So, from a person wo plays this game for months and is still bad at it (me! ), I have 2 questions:

1)How does exactly trail braking work? I know that, in theory, it is the action of breaking into the corner in order to help the car keep the weight distribution correct. EVERY SINGLE ATTEMPT AT THIS HAS SENT ME INTO THE FENCE!! No matter how light or hard I attempt this maneouvre, I fail.

2) In this video, on lap 1 and 2, several drivers press the brake and the accelerator simoultaneously. I've seen this also done in F1 races, but I am clueless as to how might this help the cornering. Help?

1. For good trailbraking you first go and setup your car to understeer. That means, with neither gas nor braking, the car understeers in corners. Then, while entering a corner, you brake slightly so the balance of the car moves forward and the car doesn't understeer anymore.
In a neutral or oversteery setup trailbraking will fail.
2. I usually use left foot braking (brake & gas simultaniously) only to charge up the turbocharger before the apex of the turn. That way I get over the turbolag and can accelerate with full boost out of the corner.
You can also use a tip of gas to modulate the weight distribution of the car, but it's a whole lot of work for few effect.

Vain

I found a smidgen of trail braking helps get the nose of the FXR into high speed corners. And that's with quite a loose set.

Haven't found it to work with any other cars though (yet).

Quote from Vain :

2. I usually use left foot braking (brake & gas simultaniously) only to charge up the turbocharger before the apex of the turn. That way I get over the turbolag and can accelerate with full boost out of the corner.
You can also use a tip of gas to modulate the weight distribution of the car, but it's a whole lot of work for few effect.

Vain

Hmm... I once drove a very understeery LX4-Setup (Q)... Brakes to make the rear turn 'round, throttle to straighten it up again... Went much faster through tight corners with that...

And it's quite a difference if a setup is oversteery at braking (so you don't wanna trailbrake) or on power (where trailbraking might help)...

1. How the car responds to trailbraking depends on how it's set up, because you're not only affecting the weight transfer but also the traction budget of each tire. If a tire has to do lots of braking, it'll have less traction available for cornering and vice versa. If you want to learn more about this, read up on the Kamm circle or in German "Kammscher Kreis" (http://de.wikipedia.org/wiki/Kammscher_Kreis).

Lots of front brake bias will induce understeer when trailbraking, lots of rear brake bias will induce oversteer.

If you have a car that understeers a lot by nature (XFG or UF1 for example), you usually change the setup (suspension, tire pressures, ...) to combat that. However it'll also be more difficult to turn in with this new more oversteery setup. In this case you would add more front brake bias and use trailbraking to induce a bit of understeer when entering a corner. Once the suspension has settled and you're near the apex, you would release the brake and the car would be neutral.


If you have a car that oversteers a lot by nature (LX for example), you do the exact opposite. You make the setup more understeery and use a bit more rear brake bias to assist turn in.




2. Do you mean left-foot braking or heel-toeing(right foot on both pedals)?
Heel-toeing is used to blip the throttle on downshifts to avoid locking up the drive wheels.

Left-foot-braking is usually used for turbo cars to maintain boost while slowing down, as Vain said. F1 drivers also use left-foot braking to adjust the balance of the car while braking. More throttle = less brake force on the rear wheels = more front brake bias. Not even all F1 drivers do this, so I don't think it's necessary for F1.

2 thoughts behind trail braking

1 is the getting the car to turn in by unsettling rear reason as mentioned elsewhere ( in a rwd car you can get similar effect by keeping throttle closed and / or changing down as you turn in. best exponent of this in real life that i ever saw was penti arikala in the hs2300 chevette which was nose heavy and didnt like to turn in on loose surfaces)

2 the idea of a "friction circle", i first read this in an article by jackie stewart in about 77 or 78. the idea was that a tyre has a finite amount of grip and if your using a lot of it to accelerate or brake then you have little or no latteral grip or vice versa, hence when your really hard on the brakes and the moment you turn steering the front wheels lock. the idea is to try and drive the car as near the circumfrance of the circle at all time so you brake as hard as you an and then as you start to introduce latteral forces you reduce the braking effort. theoretically you should reach the apex of the corner at maximum latteral grip and then as the radius and latteral forces reduce slowly introduce accelerative forces till at the exit the latteral forces are nil and you are either applying as much acceleration that the tyres can handle or full power if that is insufficient to brake traction. we all tend to attempt the exit side naturally and tc on cars like bf1 is an automatic way of getting close to this ideal. the technique ( as far as i understand it) is of most use in vehicles where there is not an excess of power and so speed over the whole of the corner becomes more important than speed at the exit. stewart comenting in about 81 felt that didier pironi was probably best at it in f1 durring the skirted ground effect era of f1 when, untill turbos started to produce huge power figures, there was more grip than power.

Here's an article with throttle and brake input comparisons for Barichello and Schumacher:
http://www.blinkerfluid.net/f1racing.pdf

Perhaps an interesting read if you want to learn about left foot braking in F1.

whats interesting is how schumi keeps the throttle on a bit, presumably since the brake effort is that which is actually felt by the tyres, he uses a touch of throttle to reduce the apparent rear brake effort or hes using it so there is no sudden shunt in driveline as engine starts to drive wheels as opposed to wheels driving engine whilst slowing, also the gradual trailing off of brakes whilst accelerating is interesting, i'd assume it alters the balance bewteen front and rear on exit of bend. possibly given his history and current fondness for karting its a throwback to having rear braking only and using throttle and brake as a crude form of antilock / traction control.

of course in turbo cars, left foot braking has the advantage of allowing throttle all the time so reducing lag years ago audi discovered after 1 day of a rally that the master cylinders in mikolas quatro had been connected to the wrong circuits so the front master was working rear brakes and vice versa, mikola admitted that although the car felt a bit different it wasn't actually apparent the brake effort balance was wrong and hadn't attempted to adjust it as the main reason he left foot braked the quatro was to reduce the lag, on fwd cars of course left foot braking not only helps balance the car but in slippy conditions can once again act as a form of traction control on the front wheels.

one final advantage is the reaction time when going from accelerate to brake and back again. if you right foot brake and want to slow down, the first thing you do is to stop accelerating and then you start to brake, with left foot braking the actions are simultaneous. when im driving an auto i always left foot and especially if its fwd i tend to be playing with brake whilst on the power if going through bends as it allows subtle adjustments to line etc which due to torque converter an auto box desnt allow through throttle.

if youve got a fwd and it snows, go find an empty car park and have a go its surprising just how much extra control you have

1. With an understeering setup and gentle use of the brakes. Try adjusting castor and downforce until the car is less twitchy.

2. I use both pedals down in LFS sparingly in the Fox, but used to do it in the saloons (the ones you get in demo) on patch Q. It had the effect of stiffening the car up for a bit as all four corners pushed into each other, but also had the side effect of reducing your front grip, allowing you to introduce a moments slide and achieve a more rapid change of direction, it can also be used to neutralise body roll. It's benefit is entirely situational, I was using it going through the right-left hander after the Blackwood mainstrait, and sometimes on the second last and last corner. The gain is absolutely minimal, the loss for getting it wrong is a close up of the track spectators.

On those rare ocassions when I have been able to race a proper car with gears I ocassionally blip the throttle on downshift - but this is a different thing to "two peddling" as I call it.

It's most useful as a technique when in a gokart for taking hairpins, I find in big cars the differential tends to absorb the effect, I guess it depends on your diff setting, but i'm no expert there.

Before attempting 2 you should ensure that your steering wheel driver software recognises the accelerator and brake as different axis. If you do not have the bars onscreen then put the car in 1st, floor it and then brake and see if the engine revs stay high and wheels continue to spin. If your pedal action becomes one or the other or neutralises you have a single axis controller and trying to use both pedals together will do you no good what-so-ever.

When talking about the diff I remembered a technique that is special to LFS.
The diffs in LFS aren't preloaded. That means under neither brake nor gas the diff acts pretty much like an open diff and wheelspin is pretty easy to achieve (for example, BWGP Rev, the entrance of th righthander just before sectortime 1). On such problematic sections I often apply a bit of throttle to keep pressure on the diff. That way wheelspin is limited and the car handles much better.
Read up on limited slip differentials (LSD) (f.e. Audi's TorSen Diff) and imagin that the diff doesn't lock at all as long as the car is between power and coast to get a better understanding of the problem.

Vain