This is a part of driving that’s normally taken for granted. What’s important is that it directly impacts vehicle performance. It allows you to accelerate, turn, stop and retain control of your vehicle. We’re talking about grip. It may sound simple, but there’s more to it than you think. Read on and learn all about it.
Understanding, recognising and maximising grip
Gripping Factors So you’ve got a car. You enjoy driving. You wait for opportunities to get out on weekends and explore the roads. It’s fun, right? But have you considered the
unseen forces that come together and allow you to indulge in this activity? It’s what we call grip. It is a result of a combination of three factors —the contact patch of the tyres, the friction between the surface and the tyre, and the vertical load on the tyre.
The Contact Patch Only a small area of the tyre actually makes contact with the road surface at any given time. This is called the contact patch. It can supply a limited amount of grip. This grip is divided between longitudinal, or front to back, and lateral, or side to side, directions. Longitudinal grip applies under acceleration or braking while lateral grip applies while cornering or steering.The important thing to keep in mind here is that if all the available grip gets used in one direction, say longitudinal, there will be none available for the other, i.e. lateral. The sensible thing to do is to perform these grip-demanding actions separately. This means that when you’re accelerating or braking, keep steering inputs to a minimum. If you need to turn, first brake in a straight line, then release the brake before steering the car into the turn. Doing this reduces the grip demands on the tyres and allows the driver a ‘grip buffer’ which can be used in case of emergencies. Professional drivers tend to drive on the limit and combine braking and steering (trail braking). They have to balance these forces well as a slight miscalculation can have them sliding out of control. What’s important is that all driving inputs need to be given as smoothly as possible.
Friction The level of friction between the tyre and the surface it’s being driven on depends on the type or compound of the tyre and the type of surface. Concrete, gravel, mud and tarmac all offer varying levels of grip. Levels also change depending on whether the surface is wet or dry. What’s been driving over these surfaces also matters. Older vehicles, or even badly maintained ones, especially in the wet tend to leak oil, making the roads very slippery. In these cases, being alert and driving carefully while maintaining a safe distance from other vehicles will be helpful.
Vertical load The more weight there is on the tyre, the more it will be pushed into the ground and the more grip it will have. Now this does not mean you load up your car with cement bags. The car will still have to accelerate, decelerate and turn. The added weight is a disadvantage here. Fear not for the dark arts of aerodynamics come to
the rescue. You’ve obviously seen cars with wings/ spoilers on the boot. These work like aeroplane wings, just upside down. So instead of creating lift, they create downforce and push the car into the ground. The faster you go, the more downforce it generates, and the more grip you have. There’s obviously more to it, but from a grip point of view, this works.
Maximising Grip A simple but effective way to maximise traction is to use drive smoothly. The way you shift gears, accelerate, brake and steer can either increase or decrease the amount of grip. But there are specific things that can be done to help maximise grip.
Weight transfer We’ve already mentioned that the amount of vertical load/ weight acting on the tyres can affect grip. When a car accelerates, decelerates or turns, the body of the car rolls, and this transfers weight on a particular side of the car. You’ve experienced this as leaning to a side when the car turns, or leaning forwards when it brakes, or being pushed back when it accelerates. When the car accelerates, brakes or turns, the body of the car rotates in the opposite direction. This compresses the suspension on one side and releases the weight.
Aerodynamics Adding spoilers, font splitters to your car can increase the amount of grip available. But unless you drive regularly on a track or in a rally, you’ll probably never go fast enough consistently to really need these additions. If you add them to your regular road car for ‘aesthetic’ reasons, you should know that it’s mostly useless.
Tyres This is a basic point, and one that you should check on periodically. Always ensure that your car is riding on good quality rubber. Check the tread and sidewall for wear and when necessary, replace your tyres. You can check for tyres rated to offer better grip in varied conditions and those made with compounds that offer better levels of grip. Of course, you’ll also have to balance this with performance, economy and consider the surfaces you usually drive over.
The Limits of Grip As with all things, there are limits to grip levels and going from gripping to skidding is not that hard. When your tyres are pushed beyond their ability to grip the road surface, traction is lost and the car skids. Usually with a lot of tortured tyre noises. Generally, skids either affect the front tyres or the rear tyres. When the front tyres skid, the car tends to continue straight despite you wrangling with the steering wheel to try and get it to turn, i.e. it understeers. Most front wheel drive cars will do this. Dealing with it is simple. Gently back off the throttle. Once you slow down, you’ll recover steering ability and turn.
When the rear breaks traction, the car rotates far more than intended into the corner, i.e. it oversteers. To counter oversteer, you’ll need to reduce pressure on the throttle and steer into the slide (dab of oppo, as enthusiasts call it). You’ll need quick reflexes and have to turn smoothly and very quickly to avoid ending up sideways or even backwards.
Whether it’s understeer or oversteer, it is likely to be quite scary. Try and keep calm, smoothly make the adjustments to throttle and steering and you should come out of it unscathed. Of course, preventing a skid is far better than having to counter it. There’s very little need for you to explore the fine line between grip and slip. Practice
smooth driving and cornering techniques and you’ll mostly not have to worry countering skids.