« Fire in the Sky | Main
Thursday
Aug252011

Subies in the Dirt - A Day at Dirtfish Rally School

Dirtfish Rally School – a literal kick in the ass. Through the seat of your pants (aka ass), you can feel the four wheels of the 300hp Subaru STI, turbo wound up, clawing sideways through the loose gravel of the Dirtfish teaching track.

For my birthday, the lovely Amigoette gave me a driving class at Dirtfish.  I haven't been so squirrelly about something in a long time, having no idea whether I could do it or not. By the end of the class I was feeling very comfortable hurtling into a corner on a surface with barely any traction, the car sideways to the curve of the corner and with gravel flying, punching it at the exit sending the car skating towards the next corner.

The Class:

I signed up for the Dirtfish Rally School half day class made up of eight students and five instructors. The class begins with thirty minutes of classroom instruction on the basics of turning a rally car: backing off the throttle quickly to transfer weight to the front wheels, left foot braking to get the car to rotate, and looking ahead towards the exit of the corner – not at the track in front of the car.  Three simple (sounding) things that took me two hours to learn the correct timing so I could link them together in a smooth transition. Two people share a car and instructor. You spend half the time watching with the fifth instructor and half the time driving with your instructor.  For each new section of track, you first ride as your instructor drives, showing you the line and explaining the cornering technique required.  Then you drive 3-4 laps, trade off the car, watch the others drive, then get back in the car.  The time spent watching is good to let the adrenaline calm down and observe the corner entry and exit points the other drivers take – and how well they work.  

The Cars:

Bright orange 300 horsepower Subaru STIs are your ride for the day. Left basically stock, the interior gutted of everything but the dash board (minus all the vents, knobs, and anything loose) and the stock seats.  A complete roll cage encases the cockpit; it's a very cool, secure feeling to climb through a bunch of bars into the car, .  Once seated, a 4 point seatbelt wraps over both shoulders to a single point release.  You wear helmets with an intercom between you and the instructor who rides as navigator. 

The brakes have been changed to smaller calipers to accomodate 15" wheels with very sturdy 15x205 rally tires. A taller profile keeps the diameter similar.  The vacuum boost/assist for the brakes is removed so that pedal pressure remains constant when the engine is throttled and backed off under left foot braking.  Therefore, VERY high brake pedal pressure is required.  It was hard to get used to it. Consistency of pressure over ease of use means a lot of quadricep is required. At ten mph lining up in the queue, you had to really be careful not to hit the car in front of you.   The ABS is removed so that you can lock up the brakes. The calipers have rock scrapers that clean the inside of the wheel so rocks don't jam between the calipers and the wheel.  A hydraulic handbrake is added that works the rear calipers (not the parking brake), but they don't teach that till the more advanced classes. 

The STI electronic adjustment system for the differential split is removed.  The A/C is gone. There is LOTS of heat coming off the engine both inside and in front of the car.  The cars are left running between hot laps to keep the water and oil circulating. All the dash warning lights are on constantly because the engine management, ABS,  and suspension management are disconnected.

The shocks have been replace with Tein coilers.  The suspension takes an amazing amount of abuse  My stiff street suspension would last fifty feet and be broken. Other than the coilovers, the suspension looks stock.

The transmission is stock and the courses we used are set up for second gear.  Once going, you don't shift. Speeds ranged from 20 to pushing 50-60, the engine coming on good turbo boost just above the bottom speeds.

With no interior, the pounding of rocks spraying the underside of the car sounds like it will tear the car apart – takes some getting used to. Underneath the car are two large plates that go from the front axles past the rear axles.  Hinged at the front and hanging about three inches off the ground on links at the rear, they take most of the abuse.  After every class, the cars are cleaned and sprayed to get all the rocks out.  Every night the rock panels are swung away with the car on a lift, all the wheels are removed, and the under carriage, wheel wells, brakes, and suspension cleaned of rocks.  Every three days, the oil and fluids are changed.

The track:

Most of the track is 1" crushed rock over sandy dirt.  The track is graded everyday and sometimes in between hard runs.  Water is added to keep the dust down. One fast corner had hard washboards (4-5" high; spaced a foot or two apart), and some of the corners were 6-8" deep in gravel if you went offline after the groove was cut.  Slippery as shit.  NO turning traction at speed. 

Driving:

The cars barely turn by just steering, it's way too slick.  Turning the wheels did nothing and without "rally technique" the fastest you could drive a corner without pushing/understeering towards the outside was about 15mph.  This spooked me for the first laps on the slalom course.  All turning is done with the brakes. Very, very little with power on oversteer.  Not what I expected and my pavement skills were useless. The technique is to keep the throttle on in a straight line, lift off the throttle quickly to transfer weight to the front wheels, turn the wheel, and let the car rotate. To rotate quicker, you mash and hold the brake with your left foot. The car doesn't really carve through the turn like on pavement, but rotates on its axis as the direction of travel remains a fairly straight line. When the car is pointed at the exit of one corner and the entrance of the next, you quickly straighten the steering wheel to stop rotation, roll on the throttle to transfer weight back to the rear wheels, and head in a straight line for the next corner, gravel flying.  It's all about weight transfer from the rear to the front tires to begin rotation, and then back to the rear to accelerate.  If you let up on the brake in the middle of the corner, the car stops rotating and quickly heads for the outside of the corner.  Adding power without braking just increased understeer.  Left foot braking with the throttle on, wheels spinning, and a cacophony of rocks pounding the bottom of the car – very disturbing at first.  A critical component to keep it all working is to be looking at the end of the corner when you start sliding in, and then way ahead to the next corner once rotation starts.  Look at anything else such as the track in front of the car and you go there, stop rotating, or understeer off the corner. I only went off course once, pushed wide and killed a cone.

As I got the feel of using my left foot to brake and how hard the brakes were to push, I could start going deeper into the corner before braking.  If you lift off the throttle before you go in, you lose the ability to transfer weight forward with a quick lift, and the car goes to the outside.  Like skiing moguls, looking towards the next turn while jamming into the one underneath.  The most fun corners were two on either end of a big sweeper.  Through the sweeper, there is lots of turbo boost and the car, four wheels spinning, was controlled with very subtle steering and left foot braking while the throttle was on hard.  The corners at the end were sharper than 90 degrees.  Look way ahead, lift quickly, rotation starts, hard brake, rotation quickens, throttle on hard, straighten the wheel, off the brakes. All as a thousand rocks clatter against the bottom of the car. Then with engine growling, head straight for the next turn. Heart pounding fun. At the end of the class, the instructor takes a hot lap while you rideas the passenger. Way fast and amazing.  Shows how much you can learn in car handling.

I now look at gravel roads envisioning sliding turns and flying rocks.  I want more.

Kkz

Dirtfish from Ken Zeman on Vimeo.

 

 

Reader Comments

There are no comments for this journal entry. To create a new comment, use the form below.

PostPost a New Comment

Enter your information below to add a new comment.

My response is on my own website »
Author Email (optional):
Author URL (optional):
Post:
 
All HTML will be escaped. Hyperlinks will be created for URLs automatically.