This article first appeared in the May, 2016 edition of SportsCar Magazine. SCCA members can read the current and past editions of SportCar digitally here after logging into their account; To become an SCCA member and get SportsCar mailed to your home address monthly in addition to the digital editions, click here.
“Your primary job as a driver is weight management.” I heard and learned this from the Skip Barber Racing School and my hero, Terry Earwood, years ago. Regular readers will recognize it; I speak of it a lot. It’s fundamental. But what I’m really emphasizing normally is front-to-rear. How it is critical to leave your weight forward when you still need to turn, with patience before accelerating, eyes and thoughts on the apex.
Well, there is another transfer I always pretty much ignore: side-to-side. Transitions. It’s far less important to the driver inputs, because it doesn’t affect turning as much. Or does it? Yeah, when you crank the steering, weight transfers to the outside. We see it in body roll and feel it in our necks. Lateral Gs – the massage of the racing gods. In transitions, weight transfers to the other side. Boom.
Ultimately, the driver controls the speed of that transfer, but the suspension settings control the balance of it while it flows or throws to the outside. This is what shocks are all about. Think about it: they only work while moving.
Say you’re a lumberjack (no, really, stay with me here), and a small tree next to you is falling over. The tree is heavy, and while it’s falling there is no resistance until it slams down on the ground. So, you step in and try to hold it up. You are now the shock, and while you resist the falling, the weight of the tree pushes down on you, transferring some of its weight to the ground through your manly boots, but not all of it, unless you stop it completely.
Really, there are two lumberjacks at work. The one holding the tree up is compression damping of the outside shock, and there’s another logger on the other side holding the tree back with a rope tied to the top. That one is rebound of the inside shock.
Hold lightly against the tree, and there’s less pressure on your feet, so the tree hits harder when it finally lands. Hold tighter, and you slow the tree, so it does not land as hard. Resist with all your muscle and nearly stop the fall, and nearly all the weight hits the ground, through you, way before the tree reaches Mother Earth. In this way, the shock (you) controls how quickly the load gets to the ground (your tires).
When the driver moves a control – steering, gas, or brake – that tree is pushed over in a direction, and the shocks determine how fast it falls. The springs and anti-sway bars set how far it goes (engineers, we’re leaving roll centers and geometry out for another column).
Ever throw a car around? Of course you have, this is the Sports Car Club of America! Yanking the wheel over pushes that tree over faster, and yes, makes it slam the ground harder. Well, your tires are that ground. The harder that weight hits the rubber, the easier it is to break it loose. Tires don’t like sudden shocks. That’s why smooth is fast, people. That’s why fast drivers have slow hands, in a good-handling car.
Football fans, you know the expression of a great pass receiver having soft hands? It’s the same concept. When the ball hits his hands, he slows it quickly but gradually. Pooooffff. Sticks like glue. Not puh-wannng, bouncing off, rock hard (ooh, a bad junior high sports memory just flashed). Great drivers handle tires like great receivers handle footballs. I was not a great receiver.
Fast drivers have slow hands, yes, but not in transitions. Fast hands in transitions. Autocrossers know this. Right-left-right. Offset gates. Slaloms. On road courses they are “The Esses,” chicanes – and many times, slower traffic! Rolling chicanes. It’s all part of the thrill.
Why fast? To max-out a slalom or chicane, you must go from turning one way to the other, instantly. There is no straight. Any time you are not turning with full possible force is wasted time, so the object is to transfer the load as quickly as possible, but land softly, like the football star making a great catch. In a normal corner, the turn starts gradually. The straight blends into the turn. In a transition, it’s instant: lefffffttt – right!
The sooner the full load gets to the outside tires, the sooner the car can change direction, and the faster you can go. But too sudden, and what happens? The tires get shocked and let go, sliding out. The more grip there is, the more aggression the tires can handle. Slicks and downforce allow stronger inputs. Require them. Reward them. This is why drivers often find it much harder to go from real racecars to street-stock. They must slow everything down. Like driving in the rain. Lower grip rewards gentler inputs. Can I get an “amen” snow-belt drivers?
Stiffer shocks slow the body roll but can speed the weight transfer. Stronger springs reduce the movement and the weight-wait time. These are great for transitions because they make the load jump so quickly to the other side, with shock control.
Weight transfer and body roll have momentum. Think of that tree, falling fast versus slow. If the body rolls too fast, it lands hard and can knock the tire free. Imagine a Porsche 911 that’s too soft in back. Entering a turn, that body wants to keep on rolling, causing entry oversteer, even though softer springs give more stick, by the book. The same is true for you, front-drivers. Too soft, and you hurt your front grip, contrary to standard thought.
Further, because of the momentum of all this weight movement, you can and must use the power a lot sooner than in a normal corner. As in, before you enter, even. This flopping side-to-side often causes oversteer – think Scandinavian flick rally driving. A little power balances that. Exiting a slalom or chicane? Flat-out, baby!
Late apex the entries to transitions to set up the exit, then hard on the gas as you exit, to keep the tail from wagging as all that weight swings over. If you have front-drive, even better! That often-frustrating power-understeer is now your friend.
The upshot is to go side-to-side as fast as your tires can handle it. I’vealways enjoyed this left-right snap. It’s freeing. Haul-azzz. More like flying the car, yet very different from entering a turn from a straight.
Words by Randy Pobst
