Have you ever wanted to perform an alignment of your car at home for free? As a general rule, I never let a garage touch any of my cars unless it’s somebody that I know and I’m giving them a very specific task. With car maintenance I often find that if you want it done right then you have to do it yourself. How many stories have you heard of people going in to get an alignment and driving out with a car that doesn’t travel straight? Far too often.
When I replaced the inner and outer tie-rods on my E36 BMW 325is, it was important to get a proper alignment done to ensure that the tires would last as long as possible and to provide the coveted BMW “ultimate driving experience”. What’s more, I wanted to make sure it was done right for the right price. BMW wanted around $350 to do a 4 wheel alignment. Absolutely insane!
I’d to preface this method by telling any skeptics out there that this is the method we use to align our Formula 1600 open-wheel race car. In fact, it’s the established method. I also watched the Ferrari of San Diego racing team use this technique on a 458 Italia during the Montreal Grand Prix. I guarantee you that if this is good enough for the track, this is good enough for any street car. Finally, with that out of the way, here’s what you’ll need:
- A thin piece of string longer than the car (dental floss works well)
- A couple of stands to hold the string taught from front to back at wheel hub level
- A level
- A caliper or very accurate ruler (1mm accuracy or better)
- Whatever renches you’ll need to adjust the tie-rods
Alignment Spreadsheet & Calculator
I’ve created a nifty Excel spreadsheet that will automatically convert your measurements into a toe angle and camber angle.
Download: Alignment Spreadsheet & Calculator
Level the Car
This shouldn’t be too hard to do. Find a flat, level surface where you can work on the car and park it there. Alternatively, I stopped at at the foot of the driveway half on the road such in neutral and rocked it forward and back by hand until it found its level. I then double-checked with the level.
Straighten the Steering Wheel
This part is quite important. If you want your car to drive in a straight line when the wheel is straight then you must keep the wheel straight through this entire process. It is possible to have equally valid alignment settings when the wheel is not set straight, but we definitely don’t want that. It’s annoying. Straighten your wheel and check often to make sure it stays that way. If your wheel gets turned once mid alignment you will absolutely have to start over.
Square your String to the Chassis
Easier than it sounds. All you need to do is run the string from the front of the car to the back at wheel hub level. Make sure to keep the string taught with your stands. These can be as simple as a piece of wood with a nail in it for all intents and purposes.
The goal is to then get the string to be of equal distance from the front wheel hub as it is from the rear wheel hub. The actual distance doesn’t matter so much, just that both distances be the same. This step assumes that the offset of each wheel is the same. For most stock cars this is the case. Once this is done, your string will be perfectly square with the car’s chassis.
Measure Your Toe Angle
This measurement is taken by lining up your caliper or ruler at string level and measuring to the outer edge of the wheel on the left and right. Measure the left side of the wheel first and write down your distance. Then measure the right side and write that down too. Repeat this for the rear wheels. Note that you should never measure to any point on the tires because they are rubber and will always have small deviations. We want the highest possible accuracy.
If your toe angle is 0 degrees then both your measurements will come out the same. Zero toe is what most street cars run on the front end, but you should Google the proper alignment settings for your car to be sure.
Now you should pull out your wrenches and adjust the tie-rods either in or out depending on your car and what you found your toe angle to be. For tie-rods connected to the front of the hub, lengthening the tie-rod will toe the car out. For tie-rods connected to the rear of the hub, lengthening the tie-rod will toe the car out. The converse is true in both cases for toeing it in.
Your goal will be make adjustments and re-measure the distance from the left and right of the wheel until it is perfectly straight when the wheel is straight.
Rinse and Repeat
Once you have gotten the alignment of one wheel correct, repeat it for the next on the side of the car you are working on. Once that’s done and you are happy with your measurements, you can switch your string to the other side of the car and repeat the same steps. Bear in mind that you have to make sure your steering wheel is still perfectly straight. If it isn’t or moves from one side to the other, your toe angle will be off.
Using this Method for Camber
A slight variation of this method also works for setting your camber angle if it is even adjustable on your vehicle. The only difference is that we have to hold a string with a weight on the bottom to droop down at the same outward distance as the string until it crosses it and forms a + at the wheel hub level. Usually you’ll want a buddy to help you hold it off the top of the tire for this part. You then measure to the top of the wheel and the bottom of the wheel and make your adjustments based on your measurements.
Typically you’ll want to Google the correct camber settings for your car as they all vary and likely won’t be 0 degrees as is often the case with toe angle.