Understanding Trail Braking

A little trail braking is always used on the rally stage to avoid accident.
A little trail braking is always used on the rally stage to avoid accident.
A little trail braking is always used on the rally stage to avoid accident.

At the beginning of any track day and even some driving schools, the instructor – one who doesn’t want their cars balled up in the guardrails – will explain that you cannot brake and turn simultaneously. This is, of course, not entirely true. Both inputs can, and usually are, used at the same time. The reality of the matter is that, if done incorrectly, it’s very easy to spin, and so it’s sometimes totally disregarded if not ill-advised.

The reason it’s so valuable is that it will shorten braking distances, occasionally shorten the corner itself, and help exit speed tremendously. It’s also very hard to do right, which is why those who can can pull huge lengths on their competitors. To trail-brake correctly you have to take into account the braking characteristics of your particular car, its handling characteristics and whether trail-braking is appropriate for the corner you’re dealing with.

Let’s begin from the top. Trail-braking works well with any car, but it has to be done differently depending on the car itself. If the car is very stiff and offers a stable aero platform, it should be braked hard and as the corner approaches, the pressure released progressively as the wheel begins to turn into the corner. This is basically true with every car, but with these types of vehicle, the grip affords a faster brake application and release. By the same token, the pedal pressure is progressively released in a softer, less grippy car, but sometimes at a slower rate and with a little more modulation in the middle.

Oversteering into a corner helps shorten it.
Oversteering into a corner helps shorten it.

How late and how hard to drag the brakes into the corner is the hard part to master, and it’s quite frightening to do. The car will be up on its nose, with the rear unloaded somewhat, and the likelihood of the car rotating is high. This is the objective, but too much rotation at the rear means a big slide or worse, a spin. Therefore, the pedal and steering must be synchronized precisely to avoid a mistake.
The more prone for oversteer a car is, generally speaking, the more willing it is to rotate into the corner. This is especially true on entry under braking, so dragging the brakes late into the apex is needless and can result in a spin or a big slide. If the car is unloaded for a long period at the back end and it begins to corner, it will slide, so sometimes a little maintenance throttle, even turning into the corner, is needed to keep the back end underneath you.

If the car is the kind that understeers a lot on corner-entry, trail braking is very useful. As a side note, it’s also something that can be used as the race wears on and degrading tires are not as willing to turn into the corner as they once were. With this kind of car, generally speaking, the longer the nose is loaded, the more grip the front tires have and the more responsive the steering will be. It’s now obvious how much of a balancing act this cornering phase is, and how it requires great sensitivity.

Here, a tiny bit of oversteer on entry can be seen with the front-wheel angle, but would be hard to notice from the outside.
Here, a tiny bit of oversteer on entry can be seen with the front-wheel angle, but would be hard to notice from the outside.

Longer, slower corners can really benefit from a long, slow release of the pedal – sometimes the brake is held until the apex. Turn Two at Laguna Seca is a great example of this type of corner. With two apexes, the car should be first braked heavily in a straight line, then as the steering loads up, the pedal should just begin to bleed off. In the middle of the corner but well before the second apex, the rear end should just rotate slightly towards the apex so that the steering lock can be released as the last phase of the corner is straightened. Even going wide isn’t a huge deal since it is compensated by the straightening of the corner and the ability to go full-throttle earlier.

Shorter, faster corners are where trail-braking is a no-no. Turn Six at Laguna Seca is a good example of this sort of corner. Generally speaking, the braking should be done in a straight line, and since the speeds are higher and the car more sensitive to inputs, the turn-in should have little or no accompanying braking. The car is turned quickly and to stabilize the rear in this quick direction change, a little throttle is needed.

This is a little too much rotation, and while not devastating, is not ideal.
This is a little too much rotation, and while not devastating, is not ideal.

Trail-braking is perhaps one of the scariest parts of cornering, especially when a corner is preceded by a long straight and braking forces are high. It can feel unnatural if the general rules of Track Driving 101 are adhered to, but it’s always these little tweaks that separate the good from the average. As with everything in cornering, sensitivity is important, but it takes even more here. How quickly the steering lock is put on and how quickly the brake pressure is released can cause the car to understeer, neutral steer, or oversteer, and it takes the perfect synchronization of the two to get the most from.

About Tommy Parry 102 Articles
Tommy Parry has been racing and writing about racing cars for the past seven years. As an automotive enthusiast from a young age, Tommy worked jobs revolving around cars throughout high school and tried his hand on the race track on his twentieth birthday. After winning his first outdoor kart race, he began working as an apprentice mechanic to amateur racers in the Bay Area to sharpen his mechanical understanding. He has worked as a trackday instructor and automotive writer since 2012 and continues to race karts, formula cars, sedans and rally cars in the San Francisco region.
  • Terry Smith

    Great article, and very informative. Thank you!

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