The importance of correct wheel alignment and how it can affect performance

Forget your chalk and string: a proper wheel alignment takes computing power

Photographers: Paul Tuzson

For most guys building cars it’s all about more power, but getting that power to the ground and controlling it is more important. No point having a gazillion horsepower if your wheels and tyres are fighting you every step of the way. In other words, it’s all about wheel alignment. Jason at Straightline Automotive sets up plenty of street/strip cars for the straight and narrow, so we dropped in to get a line on what’s involved in getting your classic running true.

First published in the January 2014 issue of Street Machine

“People don’t understand that it’s all well and good to have heaps of horsepower, but the set-up has to be balanced,” Jason says.

All four corners of the car have to work together. Fundamental things like good springs, shocks, anti-roll bars and the like are the foundations of a well-balanced package, but correct alignment is vital to finishing it off. Even with the best components, if the alignment isn’t right, you’re not getting the most out of your set-up and it could be costing you dearly in outright performance.

Most people don’t have any trouble visualizing degrees, but each degree is divided into 60 parts (called seconds) to achieve the accuracy required.

Small changes can have big consequences. Even clipping a gutter at just 10km/h can bend things enough to affect alignment. Harder hits can start to bend things noticeably. If the adjustment points on one side of a car have more thread showing than those on the other side, it’s a pretty good indication that the components are damaged in some way and might need replacement.

To be safe, if anything relating to the suspension has been changed, the car should be re-aligned.


There are many terms used to describe the settings related to alignment, but in general there are just three main settings changed during an alignment; caster, camber and toe.

Caster describes the pivot axis for the stub-axle. If the axis was vertical when viewed from the side of the car, it would be said to have zero degrees of caster. If the axis is laid back with the top pivot point further to the rear than the lower pivot point, it’s said to have positive caster. Negative caster is when the pivot axis leans forward, but isn’t used on rear wheel-drive street machines.

Camber describes whether the wheels lean in or out. If the top of a wheel leans in towards the centre of the car, it’s said to have negative camber. If the top leans out it’s positive. Again, positive camber isn’t used on a street machine.

Toe is whether the wheels splay in or out at the front. Toe is simply referred to as toe-in or toe-out.


Ensuring that the tyres are in suitable condition is extremely important. They need to be properly inflated and in good condition because both can affect proper wheel alignment.

Not surprisingly, aligning a car with worn tyres is a waste of time, particularly if they are worn unevenly. Maintaining even wear is a good reason to adopt the practice of rotating wheels/tyres. Of course in practice front and rear tyres will likely be different sizes for a street and strip car so it’s more a matter of swapping wheels from side to side.

This also brings up the matter of matching tyre types. Run radials with radials, and cross-plies with cross-plies. Jason says cars with mixed types are impossible to align properly and not a good idea generally. So, with the suspension in good condition, and the tyres all sorted, it’s ready for alignment.


The first step for Jason is to ensure that the car is square. Infra-red measuring heads are mounted to the rim of each wheel, levelled and then locked in place. Then the computer reads the data and calculates the position of the front wheels in relation to the rears.

Camber and toe are readily determined but caster is a touch trickier. The front of the car is lifted and the wheels are turned twenty degrees in each direction. The changes in wheel orientation allows the computer to calculate caster. Once this is done, the steering wheel is set to the straight-ahead position and locked firmly in place, so that nothing can move as adjustments are made. Same goes for the brakes.

Alignment machines contain data for a wide range of cars. Jason says it’s best to start with the factory settings, particularly if the car is at standard height. Naturally, most street machines, classics, hot rods, vans, customs and muscle cars have been lowered at some point in their history and some compensation is required for the altered geometry. Effects can vary, so experience is necessary to understand what’s required for various cars, suspension set-ups and intended uses, as the interactions between caster, camber and toe are very complex.

Everything has to be adjusted in the right order. Caster is first, because if camber is done first then subsequently adjusting the caster will throw the camber out again. In fact, all adjustments have an effect on other adjustments, but doing caster first minimizes such effects.


More positive caster increases straight-line stability, but it also increases steering effort and reduces cornering performance. So less positive caster increases cornering performance but going too far can make a car ‘darty’ and less stable. It’s important to keep all adjustments even from side to side. If there’s less positive caster on one side than the other, the car will pull to that side.

Track and road settings are different because all roads have a slight crown so that water flows off them. In a pure street car, Jason adjusts one side of the car slightly differently to compensate for that.


Lowering a car increases negative camber. In a drag car, reduced negative camber is a good idea because, as the front of the car lifts, the suspension falls into significant negative camber. When the wheels drop back onto the track, the camber is still present and will remain so to some extent because a drag car remains light at the front.

Reduced negative camber makes the car more stable and helps it to track straight, but a circuit car is different. As the body rolls over through a corner, negative camber helps maintain the tyre contact patch by keeping the wheel upright.


If toe is uneven on one side, a car will dart in that direction. Uneven toe can also be the cause of unequal steering effort on one side. If there’s too much, tyres will wear unevenly with feathering. Excessive toe will also create drag and can slow a car down, but just the right amount of toe will help a car maintain stability under all conditions.


A car may be perfect on the alignment rack, but that doesn’t necessarily reflect what happens on the road. It may pull to one side simply because one bolt is tighter. Jason explained that cars with big wheels on the back and littles on the front will almost always pull in one way or another, and older cars that have steering boxes can also have a bit of play in the system which also affects things. Basically, these things can’t be determined properly until the car is rolling and the relevant forces are brought into play. Jason says he gets them as close as possible on the rack, but always finishes with a test drive to confirm the results and make fine adjustments.

Getting your car aligned properly will have a number of benefits. Your car will be faster on the track, and more stable and controlled. Plus your tyres will last longer, so you’ll save money.

Wheel alignment is a tricky business so you’re better off getting it done by an experienced technician.


1. Most cars with standard suspension are square at the back, but sometimes things change. Here, the distance between wheel and arch is being checked. This should be the same on both sides of the car.

2. The adjustment points for caster, camber and toe. This car hasn’t been restored underneath although the components are in good mechanical shape. It’s intended for serious street and strip use.

3. In a car that hasn’t been restored, the bushes can be in pretty bad shape and this will prevent proper alignment. When a car has been restored properly like this one, more accurate results are possible. All the cars here were restored by Competition Engines in Victoria.

4. When a car is heavily customized, it’s important to check that everything at the rear end is where it’s meant to be. Here, the original factory pick-up points are used so it shouldn’t be too far out.

5. In a fully fabricated rear end like this, extensive checking will be necessary. If no standard reference points remain, it may be necessary to find a centre point at the front cross-member and another point at the rear. One car Jason set up this way went from 8.10 to 7.90 just because of the alignment!

6. To find caster, the front of the car is jacked up on the rack and the wheels are turned from side to side.

7. During alignment, the steering wheel and brake need to be locked in place to prevent movement.

8. Corrections are shown on a screen. It’s a matter of getting a car to factory specs and then making whatever changes are needed for the particular application.

9. Caster on a Falcon is adjusted by winding the radius rods forward or backward. The rear ends of the rods are attached to the outer ends of the lower control arms, and pull them forward or backward accordingly.

10. On Falcons, camber is adjusted by an eccentric bolt at the inner end of the lower control arm.

11. Toe is adjusted by winding the ends of the steering tie rods in or out.

12. This is toe-in.

13. Corner weights measured with accurate, portable scales and tyre temperatures are essential tuning tools for dedicated race cars.

14. On Holdens, camber is adjusted by inserting shims behind the mounting point for the upper control arms.