Get Aligned: Alignment Techniques for Hot Street Cars

We’ve all read the stories on how to install the trick, high-dollar suspension components on older cars. However, what attracts far less attention is what alignment settings do you use and where do you go to get the car aligned? In our experience, many production alignment shops don’t want to bother with a hot rod or modified cars. This is likely because the shop can align two stock production cars in the amount of time it takes to achieve a custom alignment with a Pro Touring car.

This is our alignment test machine set up on JCG Custom’s Hunter Hawkeye Elite digital rack. The machine has the ability to deliver precision down to hundredths of an inch for a precise alignment. Photos by Jeff Smith

Another big reason is many shops don’t want to work on a hot rod is that this involves creating custom alignment specs, more in-depth knowledge of alignment settings, and attention to detail that many production shops are not willing to expand. Of course, some shops perform custom alignments. Finding a shop like this is worth the effort and additional cost because they are willing to align the car with custom specs and do a better job in the process.

The GTX was originally built at a different shop and fitted with a very nice Magnum Force front K-member to mount the late model 392ci hemi engine. This also converted the front suspension to Viking double adjustable coil-over shocks and rack and pinion steering.

In this case, the car in question is a ’68 Plymouth GTX with a Magnum Force front coil-over-shock conversion with rack and pinion steering matched with a late model 392 late model Hemi crate engine. The car had been passed around to several shops after the conversion, and the alignment was merely eyeballed and sent on its way. While the engine ran great, it tended to wander dangerously at anything over 30 mph, and a mere glance at the front tires was enough to reinforce the camber settings were not ideal.

Here was a classic situation where money was invested in a quality front suspension, and yet the car was not fun to drive. In fact, it was borderline dangerous with a pull that demanded an effort to keep the car centered on the road. A less experienced performance car fan might immediately blame the custom work and hard parts when all it needed was a professional front end alignment.

The call went out to Cris Gonzalez, owner of JCG Customs in Oxnard, California to schedule a little alignment attention for this machine to make it much more fun to drive. JCG specializes in building complete cars with an emphasis on a track day, autocross, and Pro Touring machines. He recently added a very nice Hunter Hawkeye Elite machine that is capable of precision four-wheel alignment. This is especially critical for sports cars and Pro Touring cars with independent rear suspensions, but is also useful for all cars to indicate if the rear suspension has perhaps suffered damage or just through age is not parallel with the front suspension.

The first job for JCG’s alignment specialist Emilio Albor is to set up receivers placed on each wheel that are scanned by the machine’s infrared beams to deliver the settings.

The original builder never properly set the alignment with camber at 0.8 degrees positive on the left and 1 degree positive on the right. As this Hunter screen shot shows, this tips the top of the tire outward, which is not a desired setting for proper handling.

JCG’s alignment specialist Emilio Albor put the car on the rack and began by checking the initial alignment. We’ve listed the as-delivered settings, along with the original 1969 factory specs for this car as well as the final alignment settings. As it rolled in, the camber was set positive, which does not help handling although the caster was close along with the toe. Nevertheless, several important steps were necessary before Albor could add his final settings.

Alignment Specs 

Angle Stock 1968 Measured  JCG Spec
Camber + 0.5 Left

+ 0.25 Right

+ 1.0Left 

+ 0.8 Right

– 0.3 Left

– 0.3 Right

Caster  +0.75 + 3.4 Left

+ 4.8 Right

+ 4.4 Left

+ 4.4 Right

Toe-in 1/16 per side 0.160” Left

0.020” Right

0.03 Left

0.03 Right

(+) indicates Positive Camber or Caster

(-) indicates Negative Camber or Caster

Many enthusiasts don’t realize that ride height has a significant effect on alignment settings. This demanded first that Albor set the tire pressures on all four corners and then carefully measure the ride height. There are many ways to accomplish this, but JCG measures from the lower edge of the wheel to the top of the wheel opening. Albor discovered the right side was lower by 3/8-inch and since the shocks had only 2 inches of available compression travel, he decided to raise the right side rather than lower the left.

After measuring the existing settings, Albor first set tire pressure and then accurately measured ride height. He uses the bottom edge of the wheel to the fender lip as a more accurate measurement. He discovered the right front was low by 3/8-inch.

Ride height has a major affect on alignment so the first requirement was to raise the right front coil-over to even the ride height. He raised the right instead of lowering the left side because shock travel was already somewhat limited.

There is a specific procedure to set the front alignment on any car. Camber is always set first. In this case, the initial position found the camber at 1degree positive with the top of the tire angled outward from vertical. To improve handling and limit tire wear for this application, Albor established a ¾-degree negative setting which angles the top of the tire inboard from vertical. To adjust this, Chryslers use an eccentric which move the upper control arm pivot point in or out as required. Once he had the camber set on both sides, that allowed him to then move to the caster settings, which required minimal tuning since they were already very close, arriving at 4.4 degrees positive for both sides.

The first adjustment to be made with any alignment is the camber. The Magnum Force front clip uses tubular upper arms but they still bolt to the stock upper control-arm mounting points which are adjusted with eccentrics rather than shims. This shows Albor adjusting the eccentrics to move the upper control arm position to pull it in at the top, which increases negative camber.

Caster is the tilt of the tire as viewed from the side. Positive caster is the tilt of the top of the spindle rearward of the axle centerline as indicated here with the rod. Negative caster tilts the top of the spindle tilts forward. This photo shows the top of the tire tilting rearward for positive caster as viewed from the driver side.

Camber is the tilt of the tire away from the center of the car (positive camber) or the tilt inward toward the center of the car (negative camber). This screen illustrates the tire with a slight amount of negative camber – 0.3-degree. It also shows the tire with a slight amount of toe-in.

This left toe-in as the final adjustment. As the GTX rolled in, it had close to 3/8-inch toe-in on the left side with nearly zero on the right. This is where the Hunter machine’s capability to measure from an exact centerline to give individual left and right toe-in specs is a significant advantage. It required several adjustments to not only achieve the proper 0.03-inch toe-in (roughly 1/32-inch) for each side but also to ensure the steering wheel pointed straight ahead.

Toe is always set last because any adjustment to camber or caster will affect the toe setting. Since this car is intended as a highway cruiser, Albor set the car up with 0.030-inch of toe-in per side. That’s less than 1/32-inch per side.

Albor started the engine several times to help hydraulically center the rack to make sure the wheel would track straight before finalizing the toe setting. He says that if you don’t start the engine and energize the power steering hydraulics, the pump will often later take up slack in the system. This results in the wheel likely not centered which is discovered in the test drive, requiring a second adjustment. Alos, once the steering wheel is centered, this can affect the final toe-in slightly, so Albor went back under the car one last time to finalize everything.

This is a photo of the Hunter display revealing the final alignment specs with 0.3-degree of negative camber, 4.3 to 4.4 degrees of positive caster, and a toe-in of 0.030-inch per side. Each side can be called out individually because the machine automatically measures from the vehicle’s digitally calculated true centerline.

As part of the Hunter system report, you can see the wheelbase is within fractions of an inch of its 115-inch wheelbase, but note that the new front suspension widens the front track to 63.2 inches compared to the rear track width of 60.5 inches. Most production cars (with some exceptions) maintain the same track width front to rear.

To put the toe-in spec of 0.030-inch into perspective, a 1/32 of an inch equal 0.03125-inch per side for a total toe-in spec of less than 1/16-inch. While this might be on the verge of splitting hairs, it does point out the advantage of using an alignment machine with this kind of precision. Yes, you can do toe-in adjustments yourself on your garage floor with a couple of straightedges and two tape measures, but there are limits to the precision. Unless you measure toe from the centerline of the vehicle, you have no way of knowing what each tire has for the actual toe.

This screen shows similar information but in a different configuration. There’s a minor difference in wheelbase of 0.2-inch, the lateral offset indicates the track width difference front to rear, and the rear axle offers no offset so it is centered in the car.

The final check on any alignment is to take the car for a short test drive. Albor told us that sometimes the numbers would be well within spec and yet the car will pull to one side. The quick check for this is to switch the front tires and then drive the car again. Sometimes the tire switch will move the pull to the opposite side, which indicates a problem with the tire. However, he’s also seen issues where the pull is caused not by the alignment but due to brake drag that can be caused by a stuck caliper piston or other brake malady. He also told us that caster numbers that are off could also cause a pull to one side only when the brakes are applied.

As a final test, Albor took the GTX out for a simple test drive to make sure the car tracked straight with no pull to the left or right. He experiences a nearly imperceptible pull to the right which he counteracted by adding one psi of tire pressure on that side, which reduces rolling resistance.

The test drive was successful except that Albor felt a very slight pull to the right which he felt might be caused by the tire, so he added 1 psi of pressure to that front tire to slightly reduce the rolling resistance. With that, the GTX was now ready to take on the road with a renewed sense of freeway speed confidence bolstered by the knowledge that the tires are at least now all pointed in the right direction.

About the author

Jeff Smith

Jeff Smith, a 35-year veteran of automotive journalism, comes to Power Automedia after serving as the senior technical editor at Car Craft magazine. An Iowa native, Smith served a variety of roles at Car Craft before moving to the senior editor role at Hot Rod and Chevy High Performance, and ultimately returning to Car Craft. An accomplished engine builder and technical expert, he will focus on the tech-heavy content that is the foundation of EngineLabs.
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