Like many of you, doing my own car maintenance is a big part of my life. Not only does it offer some financial advantages, it also gives a little relief from, well, everything else. Call it automotive catharsis. Some jobs, though, I always left to the pros—until recently, when I decided to give a front-end alignment a stab. I figured, how hard could it be?
My wife would murder me if I turned our garage into a paint booth, my welding can be best described as “not too bad for a meth-addled chimp,” and I don’t yet own a tire mounter or balancer.
But front-end alignment, which usually requires fancy machines and/or real money to have it done in the shop, seemed do-able without all that— at least according to my own research on the topic. My guinea pig would be my 1967 BMW 1600, since the current set of tires needs to last and I’m about to set off on a road trip.
Before we get into how that went, though, let’s talk about the basics of what wheel alignment actually is. To that end, I made some helpful illustrations:
To put it very simply and in terms most drivers will understand, if the car’s alignment isn’t correct, it won’t drive straight and will require correction on the steering wheel. This is annoying and even dangerous.
To illustrate how this works, let me show you the measure of how parallel (or not) the wheels are, as viewed from above, in relationship to each other and to the body of the car. Toe-in results from the leading edge of the wheels and tires being closer to each other than the trailing edge. Toe-out is the opposite.
This is the measure of the vertical plane of the wheel as it is perpendicular to the ground. Positive camber means the top of the wheel and tires are leaning out. Negative camber means the wheels are leaning inward. Typically, you want 1-1.5 degrees of negative camber to give your tires a nice, flat contact patch when you corner. Any more and you’ll just wear down the inside of the tire.
One thing you probably don’t want? What’s called “Hella flush,” which usually means so much negative camber you’ll need to replace your tires as often as your oil, since they’ll be leaning so far in that the inner tread will wear out long before the outer one.
This is the rotation of the wheel assembly along its own axis, typically being the angle between vertical and the lean of the strut assembly. Positive caster, when the suspension is “leaned back” creates steering stability at high speeds. Too much, however, and it begins to affect camber in turns. You almost never need to adjust this on road cars, if you even have the option to.
Lucky for me, on the BMW, I only had to worry about toe-in/toe-out on the front wheels, since that’s all the car is designed to be adjustable.
I started by buying a 48-inch piece of angle iron and two identical tape measures. I cut the angle iron into equal 24-inch pieces and set them and the tape measures aside for later. I then jacked up my car and centered the steering box arm, confirming that the steering wheel was centered as well. I centered it by measuring the distance that the tie rods stick out on each side, and turning the steering wheel until they were equal.
Next, I loosened up the nuts on the tie-rod assemblies and dropped the car back down to the ground. Now, the car was ready for adjustment.
I’ll note here an important proviso: Before and after making adjustments, be sure to set your car down on the ground, and roll it back and forth a few feet a couple of times. This will let the suspension settle into normal ride height, making the measurement of the new adjustment accurate.
Onward: grabbing the angle iron sections and laying them on bricks, I set them next to each of the front wheels. I then laid the tape measures on the leading and trailing edges of the steel to take measurements. It looked like this:
For parallel wheels, the measurements should be the same. Unfortunately, mine were toe’d-in by a little over half-inch, which is probably what killed my previous set of tires.
So, I made small, half-turn, adjustments in the tie-rods to bring the wheels back to parallel. Again, I rolled the car back and forth a few times to settle in the suspension, and I remeasured. This time, the measurements showed a toe-in right at 1/16-inch. Perfect. (This might differ for you, as some vehicles like their wheels to be perfectly parallel, but my BMW benefits from the slight toe-in.)
Finally, I tightened up the tie-rod clamps and took it for a test drive. I quickly discovered that the steering wheel wanted to pull a little to the right. This means that the wheels were parallel with each other, but not with the steering arm. To correct this, I brought the car home, loosened the tie-rods, and adjusted the passenger-side tie rod “out” a quarter turn and the driver-side “in” a quarter turn. The result was the same set of dimensions from before, but now my steering wheel was straight.
And that, as, they say, was that: a front end alignment for less than $20. Time for a beer.
The place to begin is right where you are: the internet. Look up specifications for your particular model. If your car is old enough, you might even find a DIY article. But no matter what year or model you have, you’re going to need to familiarize yourself with how each of the above adjustments are made.
Once that’s done, the first thing you’ll need to check for after jacking up your car is broken and/or loose parts in your steering system. If bushings or joints are worn out, an alignment is a waste of time. To do an alignment is to fine-tune the steering joints; if the rest of the joints are worn out, all the fine-tuning in the world won’t help.
If the steering system is in good, working order, move on. Most cars on the road today utilize a rack and pinion, which means that you’re going to be loosening and turning the tie rods between the rack and the wheel. On the rear, you’ll still have horizontally mounted tie rods, but they won’t be attached to a steering rack, unless you have four-wheel steering. (High five yourself if you do.)
For camber adjustment, many cars use an offset bolt for one of the two that connect the strut to the wheel knuckle/housing. Some older cars use ball joints that adjust by rotating them.
Again, the internet is your friend, and so is a long afternoon of trial-and-error. What else are cars for?