THERE is something about monster trucks that captivates young kids, especially boys.
Just ask parents who have shelled out for tickets to the Monster Jam shows in Brisbane, Melbourne Sydney and Perth this October.
Some kids are simply obsessed with something that has such big wheels, while many others have an appetite for the destruction these machines wreak.
Many parents, including this writer, have been drawn into the world of monster trucks through their kids (OK, I confess, I was fascinated as a child too).
The wanton destruction and the lack of mechanical sympathy on display during the freestyle sessions, which few trucks survive intact, can grate with adult automotive enthusiasts.
However, the engineering involved in building trucks that can perform stunts such as a complete backflip and keep driving can’t be anything but impressive.
The Monster Jam trucks are built on behalf of the series promoter and share the same basic construction of a superthick tube frame that is built to cope with massive stresses.
They all run 1.7m tall tyres that were originally designed to traverse farmland. Each team cuts the tyre tread down to make the trucks handle better.
There are occasional punctures but the tyres are durable given the forces involved and some of the metal they hit, such as wrecked cars.
Monster trucks run massive oil and nitrogen filled shock absorbers (two per wheel) plus springs, that work hard to absorb the forces generated by jumping a five-tonne truck. The huge tyres also compress on impact and rebound, causing the trucks to bounce up in the air (often with spectacular results). To jump so far into the air and do wheelies on demand, the trucks need a lot of power.
This is taken care of by an all- aluminium 9.4-litre Merlin motorsport supercharged V8.
Running on potent methanol fuel, also used by top speedway and drag racers, the engines pump out an incredible 1120kW and turn old-school two-speed Powerglide automatic transmissions.
The main appeal of monster trucks is on show in the freestyle competition, in which drivers win points for the most spectacular jumps, rolls, donuts and crashes, but there is also a racing component.
Monster Jam trucks are not agile when it comes to the tight turns of the race circuits, which are confined to sports grounds, but they are surprisingly fast.
In fact, the team that runs the iconic Grave Digger truck insists it is a smidgeon faster from 0 to 48km/h on dirt than a Nissan GT-R on dry bitumen, completing that dash in just 1.52 seconds.
Hustling a monster truck around in an enclosed space like an arena is not easy. They have rear-wheel steering to reduce the otherwise vast turning circle.
The locked rear differential keeps both rear wheels turning at exactly the same rate — this would make turning on tarmac extremely difficult but actually allows for better cornering on dirt because the rear wheels start sliding straight away.
One of the key elements that helps create spectacular monster truck action is track design. The type of jump, including the angle and the shape, enable particular tricks. One style of ramp enables drivers to attempt backflips, which are now fairly common in Monster Jam shows.