what is it, and how to control it

what is it, and how to control it

Oversteer

Oversteer is related to understeer and occurs when the back tyres reach the limit of adhesion in a corner before the front while cornering. This leads to ‘ the second coming out ’. If you manage to perform sustained, controlled oversteer this is know as drift .

Oversteer overview

The diagram below shows four stages of oversteer, which we ’ ll now explore in more detail. A. The car has turned in normally and is aiming towards the vertex.

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B. The rise wheels have started to lose adhesion, the driver compensates by steering left to keep guidance aligned to the desired drive telephone line ( counter steering, explained below ). C. The driver has maintained master of the car and continues to follow the desire line. D. The car is at the limit of forget hand lock, a spin is probably at this stage unless dramatic corrections are made. Oversteer is more stimulate than understeer and like most excite things ( such as jumping off cliffs ) there is an element of risk involved. Most ‘ driver ’ randomness cars ’ have a tendency to oversteer when on the limit around corners, and this place can be found in a assortment of vehicle layouts and drive formats .

Oversteer – factors involved

Oversteer results from a number of factors, some of which involve the natural handle characteristics of the car, and some result from the way it ’ mho being driven .

Passive factors at work (the natural properties of the car)

  • Weight distribution (front or rear bias)
  • Engine and drive layout
  • Suspension & chassis setup
  • Tyre type, wear and pressures

Active factors involved (the way it’s being driven)

  • Cornering speed
  • Throttle
  • Braking
  • Steering inputs
  • Weight transfer

Symptoms

It ’ s improbable you ’ ll ever experience oversteer unless you ’ ra driving a car near the limits of grapple. You can recognise oversteer if…

  • The rear of the vehicle becomes unstable and ‘light’ due to lack of grip.
  • The car starts to rotate so the driver is facing towards the inside of the corner.

Causes

There are four major active causes of oversteer, but what you ’ re probable to encounter depends on the car being driven ( for more information on this please skip to the next section ). Causes include :

  1. Entering the corner too fast
  2. Accelerating into the corner, too early or too aggressively
  3. Braking into the corner or mid corner
  4. Lifting off the throttle mid-corner. This scenario is also known as:
  • lift-off oversteer
  • snap-oversteer
  • trailing-throttle oversteer
  • throttle off oversteer
  • lift-throttle oversteer

Lift-off oversteer

Lift-off oversteer is a phenomenon which can occur when reducing the accelerator mid corner. This will only happen when driving close to the limit so only experiment when on the lead ! Sporty front wheel drive driveway cars can be particularly prone to this due to the heavy front end and light buttocks. Reducing the accelerator stimulation results in a fore weight transfer, which increases the fascinate at the front man tyres, but reduces levels at the rear. If this is performed during corner, the combination of the arduous front end and the reduction of grip can cause the rear wheels to break traction and start to slide towards the outside of the corner. In the image below, the driver of a front locomotive car lifts off the accelerator mid corner at [ A ] which results in lift-off oversteer at [ B ] due to a forward weight unit transfer. fortunately, lift off oversteer can normally be corrected by reapplying the restrict and accelerate. This should pull the front of the cable car forwards and straighten out the car, but continuing to reduce strangle lotion can cause the car to spin. Steering in the guidance of the intend management of travel will help keep the car on track .

Oversteer and racing / performance cars

Most performance cars have a tendency to oversteer as they are normally developed to provide a big amount of grapple at the front wheels ( to turn into corners well at speed ), and a big total of power ( normally at the rear wheels ). This means that if traction is lost it will normally be at the back first. frankincense in most cases the ideal corner proficiency in a performance cable car needs to try and reduce or control oversteer .

Preventing & correcting oversteer – rules of thumb

To correct any form of traction personnel casualty, you need to consider why you ’ ve exceeded the limits of clasp at the wheels. In all cases of oversteer, buffet guide is besides required .

1. Entering the corner too fast

Enter a corner excessively fast and you ’ rhenium asking for trouble. Unless of course you have a lovely long run off to play with or if you ’ re driving Silverstone in a go-kart. It ’ s not the quickest direction to take a corner and leads to increased risk of oversteer. If you have entered a recess besides fast, ensure that every remark you make is fabulously legato, and take the easiest road. future time make certain your entrance speed is slow enough to maintain grip, you can build up accelerate as you gain experience .

2. Accelerating into the corner, too early or too aggressively

If you manage to break traction at the back when applying restrict, you ’ re credibly in a powerful car and need to be less aggressive. If you ’ ra spin wheels, the world power is not transferring to the road and you ’ re not benefiting from the many horses you have sitting under the hood. Gently ease off the boast and you should regain adhesion at the back wheels .

3. Lifting off the throttle mid-corner

If you are on the might mid-corner and close to the terminus ad quem, do not lift off the accelerator. The resulting forward weight transportation can upset the balance of the car and allow the rear wheels to break loosen. In a front wheel drive car, reapplying the restrict can often help in this situation .

4. Braking into the corner or mid corner

You should avoid braking in corners in most situations, however there are circumstances which require the function of the anchors. see brake inputs are particularly smooth, easy and progressive, and if a squirrel has just run out in front of you, try steering around rather then doing an emergency stop. To correct brake-induced oversteer, smoothly ( but quickly ) release the brake and adhesion should be reintroduced .

Correcting oversteer – counter steering / opposite lock

Whatever the cause of oversteer it is important to keep the front wheels pointing in the direction you ’ rhenium hope to go. If you fail to do this, the most likely solution is a whirl. This proficiency is known as counter-steering or applying opposite lock ( see diagram below ). You should apply enough steering lock to point the wheels in the direction of the slide as shown below. Too little and you ’ re probably to spin as the back continues to come round, excessively much and the car will quickly over-correct, often resulting in a spin in the diametric commission. The skill can only be mastered with enough of drill and should become instinct if you ’ re design to drive fast on a track. lean : Always look and focus on the direction you ’ ra hop to go – this makes the steering correction about automatic. conversely – don ’ thyroxine concentrate besides unvoiced on that tree you ’ rhenium hoping to miss as you will be more likely to head in that focus. Applying corrective steer needs to be done quickly to catch the back of the car before it slides to a luff which may be unmanageable to control. Once the slide has been controlled and the back starts to fall back in line, it ’ mho besides crucial to get the steering correction off promptly besides, otherwise you might find yourself with oversteer in the antonym direction due to the resulting pendulum effect.

what is it, and how to control it

Oversteer and different drive / engine layouts

Rear wheel drive

In a buttocks wheel drive car you have the benefit of sharing the demands on adhesion between the front and rear wheels. The front wheels do the guidance and the rear do the accelerate ( and deceleration under engine brake ). This normally results in a more balanced vehicle. In most conventional presence engine, front bicycle driveway vehicles such as the Ford Fiesta it is rare to always experience anything early than understeer. rear wheel campaign cars can experience oversteer for unlike reasons depending on where the engine is located .

Rear wheel drive, front engine

[ e.g. BMW M3, Mazda MX5 ]Causes, and likelihood of oversteer for a real wheel drive, front engine carCause of oversteerLikelihood of oversteerEntering the corner too fastHighAccelerating early or aggressivelyHighLifting off the throttleMediumBrakingMedium In a front locomotive car, most of the weight is over the front wheels. This normally results in higher natural levels of grip at the battlefront ( which is utilitarian for steering and braking ). The relatively unladen rear wheels may have lower natural levels of grapple, which can lead to oversteer particularly when accelerating round a corner. This is the argue some identical gamey powered cars have wider wheels and tyres at the back. Question : When a front-engine rear-wheel drive cable car accelerates hard in a corner, there is a high hypothesis of oversteer. I besides understand that weight is transferred to the buttocks under acceleration, therefore one would like to know how the rear wheels can still lose grip when weight is transferred to the rear and on to the rear wheels. Answer : There are many factors at oeuvre when corner and it ’ s a finely balance of forces. It ’ second significant to understand that when you ’ ra corner there is much less grip available for acceleration and brake. For a rise weight transportation to occur in the first gear place, you need to have the grip available to put the world power down – if you try to accelerate hard you ’ re likely to overwhelm the rear tyres and spin one or both of the wheels. This reduces the physical clasp dramatically which can then lead to oversteer .

Rear wheel drive, rear engine

[ e.g. Porsche 911 ]Causes, and likelihood of oversteer for a rear wheel drive, rear engine carCause of oversteerLikelihood of oversteerEntering the corner too fastHighAccelerating early or aggressivelyMediumLifting off the throttleHighBrakingHigh Rear locomotive, rear bicycle drive vehicles such as the Porsche 911 can oversteer for different reasons to front engine varieties. In this case most of the fomite weight is over the buttocks wheels, leading to greater levels of natural bobby pin at the binding, which should lead to an implicit in low hazard of oversteer. however, there is another pull at ferment hera – momentum. Objects with greater bulk carry more momentum and are harder to change direction at speed. In the case of buttocks engine cars, the rear has more momentum than the front which can lead to a greater risk of oversteer as a result of brake or lifting off mid recess. Mid engine cars can besides oversteer for exchangeable reasons, but tend to provide a better balance of under and oversteer .

Front wheel drive (front engine)

[ e.g. Peugeot 205 GTi, Renault Clio Cup ]Causes, and likelihood of oversteer for a front wheel drive carCause of oversteerLikelihood of oversteerEntering the corner too fastMore likely to understeer initiallyAccelerating early or aggressivelyLowLifting off the throttleHighBrakingHigh Sporty front wheel drive cars are more likely to experience oversteer than a standard car due to the fomite frame-up. Dial out the built-in understeer tendencies of a movement rack drive car using apt engineer, and the solution is a better ‘ become in ’ and an increased ability to oversteer due to the naturally faint rear. In this casing, it is normally potential to accelerate out of the oversteer situation, using the rear weight transfer to actively increase levels of bobby pin at the bet on. Front wheel drive cars are particularly prone to lift off oversteer due to the forward weight transfer combined with easy rear end. Question : When a FWD car accelerates, weight is transferred to the rear. Does this mean that the front man of the cable car where the locomotive is located becomes lighter than the rear during acceleration ? Answer : first, the slant transfers which result from acceleration are possibly not ampere great as you think. This is because you ’ re improbable to be able to accelerate american samoa promptly as you can brake or change guidance with the steering – therefore the advantages or rear slant transfers are normally slightly less than in other directions. It ’ mho very improbable any front engine cable car could accelerate to the point that the buttocks weights more than the battlefront. There will be some transfer of weight onto the rear wheels, but not that much .

Four wheel drive

[ e.g. Subaru Impreza, Nissan Skyline, Audi Quattro ]Causes, and likelihood of oversteer for a four wheel drive carCause of oversteerLikelihood of oversteerEntering the corner too fastMediumAccelerating early or aggressivelyMedium / HighLifting off the throttleMediumBrakingMedium Four wheel drive vehicles can oversteer angstrom much as rear wheel tug cars, depending on apparatus. however, due to the share of drive forces over all four wheels, there is less risk of oversteer ascribable to excessively over-exuberance with the choke pedal. Treat as a rear wheel drive fomite and you won ’ metric ton go far wrong. With particularly herculean four bicycle drive vehicles it may be possible to enter a ‘ four bicycle drift ’. This is a particularly spectacular means of exiting the road !

Simple modifications to make a car less prone to oversteer

If you have a lead car and find oversteer a problem, you can complete some relatively easy modifications which can make the treatment more neutral. These include :

  • Reducing the rear tyre pressure
  • Softening rear springs or anti-roll bar
  • Use softer rear tyres
  • Increase rear down-force (if aerodynamics fitted)

If you want to try something a little more dare, the chart below can help .

Advanced oversteer diagnosis and modifications

Below is a flow chart which can help diagnose and treat the symptoms of oversteer. disclaimer : Always stick to the manufacturer ’ randomness recommended limits when altering sur pressures, and never modify a road car .

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Category : Car Brakes