Race Driving Fundamentals: Oversteer
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Oversteer
06.24
| 00:00 | - Like understeer and front wheel drive cars, oversteer and rear wheel drive cars have a long and colourful history. |
| 00:07 | As the name implies, oversteer is simply the opposite of understeer, where the rear of the car breaks traction or starts to slide before the front. |
| 00:15 | The car is now going to oversteer which means it will track a tighter line through the corner than the one the driver intended. |
| 00:22 | This may also be referred to as the car being loose or over rotating and is essentially the rear of the car trying to pass the front when the steering lock is applied. |
| 00:32 | This is a result of more grip being available at the front of the car than what is available at the rear. |
| 00:38 | One of the most important aspects of dealing with oversteer is being able to feel when it's occurring. |
| 00:44 | You'll feel the car begin to rotate around you and this feeling will be transferred from the chassis through your seat and then into your body. |
| 00:52 | This is just one of the reasons why a solidy mounted tight fitting and supportive seat is essential. |
| 01:00 | This feeling of the car rotating around us will also be coupled with the need to reduce the steering lock in order to maintain our desired line through the corner. |
| 01:09 | The amount of steering we need to remove will depend on the severity of the oversteer. |
| 01:14 | A small amount of oversteer will only require a slight reduction in steering lock in order to maintain our line but if it's severe enough, we'll need opposite lock which is when we need to physically turn the wheel the opposite way to the direction of the corner. |
| 01:28 | Unlike understeer, oversteer requires a lot more work from the driver in order to control the car and prevent a loss of control or a spin. |
| 01:36 | If a reduction in steering lock or potentially opposite lock isn't applied quickly, a spin is the usual outcome. |
| 01:43 | While most track days enthusiasts will have a natural reaction to apply opposite lock beginners will usually be too slow to apply it and this is often coupled with too much opposite lock which makes it difficult to quickly regain control. |
| 01:56 | As we gain experience driving the car on the limit, we'll naturally encounter oversteer frequently and as we become more familiar with the oversteer, we'll actually begin to predict when it's about to happen, allowing the steering lock to be reduced when oversteer is about to happen rather than once the car has already begun to slide. |
| 02:15 | The main thing here is to not panic when oversteer inevitably happens and to try not to think of the exact amount of steering input we need. |
| 02:23 | Instead we should just focus on looking ahead at where we want the car to go and our hands will naturally follow where we're looking. |
| 02:31 | Just like catching a ball, you're never focused on how much your hands move, just the ball. |
| 02:37 | Just like understeer, a chassis that tends to oversteer can be related to the suspension setup but in reality there are also a number of ways the driver can induce oversteer which we need to understand so that they can be avoided. |
| 02:50 | The first and most well known cause of oversteer in a powerful rear wheel drive car is power down or power on oversteer. |
| 02:59 | You're going to experience this at the corner exit as you're beginning to get back on the throttle, where the combination of lateral grip and longitudinal acceleration exceeds the available grip the tyres can provide. |
| 03:11 | Next thing you know, you're going sideways looking through the passenger side window with half a turn of opposite lock and smoke pouring off the rear tyres. |
| 03:19 | While it's undoubtedly a fun way to get around the racetrack, it's not going to win you many races. |
| 03:25 | The next scenario that can result in oversteer is turning into the corner while braking too heavily. |
| 03:31 | Now I know that I've just listed this exact situation as a potential cause of understeer in our previous module but let me explain. |
| 03:38 | This really comes down to the specifics of our car and exactly how much braking we're still doing. |
| 03:46 | By now, you should understand that braking will transfer more weight to the front wheels, increasing their grip. |
| 03:52 | This of course, as we know, comes at the expense of grip at the rear of the car. |
| 03:56 | So if we're still applying too much brake pressure as we turn into the corner, this can exceed the available grip at the rear of the car, resulting in oversteer. |
| 04:05 | This is quite common in front wheel drive cars which naturally don't have a lot of weight on the rear axle line and when managed correctly, this is an advanced technique that can be used to help the car rotate into a corner. |
| 04:18 | Trying to enter the corner too fast can also result in oversteer. |
| 04:22 | The available grip from the tyres will dictate the maximum speed we can maintain through a specific corner. |
| 04:29 | If we're travelling faster than this then one end of the car is going to begin to slide and depending on the car setup this could result in either oversteer or understeer occurring. |
| 04:40 | Next we have lift off oversteer which occurs when the driver suddenly lifts their foot off the throttle. |
| 04:46 | This can happen anywhere through the corner where the driver is rapidly changing throttle positions but it's most common while accelerating from the apex where the driver realises the car is understeering wide of their intended line. |
| 04:58 | When the driver lifts sharply off the throttle, we get weight transfer towards the front of the car. |
| 05:04 | As we've learned already, this is good for increasing front end grip and reducing understeer but depending on the chassis balance, the reduction in grip at the rear which will occur, can be enough to cause sudden and violent oversteer. |
| 05:16 | The key to manipulating weight transfer and controlling the chassis balance through a corner is smooth inputs on the throttle and steering from the driver. |
| 05:24 | And as you'll learn, as we continue through this course, being smooth in all aspects of our driving is one of the secrets of being fast and consistent. |
| 05:33 | The key concept to take away from this module is that oversteer is where the rear of the car will break traction and slide before the front. |
| 05:41 | You'll notice oversteer because the car will feel like it's rotating around your body and this will require a reduction in your steering lock or perhaps even opposite lock to correct the slide and prevent a spin. |
| 05:53 | Oversteer can be a result of chassis setup or driver input, however fundamentally it's a result of insufficient grip on the rear tyres when compared to the front. |
| 06:03 | Now that we've covered both understeer in the previous module and oversteer here, it's worth understanding that understeer is a fundamentally stable condition while oversteer is a fundamentally unstable condition. |
| 06:16 | This is why we usually want our handling balance biased slightly towards understeer. |
