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auto maintenance February 08, 2018

Four-wheel, all-wheel, any wheel?

By Douglas Flint

Four-wheel drive used to be the domain of the tough guys: hunters and outdoorsmen who were willing to put up with, and actually reveled in, vehicles that drove like tanks, sucked fuel like tanks, had a big extra shift lever to engage the four-wheel drive, and made you get out and manually lock the front wheel hubs to make the car run. (Lots of fun if you wake up and there is already 10 inches of snow on the ground.)

Generally, four-wheel drive was only available on pickups, jeeps, and a few specialty vehicles such as the Ford Bronco, the Chevy Blazer, and the Dodge Ram Charger. These were all worthy names in the annals of automotive history, but not exactly family-friendly vehicles.

But in the early eighties a sea change occurred. AMC Jeep led the way with its compact Cherokee model, a reasonably sized four-door wagon with a cargo area and four-wheel drive that could be engaged without getting out to lock the hubs.

On the upper end, the full-size Cherokee had morphed into the Grand Wagoneer, a luxury sport utility with a four-wheel drive system that could “shift on the fly” and be left on all the time. They became the darlings of the horse-owning crowd, sporting good looks, comfort, and enough power and gears to pull a barn.

It didn’t take long for the other manufacturers to see that Jeep was able to name its price on products, and the competitors responded in kind. The early attempts included the Ford Bronco 2, which sold well until people learned how easily it rolled. By the early nineties the market included the Ford Explorer, the Jeep Cherokee series, the Chevy S-10 Blazer, the Toyota 4Runner, and the Nissan Pathfinder.

Some were much better than others, but they all shared the common trait of being “trucks first.” A few had independent front suspension which smoothed out the ride somewhat, but a good bump was still likely to land your coffee in your lap. The soccer moms who had shucked their minivans for the sport utility didn’t appreciate this.

The solution was to build a new class of all-wheel drive vehicles from the ground up, instead of converting existing truck platforms. This meant accepting that these vehicles would not be bouncing down logging roads, fording streams in pursuit of the elusive 16-point elk, and that the most off-roading they would do was to cross the soccer field to pick up the net.

While the big boys were being scaled down and softened up, a completely new generation of urban four-wheel-drives was rising up. Subaru, who really didn’t even make trucks, was bringing its four-wheel-drive sedans and wagons into the U.S., and quickly gained a foothold in the snowy northeast and the Rocky Mountains, where people needed a vehicle that could venture out in heavy snow and still be a practical, economical car.

Suzuki brought in its now legendary Samurai mini-truck – and I do mean truck – for in spite of its tiny size and weight, it was a true truck, with a transfer case and separate front and rear differential. It was soon replaced by the Sidekick, a four-door, slightly larger and less likely to tip over in a crosswind, and still a true truck.

Other manufacturers responded in turn with small urban trucks. The breakthrough vehicles were the Toyota RAV4 and the Honda CRV. Both were built off front-wheel-drive non-truck platforms, and thus drove and handled much more like cars. The RAV4 uses a simple all-wheel-drive system with power going equally to all four wheels, with allowance in the system for different wheel speeds. The CRV drives on the front wheels during normal driving conditions but will apply power to the rear wheels through the “dual pump system” when front wheel slippage is detected. Both were instant hits, winning praise from consumers and industry.

The competitors followed, and now the world is full of four-wheel-drive and all-wheel-drive vehicles, including Subaru, which with engine and body upgrades moved beyond the Birkenstock crowd into the mainstream (with a little help from Paul Hogan, Crocodile Hunter).

But what does all that mean? More choices and nicer things. When choosing a four-wheel or all-wheel-drive vehicle, it is important to be honest about what you are going to use it for.

If it’s just a family vehicle but you want the added safety and security of all-wheel-drive to make it to the grocery store in a storm, stick with a non-truck platform all-wheel-drive model. It will be more manageable, probably get better mileage, and ride smoother.

If you are going to tow a boat or a camper and truly get into the back woods, you want a truck-based vehicle with four-wheel drive and a transfer case. You know it is a truck-based platform when there is either a shifter or a set of switches to select “four-wheel high,” “four-wheel low,” and even “four-wheel neutral.”

And beware. Just because a vehicle looks like a 4×4 doesn’t mean it is. Almost every popular vehicle in this class is sold in a two-wheel drive version as well, and there are plenty of them out there.

Remember that these vehicles require added care. We are asking vehicles to do things they never did before in much smaller spaces. The rear differential on a Honda Pilot is practically a living thing, with electronic solenoids, clutches, and pumps. (The differential on my old Jeep is just gears made of the same metal found in tanks.)

The fluids need to be changed. Almost all the new four-wheel/ all-wheel-drive vehicles have much more sophisticated differential and transfer case and are built much lighter. The transmission itself is doing more work. A lot of them develop a rumble or a shudder going around turns, which can be cured with simple fluid changes. The stuff costs too much money to neglect.

And don’t get to feeling invulnerable! Newton’s Laws are not suspended for anyone. Ice and slick conditions can put the best four-wheel drive on its roof quicker than my ‘73 Duster. Really deep snow is always problematic, and even my mighty Jeep Grand Wagoneer got stuck a couple of times in the Great Blizzards of 2010.

And if ever you do need a tow, it should be on a flatbed truck. Towing even a short distance with two wheels on the ground can severely damage an all-wheel drive system.

Got all that? If you don’t, feel free to contact your friends at Wiygul Automotive Clinic. We’re here for you.

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