Larry Herman

Trailbraking seems to be one of those topics that gets everyone going. Even the definition of the term can spawn an argument. Rather than jump into the fray with "you should or shouldn't", I'd like to offer a few observations that I have found over the years. Maybe that can lend some clarity.

1) The tighter the corner the more it lends itself to trailbraking. You can stuff it in deep on the brakes and then blast out at full throttle.

2) Big sweeping corners need momentum and acceleration. Any "trailbraking" done here is very gentle, almost like trail-coasting into the corner. Otherwise you are just horribly slow.

3) A decreasing radius corner is a natural for lots of trailbraking.

4) Understeering cars and cars with high polar moments of inertia tend to like a lot of trailbraking. Oversteering cars and cars that rotate very easily do not. They want early power.

As always, YMMV.

}{arlequin

easiest way to learn trailbraking is to disconnect your rear sway. then go out and 'try' to match your laptimes

RedlineMan

Hmmmm....

Some interesting ideas.

- The idea that DocV related of creating rotation by reducing the load on the front tires from both braking and cornering to simply cornering seems to be putting too fine a point on it to me - and says nothing about making the **** light - but it is an interesting theory to contemplate.

- bobt993 offered a tactic that was on my mind. You need to concentrate on where you want to be slowed, not on where you start to slow. Your brain will fairly accurately calculate the rest based on feel.

- Pedro, sounds like Turn 6 at Mid Ohio. Sweeper at the end of the back straight followed by a slow turn to the left. Make the sweeper into part of the straight and TB heavily to maintain top speed AND rotation. I was working on it there a month ago, to mostly middling but occasionally positive effect. I don't know the track or complex you speak of, but your description and tactics sound spot on!

- Stacy, just what I was thinking, and thinking of the same turn there to try it in (how about into 4 as well?). Like I said, envision where you want to be slowed, not where you start.

- I have ALWAYS been a big LFB'er, and a balance trail braker, and I also know this is not the same as a high-entry-speed-ROTATIONAL TB'er. Re-programming is hard, with the DE-programming part perhaps the hardest.

- C'mon Larry. I've been waiting for you, and I know you have a lot more to say... This is a discusion of ROTATIONAL TB, and I know you have some chops here.

- Making the car handle "poorly" wil certainly change your tactics, but I don't see where that will reprogram your reference points at all. It is still the same battle; go deeper, brake later, while turning.

Keep chewing...

sjanes

T4 at Tremblant is a big trail braking area, but I first practiced it at T8 since the straight before it gave me more time to think about what I wanted to do. After I became more comfortable with trail braking, I introduced it into T4 and it was a big difference.

Also, at Calabogie, there is a decreasing radius corner (called "Temptation") that basically requires heavy trail braking to be fast. I do so much braking after turn-in that I have to go down a gear (4 -> 3) mid-corner.

You don't have to make your car handle poorly, just add a bit of understeer. I used to setup the car for a balance of slow and fast corners, but after getting more comfortable with trail braking, I have a mild understeer setup that still lets me get into the corner well, but is more stable in the high speed sweepers. I've seen you drive, you don't need an understeering pig.

Larry Herman

Ok, you asked for it. The purpose of rotational trailbraking is to help get the car to rotate into a corner with less steering input so that you can get on the gas and power out of the turn. You are purposely dragging the brakes into the turn to keep weight on the front tires to get them to grip and follow your line toward the apex. If your car is understeering while you are trailbraking, you are not keeping enough load on the front. Do not confuse this, however, with turning in while you're braking at 10/10ths. That will never work as you are already at the limit of the front tires, and then the car will just plow.

You need to be easing off of the brakes, and transferring some of the tires grip to cornering. The more you come off of the brakes, the more you can turn the wheel. Done correctly, you are optimizing all of the grip of the front tires, from braking to combined to total cornering load. At a certain point though, the rear tires are going to join in the fun.

Trailbraking is all about balancing the car on the outside rear tire. As you brake and turn, the rear tires will need to develop cornering grip. In the beginning the back of the car is light, the grip will be reduced, but as you come off of the brakes, it will start to load, and the grip will increase. The back of the car should feel very nervous at this point, because it is now the rear tires that are setting the limit of your cornering speed. The net result of going over the limit here is an early spin. Here is where the strategies of trailbraking diverge.

In some turns, like 17 at Sebring, a big decreasing radius turn, you want to continue to slow and tighten the wheel and keep the car balanced on the rear tire until you get close to the apex, then you can pick up the gas. You are continuing to hold the car in a slowing and tightening mode until you have reached the point at where you want to apply acceleration through the rest of the turn. In other turns, like the tight contstant radius 90° turn 1 at Watkins Glen, you run the brakes hard into the turn, and when the back gets so loose that it wants to come around, you pin it with the gas, and accelerate out from there.

These are two completely different styles of trailbraking, done for different reasons. The first is done to "hustle" the car into the apex, because the turn is so long, and the entry is so wide that you cannot get on the gas in the beginning of the turn. You are "slowly" slowing the car, balancing the car on the steering and brakes and maintaining as much momentum as you can before you get back on the gas. The second is done for precisely the opposite reason. The turn is short, you can get back on the gas right away, and so you are using trailbraking to delay the onset of initial braking, to coerce the car to rotate, and then to get the rear to hook up so you can floor it throught the turn.

Chew on that for a while John.

sjanes

^^^^ That's a pretty good description ^^^

The only thing I would add is that for TB to really be effective in rotating the car, the driver must first be able to drive on 'slip'. I tend to separate driving ability based upon driving on 'grip' and driving on 'slip'. Those that drive on grip are 'on rails', and when TB into a corner, the car just slows down as it approaches the apex. Those that drive on slip (remember Larry's post about cars handling like **** at the limit) only have to give the car small input during a corner to get big results. When you drive on slip, TB can really cause a lot of corner entry rotation and allows the driver to get on the throttle early. TB while driving on slip is a lot harder as small changes in speed and balance can have big effects.

Just my $0.02 Cdn (now almost $0.02 US )

TD in DC

Larry and Stacy,

those are both great explanations. Stacy, the thought you are expressing is exactly the phenomena I have been thinking about lately. Sometimes it is "easier" to drive a car the faster you go since less inputs are required to get more dramatic response. And you are also correct that it is why the timing of trailbraking correctly can take some getting used to.

TD

sjanes

easier only if you have a feel for the car. The transition from 'grip' to 'slip' is really the reason why people suggest staying on street tires and/or using "slower" cars to learn on. It's a hump some never get over.

Larry Herman

I like that description. For such a short little phrase, it conveys a lot.

TD in DC

I'm no expert, but feeling this transition from driving with the front of the car ("grip") to driving with the rear of the car ("slip") was a real breakthrough for me this year. I am still not good enough at doing this with the correct timing that I am confident to trailbrake seriously during races (I don't want to take out someone else's car if I screw up), but I get it right in DEs now and again and man does it feel right. As you know, I am NOT talking about Dukes of Hazzard rotation, but rather that great feeling of getting the car up on its toes so that slight changes in braking or throttle pressure result in immediate response from the car.

Previously, I thought that my car handled poorly because it understeered at entry and oversteered at exit if you straightline brake and then accelerate from shortly after turn-in through the apex to track out, which can be very scary (although I am used to it now). More and more I think it actually has been set up for trailbraking the entire time, and I just didn't know it or know how to trailbrake. Man does the car respond well to trailbraking.

M758

Autocrossing is a great way to make the transition. The price for learning by trial and error is quite low.

mdrums

As a newbie at all this, that is exactly what I've found myself. Auto Cross is extremely safe and a whole heck of a lot of fun too.

TD in DC

Begs to differ . . .

Gary R.

Great discussion here, I find it all very interesting.

bobt993