Many 4×4 trucks in the 1970s and 1980s came with full-time four-wheel drive. Rigs equipped with the NP203 transfer case are an example. There are some distinct advantages to full-time 4×4, so let’s look at a few.
No need to lock hubs.
On most full-sized four-wheel drive vehicles, the operator has to get out and turn the hub locks on the front axle in order to engage the four-wheel drive. But transfer cases like the NP203 keep the rig in four-wheel drive at all times, so there is no need to exit the vehicle. The four-wheel drive options are controlled completely from within the cab of the truck.
Although a full-time rig is always technically in four-wheel drive, the front and rear axles aren’t working together positively when in regular drive mode. There are spider gears within the transfer case that allow slippage between the axles for smooth street driving. So if the driver finds he or she needs more from the rig in adverse conditions, he or she can simply move the floor shifter into hi or lo-lock, and the vehicle will then be in true four-wheel drive.
Full-time 4×4 is better for ice and snow.
Because of the aforementioned slippage allowed between the axles, a full-time four-wheel drive rig tends to handle much better in icy and snowy conditions. That can mean big safety advantages over other four-wheel drive equipped rigs. If you have ever driven in deep snow or on large patches of ice with a truck that has manual hubs, you know what I mean.
For that reason, many people who live in mountain communities or areas where the winters get rough tend to prefer a full-time four-wheel drive rig. Another reason is that if the snow is deep enough, it can cover the front wheels, which means the driver has to dig down to the axle centerline in order to unlock the hubs–and sometimes, the locking mechanism is frozen into place. There are none of those hassles with a full-time truck.
Easier smog tests.
If you live in an area that requires smog testing, the acquisition of a full-time rig makes things easier. Because the truck is always in four-wheel drive, it cannot be put on the rollers used in regular smog testing. Instead, they do a tailpipe sniff and eyeball inspection and nothing more.
During regular smog tests, the rear wheels of an automobile are placed between two rollers built into the shop floor. It is then tested at various loads and RPM ranges. But if you were to place a full-time rig into the floor rollers, it would just walk right out because the front wheels are pulling. Therefore, it’s a sniff-and-go situation.
While there may be other benefits to full-time four-wheel drive, we’ve covered the basics. Hopefully, readers of this article will get a better understanding of what it means to be in four-wheel drive all the time.