Braking: threshold, ABS and trail braking.

Threshold braking

Wikipedia describes threshold (or limit) braking as varying pedal pressure to get the most braking force, ideally right where the wheel is just starting to slip. Past that point the tire slides, and a sliding tire generally has much less grip than one that is still gripping, so the car takes longer to stop and you lose steering. Wikipedia adds that the available grip changes with the surface, temperature, tire compound and wear, which is why the technique is hard to do consistently.

Blayze coach Dion von Moltke puts it more simply: brake as hard as you can without locking the wheels or setting off the ABS. His way of finding that edge is to start from a conservative brake marker, build pressure until a lock-up or the ABS tells you that you have gone past the limit, and only then move the brake point deeper once you know how much pressure the car takes. That is work for a track session, ideally with an instructor watching.

The shape of a brake application

Driver61 breaks the pedal trace into four phases:

1. Move quickly from throttle to brake.
2. Build pressure to the maximum.
3. Modulate it near the grip limit.
4. Release smoothly toward turn-in.

A Blayze newsletter makes the contrast with everyday driving: on the street, drivers ease in and reach peak pressure at the end of the stop; on track, peak pressure comes early in the braking zone and is then released gradually. That is a description of two different jobs, not a suggestion to practise the track version on public roads. The same newsletter recommends keeping the heel planted (a heel stop helps) and wearing thin-soled driving shoes for feel.

Not every corner wants the same pressure. Driver61 says fast corners call for lighter braking over a longer distance, because a big stab just before turn-in throws weight forward suddenly and unsettles the car. It lists the most common braking mistakes as a slow change from throttle to brake, uneven pressure, and braking too early or too late, and says most of them come from poor vision (see vision).

Brian Beckman's Physics of Racing (Part 11) adds two physical points: braking distance grows with the square of the starting speed while braking time grows in a straight line with it, and overheated brakes can fade or boil the fluid. Brake fluid and pads for track use are covered on track day car prep.

ABS: use it or stay just under it?

Driver61 says ABS lets you press hard while the system pulses the brakes so the tires keep turning and you can still steer. It calls ABS less efficient than good threshold braking, and points out that ABS does nothing about weight transfer, so you still need a smooth release.

Ross Bentley says the answer depends on the car. With a highly refined system (he gives the Porsche GT3 as an example) you can press hard and let ABS work; with a less refined one, staying just below activation may stop the car shorter. He also says that on most modern cars, briefly getting into the ABS is generally better than using too little pressure, and that many drivers do not press hard enough at the start. Even with full ABS in the straight-line part of the stop, he says you should still trail off the brake gradually into the turn, and he recommends testing on track, since on some systems just touching the ABS may stop the car faster.

Brake bias

Brake bias is how braking force is split between the front and rear axles. Driver61 says the goal when adjusting it is for both axles to reach the grip limit at the same moment.

Releasing the brakes, and trail braking

Wikipedia defines trail braking as keeping the brakes on past turn-in and easing off gradually, with full release somewhere between turn-in and the apex. Adam Brouillard of Paradigm Shift defines it more broadly as any slowing that continues past turn-in, and says the term only exists because many drivers used to believe you should brake in a straight line only. Bentley agrees that even a short distance past turn-in counts, says you do not have to brake all the way to the apex, and notes it can be done with either foot.

Some coaches put the emphasis on the release. Bryan Van Noy, writing in NASA Speed News (2025), argues that when and how fast you come off the brake matters more than how hard or how late you brake. He says releasing too much too soon can cause understeer, that light pressure helps the car rotate by taking load off the rear, and that "the steering wheel is also a brake." Bentley says popping off the brake suddenly unloads the front tires and the car turns in poorly.

How much trail for which corner

Von Moltke describes the main benefits as rotation and the ability to brake deeper, warns against trail braking just for the sake of it because it can over-slow the corner, and suggests the name "directional braking." Driver61 says trail braking uses far lower pressure than straight-line braking and is mostly about adjusting the car's balance rather than slowing it. Brouillard says the goal of corner entry is to arrive at the right apex speed and angle in the least time, not to brake as hard as possible, and that drag, tire slip and engine braking also slow the car; in a fast corner a brief lift may be all the slowing needed.

Beckman (Part 23) argues trail braking closes the gap between coming off the brakes and reaching the cornering limit, worth perhaps a car length or two per corner. He also warns that overdoing it brings too much entry speed, and he considers entry mistakes worse than exit mistakes. Wikipedia notes that trail braking in cars works best with front-biased brakes: too much can cause heavy understeer, and with near-neutral bias it can lock the rear wheels and spin the car.

Why it helps the car turn: two explanations

• Bentley, Van Noy and von Moltke say keeping weight on the front tires helps the car turn.
• Brouillard disagrees. He argues that because of tire load sensitivity, moving load forward actually reduces total turning ability, and that trail braking is really about following the traction circle: as steering angle rises along the ideal entry path, braking has to come off in proportion. See weight transfer and the friction circle.

When it gets taught

Programs do not all introduce trail braking at the same stage. According to a sponsored Motor Sport article, Skip Barber Racing School teaches threshold braking and race downshifting in its three-day course and saves trail braking and rotation for its two-day advanced course. Von Moltke describes a progression for beginners: a conservative brake zone, release at turn-in and coast to the apex, then gradually brake later and carry a little pressure past turn-in when apexes are being missed or the car will not rotate. He also criticizes grassroots groups that teach only braking in a straight line, and Bentley says instructors who tell novices never to trail brake are wrong. Follow the progression your school or instructor sets. Matching revs on the downshift is covered on heel-toe.