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Shifting Gears: The 4WD can out-climb and out-cool any 2WD v
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Posted by nwv_admin Thu Jun 2, 2005 13:22:00 PDT
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0 responses 0 comments In the auto world, a relative newcomer in interest is the four-wheel drive (4WD) vehicle. Four-wheel drives are most notably remembered as the Willy's Jeep (which originally meant general purpose, or GP, then eventually became known simply as "Jeep"). This was a one-quarter ton vehicle designed to ford streams, travel in harsh conditions and drive over obstacles in a wartime backdrop.

The public saw the value in the 4WD vehicle and the major automakers began offering the systems, mostly in trucks and pickups. By the early 1970s, raising the height for more clearance and putting huge tires and wheels on them for the perceived utility and overall "shock and awe" effect became very popular, as it still is today.

The military utility vehicle that replaced the Jeep, the Hummer, is now the undisputed king of the macho 4WD vehicles, as it is now offered for public use.

Four-wheel drive vehicles are entirely different beasts than their 2WD siblings. But at a glance, it appears simple to make a 4WD vehicle at an auto assembly plant that is producing the same 2WD vehicle -- throw a few extra parts on, a few extra knobs and levers in the cab and top it off with an addition of $2,500 to the price tag. In reality, it isn't that easy. While the bodies, interiors, engines and transmissions are similar, the entire underside of the vehicles is completely different -- from the brakes, axles and suspension to the frames. Four-wheel drive components are more heavy-duty and add up to much more vehicle weight.

One of the key differences between the 2WD and 4WD is that a 4WD has a transfer case located behind the transmission. This is the item that splits the engine power to both the front and rear axles and to which the extra levers in the cab are connected. A 2WD vehicle does not have this, as the power goes only to the rear axle out of the transmission. The steering and suspension of a 2WD is significantly more complex than a 4WD, making the ride much smoother. The 4WD front drive system uses a live front axle, much like the rear, sprung with stiff leaf springs rather than the smoother coils of the 2WD vehicle. Because of the weight of these drive components, a similarly equipped 4WD vehicle cannot pull nearly as much weight as its 2WD sibling, but the 4WD, with its high lift and big tires, looks really cool! It's a fact that a 4WD vehicle can out-climb, out-clearance and out-cool any 2WD vehicle.

What, if anything, will these modifications do to that 4WD with those nice new wheels, tires and 6-inch lift? When larger tires are installed on a vehicle not factory engineered for this equipment, greater stress is placed on the transmission, wheel bearings, tie rods, the pitman arm and the power steering system. Raising the vehicle also changes the geometry of the suspension components, and altered tire sizes can make the speedometer incorrect and raise the gear ratio. The best thing to do, should you decide to put these big wheels and tires on, is to visit a 4WD specialty shop for specific recommendations.

These 4WD vehicles are fun and look really off the hook, so don't just ante-up for the rims and tires, do it right! Change the gears and speedometer. In the end, you'll be glad you did.

Until next time, be safe, have fun and happy motoring!

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