Braking - Turn Fast! The Road Racers Reference Center

Discussion in 'Autocross/Road Racing' started by Bud, Jun 27, 2008.

  1. Bud

    Bud GG EVO IX MR

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    Tire Traction - Turn Fast! The Road Racers Reference Center

    Tire Traction

    Assuming equal horsepower and driver skills, the fastest car around the track will be the one with the most tire traction. Traction aids in acceleration, braking, and cornering.

    "Handling" is all about maximizing tire traction. Regardless of how much advanced hardware the car has, the bottom line is that the car's entire braking, accelerating, and cornering performance has to be translated through the four small patches of rubber in contact with the road. Think about it. Ignore absolutely everything about a car except for how much rubber is in contact with the road. Maximizing the performance of these four small patches is what "handling" is all about.

    Maximum traction, of course, is affected by the suspension design, the type of tire, it's rubber compound, its contact patch size, and several other factors. Once a given car and tire is selected, there is still the task getting the absolute most out of that specific tire.

    After-market products which can help improve tire traction include anti-roll bars, shock tower bars, stiffer springs, adjustable shocks, wheel alignment kits, and others. Used properly, these items are designed to maximize the contact patch of the tire during dynamic conditions. Used improperly, these same components will actually deteriorate traction and handling under race conditions.

    Another major factor in tire traction, often overlooked, is the driver. A practiced driver having very smooth control of the car, and high sensitivity to the tire's traction performance can improve the car's lap time as much as just about any single after market hardware modification, and it's free. Give a pro driver your car for a 30 minute session, and he'll likely best your times by an amount you thought impossible.

    To do this, the driver must fully understand the tires, how their maximum performance is achieved, and have enough practice time developing a sensitivity to how the tire is performing at any given moment on the track.

    Three factors determine the maximum potential grip of a tire: the coefficient of friction provided by its rubber compound (stickier is better), the amount of rubber as determined by the tire size (bigger is better), and the amount of downforce applied to the tire (pushing down adds to the total friction applied). Of course there is a limit to all of these, and a point is reached where more is not better.

    http://www.turnfast.com/tech_handling/handling_tractn
     
    Last edited: Sep 8, 2008
  2. Bud

    Bud GG EVO IX MR

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    Slip Angle - Turn Fast! The Road Racers Reference Center

    Slip Angle

    There are two factors in reaching and sustaining the maximum traction performance from the tire. First, a tire's maximum traction potential is actually reached when there is a small amount of slippage. This "slippage" is translated differently for braking, accelerating, and cornering.

    Under braking, the peak performance of the tire is reached when the tire is turning slightly less than a one-to-one relationship of the distance traveled. In other words, if the car were at a steady state, and the wheel turned 10 times to cover a certain distance, under braking, the wheel would now turn perhaps only 9-1/2 times to achieve the peak slippage performance. It is possible to learn how to feel the car through the brake pedal, steering wheel, and seat and sense this tiny bit of extra braking force from the tire.

    In acceleration, the tire should travel slightly more distance than the distance of the acceleration (spin just a bit faster than normal). The tires will actual slip; not a lot all at once to result in free wheelspin, but ever so slightly during the whole acceleration phase. When you can sense this slip, and control it, this is when you're getting maximum acceleration from the vehicle.

    In cornering, this slippage is present when the wheels are actually turned just slightly more than the actual amount required to go the intended path (this difference is an angle and is where we get the term "slip angle" from). To accomplish this slip angle the car must actually be sliding ever so slightly during cornering. Not a big power slide, just a little extra slip. At first, this can feel very uncomfortable, as though you are starting to lose traction. In fact, this is where the car has its greatest traction. The tricky part is approaching this limit and not crossing it. If the car is not sliding at all, then it isn't going fast enough. If it is sliding enough to actually drift (or have noticeable understeer, or oversteer), the tire is being used beyond its limit. The corner speeds will be slower, and the tire will wear out much more quickly.

    In each of these cases, we emphasized the "slightly" aspect of this slippage. Too little, and the tire does not reach maximum performance. If the car feels "hooked up on rails," then the car is not being driven fast enough. Until you feel that tiny bit of slip, you can go faster. Knowing how to approach that point without exceeding it takes a great deal of practice. Too much slippage and you'll exceed the tire's limits and the tires slide excessively resulting in locked-up braking, wheel spin in accelerating, excessive sliding during cornering. Ultimately they will overheat, get slippery, and wear out much faster.

    The amount of slippage required is different for each tire, but we're talking in the range of 4 to 10 percent. When cornering, the steering angle input is perhaps 5 to 6 degrees more than required to negotiate the turn. However, to keep this from turning the car too much for the corner, it has to be pushed with speed to generate that little bit of slip to compensate. Racing tires will perform best with a little less slippage than a street tire. If you learn to race on a street tire then switch to racing tires, you'll have to learn to back off a little, and be smidgen more gentle with the race tire.

    How should this slippage concept affect your driving? If you look at the graphs which illustrate the affect of slippage on traction, you'll see that at the peak traction point, there is actually a pretty wide margin of slip that will generate maximum traction. If you tend to drive in the latter part of that band, you'll acheive good cornering performance, but being closer to the edge the tire's limits, you'll build more heat and generate greater tire wear. The tires will feel great for a while, but they will wear out sooner, and the last several laps in session will have poor performance. If you drive within the earlier part of that peak traction band, your traction performance will remain consistent over a longer period of time. In time trials, you won't see much of a difference (except in replacement tire costs), but in racing, this will put you farther ahead of the competition in longer runs.

    A time that you may need to drive in latter part of the traction band is when the track is cold, and you must push the tire harder to keep heat buildup in the tire.

    http://www.turnfast.com/tech_handling/handling_tractn
     
  3. Bud

    Bud GG EVO IX MR

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    Driving Smoothness & Traction - Turn Fast! The Road Racers Reference Center

    Driving Smoothness & Traction

    One more principle to learn. A tire's maximum traction potential will not be realized unless it is brought to that point gradually. This is true of just about everything dealing with frictional traction, and you experience it regularly in everyday occurrences.

    Imagine this experiment. Place a piece of paper on a table, and an ordinary breakfast bowl on the paper. Start pulling on the paper slowly, then gradually faster. The bowl remains on the paper and is dragged along with it. Next, yank the paper immediately. It will come out from under the bowl leaving the bowl unmoved, or barely moved. Same bowl, same paper, same table. What was different? The acceleration of the forces applied. In your car, the tires are the paper.

    Ease the car smoothly into a corner, and the tire will have a high level of traction. Jerk the steering wheel too quickly, and the tire will not maintain grip with the road. Same car, same tires, same road. The difference is the acceleration of the forces, or the smoothness with which cornering, acceleration, and braking forces are applied. Smoother is grippier.

    The principle of driving smoothly is paramount to every factor of improving a car's handling performance. All the hardware in the world will not fix a car with a driver using "jerk and stab" braking, accelerating, and turning control behavior. Inexperienced drivers frequently blame the lack of the greatest hardware in their car for performance problems which are actually caused by their driving style. There's enough stories to suggest even a few pros have this habit. Be honest and analyse your driving, or get an experienced instructor to analyse it for you.

    One of the common faults and gripes of new drivers is front end push (understeer) when entering a corner. "Man, my car slides something horrible going through the first half of that turn." There is significant probability that the car is fine, but the driver is braking too late, too hard, and is rushing the turn-in with a sudden steering movement. Brake sooner, let up sooner (and more gradually), and ease into the corner with a larger and smoother radius. This will likely cure the understeering problem, and will most certainly reduce it if suspension setup is an issue.

    Smooth driving maximizes tire traction. Maximized tire traction is what leads to fast driving. We repeat -- smoother is grippier.

    http://www.turnfast.com/tech_handling/handling_tractn
     
  4. Bud

    Bud GG EVO IX MR

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    Weight Transfer - Turn Fast! The Road Racers Reference Center

    Weight Transfer

    A fundamental topic in any discussion about handling is weight transfer. If you do not fully understand weight transfer, you will not be effective in understanding how to adjust the car for maximum handling performance.

    Given a certain car weight, there is a certain amount of mechanical downforce applied to each tire. As we stated in the tire traction article, this downforce impacts the grip potential of the tire. While a car is braking, accelerating, or cornering, the effective mechanical downforce on, and therefore the grip of, the tires is constantly changing.

    These changes are referred to as "weight transfer." Of course, the weight of the car isn't changing, or moving about the car, but the forces on the tire contact patches are changing due to inertia and momentum. If you were to have a set of scales under the tires while driving, you would see what appears to be a constant changing of the weight at each tire, hence the name.
    What does Weight Transfer Do?

    Referring to the figures, we have illustrated a street car weighing 3000 lbs, and with a typical FWD street car's weight distribution of 60% front and 40% rear. We'll assume the car's side to side weight distribution is equal. We see that when standing still, the front tires have 900 lbs of weight load, and the rear tires have 600 lbs each.

    Anytime the car's direction changes through braking, accelerating, or cornering, each tire will experience a gain or loss of mechanical downforce, such as the examples illustrated. This weight transfer has significant impact on traction. Unfortunately for us, the net sum of the traction of the four tires does not stay equal. What is lost from the unloaded tires is not entirely transferred to the loaded tires. Overall there is a loss in traction.

    Because of this, race car design, and some of the modifications you make to your street car, are designed to minimize weight transfer. It cannot be eliminated, but it can be reduced. The more it is reduced, the more traction is retained. By reducing the increase in load on the loaded tires, we can reduce the work they have to do. By reducing the loss of load on the unloaded tires, we retain the traction they can provide.
    How can Weight Transfer be Minimized?

    Contrary to what you may be inclined to believe, the amount of weight transfer is not altered by springs, shocks, anti-roll bars, etc. Weight transfer is a result of inertia and momentum. These suspension components cannot change that. What these components can do is impact how much the suspension moves in response to the load change, and how quickly the load transfers to the tire contact patches.

    The amount of weight transfer is dominated by the vehicle's weight, location of the center of gravity, wheelbase, and track, and the amount of force applied during braking, accelerating, and cornering.

    Weight transfer is a function of the vehicle's weight and the forces acting on that weight. Reduce the weight, and ou reduce the product the of the forces involved.

    The center of gravity is the fulcrum point through which the vehicle's weight is multiplied by dynamic forces. In particular, the higher the CG point is, the greater the effect of the forces. Reduce the CG height reduces the product of the forces and vehicle weight.

    The longer the wheelbase and wider the track in relation to the height of the center of gravity, the more resistance the car has to weight transfer. They behave as counteracting lateral levers to the vertical lever of the center of gravity point.

    Another important concept of controlling weight transfer besides minimizing it, is to control where it is transferred. Where weight transfer occurs is related to the static weight distribution of the car, the roll couple distribution of the car, the height of the roll center of the car, and the slope of the roll center in relation to the ground plane.

    Roll couple distribution is the relative roll stiffness between the front and rear of the car, and the left and right of the car. In cornering, the front of the car may roll less than the rear of the car. This has impact on how the weight transfer is distributed.

    The roll center is the line through which the vehicle rolls. It is not necessarily parallel to the ground. Weight distribution, and roll coupling distribution can create a roll point at the front of the car which is lower to the ground that the roll point of the rear of the car. This creates a sloped line. The angle of this line has influence on how much weight is transferred, and where it goes.
    Vehicle Weight Distribution

    Modifications which reduce vehicle weight and the location of the center of gravity impact the amount of weight transferred and where it is transferred. Reducing a vehicle's total weight reduces the amount of weight transfer. Redistributing that weight front & rear, or side to side will change how that weight transfer is distributed among the four tires. This affects the individual mechanical loading and therefore grip of the tires.

    Removing weight from the car reduces the work the tire must do, and improves grip. Balancing the weight evenly in the car provides an even distribution for balanced response to dynamic changes. Intentionally biasing the weight distribution to a specific side or quarter of the car might be advantageous for the net results of grip under dynamic conditions. (You might want to shift weight to the right rear of the car at a track with a lot of high speed right turns to reduce the load of the left front tire, and increase the load of the right rear tire for more balanced grip during cornering).

    Static weight distribution can be changed by physically moving objects within the car (relocating the battery, removing items from the car, etc.). It can also be changed by altering the ride height of individual corners of the car. Lifting a corner alters the CG location and in effect, increases weight distributed to the opposite coner. This is done primarily through coil-over shock & spring setups and by spacers.
    Relocating the Center of Gravity

    Relocating the CG to a more favorable position can also reduce weight transfer. Without getting into the engineering of it all, the location of the center of gravity acts as lever handle. We know from basic physics that a lever can be used to increase force and work. If the center of gravity is very high, there is essentially a long lever in the car. During braking, accelerating, or cornering, the G forces are amplified by this lever created between the CG point and the tire contact patches. The further apart they are, the greater leverage, and the greater the weight transfer.

    With a given car, you can't change the CG location dramatically, but you do have some ability to affect the center of gravity enough to make major improvements to the car's handling performance. If you're willing to sacrifice some comfort, convenience, and looks, you can subtract and relocate weight to affect the front to rear and the side to side weight centers. You can also alter the CG height by lowering the car with lowering springs, lower sidewall tires, and to a smaller degree by adding removing, or moving weight in the car.

    Once you have selected your car, there's nothing you're likely going to do to change the wheelbase or track width. You might increase track width a little with wider wheels though.
    Weight Transfer and Suspension Components

    We said that springs, shocks, etc. cannot change the amount of weight transfer. What they can change is the rate of the weight transfer, and the impact weight transfer has on the suspension geometry caused by dive (braking), squat (accelerating), and body roll (cornering).

    The rate of weight transfer impacts the responsiveness of the car to driver inputs. The faster the weight transfer, the quicker the response. This allows the driver to have greater control of the car. However, a faster weight transfer requires greater skill of the driver. Smoothness and quicker reaction sensitivity to the tire traction are needed. It turns out that shocks have the largest impact on rate of weight transfer. The stiffer they are, the faster the tranfser.

    The impact of weight transfer on suspension geometry has to do with maintaining as large and flat a tire contact patch as possible. When the body rolls, dives, or squats as a result of weight transfer, the geometric relationship of the suspension components to the body and the wheel changes the shape of the contact patch. For the unloaded tires, the patch size will be reduced. This effect must be minimized. Changes in shocks, springs, anti-roll bars, and wheel alignment are made to maximize the tire contact patches of all tires during the dynamic changes of weight transfer.

    In the next articles which cover the major components, we'll define what those components do, and how they can be manipulated to control the effects of weight transfer and the changing tire contact patch size.
     
  5. Bud

    Bud GG EVO IX MR

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    Chassis Braces - Turn Fast! The Road Racers Reference Center

    Chassis Braces

    Even though it is made of steel (and whatever else), the chassis and body of every car flexes. As a car progresses through a turn, the forces involved will cause the car to twist. This needs to be minimized.

    This twisting is not the slanting of body roll as the springs stretch on one side and compress on the other. This is an actual twisting of the floor pan and body panels. Like the flexing of a suspension system, this twisting impacts the tire contact patches, and in fact affects the suspension system by changing the suspension system's alignment with the body and with the road surface.

    The most common after market street modification to reduce twisting is to add shock tower braces. The car's body structure by necessity has several very large cutouts to accommodate doors and windows, the engine hood, and the trunk or hatchback door. These holes, like large holes cut out of a box, reduce the strength of the body and make it easier for the car to twist.

    Shock tower bars add a solid bar across the tops of the shock towers (they just happen to be a convenient point that can be connected with a straight or nearly straight bar) to fill the gaps in two of the largest holes--across the engine bay and across the trunk cavity. During cornering these bars add strength and reduce the overall twisting of the body.

    Aftermarket tower braces are typically fairly easy bolt-in items. In addition to installing these, shops which specialize in modifying your particular car may also know of unique weak spots in the car's chassis that benefit from special bracing as well.

    Is one bar style or make going to be functionally better than another. Probably, but overall they're all going to be very close, and likely beyond your ability to tell the difference. Some cars are going to accommodate bars which go directly from one tower to the other. Other cars may not have space in the engine bay to do this, and may instead connect the shock towers to the firewall. Likewise, some cars will have room for rear tower bars, and others will not.

    The next stage in stiffening the chassis is usually adding a roll cage. Though primarily a safety feature, roll cages are welded or bolted to the chassis in several places which adds to the chassis' resistance to twisting.

    There are numerous styles of roll bars and roll cages. The difference between a roll bar and cage is the complexity of the structure, and its scope of protection. Generally, the roll bar's purpose is only to provide a crush resistant structure above the driver's head. This is usually a single bar with support bars to have four points of contact with the car chassis for strength (a two-point roll bar is useless for racing).

    A roll cage is a more complete structure designed to protect the driver from all sides. Obviously, the latter is safer, but may be impractical for the dual purpose street car as it will require significant modification to the car's interior panels.

    For time trial driving or autocrossing, the four point roll bar adds a significant level of rollover safety without sacrificing the interior of the car much. It will render the back seat unusable for passengers however. Even if passengers fit, the proximity of the steel bars designed for front passenger safety, makes for a very dangerous environment for rear passengers.

    http://www.turnfast.com/tech_handling/handling_chassis
     
  6. Bud

    Bud GG EVO IX MR

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    Braking and Accelerating

    One of the keys to good race driving is smoothness, and this most certainly applies to the use of the brake and accelerator pedals.
    Braking

    On the street, braking and accelerating are done at relatively low levels compared to the vehicle's capability. The tire's traction limits are rarely maxed out. Sure, you can romp on the gas and spin the tires at a light, or slam on the brakes and slide the car a little, but its very easy to bring the car back under control because the amount of traction you need versus what you have is quite low. In other words, you back way off and you're usually right back in control.

    In the rain, or especially the snow, you know you have to be much gentler and smoother with the brakes and with the accelerator. If you lose control on a wet or snowy surface, it can be much harder to regain control. There is much less traction to work with.

    Braking and accelerating when racing on a road race course, even when dry, is treated something like driving on a wet surface--gently and smoothly. Braking and accelerating are used in conjunction with the corners--you brake going into them and accelerate coming out of them. Because the objective is to have the car moving as fast as possible through the corner, the tires will be utilizing most of the available traction (done right they should be using 100% of the available traction, some would say about 104% which will make sense when we talke more about tires). The driver must be very smooth with the use of the brakes going into the corner and the accelerator coming out of the corner. A sharp change in braking or power at these points will upset the car's traction balance just as quickly as if you were driving on ice. Working within the last 1% of traction means there is no reserve to call upon to gain control of the car back. Even the pros very rarely recover a car that has lost control. It's not because they don't know how, it's because there's no traction left to work with. It is imperative to learn how to be consistently smooth in braking and accelerating on a road course.

    There are three phases in braking. First, braking begins with a rapid, but not instant, application of as much braking force as possible. How rapid the brakes can be applied will depend on the the suspension in the car. The stiffer the springs and shocks, the more rapidly maximum braking can be applied. Soft springs will have significant forward roll which will require a little longer and smoother ramp-up of braking to keep the car stable.

    Second, once the car settles onto the front tires, you'll be trying to minimize the length of the braking zone, so it will require taking the tires to the edge of locking up. You'll need to be very aware of the vibrations in your foot from the pedal and in your hands from the steering wheel to feel that small difference (therefore racing shoes are highly recommended. You just won't feel much from the pedals in Air Jordans). The car will travel some distance using a fairly constant brake pedal pressure.

    The third phase is towards the end of the braking zone when the vehicle has been slowed to near its final speed. Gradually release pressure off the pedal making the transition from full to zero braking force as smooth as possible. During braking, the front tires are under heavy load which increases the available traction. A sudden release of the brakes will abruptly reduce the load and reduce the traction potential of the front tires which at this point is needed for turning into the corner.

    The turn-in is one of the points where the car will be the most sensitive to sudden weight transfer transitions as though it were being driven on ice. Indecisive braking resulting in a last second extra tap, or a sudden release of the brake pedal will unsettle the car's handling and force the driver to slow down to gain control and hopefully avoid a spin.

    As the braking zone completes, and you ease off the brake pedal, you will have to apply some throttle to reach a steady state of neither acceleration or deceleration. Depending on the shape of the turn, the steady throttle zone will vary, but with a typical late-apex corner, it will be from the turn-in to just before the apex.
    Accelerating

    From this point to the turn's exit point, the use of the accelerator must be equally smooth for the same reasons they were for braking. Through the turn, the car will have settled with a certain loading of each tire. A sudden change in that with the accelerator can also upset the available traction on one or more tires and cause a loss of control. Controlled use of the accelerator is a matter of depressing and releasing it in smooth motions. Don't make sudden jerks in pedal position.

    In a typical street car, applying the accelerator smoothly isn't as difficult to master as smooth braking. Once a car is moving fairly fast, most street cars just don't have enough horsepower to really cause trouble under most acceleration circumstances. Even the factory exotics and highly modified street cars rarely have more than 400 horsepower, and in a car weighing 2500 to 3200 pounds, that just isn't an overabundance of power to learn to control. The typical professional open wheel cars weigh 1500-1800 lbs, and have 700-900 horsepower. That's about 5x the power to weight ratio of your typical street sports car.

    Nevertheless, whether its relatively easy to control or not, the introduction of 5 hp too much at the right point, and you may as well have an extra 900. Coming out of a turn, as soon as the car begins to straighten out, gradually apply more power the straighter the car gets. Use smooth consistent pedal pressure--indecisive on and off stabs will end up being slower than a smooth increase.

    Because most street cars aren't overly sensitive to rough throttle control (although there are definately some exceptions), it's easy to develop bad habits with the accelerator. Even though you may not have to be ultrasmooth to maintain control, having the discipline to develop smooth control will still improve lap times, and should you have the opportunity to drive a higher horsepower car, you'll have the skills to keep the car pointed in the right direction.

    http://www.turnfast.com/tech_driving/driving_braking
     
  7. Bud

    Bud GG EVO IX MR

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    Visual Field - Turn Fast! The Road Racers Reference Center

    Visual Field

    One of the first things you were probably taught when learning to drive, was the simple principle of "look where you want to go." You were told, "don't look at on coming traffic, look at the cars in your lane in front of you." "Don't stare at the dividing lines, look at the road between them." "Don't look at the wall beside you, look at the lane in front of you." All sound, practical advice, and the same goes for racing.

    If you've played, or even watched, just about any sport, you'll notice that the player is constantly looking forward, and not at what he's doing. In basketball, soccer, or hockey a player does not watch himself handle the ball or puck. Rather, he looks down the playing field at where he wants to go or pass. The player’s field of vision is not the few feet in front of him, but the whole field before him and beside him. The more of the field area the player can see and keep track of, the greater are his abilities to avoid opponents, plan a path through the field, and anticipate the movements of others.

    The distance and amount of territory the player can keep track of is called his visual field. This requires the combination of two distinct skills. First, the player must look farther ahead than his immediate surroundings. He has to look where he wants to be, not where he is. Second, even though the human eye has a narrow field of focus (only a small portion of what the eye sees is in focus), the player must be able to distinguish activities in those areas that are not currently in focus.

    These skills are critical to race driving as well. It should be apparent how they would apply to road full of cars driving for position, but they are equally important for a single car to navigate an empty track at maximum possible speed.

    There is a tendency by inexperienced drivers to focus with a tunnel vision right in front of the car. It's a natural reaction. The amount of information the driver is thinking about can be overwhelming, and it is easy to become visually fixated on what is happening right in front of the car. Looking farther ahead requires taking in even more input. At first, it can be very difficult, but as the driver develops shifting, braking, and traction sampling skills into “second natureâ€￾ habits, he can spend more conscious time expanding his visual field. An every day example of these skills at work can be drawn from the scenario of trying to walk faster than everyone else through a crowded sidewalk. Think of how you do this. Whether you're conscious of it or not, your brain tries to anticipate the movements of those in front of you. By gauging the rhythm and timing of your speed along with the speed and position of others on the sidewalk, your brain calculates when and where "openings" should appear that you can walk through. In order to make these calculations in time to be useful, you must look a certain distance ahead of where you are. The faster you want to go, the farther ahead you need to look. If you were to look at the ground, or only a couple feet in front of you, you would frequently bump into people. You achieve a certain level of fluid movement through the crowd by looking ahead and anticipating your environment’s changing conditions, while keeping tabs on your immediate surroundings through peripheral vision. Your body responds automatically by adjusting speed, and your side to side position as you “dodgeâ€￾ the people around you.

    This same technique applies to driving on the track. A driver cannot be focused on where he is on the track. He has to be focused on where he wants to be next on the track. To drive the smoothest and fastest line through a corner, or a series of corners, your brain must get input from far enough down the track to calculate the smoothest lines, and anticipate the amount of steering and pedal input to use.

    Driving through a corner consists of four phases, and requires that the driver be looking ahead at least one, if not two, phases at a time. The first phase is the braking zone before the turn. The second is the turn-in, the third is the apex, and the fourth is the exit. If the driver is focused only on the current phase where the car is, he will not be driving smoothly or as fast as is possible through the corner. Each phase will seem like a surprise and will be driven as a jerky sequence of four lines rather than as one fluid path.

    To describe the use of an expanded visual field through the corner sequence, we'll describe a typical turn after a long straight. As you approach a corner, your focal point will be the braking reference point. A few car lengths before you reach the braking point, your eyes must focus on the turn-in point. From your peripheral vision, you will notice the braking reference point and apply the brakes. Your eyes are still focused on the turn-in point, and as you approach and get within a few car lengths, your eyes must now look to the corner apex. Keeping the eyes focused on the apex reference point, use your peripheral vision to notice the turn-in reference point and begin the turn-in. Now, as you are approaching the apex, stay focused on the reference point until a few car lengths away, where you will once again shift focus to the next point which is the exit reference point. You will drive through the apex looking at the exit point, not the apex marker. As you approach the exit point, your focus should now shift to looking down the straight, and you will use your peripheral vision again to drive out to the actual exit point as you reach it.

    In some situations such as tight chicanes or esses, you may need to be looking through several corner reference points, and driving through them almost entirely with your peripheral vision.

    Using your peripheral vision while also focusing in the center of your vision takes some practice--especially at the speeds involved of race driving. If you have already been track driving for a while, at first, this technique may slow you down due to the uncertainty of using your peripheral vision. However, once you get used to it, you will notice that you'll hit your reference points more consistently, and you'll carry a couple more miles per hour through turns you thought you were already maxing out. Developing these skills can takes a few weekends on the track. However, stick to it. Develop the skill first, then bring up your speed. In the end you'll go much faster.

    To practice looking ahead, make sure that you are looking through the center of the height of the front windshield. Several school instructors will even suggest that you put a thin tape line on the windshield as a reminder to be looking above it farther down the track until you fully develop this as a habit. These skills can also be practiced during street driving. Around street corners or on windy roads, practice keeping your focal point well ahead of where you are driving, and "seeing" with your peripheral vision.

    http://www.turnfast.com/tech_driving/driving_visualfield
     
  8. LegMaker

    LegMaker LMI - LegMakerIntakes

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    one of the first things i was taught while at the keith code superbike school maaaaaaaany years ago! good info rick!!!
     
  9. Bud

    Bud GG EVO IX MR

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    Oct 14, 2007
    Trackside Preparation - Turn Fast! The Road Racers Reference Center

    Trackside Preparation

    When you arrive at the track, you'll need to prepare your car (even a totally stock one), and be equipped for both variety of mechanical mishaps, and your own comfort.

    You'll encounter more situations each time you go, but this list should help prepare you for your first time or two until you get the feel for what you want to bring with you, and what you'll need to do to your vehicle.

    Tools -- the amount and type of tools you take with you to the track will depend on how much adjusting or repairing of the vehicle you expect to perform, and how much adjustable race hardware your vehicle has. However, you should have a minimum set of tools with you. Race driving pushes your car much harder than street driving, and you may end up having to repair failing hardware. At a minimum, you should have the following items with you:

    * a basic set of hand tools (wrenches, screwdrivers, pliers, hammer, etc.) to perform the tightening or replacing of minor service items
    * tools to change a tire, including a tire repair kit, and an adequate jack
    * air pressure gauge with a bleeder valve (preferably an oil-filled one reading no more than 50-60 psig)
    * a small 12-volt air pump with a tire adaptor, this is needed to adjust tire pressures up
    * a wooden block or other item to stop the car from rolling when parked (do not use the hand brake after driving on the track, it will warp the rear brake rotors)
    * a spare set of brake pads, and the tools required to change them (know how to do this before you go!)
    * spare fluids including enough oil to refill the pan, coolant, and brake fluid
    * items that will be handy for emergency repairs such as duct tape, electrical tape, large tie wraps, and bailing wire
    * buy a box of rubber gloves from the drug store -- they're a few dollars for 40 or 50 gloves and they save a lot of time and hassle in cleaning up between sessions

    There are dozens of other specialty tools or tools of convenience that you may begin to collect as you discover new needs at each event.

    Comfort -- chances are you'll run with an organization that will rotate several groups on the track. You'll have plenty of time between sessions to fill in. You'll want the typical items you'd take for a day in the park: chairs, drink coolers, snacks (healthy, energy building ones!), etc. You'll likely spend most of the time socializing between sessions, but just remember you'll be at the track for a full day or more--take the things you need to be comfortable and enjoy it. A good idea is to take some of the printed pages from this site or the race books you've been reading. You may encounter something on the track that you want to refresh what you've read before.

    Vehicle -- any club worth running with will insist on a general safety inspection of the vehicle. Additionally, you'll want to be sure the vehicle has been properly serviced. For your own safety, and those around you, do not ignore the importance of maintaining your car's mechanical well being. Find out what the safety inspection will be, and make sure your car will pass ahead of time.

    Most safety inspections, at a minimum, include checking the condition of the brakes, tires, and wheel bearings, making sure there's no fluid leaks, that the battery has a tie-down clamp, that there are no loose body parts, and that all brake lights function properly.

    In addition to this, you will want to be sure that your car has been properly maintained. A half-hour of race driving on a track will stress your car far more than any hot rodding around town you've ever put your car through. Be sure it's in good condition. Fresh oil, all fluids in good condition and at the proper levels, lots of brake pad, lug nuts checked, filters all clean, and spark plugs in good condition are all items you need to check before leaving home.

    Before going onto the track itself, be sure to remove everything that is not a permanent fixture in the car. Take out all loose items you keep on or in the dash, under the seats, in the trunk, and even in the glove box. Remove the spare tire and tools, and remove the floor mats. If your car's wheels have hub caps, even the small center bolt cover plates, remove those too. Absolutely everything should be out of the car. This is a safety issue. If you end up off the track, in a spin, or if you are hit or roll, loose items that normally seem harmless can cause significant injury.

    The other thing most tracks and organizations will ask you to do is tape up the lenses of all lights or other plastic trim items like that. Loose stones, tire chunks, or other track debris can get tossed up and break light lenses which just adds more debris to the track. You'll want to use a tape that has enough stick to do the job, but not one that will gum up your car, so don't use common duct tape, masking tape, or electrical tape. From your car's perspective, the more you cover, the less will get scratched or cracked.

    Tires -- one of the common "mysteries" and subjects of paddock chatter in club time trialing is tire pressure. There's two parts to the "what pressure to use" question. First, racing will dramatically heat up your tires--much more than driving on the street. The starting pressure of the tires when they're cold is going to be several pounds lower than you're used to using. Second, tire pressure is often one of the very few things you'll have available to tune your car's handling, and you may need to fine tune the pressure of each tire for the best performance. Read the Tire Notes article in the Practice Sessions tab for a lot more detail about this subject.

    http://www.turnfast.com/tech_intro/intro_trkside
     
  10. Bud

    Bud GG EVO IX MR

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    I posted this 2 minutes ago...YOU are a fast reader!

    I came across this site tonight....Good stuff!!!
     
  11. LegMaker

    LegMaker LMI - LegMakerIntakes

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    no, i had three minutes to actually read it........ remember, i am a very edumacated guy....... hahahahahaha
     
  12. MotherMopar

    MotherMopar The One, The Only... MOMO

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    Good stuff bro. I'm putting a piece of tape on my windshield when I get precious back.
     
  13. MotherMopar

    MotherMopar The One, The Only... MOMO

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    Great... how am I gonna squeeze a front stb in my car? Wondering: if they have a smaller rear stb than you do, bro? I need the trunk space for Bryce's stroller, etc.
     
  14. Quick

    Quick Mgmt. - I can't help you

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    What? Physics please?


    Ok, I'll help here. There is a distinction between static friction and kinetic friction. In almost all cases (like friction between a tire and the road) static friction will be significantly greater than kinetic friction. Any truck driver knows this. Once your unsecured load STARTS to slide it's gone. This is important because if you're decelerating in a straight line the load is very likely to strip the cab (and often the motor - not that you care at that point) cleanly off the frame.

    For an experiment try pushing a refrigerator or the likes across the floor. It takes a lot more effort to get it moving than keep it moving once it starts to slide. You're exceeding the static friction to get it to start to move. You're exceeding the kinetic friction to keep it moving. So... a tires greatest traction will be achieved at the point just before it starts to slide. Once it starts to slide you've lost some traction.

    Now, it IS most probably true that for a human to determine this point they will have to exceed it. You're not going to know that you've approached the point until you've gone past it. That's fine. I agree with that. But they are flat out saying that a tires maximum traction is reached when it's sliding. I think that's BS.

    http://hyperphysics.phy-astr.gsu.edu/hbase/frict2.html

    Just so this isn't taken in the wrong way. I am not questioning what they are telling you to do to get the best performance. I'm just questioning the claim they present as being behind it. (did that make sense?)
     
    Last edited: Jun 27, 2008
  15. NetNathan

    NetNathan Not the Momma

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    More great info..and I just thought I went into the corner too fast and the tires lost traction.

    Alright Rick,
    Now that you have become our road race info man, when ya gonna get the on board camera setup so we can see. I HEAR you are a killer in the twisties.
    So are you drifting.. oops... I mean... "slipping"... the corners now?
     
    Last edited: Jun 27, 2008
  16. Bud

    Bud GG EVO IX MR

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    Ryan has already contacted Razors Edge and BMC to see if they can fabricate a STB to accommodate the Vortech.
     
  17. Bud

    Bud GG EVO IX MR

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    Road racing I slip the corners....drifting, I take it one step further! I'll let you decide if it was intentional or not! One things for sure.....I know how to correct either one! LOL
     
  18. Stretch

    Stretch Silver Supporting Members

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    Cool... wondering how they will set it up if possible seeing hows there no clearance between it and the firewall.
     
  19. 6.1luvr

    6.1luvr Baptized by Fire

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    Good Read and Very informative Rick!..........Thanks.
     
  20. nevinsrt

    nevinsrt Getaway driver for hire

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    Awesome!!!