How to Build a Single Seat, Off-Road Race Car

Written by william machin
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How to Build a Single Seat, Off-Road Race Car
Single-seat off-road race cars compete with motorcycles and race trucks. (extreme off-road image by krysek from

Class-1 single-seat is one of the original off-road racing classes, dating back to the first Baja races of the late 1960s. Designs have come a long way since those racers took to the courses with stock VW engines and double-shock suspension. Improvements such as hydraulic disc brakes, double A-arms, fuel bladders and transmission coolers are now standard in today's single-seat cars. Building a single-seat off-road race car requires mechanical and welding expertise, along with a shop full of tools and fabricating equipment. In addition, cars must be built to class specifications set forth by SCORE International.

Skill level:

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Things you need

  • Race car platform
  • Suspension and steering
  • Transmission and drive train
  • Air-cooled engine and accessories
  • Roll cage materials
  • Electronic components
  • Brakes, wheels and tires
  • Lights and accessories
  • Seat and racing harness

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  1. 1

    Elevate the race car platform frame on jack stands. Install the front and rear suspension arms. Install the steering arms, steering box and the front wheel and rear wheel hubs.

  2. 2

    Fabricate the front shock towers and rear shock mounts using aluminium or steel plate with welded seams. The number and style of shocks is optional.

  3. 3

    Roll the rear axle and differential in place at the rear of the platform using floor jacks. Mount the rear axle to the platform frame. Mount the transmission and complete the drive train installation.

  4. 4

    Fabricate engine mounts at the rear of the platform. Mount the four or six cylinder air-cooled engine on the platform. Fabricate mounts and install the oil cooler and transmission cooler. Plumb the lines to the oil filter console and the transmission.

  5. 5

    Plumb the hydraulic brake lines to all four wheels. Mount the master cylinder at midpoint of the frame. Install the clutch, brake and accelerator pedal assemblies and linkages.

  6. 6

    Install the fuel cell and fast-fill cap. Plumb the fuel lines to the electric fuel pump. Include one or more in-line fuel filters. Include an overflow line.

  7. 7

    Fabricate the roll cage using 2-inch or 3-inch tube steel. Fabricate the engine guard using the same material. Weld the roll cage to the frame. Weld the engine guard to the frame and the roll cage.

  8. 8

    Fabricate a battery box and cover using lightweight aluminium or plate steel. Install the wiring harness for the engine and fuel pump, brake lights and off-road lights. Install a buss bar. Include the necessary resistors and rectifiers for a computerised ignition system.

  9. 9

    Complete the installation of the steering components including the steering wheel. Install the brake, clutch and accelerator pedals and linkages for each. Mount the fuel, engine temperature and oil pressure gauges. Install the single seat and quick-release racing safety harness.

  10. 10

    Mount the disc brake rotors and calipers at the front and rear wheel hubs. Connect the hydraulic brake lines. Install the shocks and mount the wheels and tires on the race car. Install the lights and 12-volt battery. Complete all electrical connections, including fuses.

Tips and warnings

  • Materials and procedures vary from one racing shop to the next.
  • Retain the consulting services of a qualified off-road car builder.

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