SCORE Journal - The Official Publication of SCORE Off-Road Racing
Issue link: http://read.uberflip.com/i/875606
On A Wing And A Prayer Although It never saw a victory, Mickey Thompson’s Challenger IV was one of the most influential vehicles that changed off-road motorsports. By Dan Sanchez Photography By ICON Media People who knew Mickey Thompson described him as an innovator; a trait that ultimately led to the creation of SCORE International and off-road racing as we know it today. A racer at heart, Thompson participated in many of his own off-road racing events and in doing so, ultimately became frustrated at the lack of capabilities the current off-road vehicles had at the time. In the mid-1970’s Baja racers were using lightweight buggy chassis with VW engines, so Thompson decided to design his own vehicle that would truly change the way racers and vehicle designers build unlimited vehicles today. The vehicle began when Thompson purchased a couple of buggy chassis that were originally built by Smokey Allerman for Larry Minor. Thompson had his then crew chief John House, along with Bruce Paris and son Danny Thompson work on the car, and in 1977 the Challenger IV was born. The Challenger IV debuted at the 1978 Mexicali 250 and was noticeably very different from the rest of the competition. While every other Class 1 buggy was VW powered and had 10-inches of suspension travel, the Challenger IV had a 700 horsepower Chevrolet V8, 18-inches of rear travel and 15-inches of travel at the front. Essentially, it was a sprint car made to run in Baja. The vehicle was most recognized for its large wing that offered it stability at high speeds which, according to his son Danny Thompson, helped stabilize the car, as it could accelerate very quickly. To achieve the capabilities designed in the Challenger IV, new shocks had to be built for it. “I remember my dad building so many prototypes of shocks that they filled a whole back room at the shop,” said Danny Thompson. “My dad had the engineers working long hours trying to build something that would offer more wheel travel and not break.” The result of the effort was utilizing dual 41-inch long shocks with cooling fins that were used with dual coil overs on the vehicle. From 1978 to 1980, the Challenger IV lead many off-road races, including the SCORE Baja 500 and Baja 1000 but because of its speed, the vehicle often broke and posted DNFs. Thompson ultimately retired the Challenger IV and built the Challenger V utilizing more advanced technologies available at the time. The vehicle sat for several years until the death of Thompson and his wife Trudy in 1988. The Challenger IV was taken to their daughter Lyndy Thompson’s home in Eugene, Oregon where it sat for more than a decade until it was acquired by Rory Ward in 2011, and started on a restoration. “It took three long years for the restoration to be completed on this vehicle,” said Ward. “We finally got it race ready and competed with it at the 2014 NORRA Mexican 1000. In true Mickey Thompson fashion, the Challenger IV was fighting for the lead but had to retire with overheating issues after 600 miles into the race.” The Challenger IV looks much as it did in the 1970’s. The original engine, however, was long gone so Ward installed a 383 Chevy that utilizes a Holley four-barrel carburetor with a large K&N air filter on top. REF Unlimited headers feed out to side pipes that run along the length of the vehicle, while modern Kroyer CNC machined pulleys operate the alternator and Howe steering pump. Earl’s Performance hoses replaced much of the vehicle’s plumbing while an ACCEL ignition system fires up the vehicle when it roars to life. The transmission is a Gearworks two-speed Powerglide that uses a titanium safety scatter shield and is linked to the original shifter mounted to the right of the dash. The two-speed trans feeds the power to a magnesium Dana 60 that was built by Sandy Cone. To keep the engine cool, a C&R racing radiator sits at the nose of the vehicle, but electric fans are also mounted inside the cab to pull out the hot air from the engine and helps to keep the driver cooler. While the chassis is original, as well as the original wing made by Larry Stork and Scott Neth, the body needed to be restored. Nye Frank reproduced the aluminum body panels before they were powder coated yellow by Allcoat. Sitting for more than a decade turned the vehicle’s electrical system unusable, so Ward had TRH Wiring rewire the entire vehicle, which included the use of its four original Cibie Oscars lights mounted to the front nose. Aside from the most notable part of the vehicle, the two-stage wing, the Challenger IV’s suspension, and 41-inch rear shocks are what also gets noticed first. Because the originals were Thompson’s designs, Ward had to work with King Shocks to create pieces that would fit and operate on the car’s original torsion bar suspension. The company came up with a version of its 3.0 coilover for the rear, and 2.5 reservoir shocks for the front. The torsion bars were replaced by Sway-a-Way units and the suspension kept its original appearance utilizing modern components. Ward utilized a set of Centerline wheels, 15x7.5 front and 15x9 rear with Halibrand knock-off hubs. The wheels were mounted on a set of Mickey Thompson Baja Belted tires on the front (33x14.50x15), and Mickey Thompson Baja Kings rear tires (36x13.50x15). All four wheels utilize modern Wilwood caliper and brake rotors to help stop the vehicle. The single driver’s seat was reproduced to what the original looked like by Mastercraft who also added its safety harnesses. One look at the steel steering wheel and you’ll see that Mickey Thompson wanted to reduce weight anywhere he could find it. The dash is simple but has a variety of old-school toggle switches with an Auto Meter ProComp tachometer mounted to the center. “It’s one hell of a ride,” says Ward about driving the Challenger IV. “It wouldn’t have all come together, however, without the help of many people, including Curt Leduc, Collins Motorsports, Pete Corwin, Bear Race Cars, SBP Motorsports, Mickey Thompson Tires and Lyndy Thompson.” Although the Mickey Thompson Challenger IV is now retired from any type of racing, the vehicle is still mesmerizing to look at and admire. There aren’t too many drivers who would sit behind the wheel of a vehicle like this for 1000 miles and not come out with any bruises. Nonetheless, the Challenger IV provides a look inside the mind of one of the motorsport’s most influential minds and leaves you to reflect on what it took to get off-road motorsports to where it is today. Mickey Thompson Challenger IV Specs Owner: Rory Ward Chassis: Challenger IV Built by: Smokey Allerman, John House, Bruce Parrish and Danny Thompson. Engine: 383 Chevy, C&R radiator, REF Unlimited headers, Howe PS, Kroyer pulleys, Holley fuel system. Transmission: Gearworks 2 speed powerglide Shocks: Front- 2.5 King smooth body Rear - 3.0 King Coil Over Springs: King Seats & Safety: Custom Mastercraft “Suspended” suspension seat/belts, Titanium trans scatter shield. Rear Axle: Magnesium Dana 60 prepped by Sandy Cone, Halibrand knock-off hubs. Brakes: Wilwood calipers and rotors Steering: Saginaw prepped by Howe Performance Wheels: Front- Centerline 15×7.5 Rear - Centerline 15×9 Tires: Front - MT Baja Belted 33×14.50×15 Rear - MT Baja Kings 36×13.50×15 Lighting: Original - Cibie Oscars NORRA - Baja Designs XL Pro Squadron LED’s Body: Powdercoat - Allcoat, Aluminum Body - Nye Frank, Wing - Zoom Factor (Larry Stork & Scott Neth). Special Notes: Wiring: TRH Wiring Plumbing: Earl’s Performance Ignition: ACCEL Fuel cell: Pyrotect (44 gallons) Torsion bars: Sway-a-way Filters: K&N Filters Special thanks: Collins Motorsports, Pete Corwin, Bear race cars, Curt Leduc, SBP Motorsports, MT Tires and Lyndy Thompson.