How do I Build an S10 Drag Racing Truck?by Richard Rowe
In this day and age of front-wheel-drive compacts and million dollar muscle cars, many have turned to once-alternative rear-drive chassis like the compact S-10 pickup for dragstrip performance. The S-10 has a lot of things going for it. Light weight, plenty of room under the hood and almost unlimited parts availability make the S-10 a real contender on the quarter-mile. The only real problem with the S-10 is its truck-inherent weight distribution. The back of the truck is extremely light, which makes for poor traction and requires some special consideration in engineering.
Building the Truck
Move the front axle forward as far as possible on the chassis. Lengthening the wheelbase in this way will effectively move the engine and transmission closer to the rear axle, helping to achieve that ideal 50-50 front-rear weight distribution.
Install the engine as far back in the engine bay as possible. You might even want to consider cutting the firewall to move the engine back far enough that the front of the block is behind the front-axle centerline -- making the S-10 a true front-mid-engine configuration.
Remove the stock fuel tank and install a racing-spec 10- to 15-gallon fuel cell between the rear axle and rear bumper (so that it hangs down between the frame rails). You do this for two reasons. First, moving the fuel cell behind the rear axle will give you a ballast tank behind the rear axle, allowing you to make minute adjustments to the truck weight distribution just by adding or removing gas. Second, the stock tank will get in the way of your new four-link rear suspension.
Install a four-link rear suspension, and set it up so that its effective roll center lands just below the centerline of the front axle. To find the suspension's roll center, draw an imaginary line forward following the angle of the lower rear control arm and the upper rear control arm. The suspension roll center is where those lines intersect.
Cut out the stock rear wheel-wells and install the widest possible tires. Don't bother reinstalling new wheel tubs; just cut as much of the bed floor away as possible and cover the bed itself with a fiberglass tonneau cover. Doing so will give you instant and easy access to the rear suspension for minor adjustments at the track.
Install a sheet-metal belly-pan to cover the underside of your truck chassis for better aerodynamics and stability at high speed. You might want to take advantage of that giant hole you opened in the bottom of the truck's bed by blending the back of your belly pan up over the rear axle. This will create an area for high speed air to expand under your truck at high speed (diffusion chamber), creating a vacuum (downforce) and increasing high-speed stability with little penalty in aerodynamic drag. Turning your belly pan into a "diffuser" in this way will reduce the ease of suspension adjustability, but it will pay dividends in safety and speed.