Frontend Alignment
Everybody knows that when you buy a new set of tires one of the most important things you can do is to have the vehicle alignment checked. Suspension settles over the years, ball joints wear and tie rods can become bent or come out of adjustment. We've seen instances where a new set of tires has been damaged in as little as 100 miles because they were driven on after installing replacement suspension components but before checking vehicle alignment.
Indeed, the cost of an alignment is modest compared to the cost of tires, but there are other considerations involved. One of the most obvious ones is vehicle performance and safety. A bad alignment can leave you struggling to maintain lane control at freeway speeds, and a small amount of input results in the car lurching to one side or the other.
Sometimes a diagram can be...
Sometimes a diagram can be helpful to visualize the concepts we're talking about. This is the factory drawing for our '67 Fairlane Ranchero front suspension. It is taken from our 1967 Ford Shop Manual. To visualize adjustments, draw a vertical line in your mind between the two ball joints. To the extent that this line might deviate from vertical when viewed from the side is a caster adjustment. To the extent that it deviates from vertical when viewed from the front is a camber adjustment. The camber adjustment eccentric or cam is also shown in this diagram of our Ranchero suspension.
At the same time, an incorrect camber setting can leave you squealing through the most modest of turns. If your car shows any of these symptoms or if your vehicle alignment is an unknown quantity then checking your frontend for all the right specs is one of the best things you can do from both a vehicle safety and tire longevity standpoint. Another consideration is that a correctly aligned car is a pleasure to drive. Since the classic Ford vehicles we're interested in don't have four-wheel independent suspensions we won't discuss rear alignment except to say that similar considerations are involved.
If you've got several cars or are constantly changing alignment on a favorite because you alternate between street use and track use then the ability to check and adjust alignment at home or at the track can be a great asset. Fortunately, tools suitable for personal use are now available to check your classic Ford vehicle's alignment.
Negative Caster
Center Line
...
Negative Caster
Center Line
Positive Caster
Front Of Car
This photo illustration shows the caster line as viewed from the side as well as the change possibilities for camber as viewed from the front of the vehicle. As shown, the camber is the deviation from vertical of the line drawn through the centerline of the tire tread face.
To begin our alignment lesson we ventured out to Marlo's Frame and Alignment in Canoga Park, California. There we were able to take advantage of Marlon's years of experience as he explained the ins and outs of front suspension alignment. Marlon doesn't have a laser-guided rack but rather uses old-school expertise and tools to align his customers' vehicles. As you will see, the tools he uses are similar to ones you can buy to attend to your alignment needs. After we go over an alignment procedure with him to get down the basics we'll also have a look at some of the vehicle-alignment tools available from the Eastwood Company.
There are three main aspects of vehicle frontend alignment. They include camber, caster and toe. Camber is the angle of the wheel, measured in degrees from exactly vertical, when viewed from the front of the vehicle. If the top of the wheel is leaning out from the center of the car, then the camber is positive. If it's leaning in then the camber is negative. If the camber is out of adjustment, it will cause tire wear on one side of the tire's tread. For example if the camber is excessively negative then the tire will wear on the inside of the tread.
When you turn the steering wheel, the front wheels turn on a spindle that is attached to the suspension at the upper and lower ball joints. Caster is the angle of this steering pivot, measured in degrees, when viewed from the side of the vehicle. If the top of the pivot is leaning toward the rear of the car, then the caster is positive, if it is leaning toward the front, it is negative. If the caster is out of adjustment, it will cause problems in straight line tracking. If the caster is different from side to side, the vehicle will pull to the side with the less positive caster. If the caster is equal but too negative, the steering will be light and the vehicle will wander and be difficult to keep in a straight line. If the caster is equal but too positive, the steering will be heavy and the steering wheel may kick back when you hit a bump.
Here the caster and camber...
Here the caster and camber gauge is affixed to the wheel. Using a bubble level on the tool, both caster and camber can be measured on a scale indicating degrees of deviation from zero. By observing the position of the bubble on the scale, Marlon is able to determine what adjustments need to be made. He'll take measurements with the wheel turned left and right, lock to lock.
On our Ranchero, the caster...
On our Ranchero, the caster is adjusted by shortening or lengthening the lower strut rod. Shortening the rod will bring the lower ball joint forward adding a little positive caster to achieve the setting desired. On earlier cars, such as '65-'66 Mustangs, the caster is adjusted by adding or subtracting shims from behind the upper control arm. Thus, on earlier cars the adjustment is achieved by moving the upper ball joint relative to the lower, instead of just the opposite.
With the wheels straight ahead,...
With the wheels straight ahead, Marlon checks the camber settings on the Ranchero. Our Ranchero was a little too knock kneed and we needed to remove a little excess negative camber. As the suspension wears or works its way out of adjustment it tends to add negative camber, taking the adjustment out of factory specs.
On our car the eccentric will...
On our car the eccentric will be rotated to bring the control arm in toward the centerline of the vehicle. This will bring in the lower edge of the tire, restoring a more nearly vertical condition. Still, a little negative camber is desired in the setting to keep the tire contact patch as flat as possible during cornering. This will aid adhesion and prevent running on the outer sidewall during hard cornering. On earlier cars this eccentric wasn't present and lower control arm position was fixed in this respect. Camber was adjusted by adding or subtracting shims at the upper control arm.
The best way to visualize caster is to picture a shopping cart caster. The pivot of this type of caster, while not at an angle, intersects the ground ahead of the wheel contact patch. When the wheel is behind the pivot at the point where it contacts the ground, it is in positive caster. Picture trying to push a shopping cart and keep the wheel ahead of the pivot. The wheel will continually try to turn from straight ahead. That is what happens when a car has the caster set too far negative. The factory caster setting for classic Ford cars calls for a small amount of positive caster.
The third dimension of our alignment is the toe measurement. This is the difference in the center to center distance between the front of the tires and the back of the tires. It is measured in fractions of an inch and is usually set close to zero, which means that the wheels are almost parallel to each other. Toe-in means that the fronts of the tires are closer to each other than the rears. Toe-out is just the opposite. An incorrect toe-in setting will cause rapid tire wear. For racing purposes, toe-in is subtracted or eliminated to aid quicker response when cornering. However, a vehicle aligned this way won't be much fun to drive on the freeway.
Bushings: Stock Versus Modified
It's a fact that when Ford designed the original suspension many important moveable junctures or pivot points had rubber bushings as original equipment. Both upper and lower control arms were attached to the car using a bushing with a steel center and a rubber jacket. While the rubber dimension of these components reduced vibration and promoted a smoother ride, after a certain amount of time these bushings would begin to compress and come out of round. In addition to losing the correct alignment adjustment, a certain amount of play was created, allowing the component to move around freely-not the best of circumstances for correct vehicle alignment or concise steering. Now there's a great bolt-in alternative from Fly-Ford Racing that gives a near-stock appearance without any suspension or frame modifications.
Here Marlon uses a toe-width...
Here Marlon uses a toe-width bar with the correct setting for a small amount of toe-in dialed in. Because there is a slight disparity between the setting and the spec, an adjustment will have to be made. The total amount of toe-in required will be adjusted for at both wheels, with each contributing to half of the adjustment. That way both tires will wear evenly.
As you can see in this photo...
As you can see in this photo the rubber collar has been eliminated and replaced by oil-impregnated shaft bushings, complete with grease fittings. For exact control and long service life they're the hot set up.
However there is a way to...
However there is a way to retain your stock classic Mustang suspension components and eliminate these OE variables. Marlon Mitchell's Fly-Ford Racing now offers the Blueprint Series of modified stock suspension components. The parts have been upgraded with oil-impregnated shaft bushings, complete with grease fittings. By upgrading the stock rubber bushings with these lubricated hard points, the weaknesses inherent in the original bushing design have been largely eliminated.
Next, the toe-in adjustment...
Next, the toe-in adjustment is accomplished underneath the vehicle by adjusting the length of the tie rods. Since each tie-rod sleeve uses one normal orientation thread and one reverse thread, the tie rod length can be shortened or lengthened simply by twisting the tie-rod sleeve one direction or the other. Once everything is locked down Marlon will recheck all settings to be certain that each one remains in spec.
If you're interested in checking...
If you're interested in checking on your classic Ford alignment at home the tools to do so are now easily available at a reasonable cost form Eastwood. This is its Fastrax Camber Caster Gauge. With this tool you can check camber and caster both home or at the track. It fits most 13- to 18-inch wheels and displays camber in a range of +/- 4 degrees. The range of measurement for caster is -4 to +12 degrees. The Fastrax is zero set for level floors, but adjusts to any surface. The tool is constructed of anodized aluminum, has a locking adjuster, and a calibrated bubble level. The tool includes complete instructions and costs only $199.95.
This tool measures toe-in...
This tool measures toe-in and toe-out on an easy-to-read gauge. To use, set the gauge at the rear of the front tires and take your measurements. Then, transfer the tool to the front of the tires and measure the difference. If necessary, adjust the tie rods in or out half the distance of the dial reading. The cost of this tool is $54.99. In a pinch you can use a tape measure to adjust toe-in specifications but for a more consistent and accurate reading a rigid bar is more desirable.
Just as at Marlon's shop the...
Just as at Marlon's shop the Eastwood gauge attaches directly to the wheel. If you'd like to duplicate the turntable function at home we've heard of folks using cookie sheets on the bottom and vinyl floor tiles with a dollop of grease between the two surfaces. As long as your garage floor is flat you're in business.