Millen's response to my interrogation starts out well. He explains that the front anti-roll bar has a thinner wall thickness in the center, so it isn't really as stiff as it appears. That said, both the front and rear bars are much larger than on a traditional racecar. This is to keep the car flat during quick transitions from one direction to the other. And more roll rate makes it easier to overcome traction.
Things go downhill with alignment settings. In regard to rear toe-in, Millen says that since the tires are spinning, mechanical grip needs to be increased to compensate for the lack of tire grip. I'm familiar with aerodynamic grip versus mechanical grip, but I thought tire grip was more an end product of those two things. To be honest, I'm not sure what he's saying when he describes the need for front caster. We've hit a communication barrier. It's painfully obvious that the language of drifting goes well beyond terms like 'clipping point' and 'one more time'.
Fortunately, our deadlock is broken when we get the green light to take the Solstice out on the runway for testing. Millen runs through the acceleration and braking tests while a gang of moto-cop trainees, doing drills on the runway, draw down on him with radar and laser guns. It looks like a cross between The Godfather and Star Trek.
The car hauls ass in the quarter-mile. It's a big advantage if you can gap your competitor at the start of a tandem drift competition. As one of the best-prepared drift cars out there, we expected the car to do well in this respect. Braking is another story.
Sure, Millen's Solstice has massive Rotora brakes all the way around. And no, they aren't just for show. Brakes are one of the more critical parts to a drift car. They just aren't set up for threshold braking. The bias is set with hardly any pressure going to the rear. I didn't really understand why until Millen gets sideways to show what his car can do.
Our final 'test' to attempt to compare Millen's Solstice GXP to Travis Pastrana's WRX rally car and Bill Reesman's MiG-15 is to run it through a big sweeping U-turn. While Millen admittedly could have run a faster grip style (yikes, I'm starting to use drifter terminology) line through the corner, he puts the car sideways from the braking point all the way through and beyond the exit. It's difficult to see exactly what he's doing from the outside, but then I jump into the passenger seat-not only to see the driving techniques, but also to better understand how the car's set-up works.
Instead of scrubbing speed with traditional straight-line threshold braking, Millen approaches the corner using a method called straight-line drifting. This is initiated by a quick flick of the wheel to get the car pointed into the turn, then the clutch goes in, the handbrake locks the rear tires and the wheels are counter-steered into the skid. To keep the car from straightening out, light pressure is applied to the brake pedal. More pressure slows the front end and increases the car's slip angle, less pressure straightens it out.
Millen's corner entry is initiated by revving the engine with his right heel, then finally letting the clutch out while simultaneously letting go of the handbrake. This sets the car into the familiar powerslide drift cars are known for. It's not until the car goes well past a 45-degree slip angle that the wacky drift settings start to make sense.
With the rear tires roasting away and the front tires at opposite lock, terms like oversteer and understeer are no longer relevant. Pretty much all you can control is wheel speed, so the preset orientation of the tires is critical. What little weight transfer you have is all sitting on the outside rear wheel. At this point, that wheel needs to be toed in to keep the car from spinning. To turn a little harder, applying the brakes gently slows the front of the car, tucking the nose in. Easing off the gas to slow the rear tires straightens the car out.
Suddenly, it's all coming together. But from the passenger seat, it's impossible to tell how much all that front caster affects steering resistance and front-end grip. That is, until Millen shouts: "Look!" and lets go of the steering wheel while exiting the left turn. He eases off the gas, which kicks the back end to the left. Then the change in lateral load pulls the front tires over, causing them to turn into the skid.
Thinking of caster as a means of automatic counter-steering (or caster steer) still seems sort of backward to me. But it just goes to show the creative thinking that goes into building a machine like this. -Andy Hope
2007 Pontiac Solstice GXP drift car
ENGINE
*Engine code Ecotec-LNF
*Engine Displacement/Type/Valvetrain: 2364cc, in-line four, aluminum block and head, DOHC, four valves per cylinder, variable valve timing, turbocharged and intercooled
*Internal Modifications: Thick-wall iron sleeves bored to 89mm, billet steel crank stroked to 95mm, custom pistons, rods and cams, CNC head porting, hydraulic lash adjustment eliminated, compression ratio raised to 13.7:1
*Extrnal Modifications: Custom barrel valve intake manifold, HKS tubular exhaust manifold, GT2835 ball-bearing turbo, GT2 wastegate, blow-off valve and intercooler
DRIVETRAIN
*Layout: Longitudinal front engine, rear-wheel drive
*Drivetrain Modifications: Six-speed Tremec (Chevy SSR), Exedy twin-disc clutch and custom flywheel
SUSPENSION
*Double wishbone w/quadruple adjustable Penske shocks and coilovers (F & R)
BRAKES
*Rotora forged four-piston calipers, 330mm two-piece rotors, Rotora H8 ceramic/carbon pads (F), Rotora two-piston calipers, 298mm two-piece rotors, Rotora H6 high-ceramic pads (R)
EXTERNAL
*Wheels (Front/Rear): Racing Hart, 18x8.5 (F), 18x9.5 (R)
*Tires (Front/Rear): Bridgestone Potenza RE-01R, 235/40/18 (F), 265/35/18 (R)
*Body: Carbon-fiber hood, roof, trunk and RMR rear wing
Interior: Welded SCCA-approved rollcage, Sparco seats, steering wheel and harnesses, hydraulic handbrake