Auto Tech: A matter of balance

By Jim Kerr

When automobile owners speak of balance, they are typically talking about their tires. Tire balance is important to vehicle ride and tire life but it is not the only balance an owner should be aware of. Vehicle balance is a key characteristic that affects both the safety and the fun we have in our automobiles.

Suzuki is touting balance as one of the prime benefits of the new Kizashi Sport. This four-door, front-wheel drive sedan is powered by a 185 horsepower four-cylinder engine coupled to a six-speed manual transmission. Its specifications make it sound like any other economy sedan, but that is before the balance factor is added to the equation.

A four-cylinder engine was chosen for the Kizashi Sport because it is lighter and provides better fuel economy than a V6 engine would. Even though the V6 would provide quicker acceleration, power isn’t the main consideration when you are talking balance. The six-speed manual gearbox has a low first gear ratio for snappy response, balanced by the top two gears which are overdrive ratios for better fuel economy. The front-wheel drive Sport is over 100 kilograms lighter than the all-wheel drive Kizashi, so acceleration, stopping and cornering are quicker. Finally, there is a lower centre of gravity due to the slightly lowered ride height.

On the road, this concentration on balance makes the car fun to drive along winding roads, with minimal oversteer or understeer even when pushed to the limits. It may not sprint from corner to corner as a more powerful car would, but the predictability of handling, minimal body roll and a light, nimble feel to the car provide a sense of enjoyment. That’s balance.

Automobile manufacturers attempt to design balance into their vehicles but often, there are compromises. Take pickup trucks: with a large heavy engine up front and an empty cargo box in back, pickups can be a handful if you push them too hard into corners. Of course, many new trucks come with stability control to counteract their nose-heavy handling. Trucks are designed to haul, so loading them up puts some balance back into the equation, but never to the same point a well-designed car can.

Another example of unbalance would be the early Porsche 911 Turbo. This rear-wheel drive sports car had a very powerful engine hanging out behind the rear axle and very little weight up front. Step on the throttle too fast and the back tires would spin as the turbo boost cut in. Combine that with a little cornering force and you had a vehicle that could spin 180 degrees faster than the driver could blink. Porsche counteracted this by installing much wider tires on the rear to provide lateral traction. It helped but the car could still be a handful when driven aggressively.

Porsche’s mid-engine Cayman and Boxster are prime examples of well-designed balance. They are not the most powerful cars in the Porsche line-up, but display nimble, very neutral handling on corners and have almost no body roll while at the same time providing a comfortable ride. Balance isn’t about maximum cornering or the highest top speed. It’s about driving enjoyment during everyday driving. If everything is right, it just feels natural.

So how do you tell if a vehicle has good balance? Trust your senses. If it feels right when you turn a corner or brake to a stop, that’s a start. When taking a corner, the steering shouldn’t need correction to maintain the vehicle’s line around the turn. Body roll should be minimal to increase vehicle lateral traction and passenger comfort.

To determine if the vehicle understeers or oversteers, turn a corner while travelling a little faster than normal. If it feels like the front end doesn’t want to turn, then the vehicle is understeering. If the back end feels like it could slide sideways, then the vehicle tends to oversteer. It is easier to test balanced handling on ice or loose gravel – at low speed.

Balance is about combining handling, power, fuel economy and ride so that driving is fun. It can come in a wide range of price ranges and vehicle sizes. When you find that right balance, it’s difficult to keep that smile off your face.