Speed Secrets: From Karts to Cars
By Ross Bentley
February 21, 2017
How many of the current Formula One, Indy car, WEC sports car and NASCAR drivers began their career in karts and/or quarter midgets? I certainly don't know for sure, but I bet it's over ninety percent.
While most of you reading this are not using karting to set yourself up for a career driving for the Ferrari F1 team (darn!), many of you use karting to tune up your car driving skills. Many of you have kids who are in karting. And many of you could learn a thing or two about the differences and similarities between driving a kart and a car.
That's where this week's feature, written by Chris Blomfield-Brown, comes in. You may remember Chris from his articles about the use of bio-metrics to monitor and improve your driving (and he'll be writing more about that topic in the near future). In addition to his Wireless Motorsport business, Chris has worked with many kids moving from karts to cars.
Enjoy! - Ross
Many karters take the leap to cars, but they often struggle. They were fast in karts, but in the realm of cars, they no longer dominate. I’ll address some common issues that many kart-to-car drivers struggle with.
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.
To be fast in a race car, the most important thing and probably the hardest part to learn is how to use the brake pedal properly. The corner starts with the braking – so if you are not braking properly or if you are not doing the first part of the corner correctly, then you can’t do the remainder optimally. So braking is key in order to be fast.
The following is a very simple example of why braking properly is so important from a race engineer's perspective. Take 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 that glass and try to push it again. When you put weight on top of that glass, it is harder to push. So in a car, if we put more weight on a tire, 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 use of 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. So as a 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 the solid rear axle and lack of front brakes, 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 in releasing the brake and turning in.
The kart method for brake release and turn does not translate to a race car, however. In a kart, again, we release the brake; in a racing car, we need to ‘trail the brake.’ This keeps weight on the front tires – remember with more weight on top of our water glass, it ‘has more grip.’ With trailing the brakes, we end up with weight on the front, which helps the car turn.
The common error we see is that kart drivers release the brake (remove weight from the front tires), then try to turn in as they would in a kart. This causes the car to understeer. When the car understeers, the driver’s natural reaction is to move to braking even earlier. The kart driver in a car often uses good lines and good exit speed, but brakes early and may also lack mid-corner speed. This shows up in less-than-ideal lap times.
What the kart driver must learn is 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 and making the car work will give better results. There is a balance, though, between being too apprehensive and being 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 or flat spots a tire.
• 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, then start lifting off the brake pedal.
Some things you can do:
• Smooth downshifts – try to keep consistent 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 tires 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.
The last bit of advice is to stay calm, relax your shoulders and hands, breathe, 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