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Saturday, July 18, 2009

Drifting 101

What is drifting?

Drifting is an extreme driving technique. Drifting is the fastest growing form of motorsport in the world. A car is said to be drifting when the rear slip angle is greater than the front slip angle, and the front wheels are pointing in the opposite direction to the turn (e.g. car is turning left, wheels are pointed right), and the driver is in control of these factors. Drifting is not the same thing as power sliding, because drifting is more complex than that. Instead of a drift driver causing a drift and then countering to straighten out, he will again over-counter so his car goes into another drift. A good drifter has the ability to take five or six opposing turns without having traction at any point in time.

History of Drifting

Modern drifting started out as a racing technique popular in the All Japan Touring Car Championship races over 30 years ago. Motorcycling legend turned driver, Kunimitsu Takahashi, was the foremost creator of drifting techniques in the 1970s. He was famous for hitting the apex (the point where the car is closest to the inside of a turn) at high speed and then drifting through the corner, preserving a high exit speed. This earned him several championships and a legion of fans who enjoyed the spectacle of burning tires. The bias ply racing tires of the 1960s-1980s lent themselves to driving styles with a high slip angle. As professional racers in Japan drove this way, so did the street racers.

A street racer named Keiichi Tsuchiya became particularly interested by Takahashi's drift techniques. Tsuchiya began practicing his drifting skills on the mountain roads of Japan, and quickly gained a reputation amongst the racing crowd. In 1987, several popular car magazines and tuning garages agreed to produce a video of Tsuchiya's drifting skills. The video, known as Pluspy, became a hit and inspired many of the professional drifting drivers on the circuits today. In 1988, alongside Option magazine founder and chief editor Daijiro Inada, he would help to organize one of the first events specifically for drifting. He also drifted every turn in Tsukuba Circuit in Japan.

What do you need for drifting?

Drift Car

You can use either a Rear Wheel Drive (RWD) or 4 Wheel Drive (4WD) vehicle, although it is advisable to use a RWD as it is easier to induce the drift and maintain it on these types of cars. Most competition vehicles are RWD, and some of them are 4WD vehicles that have been converted to RWD. It would also be advisable for your drift car to have certain components namely:

2 Way L.S.D – Limited Slip Differential

A limited slip differential (LSD) is a modified or derived type of differential gear arrangement that allows for some difference in rotational velocity of the output shafts, but does not allow the difference in speed to increase beyond a preset amount. In an automobile, such limited slip differentials are sometimes used in place of a standard differential, where they convey certain dynamic advantages, at the expense of greater complexity.

In general, there are three input torque states - load, no load, & over run. Under load, as previously stated, the coupling is proportional to the input torque. With no load, the coupling is reduced to the static coupling. The behaviour on over run (particularly sudden throttle release) determines whether the LSD is 1 way, 1.5 way, or 2 way. (source: Wikipedia)

Stiff Suspension

Stiffening the suspension of the car helps in controlling the car while in drift. Easiest upgrades would be to replace the stock items with performance shocks and springs or coilover setups which are adjustable so you can change both ride height and stiffness.

Interior Components

Inside the vehicle, it would also be helpful to replace some stock items to help control the vehicle to induce, and stay in the drift. Most drift drivers replace the stock seats with Racing Bucket seats. These help keep the driver in place as the car goes sideways, to maintain your control of the pedals and steering wheel. The steering wheel can also be replaced with aftermarket ones which are usually smaller in diameter for easier movement, and for drifting, there are deep center ones, which allow the wheel to be closer to the driver, and farther from the console controls to avoid any mishaps. You can also install a Spin Turn Knob which allows the e-brake to not lock at the top position, so you can use the e-brake faster and without worry that the e-brake engage continuously.

Open Venue

When practicing or during events, it is better to have wide open areas to assure that cars have a enough area to speed up, and more importantly enough area to stop the car. It is also important that there are no obstructions and people within the track. Since drift cars are driven hard, there is a big chance that something will go wrong, such as tires blow up, or brakes fail. This is reason enough to keep people and other obstructions as far as possible from the cars and the track.

How do you drift?

Techniques for inducing drift (taken from Wikipedia)
The basic driving techniques used in drifting are constant, though each car and driver will employ some subset of these techniques. A similarity for all drifting techniques is to be smooth and practice. These techniques include:

Beginner techniques

These techniques do not use weight transition, so are typically the first thing the novice drifter learns. However they are still used by the most experienced drifters, and require skill to execute properly. These techniques aim to induce a loss of traction on the rear wheels, either by locking the wheel (e-brake drift), or using enough power from the engine to break the traction force (power-oversteer and clutch kick).

Hand-brake drift

While the clutch is depressed, the hand brake (or Emergency brake) is pulled to induce rear traction loss. As soon as traction is lost, the driver releases the clutch, countersteers, and depresses the accelerator. This technique is used heavily in drift competitions to drift large corners, or to trim the car's line mid-drift.

When learning to drift using this technique it is important to first countersteer and wait for the car to stop rotating and face the right direction to exit the corner, and only then to press the accelerator to give the car more gas to keep it sideways. If accelerator is pressed too soon or too much, the car will spin out.

Power oversteer or Powerslide

It is usually done at the corner exit by stepping on the gas hard, to slide sideways out of the corner. It is most commonly employed by beginners because it teaches steering and throttle control without the danger of an actual entry oriented drift.

In low-power cars power oversteer can be achieved by applying excessive amount of throttle at the end of a shift. As you are releasing the clutch during a shift, or immediately before that while the clutch is still depressed, press accelerator all the way to send more power to the rear wheels than is necessary for a smooth upshift. If done during a turn, the car will begin to slide. This technique can be used to initiate a drift at very low speeds in an underpowered car (e.g., when shifting from 1st to 2nd gear), and to enter in a higher gear while accelerating all the way up to the turn (e.g., accelerate in 2nd on the straight and shift into 3rd as you enter the turn).

The sequence of actions is as follows:

• Accelerate in the straight line leading to the turn.
• Turn the steering wheel to begin the turn.
• Clutch in.
• Shift to the next gear.
• Floor the accelerator.
• Clutch out.
• Wait for the car to go sideways, then countersteer and proceed to exit the corner.

Depending on how much power the car is making it is possible to keep the gas pedal floored from the shift throughout the entire drift, and in a low-power car this is often necessary.

Shift Lock Drifting

Shift lock (compression slide). Initiated by downshifting (usually from third to second or fourth to third, and using a very fast shift) instead of braking, without rev-matching, causing the drive wheels to lock momentarily. Helpful for very tight corners, allowing the driver to approach the corner at a slower speed and lower revs, while allowing quick acceleration when exiting the corner. This technique can be very damaging to the engine if mis-used as the ECU is unable to rev limit when the engine is oversped by the rear wheels. Premature downshifters are called "Rod Stretchers".

Clutch Kick

This is done by "kicking" the clutch (pushing in, then out, usually more than one time in a drift for adjustment in a very fast manner) to send a shock through the powertrain, upsetting the car's balance. This causes the rear wheels to slip. The foot should be at an angle (heel-toe) so the brake and gas may be pressed as well, this being needed to control speed and stop from spinning out in the drift.

Clutch kick can also be used during a drift to gain angle at the expense of speed. If the car is about to straighten itself out, kicking the clutch will cause it to rotate more. However since power delivery is interrupted while the clutch is depressed the car will lose some speed during the process.

Weight transition techniques

These techniques employ a further concept of weight transition. When a vehicle has the load towards the front, the back wheels have less grip than the front, causing an oversteer condition that can initiate a drift.

Braking drift

This drift is performed by braking into a corner, so that the car can transfer weight to the front. This is immediately followed by throttle, which in an RWD car causes the rear wheels to lose traction. FWD cars can also use this technique as it does not depend on the rear wheels being driven. In FWD cars the front wheels are not allowed to lock due to the continuous power, the rear wheels locks easily due to weight transfer and due to the general front heavy design of FWDs.

Inertia (Feint) drift or Scandinavian flick

This is done by transferring the weight of car towards the outside of a turn by first turning away from the turn and then quickly turning back using the inertia of the rear of the car to swing into the desired drifting line. Sometimes the hand-brake will be applied while transferring the weight of the car towards the outside to lock the rear wheels and help the rear swing outwards. This type of drifting causes the car to accelerate faster afterwards, because of momentum built up while drifting.

Note that the actual scandinavian flick maneuver in rally driving is more complex than feint drifting. In scandinavian flick the tires are intentionally locked by braking hard right after turning a little away from the corner. While the wheels are locked, the driver applies steering input into the corner, adds throttle while still braking and then rapidly releases the brake pedal. This causes the car to slingshot itself through the corner.

Kansei, Lift off, or Taking In

By letting off the accelerator while cornering at very high speeds, cars with relatively neutral handling will begin to slide, simply from the weight transfer resulting from engine braking. The drift is controlled afterwards by steering inputs from the driver and light pedal work, similar to the Braking drift.

Other techniques

Dirt drop

This is done by dropping the rear tires off the sealed road onto dirt, or whatever low-grip surface borders the road, to maintain or gain drift angle. Also colloquially called "Dirt Turbo".

Choku-Dori/Manji (Pendulum)

Otherwise known as over-sway, this technique is done by swaying the car's weight back and forth on straightaways, using countersteer and throttle to maintain a large angle. This is a show maneuver that usually involves many cars following the same line.

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