From Karts to Cars

Many Karters take the leap into cars but they often struggle; they were fast in karts but in the realm of cars they no longer dominate. There are common issues that many drivers face. We outline a few of the problems and solutions below.

First we need to define what the differences are between karts and cars. The absence of gears, shocks, springs, roll bars, and solid rear axle are all relevant, but the major difference between a go-kart and a racing car is the absence of front brakes.

kart rear brakes

To be fast in a race car, you must use the brake pedal properly. This is the most important and probably the hardest part to learn. The corner starts with the braking. If you are not braking at the right time or if you are not doing the first part of the corner correctly, then you cannot do the remainder optimally. So braking is key in order to be fast.

The following is a very simplistic example of why braking properly is so important from a race engineer's perspective: put a glass on a table and push it around; there is some resistance, but still it moves around easily. Now put five heavy books on top of the glass and try to push it again. When you put weight on top of that glass it is harder to push. In a car, if we put more weight on a tyre it will have more grip. As a race engineer, a lot of what we do is shuffle the weight around to give you more grip.

As a driver, you can also shuffle the weight by using the brake, throttle and steering wheel. The brake puts more weight on the front, the throttle puts weight on the rear and the steering wheel can help jack weight side to side. As the driver, you are moving weight around the different corners of the car.

How does this apply to karts and cars? To turn a kart with a solid rear axle and lack of front breaks, a driver must release the brake in order to get the kart to turn. When the brake is applied, the rear of the kart wants to sit flat and go straight. Kart drivers develop incredible timing releasing the brake and turning in.

Unfortunately, the kart method for brake release and turn does NOT translate to a race car. In a kart we release the brake, in a racing car with need to ‘trail the brake’. This keeps weight on the front tyres -- remember with more weight on top of our water glass it ‘has more grip’. Same with the car; with trailing the brakes, we end up with weight on the front helping the car turn.

getting a kart to turn requires getting off the brake

The most common error we see is when a kart driver releases the brake (removing weight front the front tyres) then the driver tries to turn in as they would in a kart. This causes the car to understeer. When the car understeers, the natural reaction is to move to brake even earlier. The kart driver who is now in a car often uses good lines and good exit speed, but brakes too early and may also lack mid-corner speed, which shows up in less than ideal lap times.

The kart driver must learn trail braking. To brake deeper, the driver needs to retain a little brake pressure into the corner to keep the weight on the front. Often being more aggressive (making the car work) will give better results. However, there is a balance of being too apprehensive vs too aggressive. A good starting point is to be more aggressive with the brakes and less aggressive with the throttle.

Braking optimally is not an easy task to master, but it is probably the most important thing to learn in racing cars. If you don’t drive the first part of the corner correctly, you can’t do the rest of the corner correctly.

 Some common braking errors:

  • Braking too easy then too hard at the end of the stop. Braking harder at the end of the stop is often why a driver pinches / flat spots a tyre.
  • Not braking hard enough at the beginning of the stop. I often tell the driver to try to lock the brakes in the first 20 meters, and then start lifting off the brake pedal.
  • Smooth down changes – try to keep consist brake pressure through the down changes. Small adjustments in the pedal box can help greatly with this.
  • Engine braking – if you are engine braking you most likely could use more rear bias. The brakes are designed to slow the car not the motor.
  • Use a brake pressure sensor with a high logging rate (100/sec) to see where and how you are braking compared to the faster drivers.

The magic is in the last part of the brake zone: how the brake is released into the corner to keep rolling speed and enough weight on the front tyres to get the car to turn in. The sooner the kart driver can master this trail braking technique, the sooner they will be at the front of the grid.

kart drivers moving to race cars

The last bit of advice is to stay calm, relax your shoulders and hands, breath and have good visual markers. If it all seems like it is happening too fast, find visual markers that are farther away.




Chris Blomfield-Brown
Chris Blomfield-Brown

Author

Chris an avid competitive cyclist has been running his race engineering consulting group for over 12 years. He also taught for various Motorsport Programs and continues to mentors FSAE and Student F1 projects and is always open for questions



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