Trail braking;

Trail braking (a.k.a. 'brake-turning', braking while turning toward the apex of a corner) is another learning curve for you to climb sooner or later. However, learn trail braking slowly; if you're used to road driving (where you're taught to finish braking before turning into a corner) then you might find it tricky to learn the extra delicacy demanded by trail braking. In PU, the trade-off between brake pressure and steering input is hard to judge when you can't feel the car turning and pitching through your body.

What is trail braking? In essence, it means continuing to brake after having turned in for a corner. The further you progress into the corner, the more you turn the steering wheel and the more pressure you release from the brake pedal. Typically, the procedure goes like this:

• You are hurtling in a straight line toward a corner;
• You apply the brakes - fully - while still traveling in a straight line;
• At some point, you release a little pressure from the brakes and start to turn in;
• As you bend into the corner and approach the throttle application point, you progressively release the rest of the pressure from the brake.

What's the point of it? Trail braking helps you rotate the car into a corner by controlling the transfer of weight onto the front tires, giving them more stick, and thus compensating for any understeering tendency the car would otherwise have.

The alternative is: do all of your braking in a straight line, then release the brakes entirely, then turn in. The trouble with this technique is that when you release the brakes, weight - and therefore stick - will be removed from the front tires, just when you need them to be loaded enough to turn the car into the corner. So - unless the car is set up to be driven like this - it will understeer away from the corner. This is typical behavior for 'street' (aka massively understeering) cars that have been adapted for racing.

On the other hand, a 'proper' race car will probably oversteer if you don't trail brake. If you turn into a corner with your feet off both brake and throttle, the front tires will have all their traction budget available for turning while the back wheels will be doing some (engine) braking. Net result: oversteer. Application of the brakes settles down the oversteer by substituting a proportionately balanced loss of steering traction (because the brakes are biased towards the front). In fact, you use the brake pressure to control the rate at which the car rotates into the corner.

How much trail braking you do at a particular corner - i.e. what percentage of the corner is taken under braking - depends on the angle of the corner. For a 60° corner,   you'd typically only trail for a few percent of the corner, for a 90° corner,   you'd typically trail brake for maybe 25% of the corner, and for a bigger corner,   you could do it for up to 50% of the corner. You are aiming to trail off the brakes until they are released completely at or before the throttle application point (which typically occurs somewhere before the geometric apex).

Another way of looking at trail braking is: what you're doing is braking so late for a corner, that you're never going to make it if you carry on in a straight line. In order just to stay on the track, you have to release a little of the pressure on the brake pedal and bend the car into the corner, just to give yourself a little more road - enough extra road to finish the braking.  If you find that you've finished braking before the throttle application point in these corners, then you didn't brake late enough. (BTW, if the car won't turn in when you release a little brake pressure, then you probably need to reduce the front brake bias; likewise, if the car swaps ends when you turn in, add some front brake bias).

Just about every corner you brake for demands some amount of trail braking. 

Alison Hine: “[trail braking] takes a good setup, a deft touch on brake, throttle and steering, and a lot of practice. I use a setup with brake balance fairly far forward (usually 58 to 60% on the front wheels) and trail brake to rotate the car. The rate and smoothness with which you trail off the brake (i.e. smoothly release brake pressure as you turn the car into the corner) is critical, and is probably one of the most difficult and subtle things to learn in GPL.”

Tim Sharp: “Some drivers brake hard enough in a straight line to slow their car down for the corner, but then they totally release the brake or go to the throttle before they get to the apex of the corner. They transfer the weight off the front tires and onto the rear wheels just when they need their steering the most. This can cause the car to go into an understeer skid. In order to keep the weight on the front and the tire contact patches expanded for optimal steering, you should use trail braking. Trail braking is simply continuing to apply a diminishing percentage of braking until you complete your turn into the apex. The transition from trail braking to the apex and the application of throttle to the track-out point should be smooth and seamless so as not to upset the chassis.”

Ricardo Nunnini: Never take your foot completely off the brake until you reach the throttle application point. From the turn in point to the throttle application point, use a relatively constant amount of brake pressure and small dabs of throttle to balance the car. Just before you get to the throttle application point, release the car from the corner by pressing the throttle and then - afterwards - fully releasing the brake.