Trail braking is the act of easing off the brake pedal while turning into a corner; it’s the overlapping of braking and steering.
That’s the what, but what is the why? Why should we, sometimes, trail brake?
It’s this third point that makes the process of learning to trail brake a bit challenging. Maybe even more than a bit challenging; possibly very challenging.
Let’s say you’re approaching a near-180-degree hairpin corner, one in which your minimum speed is 50 MPH. The challenge you’ve faced over the past many laps is that your car has a hint of understeer in the first half or so of the corner, and that means you have to wait, wait, wait… before even thinking about applying the throttle. If you could get your car to be a little more reactive turning into the corner, you’d be able to carve the right arc towards and past the apex, and be able to get back to power sooner.
At lunch, you’re talking with a fellow driver and relate what’s going on in this particular corner. You tell them that if you could just get your car to turn or rotate towards the apex a fraction of a second sooner, and with a fraction more speed, you’d set a new track record and have Roger Penske knocking on your door to sign you to a multi-year, multi-million-dollar contract to drive every race car he owns. If only….
Your friend takes a bite of their oh-so-tasty-but-bad-for-them bacon cheese burger that they’ve just paid a silly amount of money for from the paddock “café,” leans in toward you and says, “You need to trail brake more into the corner. That’ll keep more weight on the front tires and help your car turn better. When I learned to do that, I knocked 3 tenths off my best lap time.”
In your mind, you’re replaying what you’ve been doing with the brakes in that corner, and you realize that you are trail braking… but maybe not enough. “Maybe,” you think, “if I trail brake a little bit more, my car will turn better, and I’ll get back to power earlier than ever before, squirting out of the corner like a squeezed bar of wet soap.” Visions of shaking hands with Roger start dancing in your head.
Next on-track session, you’re ready to trail brake more into the Hairpin, so off you go. You deliberately and consciously trail brake more. In fact, you’re aware of the fact that the point where your foot comes completely off the brake pedal — the EoB — is almost one car length deeper into the corner. And yes! The car is turning better, almost to the point where you’re pointing towards the inside of the apex. “Wow, this trail braking stuff is powerful. I can’t wait to see my lap times!”
“What? I’m 3-tenths slower than in the last session! What’s going on? I could feel how the extra bit of trail braking resulted in getting on the throttle earlier by helping the car turn in towards the apex. Maybe this trail braking stuff doesn’t work…”
Back in the paddock after the session, you walk over to your friend who gave you the advice to trail brake more, almost ready to slap them silly for slowing you down — and accuse them of deliberately doing so. Before you have time to say anything, they ask, “Did you move your brake zone in, and if so, how much faster are you?”
“Well, I trail braked further into the Hairpin, but my lap times are worse.”
“Yeah, I guess I should have explained that a bit better. Of course, if you trail brake more, you’re on the brakes longer, and you’ll slow down more. That will help your car turn more, but your min speed — the minimum speed you’re at in the corner — will be slower, too. The extra trail braking is over-slowing your car, and that’s probably why your lap times were slower. Let’s look at the data or your video to see what your min speed was.”
Off you go, and you and your friend watch your video — the video that also shows your speed — and you notice that your min speed in the Hairpin was, as predicted by your friend, 48-49 MPH. Yes, trail braking resulted in over-slowing.
That’s when your friend then explained how you need to think about braking as a zone, from BoB to EoB, and if all you do is extend the EoB without shifting the BoB in, you’ll over-slow.
“That makes sense! But what do I do, then?”
“You need to shift your entire brake zone further into the corner. Move the BoB in by focusing your attention on a later EoB,” your friend explains, and then wanders back to their own car, and another cheese burger.
You sit in your car, close your eyes, and imagine approaching the Hairpin at speed. Close to where you would normally begin braking, you look ahead, into the corner, to around the area where you’ll finish braking — the EoB. In your mind, you can see the brake zone, from BoB to EoB; you see yourself shifting this zone in by a car’s length. You imagine how your car responds to your initial turn-in because of the weight on the front tires, as well as the extra MPH or two you’re rolling in towards the apex. The car feels alive, it has energy, you’re almost surprised at the speed you’re able to carry through the corner, and how early you’re able to get back on the throttle. “Wow, this feels awesome! I just need to do this on the track, now.”
Behind the wheel for the final session of the day, and you do what you’d just imagined back in the paddock. It feels fast, and it is. You shave 4 tenths of a second off your best lap time ever, mostly because of what you’re doing in the Hairpin, but also because you’re applying what you’ve just learned to a couple of other corners. Lap time improvements rarely come from just one corner — it’s a tenth here, a tenth there, and it all adds up.
It’s the end of the day, so you sit back and watch your in-car video and pay attention to the rolling min speed in the Hairpin.
“Cool, 51 MPH! And it looks and sounds like I’m picking up the throttle a tiny bit earlier than ever before. So, more entry speed, more min speed, more exit speed. Wow, all because I looked into the corner, focused my attention on the EoB, and shifted the entire brake zone further into the corner. Yeah, I trail braked more, but it was what I did before that that made the difference. I really get that more trail braking without moving the BoB in will usually result in over-slowing. The goal is using trail braking to allow me to carry more entry speed, get the car to rotate, and begin applying the throttle as early — or earlier — than ever before. This is so much fun!”
You’ve just flipped the “good resulting in bad” to “the good resulting in good.” Maybe even “good-er!”