Slippery when wet!

Columns: Vroom Academy
Vroom Academy continues this month with part 2 of the new column brought to you by 18 times Australian karting champion David Sera. With over 25 years of experience racing around the world in various classes and running at the top of the field, he has now turned his focus to coaching the next generation of racers. In doing this, Sera has also introduced an online coaching platform called KART CLASS, aiming to provide even more drivers with the essential information that’s easy to access, helping to develop their own skills using different levels of programs and options.(by david sera)

With some parts of the world moving into their winter months and so much rain predicted at this time in many countries, this edition of the Vroom Academy is centred on the art of driving in the rain. For most drivers, the thought of getting wet, cleaning the kart and potentially multiple spins in the gravel are enough to knock any driver’s confidence about. But the realisation is that kart races are held in all conditions, so drivers need to be able to adapt to the ever-changing situation. Horsepower isn’t as critical in the rain, with more focus on the driving and kart setup, so this levels out the competition and generally the more experienced and confident drivers come to the fore. 

The number one factor in the wet conditions is where to place the kart on the racetrack to gain the most traction. 
Now in the dry, once a group of karts start to circulate on the same line lap after lap, a dark black rubber racing line starts to form. This is easy to spot for new drivers at the racetrack, but in the rain when the track is wet this can be washed away or harder to see.
The same racing line driven in the dry generally has less traction in the rain, as rubber mixed with water has a slippery effect. The reason for this is the water sits on top of the rubber and the wet tyres need something abrasive to bite into the surface of the racetrack to provide additional grip. 
Drivers need to either drive inside or outside of the traditional dry line to be on the more abrasive surface which will give the kart more traction. If you choose to go towards the outside line (longer distance to travel) this allows you to brake later as you’re using the maximum track width, but if you make an error, there isn’t much margin before you exit the racetrack. This line is better suited to the lower performance categories as the key is to keep your momentum higher when cornering. 

The inside wet line is more accustomed to higher performance categories where the driver looks to place two wheels on top or inside of the kerb, to help rotate the kart around the corner. A driver will brake inside of the dry rubber line to gain more braking performance and then angle the kart to have two wheels on the kerb. Where drivers can come unstuck here is if they don’t get the wheels on the kerb, but drive the dry rubber line, they will notice more understeer than if they hit it correctly. This line is most used in the higher performance categories (TAG, OK-J, OK, KZ) where momentum isn’t as critical. 

To limit the wheelspin on the exit of a corner, drivers want to reduce their steering input as quickly as possible. As a driver, you also need to modulate your throttle as this is a big factor in how much wheelspin your kart will generate. If the rear tyres start to spin too aggressively, slowly reduce the throttle application then reapply it once you have the steering wheel straighter. Or, alternatively you can apply the brakes at the same time as the throttle to reduce the wheelspin on exits.
Now we have the kart placed on the right part of the circuit, we need to focus on our entry to the corner and the most common mistake drivers have in the rain is locking the brakes and spinning out of control. 

There are two methods to braking in the rain: 
1. Locking the brakes and trail-braking to the corner 
2. Using the brakes lightly and then releasing approaching the corner

If a driver is confident, trail braking on entry allows you to enter a corner with more speed as you are slowing the kart down all the way to the apex. It’s a similar approach to trail braking in the dry where a driver locks the brakes, then slowly reduces the brake pressure all the way to the corner. A common area why drivers spin on entry is that once they lock the rear tyres and the kart begins to slide, they hold the brakes at 100% still and the rear of the kart rotates them into a 180 degree spin. If you begin to lose control of the rear, rather than keeping the brakes engaged, release the pressure as this allows the rear tyres to rotate and that will straighten the kart up. Once you regain some control, reapply the brakes so you don’t run off the racetrack. This technique is more commonly used in the higher performance categories (TAG, OK-J, OK, KZ) where entry speed is higher.

The second technique is where a driver uses the brakes less and is more accustomed to newcomers or drivers who lack confidence in the rain. If a driver is constantly spinning out of control, they are more likely to use the brakes less aggressively and frequently, so they stop spinning. The one downside with this method is that a driver can’t approach the corner with the same speed as the trail braking technique, as they are using resistance to slow the kart down which isn’t as effective and it takes longer to reach the required cornering speed. 
Now that we have approached the corner with the right speed and on the correct line, we want to concentrate on how to steer when cornering. 

Drivers can be aggressive with their steering input and reach the maximum lock. This creates more scrub on the front tyres and acts like a brake, slowing the kart approaching a corner. Fernando Alonso still uses this technique in Formula 1 from his karting days. A driver will go from 0% steering input to 100% as quickly as they can, and the understeer effect normally lasts 1-2 seconds before the front tyres can react and start to turn. 
If you’ve set the kart up to have a lot of initial steer (Increasing Caster, Steering Ackerman & Front Hubs) then the above method might not be required. Drivers will approach the corner and smoothly turn the steering wheel allowing the kart itself to do the bulk of the work. 
The last area we want to discuss, when it comes to driving in the rain, is shifting your body weight in the seat. When cornering, a driver will move their body opposite of the way they are turning. For example, a driver turning a left-hand hairpin will shift their body towards the front right tyre. By adjusting your position in the seat, this takes weight from the inside rear tyre, creating more jack, and this will help rotate the kart faster. 

Note: this has more effect for taller and heavier drivers as the body weight to chassis weight could be a 50/50 split, whereas a cadet might be a 30/70 split.
Driving in the rain is an equaliser to people’s equipment, as the more skills you have in the rain are far more important than having a slightly better engine than your competitors. An understanding on when to use the above techniques, depending on your class and the corner you are approaching, will set you apart next time on track. 

Check out KART CLASS online for more tips to improve your own driving skills. All the programs, videos, E-books, worksheets and diagrams can be accessed from any mobile device. Simply create an account, choose the program suited to your experience level and have 24/7 access to the content.

The main objective for Kart Class is to offer world class coaching to drivers anywhere in the world, anytime of the day at a fraction of the cost. No extra travelling, track fees, race team fees and the challenge of accessibility for good coaching that some race tracks can’t offer. There’s also free stuff!

Why not have your karting question answered here at Vroom? Just message David Sera at Kart Class online with the subject “VROOM Q&A” and we’ll select one answer to publish on Vroomkart.

Check out the Kart Class website - plus the YouTube channel and Instagram


Created by: cggiuliano - 14/11/22

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