Frontend Alignment - Setting Things Straight

Align Your Custom Rod's Frontend at Home

Author: Ron Ceridono

Of all the chores associated with modified car maintenance, one of the most neglected could well be frontend alignment. It's one of those things that none of us pay much attention to--that is, until the car seems to have a mind of its own and wanders all over the road or the tires develop a funny wear pattern and the corners of the treads are knocked off.

Once it's obvious that the frontend of a custom car needs alignment, the challenge you may be faced with is finding someone to do it. We've been turned away from alignment shops for a variety of reasons--everything from "they didn't do specialty vehicles without published specs" to "the car was too low to get on the rack." Then there was a case where, in retrospect, we wished we had been turned away. By the time a well-meaning but ham-fisted technician was done with one of our cars, there wasn't a painted or polished suspension component that wasn't scarred. And that was after waiting a week for an appointment. This isn't to say there aren't alignment shops that do a great job on rods and customs--there are. But an overlooked option is doing the job yourself.While aligning a frontend at home might seem intimidating at first, it's actually quite easy with the simple, available equipment we're going to show here. But before we get into that, let's talk about some terms you'll need to be familiar with.

Camber
Camber is the tilting of the wheels from vertical. Positive camber means the top of the wheel leans out; negative camber is the opposite--the top of the wheel leans in. The amount of camber is measured in degrees from vertical.

Caster
In addition to being tilted toward the center of the car, the steering axis also leans toward the front or rear of the car. Forward tilt is negative caster, rearward is positive. Most cars use positive caster because it prevents road wander and helps keep the wheels pointed straight ahead (drag race and Bonneville cars often use extreme caster for high-speed stability). With positive caster, the weight of the car rests behind the tire's pivot point on the ground. So, just like the casters on a shopping cart, as the vehicle moves forward, the wheels want to go straight.

Toe
The distance between the front and rear of the tires is called toe. Most cars use a small amount of toe-in--that is, the front of the tires are closer together than the rear. Toe-in is used to compensate for the cumulative effect of all the tolerances in the steering system. Without a bit of toe-in, when the car moved forward, any slack in the various steering would let the front of the tires spread apart, resulting in toe-out. Toe-out will cause most cars to wander when going down the road.

A good indicator of proper toe setting is tire wear. While it's not very scientific, run your hand across the tire's tread from the outside in, then the inside out, and feel for sharp edges. If a sharp edge is felt from outside in, it's an indication that more toe-in is required. If a sharp edge is felt going from inside out, more toe-out is needed. Of course, if the treads feel about the same from both directions, the toe is just right. One last thing you should be aware of when setting toe--it is often changed by adjusting caster and/or camber, but adjusting toe will not affect caster or camber. For that reason, toe should be set last.

ADJUSTMENTS
Although independent suspensions were commonplace by the '50s, and all the manufacturers shared the typical short upper/long lower control arm configuration, specific components and adjustment methods varied. Consequently, the best source of procedures and specifications for alignment will be found in repair manuals that deal with the year, make, and model in question.

Keep in mind, however, that alignment specifications for most '60s and earlier cars are for bias-ply tires, so some experimenting may be in order if radials are used. As an example, most '50s-era Mopars call for -3/8 to +3/8 degree of camber. However, modern radial tires generate the most cornering force with a trace of negative camber, around 1/2-degree. So, in this case, we would opt for 3/8-degree negative camber as the best compromise between the vintage suspension design and contemporary tire technology. In contrast, early Mustang II frontends ('71-73) used 1/2-degree negative camber, while the later ('74-78) used 1/4-degree. That's an acceptable range for most aftermarket-style Mustang II suspensions, too, although you should always consult the manufacturer for alignment specs if you're using a custom IFS.

Regardless of the suspension system, changes in camber will take place as the suspension compresses and rebounds, so it is critical that the car is at ride height when any corrections are made. Adjustments are usually made by moving the control arms in or out with eccentric bushings, slotted mounting holes, or shims, depending on the suspension design.

When it comes to caster adjustments, anywhere from 0- to 5-degrees negative may be called for. Again, with modern tires you may want to go with the maximum suggested negative number to provide straight-line stability.

The last thing to be adjusted on any front end is toe. Most independent front ends will usually be set with 1/32- to 1/8-inch of toe in. Whether you've got a steering box or rack-and-pinion, toe adjustments are made with the tie rod ends. Before any changes are made, make sure the wheel bearings are properly adjusted and the steering gear is centered in its travel.

SO, WHAT DO YOU NEED?
Basically the equipment required for home alignment is a caster/camber gauge and something to measure toe. Caster/camber gauges for home use range from simple to exotic, and as you might expect, prices vary accordingly. We tried three examples from Speedway Motors, the $28.90 econo model, $110.90 magnetic version, and the $269.90 digital unit. All three did the job admirably--the econo unit is a bargain, the magnetic tells you everything you need to know at a glance, and the digital is quick and easy to use. Of course, which is appropriate for you depends on your budget and how often you plan to use the equipment. Also shown are a couple of toe gauges, one from Heidt's Hot Rod Shop that sells for $35, and another from Speedway that goes for $72. Again, both do the job effectively. Aligning your street rod at home is easy to do, and the cost of the equipment required can be recouped by doing it yourself just a few times. Best of all, no appointments will be necessary.