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Wings on FF Cars - Aero Magic

Rear Wings on FF Cars--A Professional Driver's Perspective

Andy Hope
Sep 10, 2012 SHARE
Htup 1209 01 o+wings on FF cars+acura integra Photo 1/5   |   Wings on FF Cars - Aero Magic

Wings, spoilers, bird killers, park benches—you can joke and call them whatever you want to, but competitive track car builders consider them essential. When done correctly, they help cars turn faster lap times. Yes, even when mounted to the rear of a front-engine, front-wheel-drive (FF) Honda.

Just for clarification, when I use the word wing, I actually mean airfoil. Why? Well, this is what an airfoil does; it slices through the air and pushes it up or down, depending on the user’s needs. On an airplane, for example, it pushes the air down, which in turn creates lift. On a race car, it can do the opposite, pushing the air up, creating what we call downforce. Go ahead, stick your hand out of the window on the highway and feel it. It’s real. Hold your palm flat and parallel to the ground, and then twist your wrist to change the angle of attack. Next, curve your palm to change the airfoil shape. Most importantly, note the differences that show up at different speeds. You’ll feel varying degrees of lift, downforce, and of course drag. Drag is that force pushing your hand back.

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Keep in mind that your hand makes for a pretty sloppy wing, which is probably why people can’t fly. A real airfoil can create hundreds of pounds of downforce with very little drag. Still, the principles are the same. So why would you accept an increase in drag to add downforce to the rear wheels—the wheels that don’t turn or accelerate, and barely brake? Oddly enough, the answer to that starts in the front end.

The front wheels—or more accurately, the front tires—determine how fast an FF car will go around a racetrack. They do all of the acceleration, almost all of the braking, and they initiate the turn in. Furthermore, they usually have more weight over them, forcing them to handle the better part of the cornering load. The more traction the front end has, the faster you’re going to go. Read that last sentence one more time. Now a lot of people will tell you that all the rear tires do is keep the back end from dragging on the ground. Cursed by an old-school mentality, they’re also the ones who made fun of wheelie bars on FF drag cars in the ’90s. The fast guys are doing everything they can in the back end to help the front end stick.

To clear my conscience, I must forewarn you that we are now entering into the black art of race car setup. Race cars drive on racetracks, where the surface is generally smooth, there are people with flags to warn you if something has happened around the next corner, and normally there is an ambulance on site. The cars have additional safety equipment, and while there may be as many idiots out there as there are on the street, they’ve all signed a release of liability in case you wreck or kill one of them. Race car setups should not be driven on public roads. Even the best drivers I know use a totally different setup on the street than on the track. Not so much because the race setup is uncomfortable, but because they would likely crash.

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I’ll never forget watching Steph Papadakis make one of his first passes at the Battle of the Imports in his tube-frame EK. That was one of the first FF Hondas truly built for just one purpose: to accelerate down the quarter-mile. All of its weight was sitting over a set of massive, barely inflated front tires. The rear suspension was locked down tight to avoid weight transfer and give the front end every bit of available traction. It clawed its way out of the hole and through the traps like nothing anyone had ever seen. But as soon as he lifted, that bitch turned on him. It had to be close to 90 degrees to the left, and I’d swear the back end was in the air when the parachute and an unimaginable amount of driving talent saved both him and the car.

A few years later I was helping to host a spectator event at Buttonwillow Raceway, a road circuit in central California. It was a total flop. One of the pissed-off vendors had a fully raced-out ’86 Civic on display. I offered to let him take it out on the track, but he declined, saying the car was way to dangerous to drive. He went on to explain that the car was set up for autocrossing, meaning it was built to quickly transition from left to right. The car’s front-end grip was maximized by combining extremely stiff rear springs with a giant rear sway bar. The stiff springs kept weight from transferring to the rear, keeping the front tires planted. Furthermore, the giant rear bar would lift the inside rear tire, decreasing the grip in the rear. According to him, it dominated at the relatively low-speed autocross events, but at racetrack speeds it was extremely unstable and would spin out when driven hard.

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The trend here is that FF cars both accelerate and turn better with a stiff rear suspension. The trade-off is that they get really twitchy as speed increases. Additionally, the cars want to swap ends in the braking zones because all of the weight transfers to the front tires. This causes the stiffly sprung, unweighted rear tires to hop and lock up—neither of which is good when going for consistent speed and placement at corner entry. If only there was something that would push down on the rear tires at speed, yet lighten up to let the car be agile and autocross-like at low speeds.

OK, let’s get that hand back outside of the window. At 30 mph you should feel almost nothing. At 60 you feel a lot more pressure, maybe twice as much. That’s because when your speed is doubled, the air pressure roughly gets squared. There is no magic number where wings suddenly start working, but mounting a rear wing to an FF car works out quite nicely. The air speed stabilizes the rear end when you need it to, but still allows the front end to really bite at low speeds—when you want it to.

That’s really all there is to it. If you’re dead set on hating rear wings, you’re reading the wrong issue of HT. If you’re hung up on the concept of running stiffer springs in the rear than the front, that’s OK. A lot of people are. I once had a pair of rear RSX shocks sent back to Zeal in Japan to have them revalved for 30kg/mm springs. Everyone involved questioned it until they got to the technician performing the work who said something like, “Oh, so you want them valved just like our N1 endurance cars then.”

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Of course, there is a lot more to both aerodynamic and suspension tuning than is covered here. The important thing to keep in mind is that it all has to work together. Front splitters and air dams are awesome as they increase the grip on the front end, but you’ll want even more wing on the back in order to balance it out. You’ll also need to increase your front spring rates to keep the splitter level. Then you’ll need to increase your rear rates to get your low-speed balance back. It really never ends.

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By Andy Hope
29 Articles

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