[NickW]

Originally Posted by bman

But......how you use the brake to achieve balance seems to vary depending on the corner. I'd love to hear opinions on when you want a flat chassis vs a loaded nose vs early throttle?

That's a function of how large you need the traction circle to be at whichever end you need it at most.

For some corners like at Road America's Carousel, a long sweeping slightly downhill righthander that literally lasts 10 seconds or more, a neutral throttle will help keep the car in shape, a slight lift will tuck the nose back in (gain front traction from moving polar point forward plus camber gain from front end suspension compression that results from caster amount, PLUS a larger tire contact point at the front left wheel), and a slight acceleration will push the front a bit (scrub off lateral force if you've turned in a bit too much).

Again, I'm simplifying it quite a bit, there's a lot more going on- for example, LSD locking/unlocking, the rate at which it locks/unlocks, etc. But for the most part, I think I'm not too far off in concept.

Originally Posted by bman

For some reason, I developed a bad habit of maintaining some brake pressure on ALL turn in's; a habit of trying to keep the nose down for good grip. But I'm fighting that habit and realiziing I've got to try different things.

That's the worst thing you could probably do. Don't forget about the traction circle- the more traction you use for braking, the less you'll have for turn in. You may be expanding the circle by getting on the brakes, but the effective turning traction is probably severely limited. You have to ask yourself- which is more important- braking or turning in, and divvy up the circle accordingly.

Brakes on a racecar (or street car on the track) are not for actually stopping- you never want to actually stop. Brakes are for modulating speed- a tool to get the car to behave the way you want it to BEFORE you get to the apex. I've noticed that most people tend to overbrake because they thing threshold braking into corners is the fast way- probably read it in books, but never really properly taught by someone. The function of threshold braking is far more difficult to execute CONSISTENTLY- you may be able to do it 20% of the time, maybe even 70% of the time, but to drive effectively on the track you have to learn to execute each action as close to 100% as possible. Most people I know who threshold brake to the apex (like what they teach in the Skippy books) are incredibly bad at it, tending to overly slow down their cars- you can hear their mistakes when they release the brake and get on the throttle very abruptly. Even the pros make mistakes doing this- every time you see a racecar go straight and miss the apex, the driver is probably fighting braking forces (getting the car slow enough to get within his turning traction circle).

Originally Posted by bman

T10 at VIR and T12 at Mid Ohio come to mind as examples of where I want straight line braking and off the brake early enough to insure a flat chassis at turn in. Both seem to have some postive camber at first and then flatten near apex.......so does flat apex = flat chassis??? If so, why does T1 at VIR seem to require a lot of trail brake? It has some positive camber on the entry but goes flat near the apex.... I assume it's because you're approaching at high speed, trying to maintain speed at long as possible with a relatively low speed exit? Yes? Or does it have more to do with the radius?

I understand a lot has to do with the car but are there any rules of thumb or opinions on proper chassis attitude relative to track surface (elevation/camber/radius)?

I like this thread, thanks!

I can't comment on T10 at VIR, it's been many, many years since I raced either course there and never the full course. At Mid Ohio T12 in a kart is a throttle breather- maintenance throttle before turn in and back to WOT before T13. In a car I would say that corner is a bit tricky because of the subtle off cambering of the turn (track falls away from direction of turn). The other thing to note at T12 is you have to give up some of the track out for the turn in for T13, which again you give up some of the track out to get a good run onto T14 and the main straight. If you construct your corner exits taking each turn in reverse you will usually end up with a more ideal line (at least that works for me).