A monster truck is a vehicle that is typically styled after pickup truck bodies, modified or purposely built with extremely large wheels and suspension. They are used for competition and popular sports entertainment and in some cases they are featured alongside motocross races, mud bogging, tractor pulls and car-eating robots. A monster truck show sometimes involves the truck crushing smaller vehicles beneath its huge tires. These trucks can run up and over most man-made barriers, so they are equipped with remote shut-off switches, called the Remote Ignition Interruptor (RII), to help prevent an accident if the driver loses control at any time. At some events, only one truck is on the course at a time, while most feature two drivers racing each other on symmetrical tracks, with the losing driver eliminated in single-elimination tournament fashion. In recent years, many monster truck competitions have ended with a "freestyle" event. Somewhat akin to dressage with giant trucks, drivers are free to select their own course around the track and its obstacles. Drivers will often try "donuts", wheelstands and jumps during this segment. Additional items for the drivers to crush, usually including a motor home, are frequently placed on the track specifically for the freestyle event. Other obstacles sometimes placed on the track include school buses and small airplanes. Several serious accidents have been reported, with resultant deaths and injuries.
In the 1970s, heavily modified pickup trucks were becoming popular and the sports of mud bogging and truck pulling were gaining in popularity. Several truck owners had created lifted trucks to compete in such events, and soon competition to hold the title of "biggest truck" developed. The trucks which garnered the most national attention were Bob Chandler's Bigfoot, Everett Jasmer's USA-1, Fred Shafer and Jack Willman Sr.'s Bear Foot, and Jeff Dane's King Kong. At the time, the largest tires the trucks were running were 48 inches (1.2 m) in diameter.
In April 1981, Bob Chandler drove over cars in Bigfoot in what is often believed to be the first monster truck to crush cars. Chandler drove Bigfoot over a pair of cars in a field as a test of the truck's ability, and filmed it to use as a promotional tool in his four-wheel drive performance shop. An event promoter saw the video of the car crush and asked Chandler to do it in front of a crowd. Initially hesitant because of the "destructive" image that could be associated with Bigfoot, Chandler eventually caved in. After some smaller shows, Chandler performed the feat in the Pontiac Silverdome in 1982. At this show, Chandler also debuted a new version of Bigfoot with 66in. tires. At a prior event in the early 1980s when Bigfoot was still running 48 in.terra tires, Bob George, one of the owners of a motorsport promotion company named Truck-a-rama (now the USHRA), is said to have coined the phrase "monster truck" when referring to Bigfoot. The term "monster truck" became the generic name for all trucks with oversized terra tires.
Debate over who did the first car crush is often discussed. There are claims that in the late 1970s, Jeff Dane's King Kong (who referred to his truck as the "Bigger Foot") had crushed cars at Great Lakes Dragway in Union Grove, Wisconsin. Another truck, known as High Roller (currently known as "Thunder Beast"), also claimed to have documented car crushes in Washington State before Bigfoot, though said documentation has never surfaced. Cyclops, then owned by the Dykman Brothers, also claims to have crushed burning cars before Bigfoot. However, the earliest, widely-available and verified video footage showing a monster truck crushing cars that exists shows Bob Chandler driving Bigfoot while crushing two mid-seventies automobiles in April 1981. This video was what the promoter viewed that motivated him to ask Chandler to perform the car crush in front of a crowd.
King Kong and Bear Foot each followed Bigfoot to 66-inch-diameter (1.7 m) tires, and soon other monster trucks, such asKing Krunch, Maddog, and Virginia Giant were being constructed. These early trucks were built off of stock chassis which were heavily reinforced, used leaf spring suspension, a stock body, and heavy military axles to support the tires.
For most of the early 1980s, monster trucks performed primarily exhibitions as a side show to truck pulling or mud bogging events. In 1985, major promoters, such as the USHRA and TNT Motorsports, began racing monster trucks on a regular basis. The races, as they are today, were in the form of single elimination drag races, held over a course littered with obstacles. The change to racing eventually led truck owners to begin building lighter trucks, with more power. The establishment of TNT's first-ever monster truck points championship in 1988 expedited the process and found teams beginning to use straight-rail frames, fiberglass bodies, and lighter axle components to shave weight and gain speed.
In 1988, to standardize rules for truck construction and safety, Bob Chandler, Braden, and George Carpenter formed theMonster Truck Racing Association (MTRA). The MTRA created standard safety rules to govern monster trucks. The organization still plays a major role in the sport's development in the USA and EU.
With racing taking precedence, several teams began to think in new ways as to how the trucks could be built. Towards the end of 1988, Gary Cook and David Morris debuted Equalizer, a truck with a combination of coil springs and shock absorbers as the main source of suspension rather than the standard of leaf springs and shock absorbers. In 1989, Jack Willman Sr., now with his own truck, Taurus, debuted a new truck which used a four-link suspension system and large coilover shock absorbers, and that weighed in at close to 9,000 pounds (4,100 kg). However, the ultimate coup de grâce came from Chandler, also in 1989, whose Bigfoot VIII featured a full tubular chassis and a long-travel suspension using cantilevers andnitrogen shock absorbers to control the suspension. The truck revolutionized how monster trucks were built, and within a few years most top level teams built similar vehicles.
In 1991, TNT was purchased by USHRA and their points series were merged. The Special Events championship began to grow in popularity with teams as it had open qualifying spots which the invite-only USHRA championship did not have. The Special Events series lost its Pendaliner sponsorship in 1997. The short-lived ProMT series started in 2000.
Even though racing was dominant as a competition, USHRA events began having freestyle exhibitions as early as 1993. These exhibitions were developed as drivers, notably Dennis Anderson of the extremely popular Grave Digger, began asking for time to come out and perform if they lost in early rounds of racing. Promoters began to notice the popularity of freestyle among fans, and in 2000 USHRA began holding freestyle as a judged competition at events, and now even awards a freestyle championship.
A modern monster truck is more of a scaled-up dune buggy. As such, they generally aren't actual trucks as they are commonly referred to as, and only maintain their name due to the common style of fiberglass truck bodies used on the vehicles. Trucks now have custom built tubular chassis, with four-link suspension to provide up to 4-feet of clearance. Mounted just behind the driver on most trucks are the engines, which are typically supercharged and run on methanol an alcohol and corn-based oil, and have displacement up to 575 cubic inches (9.42 L). Axles are mostly taken from either heavy-duty military trucks or road vehicles like school buses, and are modified to have a planetary gear reduction at the hub to help turn the tires. All trucks have hydraulic steering in both the front and the rear (four wheel steering), with the front wheels controlled by the steering wheel and the rear wheels by a toggle switch. The tires are typically "Terra" tires used on fertilizer spreaders, and have measurements of 66″×43″×25″ (1.7×1.1×0.6 m). Most trucks utilize a modified and/or custom designed automatic transmission, such as a Turbo 400, Powerglide, Ford C6 transmission, or a Torque-flite 727. A limited number of trucks utilize a Lenco transmission, which traces its roots to drag racing. Most of the automatic transmissions are heavily modified with transbrakes, manual valve bodies, and heavy duty gear sets. Trucks running a Lenco use a centrifugal clutch as opposed to a torque converter, which are used in automatic transmissions. Lenco transmissions are usually found in two-speed or three speed configurations, and are commonly shifted using compressed CO2.
