
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    5 Once the string is confirmed to be parallel to the rear wheel you can move to the front wheel on the same side. If your measurements on both sides of the front wheel are the same, then the wheel is in alignment (pointed in the same direction) with the rear wheel. If the distance from the string to the front of the wheel is longer than the same measurement at the rear of the wheel, then that wheel is toed in. If both measurements are larger than the same measurements to the string at the rear wheel, then the front wheel is sitting inside the track of the rear wheel which can cause handling issues you should be aware of. Obviously, if the measurements are smaller, the opposite is happening. Generally, moving the right front wheel out (increasing the track by using a wheel with a different offset or a wheel spacer) will help tighten the car up because it changes the crossweight.
    5 Once the string is confirmed to be parallel to the rear wheel you can move to the front
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    6 Now you can set up a parallel string on the opposite side of the car. To do this, you essentially create a box. Instead of placing the string based off the rear tire, measure from the first string you’ve run. This is why the string needs to extend beyond the body of the car.
    6 Now you can set up a parallel string on the opposite side of the car. To do this, you e
  • Ctrp 1204 Determining Wheel Alignment String Your Car 011
    7 Move to the front to make sure the string is the same distance front to back. Now you know the second string is parallel to the first, and because of that you also know it is parallel to the rear tire on the opposite side. Now you can measure the distances on either side of the rear tire on the side you are working on to make sure the rear is straight. If the rearend has some toe built in, you can check that too.
    7 Move to the front to make sure the string is the same distance front to back. Now you k
  • Ctrp 1204 Determining Wheel Alignment String Your Car 013
    8 Repeat the process on the front wheel and compare your measurements to the front wheel on the opposite side. The distance between the string and the wheel doesn’t have to be equal. For example, the string on one side can be 8 inches from the tires while it’s 10 inches on the other. That’s OK, what you want to be able to compare is the distances from front to back. If you want to know the track width, simply subtract the distances from the strings to the center of the tires on either side from the total distance between the two strings. What you’re left with is your track width.
    8 Repeat the process on the front wheel and compare your measurements to the front wheel
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    9 Measuring wheelbase with the string method is also simple. Use a framing square as you see here. The angle this photo was taken makes it look misleading, but here Wallace has one end of the square aligned with the string and the outside edge of the other pointing to the center of the hub. Now using a magic marker he marks the string and repeats the process at the back of the car. Once those two marks are made, he can measure the distance between the two to determine his wheelbase. Alternatively, you can hang a plumb bob from the center of the hub and mark the spot it points to on the floor. Determining the wheelbase can help you achieve proper rear alignment which is critical to a good setup. Proper alignment is a squared rear end to the center of the chassis. Of course, we’re only talking about small movements here—usually in the range of 1/8- to 1/4- inch at most.
    9 Measuring wheelbase with the string method is also simple. Use a framing square as you
  • Ctrp 1204 Determining Wheel Alignment String Your Car 017
    10 The process works exactly as before except now there are a lot less pieces to move around. The laser throws a beam that fans out vertically, so all he has to do is note the spot where it hits his tape measure.
    10 The process works exactly as before except now there are a lot less pieces to move aro
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    11 Now that we’ve spent all this time talking about keeping things “old-school” with a string, we will make a concession to modern technology. Wallace doesn’t actually string his cars with a string any more. Instead, he uses an inexpensive laser like this he picked up in a hardware store and a cheap camera tripod like you can see here. However, it’s imperative for the laser to be completely level front to rear, and especially side to side or the measurements will be off.
    11 Now that we’ve spent all this time talking about keeping things “old-school” with a st
  • Ctrp 1204 Determining Wheel Alignment String Your Car 018
    12 The laser will easily reach to across the length of the car. You still have to adjust the laser to make sure it’s parallel with the rear wheel, but now instead of sliding around some jackstands all you have to do is rotate the laser on the tripod.
    12 The laser will easily reach to across the length of the car. You still have to adjust
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    13 “Stringing” the other side of the car doesn’t require two lasers. Instead, place some tape on your shop floor at the front and back of the car and mark the spots where the laser hits it. This replaces your string.
    13 “Stringing” the other side of the car doesn’t require two lasers. Instead, place some
  • Ctrp 1204 Determining Wheel Alignment String Your Car 020
    14 Now measure an equal distance perpendicular to your two marks and move the laser so that it hits both of your new marks on the opposite side of the car. You now have a parallel line to set up your car.
    14 Now measure an equal distance perpendicular to your two marks and move the laser so th
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    15 One of the greatest benefits of using a laser is there is no string to get in the way. Wallace can jack up the car or make suspension adjustments without having to worry about hitting the string hard enough to slide a jackstand out of position and having to start over.
    15 One of the greatest benefits of using a laser is there is no string to get in the way.
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