(This article first appeared in the August 2007 issue of SportsCar magazine)

By Philip Royle

Good old-fashioned seat time – there’s no substitute. In any form of motorsport, the number one way to go fast is usually logging time behind the wheel. You need to be comfortable with the car and the stresses of competition, not to mention familiarizing yourself with the details that make up that specific kind of competition. If you’re not up to speed with the ins and outs of that form of motorsport, you can easily find yourself nervous and a little on edge. Shot nerves don’t make for smooth hands.

Beyond familiarizing ourselves with RallyCross (and consequently entering a number of events), we needed to get to know our project 2004 Nissan Sentra SE-R Spec V a little better. We originally chose the car for the purposes of RallyCross based on the car’s light weight (2710 pounds), helical limited slip differential and excellent 175hp 2.5L I-4 motor – all of which should make the car a solid front-drive RallyCross competitor. Had we researched deeper, we would have also discovered a couple of the Sentra’s quirks – quirks we would have to eliminate if we had any hopes of competing.

First, the car utilizes a drive-by-wire throttle assembly rather than a traditional throttle cable. This isn’t really a surprise considering the vast majority of new cars use a drive-by-wire setup. The downside to this system is that manufacturers often set the car’s computer to cut the throttle should the brake and gas pedals be pressed at the same time for more than a couple seconds. Nissan is one such manufacturer.

Workarounds for these systems are usually fairly simple – it’s just a matter of finding the solution. With the Sentra, the workaround involves pulling the brake light fuse. In the Sentra, that fuse is located in the driver’s compartment, on the left side of the steering wheel. The brake fuse is a 10-amp fuse positioned second from the left on the top row of the fuse box (a special thanks goes to SPDiv’s Mark Anton, who also RallyCrosses a Sentra and aided in our fuse removal when we discovered our Sentra’s shop manual had abandoned this project without us knowing). With the fuse removed, the car can be driven with one foot on the gas and the other on the brake without the car thinking it knows better.

Because removing this fuse does stop the brake lights from illuminating, if you drive your RallyCross car on public roads to competitions, we highly recommend pulling the fuse once you get to the course and reinstalling it before the drive home.

The second “quirk” is ABS. The consensus from everyone we spoke to was that ABS is bad, and thinking through how to RallyCross a front-wheel-drive car, it’s obvious why. A common technique for competing in a front-drive car is to floor the gas pedal and press the brake to slow the car, never letting off the gas (this is why we pulled the brake light fuse). Using this method of driving makes it very difficult to lock the car’s front tires, thus allowing the driver to maintain steering control – equally important is the fact that the brake pedal is pressed so hard the rear tires lock. With the front tires pulling the car and the rears tires locked, the car rotates nicely through the turns. This isn’t exactly easy on the brakes, but it is effective and far more consistent then pulling the handbrake.

Disabling ABS is usually a simple process in any car – pull the ABS fuse. In our Sentra, the ABS fuse is located under the hood next to the battery. It’s a 40-amp fuse marked “ABS SOL.”

With the two fuses sitting in our pocket and our left foot ready to practics a completely different style of driving, we took to the RallyCross course. No ABS and a throttle that doesn’t cut while left foot braking made our Sentra feel downright sprightly when compared to driving with all the fuses in place. Also, keeping the throttle planted resulted in smooth weight transfers, allowing us to drive the line we were aiming for.

Running on dirt without ABS is tricky, however, as it makes locking all four tires easy. Should you lock the front tires on a front-drive car, you stand the chance of stalling the motor. In the case of our Sentra, the motor would re-fire immediately upon releasing the brake pedal – left foot braking, however, completely eliminated this problem as it made it all but impossible to lock the front tires. It’s tempting to slightly release the gas pedal upon corner entry to allow the car to decelerate faster, but doing so while not locking the front tires proved incredibly difficult and all but impossible to repeat with any level of consistency – and with RallyCross, consistency trumps one fast run.

Our final prep for the Sentra involved setting the alignment – this is the Sentra’s final quirk. The only alignment settings that can be adjusted on the Sentra without replacing bolts, drilling out holes, or adding camber plates is the front toe. Since several RallyCross competitors told us an accurate alignment isn’t completely necessary, we chose to adjust the car’s toe while the car was on the trailer. We measured 1/8-inch of toe in, so we dialed in 1/4-inch of toe out. The difference was unnoticeable on the dirt, but since in theory toe out is better than toe in, we figured it couldn’t hurt.

With the basics out of the way, the next step is to move the car from RallyCross’s Stock to Prepared class by installing a set of rally tires and good 15-inch wheels. We’re also going to strip the car of as much weight as possible as allowed in the Prepared rules. And who knows, we may even get good at this left foot braking thing, too.

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