For obvious reasons, the steering system of a kart is rather important. All too often the components connecting the steering wheel to the front tyres - their condition, how they are fitted together and their alignment - don't receive the amount of attention they should. Apart from dangerous consequences of component failure, poor front-end alignment also costs speed down the straight AND through the corners, and can also lead to excessive tyre wear.

Try this: Inflate your tyres to race pressure. remove the chain (unless it's a Rotax or Leopard - they've got a clutch). Put the kart on a smooth concrete or asphalt surface, and install a driver. With the steering straight, push it along. If all wheel bearings are in good condition, the kart should easily roll forward, and keep rolling some distance. Give it another push, but this time have the driver hold a little bit of lock on the steering. Notice how much more difficult it is to get the kart mobile, and how quickly it comes to a stop? A number of factors contribute to this, but it amply demonstrates the point that as soon as a tiny bit of steering angle is introduced, the increase in rolling resistance (drag) is dramatic. For this reason, a poorly aligned chassis will be slow, and it doesn't take much work to get the lost speed back.

To start with, we need to acquaint you with some terms that are used in this article. If a component has a proper name, we will use it.

STUB AXLE: The stub axle is the pivoting member that includes the front axle and steering arm. Two different stub axle configurations are in common use today. If the pivot bearings are carried in the stub axle (such as Tony Kart, Arrow, Monaco, CRG, etc), it is called a 'male' stub axle. If the bearings are carried in the chassis (eg Azzuro, Monza, earlier OCR and Swiss Hutless), it is a female stub axle. There are point in favour of each design, and we will discuss these later on.
For obvious reasons, the steering system of a kart is rather important. All too often the components connecting the steering wheel to the front tyres - their condition, how they are fitted together and their alignment - don't receive the amount of attention they

STEERING ARM: The steering arm is the arm projecting rearwards from the stub axle, to which the tie rods attach. These are usually angled inwards in order to give an amount of Ackerman geometry.

PITMAN ARM: The pitman arm is the correct name for the lever, which protrudes from the steering column, and to which are connected the tie rods. The pitman arm may be a simple straight arm, a triangular bracket or a combination of both. This 'belt and braces' approach should tell you that even the kart designers are not fully convinced which design is better.

TIE RODS: The tie rods are the adjustable links that connect the pitman arm and the stub axles. They are usually either solid rod or tubular aluminium.

KINGPIN: The kingpin is the correct name for the bolt about which the stub axle pivots.
The angles and forces we will discuss are;

ACKERMAN: Ackerman, in karting, is more an effect rather than true Ackerman. the effect of Ackerman geometry is to cause the inside wheel to turn more than the outside when the kart is steered. The original intention of Ackerman when it was invented in the 1800s was to allow the inside and outside wheels to turn around a common centre, thus avoiding tyre scrub when turning. In karting, this is still a factor, but the Ackerman effect of toeing out the wheels progressively more as the steering is turned is used to accentuate weight jacking, which we will discuss later on.

TOE: Toe-in or toe-out is a measurement made when the kart is stationary and the steering is straight ahead. It means the wheels are pointed in towards each other at the front (toe-in) or at the rear (toe-out). Toe is expressed in mm, the figure being the difference between the centre line of the tyres at the front and rear. When the front measurement is less than the rear measurement, the result is 'toe-in'. There are many out there who will argue that the wheels should be set parallel (zero toe) in order to avoid 'snow ploughing' and get the best speed on the straight. This is not necessarily so, as you will read in a little while.

Toe adjustments must be made equally on both tie rods with the pitman arm locked in a central position, otherwise the one sided toe will 'split' when the kart is driven. This will result in the steering wheel being crooked at best, and the camber angles and cornering weights being out of whack. Toe and camber adjustments are best made using special equipment such as alignment plates. These plates are available from any kart shop and are fitted in place of the wheels. They allow ease of measurement with a tape measure to the degree of accuracy which is needed for wheel alignment. All steering adjustments should be made while keeping 'tracking' in mind. This means that all the wheel angles, including those of the rear wheels, should correspond with whatever is needed to keep the kart running in a straight line. Always use the rear axle as a reference for all adjustments to the front end, but before this can be done, the leveling and centering of the rear axle in the chassis must be checked.

CAMBER: Camber is a very important angle, being the angle at which the tyre surface is presented to the racing surface. Wheels that are inclined together at the top are said to have negative camber and vice versa. The usual setting for racing tyres is to have a little negative camber in order to generate the most grip. Camber angles impart a sideways force called camber thrust, and it is very important to understand this

KPI: KPI (King Pin Inclination) is the angle of the king pin when viewed from the front. In karting, the kingpin should be inclined towards the centre of the the kart at the top (positive KPI) and is usually a similar angle to the caster angle, although an adjustment of one usually affects the other. Caster and KPI work together to apply a jacking effect when the kart is steered. KPI is sometimes called SAI (Steering Axis Inclination).

CAMBER THRUST: Camber thrust is a force generated in a tyre when it is run at an angle to the racing surface. This is best understood when you consider that the cornering forces in a motorcycle are generated by leaning the bike over, thereby increasing the camber angle. The wheel effectively assumes the form of being part of a cone, and tries to roll in a circle like a cone would. Wheels with negative camber will try to roll towards each other, but the chassis resists this tendency. The result is that the tyres tend to scrub on the road, thereby slowing the kart perceptibly in a straight line. This scrub can be cancelled by toeing the wheels out slightly. So, those who argue the wheels should be parallel for the best straight line speed are only correct when the camber angle is zero. This is very important in low powered classes where every little bit of power conservation helps reduce lap times.

CASTER: Caster (or castor, although that refers more to the type of oil you should be using in the engine) is the angle of the kingpin when viewed from the side. In karting, the kingpin should always slope back at the top, and this is called positive caster. Caster is an angle which gives directional stability to the kart in the straight ahead position, and which contributes to weight jacking when the steering is turned.

WEIGHT JACKING: The effect of Caster and KPI is to make the inside wheel 'heavy' when the steering is turned. By this we mean that the inside wheel is pushed down by the geometry and the outside wheel raised. This jacks the weight diagonally across the kart, with the inside front and outside wheels taking most of the weight. Centrifugal force will then transfer the weight to the outside front wheel, causing the inside rear wheel to momentarily lift off the racing surface. This allows the kart to turn into the corner, rather than trying to push straight ahead if both back tyres retained equal grip. This effect is easily seen when driving in the wet and it is difficult to get enough cornering force to make this jacking effect work well, and gross understeer or push is the result.
Ackerman geometry causes an increase in toe-out as the steering is turned and this is more of a consideration in karting than having the wheels follow a nice 'correct' line around a corner. More Ackerman effect is needed on sticky tyres and with more powerful engines as it allows a more aggressive attack on corners. This same aggressive Ackerman will result in extra drag in corners on a low powered kart, particularly on slow corners where the excessive toe out may cause the inside tyre to scrub exiting the corner affecting speed down the following straight. If you suspect this may be happening, very carefully inspect the inside front tyre for evidence of 'reverse' scrub marks, that is evidence of the tyre being worn from the inside out, rather than vice versa.

The weight jacking effects of caster can be increased or decreased by changing the front track. Widening the front will increase the jacking effect at the expense of heavy steering and a lessening of steering feel, whilst narrowing it will have the opposite effect. Widening the rear track will allow the jacking effect to 'float' the inside rear wheel more easily, thereby assisting turn-in.
As a general rule, the front track should be run as narrow as will allow adequate weight jacking, whilst the rear should be run as wide as grip will allow. This will result in a flat cornering, predictable chassis, which hopefully will not bog the engine with grip in mid corner and slow the kart on the following straight

CAM ADJUSTERS: The cam mechanisms on king pins have a different effect on male and female stub axle assemblies.
On a female stub axle, where the pivot bearings are mounted in the chassis, and the adjustment cam is in the stub axle, rotating this cam has no effect on caster or KPI angles, but is simply a camber adjustment device. Rotating it will have a minuscule effect on the Ackerman angle, but this can be ignored. These cams can be rotated to adjust the camber to the desired amount. About one quarter to one half a degree negative is a good place to start. Ensure the wheel is pointed absolutely straight ahead when adjusted, and make sure the toe-in is adjusted properly afterwards. Toe-out of 2mm is a good place to start with the above camber settings.

PERFORMING A WHEEL ALIGNMENT: Performing a wheel alignment should be part of your regular maintenance routine, and should also be done after contact or a ride through the rough. It's amazing how often a check of the front-end reveals problems that need to be addressed.
There are a number of products on the market to perform a wheel alignment, ranging from the high-tech Sniper laser system to a simple pen and tape measure. Cost, ease of use and accuracy all vary and it will be up to you to decide your level of investment.
To set front wheel alignment, start at the back of the kart. The Reason? It's fine having the front wheels in alignment with each other, but they also need to track parallel to the rear wheels so that the kart doesn't 'crab' when traveling in a straight line. On each side of the kart, measure from the rear axle to a common point at the front (for example, the king pin). The two measurements should be the same. If there is a small variance, there should be enough clearance in the axle bearing mounting bolt holes to adjust it to be even - just loosen off the bolts slightly and tap the axle with a soft hammer before gradually retightening. Sometimes the mounting holes might need to be filed a little and if the difference is more than 3 or 4mm, it would indicate your chassis has been damaged. Also make sure the axle is fitted flat in your chassis and is not higher on one side than the other. Spooky handling and poor braking can be experienced if this is the case.
With the rear axle now parallel to the king pins, we can now turn our attention to the front of the kart. Loosen off the four tie-rod locking nuts and ensure the tie-rods can easily be twisted to make adjustments. If not, remove them, clean and lubricate the threads. Also check for straightness and the condition of the spherical rod-end bearings. Replace any damaged or worn components. Some stub axles have two mounting holes on the steering arm for the tie rods so that Ackerman can be further adjusted. Make sure the same holes are used on each side (you might need a longer or shorter set of tie rods to test the other option). Lock the steering column in the straight ahead position. This is usually done by clamping vice-grips on the plastic bush at the top of the column. 'Straight ahead' is when the Pitman arm is centralized, not necessarily when the steering wheel is straight
A quick and easy method of getting the front wheels running true to the rear is to now place a straight edge across the front of the kart (resting on the king pin bolts) then adjust tie-rod length so the axle part of each stub is parallel with the straight edge. Don't worry if one tie-rod ends up longer than the other. Most karts have the steering column located off centre which calls for uneven length tie-rods. You now have a 'square' kart with all four wheels pointing in the same direction, ready for the finer front-end adjustment.
Several methods exist, the most common being alloy wheel alignment plates or discs available from most kart shops. The most elaborate, and arguably the most accurate, are gadgets such as the amazing Sniper laser system, Exac-Toe and Triton, but a pretty good job can still be done with standard alignment plates, or even just a pen and tape measure.
Fit whatever equipment you will be using and measure the distance across the front and across the back of the alignment plates/wheels. (The Sniper system has it's own built-in grid on the side of each unit for this, so no measuring is needed.) Make sure the tape measure has a straight run from one side to the other. If it's kinked to clear a crash bar or fuel tank, the measurements will not be correct. Adjust each tie rod the same distance (to prevent toe-in on one wheel and toe-out on the other) and keep checking the measurements until you arrive at the amount of distance you require, eg the measurement across the front would need to be 2mm more than across the back to achieve 2mm of toe-out. Camber can be set in exactly the same way, except the plates need to be turned 90 degrees so measurements can be taken across the top and bottom. It's now time to tighten the locking nuts and recheck the toe setting to make sure nothing has moved.
If you don't own any special equipment, using a pen or tape mark on each front tyre is still a pretty good method, although it can be not quite as accurate and you'll need a second person to hold the tape measure. Simply mark the tyre tread (or put a fine pen mark on some race tape and stick this to the tyre tread) and use a tape measure between the two reference points. Simply revolve the wheel 180 degrees to take the front and rear measurements.
When locking up rod-ends, make sure that the tie-rod is still free to move, ie, no components bind up when the steering is turned from lock to lock. Also check that the inspection holes in the rod-ends or tie rods with some thin gauge wire to make sure you haven't run out of adjustment. Whenever camber or caster adjustment are made, or if you bend or replace any component in the steering, you will need to do another front-end alignment.
What is the best toe-out setting? What is the magic number? There isn't one. The general opinion is that 1 to 2mm toe out is correct for dry weather conditions on most karts, but check with your kart dealer or manufacturer for the correct settings for your chassis make and model. Keep in mind too that when setting the front-end with the kart on the stand you are setting the 'static' toe. This can possibly change when the kart is on the ground with a driver onboard and systems such as Sniper can measure the difference between the 'static' and 'loaded' settings