How to Build a Monster Truckby Peggy Deland
A monster truck is a normal-sized truck body with abnormally large tires and oversized suspension to accommodate them. Most monster trucks are used as show cars or conversation pieces, although some are used for demonstrations and "monster truck shows" in which they navigate obstacle courses and even drive over and crush normal-sized cars. Creating a monster truck of any size involves a lot of work and a substantial financial investment. Most monster trucks are 4-wheel-drive units.
Select a donor body (preferably 4-wheel-drive) for the monster truck. The best choices are full-sized trucks for which a supply of aftermarket parts is readily available. Mini trucks and imports like Toyotas and Nissans can be used, but remember that fitting a large GM, Ford or Dodge engine in the diminutive engine compartment in a small import truck will be a challenge--if not impossible. It is preferable that the donor truck body has an engine and transmission, even if they are non-functional, since some of the parts and mounting brackets will need to be reused.
Begin selecting upgrade parts to convert the truck into a monster truck. Many sources of such parts can be found both on the Internet and in off-road and 4-wheel-drive periodicals. (See Resources.) Get parts that will work together. Some fabrication will be necessary, but try to keep it to a minimum.
Start with the front and rear suspension. The steering axles and rear differential will have to be ruggedized, and a far lower gear ratio will be needed. Remember that monster trucks are almost exclusively 4-wheel-drive, and that both front and rear differentials will have to be geared the same to avoid damage to costly components. The suspension will be raised to 3 to 8 feet--or more--from the factory height. This will require longer driveshafts, as the distance from the transfer case to the differentials will have increased greatly.
Once the suspension, steering and related components have been upgraded, select tires to match them. It is easier to find tires and wheels to fit a particular application than it is to create an application to fit available tires and wheels. Building a monster truck on a low budget is not recommended, but if you choose to do so, it is very possible you will run into this problem. If the truck must be built around the tires and wheels that are at hand, the builder must start at the wheels and build toward the truck, instead of the reverse. This can be very difficult and limits your options.
Upgrade the engine, transmission and transfer-case components for heavy-duty use. Again, the Internet and truck periodicals will be invaluable resources. When building the engine, you will almost certainly need a supercharger. Components for a supercharged engine are different from those of a normal engine, and include lower-compression pistons, special camshafts and increased-capacity oil pans. The engine may cost several thousand dollars. This upgraded engine is necessary to supply the horsepower that is required to move the monster truck, which is far harder to push around than a standard truck and is driving four oversized, overweight tires.
Consider safety. Roll bars or an equivalent safety cage should be installed in the driver's compartment. An emergency fuel-cutoff switch is a must; many trucks have an automatic one that kills the fuel supply in the event of rollover, as well. Install superior seat belts, such as a five-point racing harness, and don't forget helmets for the driver and any passengers.
- Consider having the engine built by a custom race shop. These shops have experience with high-horsepower modified engines, which can be difficult to tune properly. An improperly tuned supercharged engine can explode, sometimes causing fatalities. Test the newly built monster truck in a large, flat, open field or another safe area. Parking lots should be avoided; if you lose control of the truck, it may cause property damage, injury or death.
- Monster trucks operate far outside the drive-train geometry for which the original truck was designed. Exercise care when cornering or starting and stopping hard, as rollovers frequently occur in monster trucks.