Fixing Oversteer

A few articles ago, we tackled understeer. What it is, what causes it, and what you as a driver can do about improving it. Moving on now, we look at the polar opposite, oversteer. This phenomenon happens when the rear loses traction and grip, resulting in the back end sliding around corners. There’s an imbalance of grip between the front and rear of the kart. In today’s article, we will take a deep dive in the hopes of understanding one of karting’s common issues.

Source: KartPulse

What Causes Oversteer?

The first thing to look at is the balance of the kart. To have proper balance with the kart, it is crucial to distribute the weight properly. This is important for Cadet classes where a lot of lead ballast may need to be fitted to the kart.

Similar to understeer, entering a corner too fast or too quickly can also cause oversteer. As the term suggests, oversteer literally means you are asking too much turn-in from the kart while not having the grip to show for it. This does not keep the kart planted with the track, leading to the eventual loss of the rears. Driving style and technique is also a major player in what leads to oversteer. As we delve deeper into the changes that can be made, the underlying theme and similarities they share is that anything too abrupt or too sudden that is done within the go-kart is what typically leads to the loss of the back of the kart.

Now, let us take a look at what you as a driver can do to take action on the matter.

Setup Changes

1. Chassis Setup

The setup of the kart's chassis, including the alignment, camber, and caster settings, can influence how the kart handles. Let’s take a look each one:

A good starting point is with the camber of the kart as how you adjust the caster will be affected. Camber in simple terms, is the angle at which the tyres are positioned. Pushing the camber to a negative setting is the way to go which essentially means the fronts are pointing at each other.

Next, we’ve mentioned before that increasing caster can help prevent understeer. With that, by decreasing the amount of caster is the way to go to prevent oversteer on entry. This is done by moving the kingpin bolt forwards. For reference, the kingpin bolt looks like this:

There are also other parts the driver can tinker around with. Raising the front ride height can help with providing more grip and removing some toe-out on your alignment.

2. Axle Settings:

Drivers can adjust the rear axle as a tuning tool, to help with the balance of the kart. In short, softer axles give more grip on entry up to the middle of the corner. Stiffer axles without saying are more firm which can help in creating a more pointy kart. Because both are polar opposites, drivers tend to go for a neutral axle as it serves as a jack of all trades that can perform decently in any condition.

3. Tire Pressure and Condition:

Incorrect tire pressure & worn-out tires can cause a loss of traction in the rear tires. If your tire pressures are set too high, they increase in temperature, and once they overheat, will provide less grip. If the driver notices the kart handling well for the first half of the race, then start to slide the longer the race goes on, this could be a sign the pressures are too high.

Tires will wear down throughout a race event. This can be seen with the indicators (dots on the tires) starting to show less depth. When this occurs, more rear grip needs to be added to the kart to compensate for less tire grip.

A Rotax Digital Tyre Pressure Gauge (Source: International Karting Distributors)

Driving Technique

1. Weight transfer

Maintaining a proper center of gravity helps with kart balance.

In the case of preventing oversteer, the driver’s position is often situated such that their weight is mostly on the rear. This can help play a part in weight transfer as this can provide more grip over the rear. If the kart is constantly sliding, shifting your body weight to the outside tires will help generate more grip in the rear.

2. Corner speed reduction

Similar to understeer, oversteer can be caused when the driver simply asks too much from the kart. It is always a fine line between pushing to the limit versus beyond it. Therefore, always remember to make gradual changes to your driving style. Doing so helps the driver find the limit while also not risking binning the kart in the gravel.

Having markers also helps to stay within the limit. From brake boards to as little as a skid mark on-track, these signifiers help mark where and what the limit of the kart is. Be sure to have pointers for crucial areas of driving such as braking, turning, and acceleration.

Slow your steering inputs on corner entry also. If a driver is too sudden with their initial input, the front will go where you want it, but the rear of the kart won’t keep up.

If a driver is experiencing oversteer on the exit of a corner, the driver can adjust their throttle application. If the throttle is placed down too aggressively, this can cause a lack of grip in the rear tires causing oversteer.

3. Risky business: kerbs

Kerbs can be your best friend or your worst enemy depending on their size and how much the kart can take. Always be sure to take proper track walks and check how much kerb you can take. In some cases, you might find yourself not even going over it. Tall and wide kerbs are usually avoided as they can easily unsettle the kart and give too much rear wheel lift. This is exactly the case as seen in the photo below. So when the kart lands, after it has got airborne, can cause a slide in the rear depending what steering angle the kart lands with.

Source: KartPulse

The Weather’s Impact

Slippery or uneven track surfaces can lead to reduced traction at the rear, causing oversteer. This is especially true in wet conditions. Because of this, setups compared to dry become vastly different.

Take for example tire pressures. For reference, it is roughly 8-15 psi that is required for go-kart tyres. However, when downpour occurs it is advised that they are inflated to as high as 20 psi so as to avoid aquaplaning. This also inadvertently increases the grip in an otherwise slippery surface.

CONCLUSION

And that concludes our article on how to combat oversteer. While all these setups and techniques in theory can solve your woes, never forget that every driver is different. Some things will work for one driver and not for another. It is important to determine which of these tips mentioned today can help you navigate your way to the top step.

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