Trailbraking in Autocross
Thread Starter
A Philanthropical Fruit
Joined: Sep 2004
Posts: 756
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From: Ann Arbor Michigan Aim: nickbeier
Originally Posted by SpecialED
Wow, either you're the world's most natural autocrosser, or the people in your region suck.
Here's some better advice for a first timer who understands that autocross involves your brain, not just your hands and your right foot.
Understand that doing well at autocross required you to go as fast as possible where/when possible, and as slow as required in the tight spots. Trying to go around tight corners with the tires howling constantly because the car can't do what you're asking it to will not give you your best times. Remember, if the tires are making a lot of noise, or if the car seems unresponsive to your inputs, you've got to back off somehow - less turning, less gas, or less braking. When you've exceeded the tires' capability, there is no benefit to increasing your control inputs.
Decide beforehand during your coursewalk where you want to be on the course (often the course is wide enough for you to make choices on where you want to place the car) and try to stick to this plan. Your path should be either the shortest distance, the smoothest, most gradual path, or a combination of both criteria. If you get off of this optimal path significantly, you will add a lot of time to your run. Your goal is to drive as fast as possible without understeering or oversteering off the line. Understeer is when the car refuses to carve a turn as tight as you want, and oversteer is when the car tries to carve a tighter arc than you requested. Oversteer unchecked will eventually turn into a spin. Oversteer may look cool and be fun, but it's generally not the fastest way around the course.
Being smooth with your control inputs - steering, braking, applying the throttle - is of paramount importance. This minimizes upsetting the chassis and maximizing your tire traction at all times. That being said, read and understand the next paragraphs!
Ideally, to go fast you want to always be accelerating - either forward (on the gas), to the side (cornering), or backwards (braking). If you find yourself on course going straight or neither on the gas or the brake for more than a half second or so, you're probably not going fast enough (or maybe you've left the course entirely).
Don't be afraid to use your brakes HARD. You'll have to if you were going fast enough in a previous section before the slow section. If your car is fairly new and has ABS, it probably can provide better braking performance than you can by modulating your pedal pressure. If you don't have ABS, use the brakes as hard as you can without locking up the tires. This is called "threshold braking," and is easier described than done, but it will come with practice. Braking hard/correctly is as important as using the gas pedal properly. Try to do all your braking while the car is going straight; you'll slow faster and with more control than if you try to ask the car to corner AND brake near the tires' combined traction limits. This is because there is only so much traction available to you, and if you ask the tire to give you too much cornering AND braking force, you won't get as much as you want of both.
Don't put your hand the on shifter while on course. Launch in 1st, shift to 2nd when appropriate, and then plant your left foot on the dead pedal and keep both hands on the wheel at ALL TIMES! You won't need 1st again unless the course has a very tight hairpin (very rare) or you spin. Don't hover your left foot over the clutch or clutch in and out of gear to modulate power. You'll have more control over the car's power and handling with the car in gear at all times.
Look ahead. That means focus your attention on where you want the car to be in several seconds, not where you are on the course right now. This is really key not only for going fast, but also to prevent you from getting lost on the course. The course will be harder to see at 30-60 mph than it was walking it at 3 mph!
Try to be within 6-12 inches of all the key apex cones. Which ones are the key apex cones? Ah! Good question! That's what the beginner walk is for, usually provided at the beginning of the event. Or, ask an experienced driver to give you some tips on what their line will be during a course walk. Eventually, you'll want to be placing the car within 3" of key cones. The best drivers consistently are even closer than that - almost running them over! If being that close to the cone saves you only .05 second per corner, on a course with 30 corners, you'll be 1.5 seconds faster at the finish line!
In slalom sections where the cones are evenly spaced, try to develop a smooth, regular rhythm to your steering inputs. Ideally, you should be turning the wheel just before or just as you pass each cone, so that the car will already be starting to transition to the other direction as soon as possible after you've passed it. If you make your steering input AFTER passing each cone, you will get progressively more "behind" - i.e. closer and closer to running into each successive cone, even at a constant speed. Try to make your steering inputs quickly but smoothly, not jerkily. All easier said than done. It will come with practice.
REMEMBER TO HAVE A GOOD TIME TOO! It's easy to get caught up in being too competitive too quickly and forget that autox is supposed to be fun.
Here's some better advice for a first timer who understands that autocross involves your brain, not just your hands and your right foot.
Understand that doing well at autocross required you to go as fast as possible where/when possible, and as slow as required in the tight spots. Trying to go around tight corners with the tires howling constantly because the car can't do what you're asking it to will not give you your best times. Remember, if the tires are making a lot of noise, or if the car seems unresponsive to your inputs, you've got to back off somehow - less turning, less gas, or less braking. When you've exceeded the tires' capability, there is no benefit to increasing your control inputs.
Decide beforehand during your coursewalk where you want to be on the course (often the course is wide enough for you to make choices on where you want to place the car) and try to stick to this plan. Your path should be either the shortest distance, the smoothest, most gradual path, or a combination of both criteria. If you get off of this optimal path significantly, you will add a lot of time to your run. Your goal is to drive as fast as possible without understeering or oversteering off the line. Understeer is when the car refuses to carve a turn as tight as you want, and oversteer is when the car tries to carve a tighter arc than you requested. Oversteer unchecked will eventually turn into a spin. Oversteer may look cool and be fun, but it's generally not the fastest way around the course.
Being smooth with your control inputs - steering, braking, applying the throttle - is of paramount importance. This minimizes upsetting the chassis and maximizing your tire traction at all times. That being said, read and understand the next paragraphs!
Ideally, to go fast you want to always be accelerating - either forward (on the gas), to the side (cornering), or backwards (braking). If you find yourself on course going straight or neither on the gas or the brake for more than a half second or so, you're probably not going fast enough (or maybe you've left the course entirely).
Don't be afraid to use your brakes HARD. You'll have to if you were going fast enough in a previous section before the slow section. If your car is fairly new and has ABS, it probably can provide better braking performance than you can by modulating your pedal pressure. If you don't have ABS, use the brakes as hard as you can without locking up the tires. This is called "threshold braking," and is easier described than done, but it will come with practice. Braking hard/correctly is as important as using the gas pedal properly. Try to do all your braking while the car is going straight; you'll slow faster and with more control than if you try to ask the car to corner AND brake near the tires' combined traction limits. This is because there is only so much traction available to you, and if you ask the tire to give you too much cornering AND braking force, you won't get as much as you want of both.
Don't put your hand the on shifter while on course. Launch in 1st, shift to 2nd when appropriate, and then plant your left foot on the dead pedal and keep both hands on the wheel at ALL TIMES! You won't need 1st again unless the course has a very tight hairpin (very rare) or you spin. Don't hover your left foot over the clutch or clutch in and out of gear to modulate power. You'll have more control over the car's power and handling with the car in gear at all times.
Look ahead. That means focus your attention on where you want the car to be in several seconds, not where you are on the course right now. This is really key not only for going fast, but also to prevent you from getting lost on the course. The course will be harder to see at 30-60 mph than it was walking it at 3 mph!
Try to be within 6-12 inches of all the key apex cones. Which ones are the key apex cones? Ah! Good question! That's what the beginner walk is for, usually provided at the beginning of the event. Or, ask an experienced driver to give you some tips on what their line will be during a course walk. Eventually, you'll want to be placing the car within 3" of key cones. The best drivers consistently are even closer than that - almost running them over! If being that close to the cone saves you only .05 second per corner, on a course with 30 corners, you'll be 1.5 seconds faster at the finish line!
In slalom sections where the cones are evenly spaced, try to develop a smooth, regular rhythm to your steering inputs. Ideally, you should be turning the wheel just before or just as you pass each cone, so that the car will already be starting to transition to the other direction as soon as possible after you've passed it. If you make your steering input AFTER passing each cone, you will get progressively more "behind" - i.e. closer and closer to running into each successive cone, even at a constant speed. Try to make your steering inputs quickly but smoothly, not jerkily. All easier said than done. It will come with practice.
REMEMBER TO HAVE A GOOD TIME TOO! It's easy to get caught up in being too competitive too quickly and forget that autox is supposed to be fun.
Whew! That was a read right there! Thanks for taking the time to share your expertise, it is much appreciated. I'll just keep braking in a strait line till I perfect that, then possibly experiment with trailbraking... long after this thread has closed.
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Joined: Oct 2003
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From: Boulder, CO
Originally Posted by beier
Whew! That was a read right there! Thanks for taking the time to share your expertise, it is much appreciated.
I just copy and pasted some of what I've written before from here -http://www.apexracinggroup.com/conte...d=20&Itemid=42
There's even more info for a first-timer autocrosser in the full article.
Thread Starter
A Philanthropical Fruit
Joined: Sep 2004
Posts: 756
Likes: 0
From: Ann Arbor Michigan Aim: nickbeier
Originally Posted by on that website SpecialED just mentioned
If you enjoy taking your car out on twisty mountain roads or carving exit and entrance ramps at twice the posted speed limit, you obviously like testing your vehicle's handling and your driving skills. Autocross is a way to quantify those skills and handling capabilities in a safe, legal environment.
