Pickup Trucks 101: Driveline Systems


Almost every driveline type available is offered in a pickup truck. Most pickups come standard with rear-wheel drive and have optional all-wheel-drive and/or four-wheel-drive systems. Here's our guide to their differences, strengths and weaknesses.

Front-Wheel Drive

There are two types of two-wheel-drive drivelines: front-wheel drive and rear-wheel drive. FWD is not common in pickup trucks. The Honda Ridgeline is only FWD pickup currently being sold in the U.S. FWD provides packaging and fuel economy benefits. Without a transfer case, rear driveshaft and rear differential, a FWD pickup provides more space for designers to work with and less overall weight.

FWD has more grip than RWD in most low-traction situations. That's because there is more weight on the front axle than the rear, unless the vehicle is loaded. FWD typically costs less, weighs less and is more fuel efficient than 4WD and AWD. Another advantage to FWD is that it is hard to put the vehicle into an oversteer situation; for drivers, this means it is easier to control when slipping.

The most significant downside to FWD is that when the wheels do slip, the ability to steer is completely lost. Front-wheel drive also means there is less room for your hands when doing under-the-hood maintenance work.

Rear-Wheel Drive

Rear-wheel drive, the second type of 2WD, is standard on most pickups sold today. This is a great option for those who put a lot of miles on their trucks but don't need the extra traction offered by 4WD. Like FWD, RWD vehicles cost less and get better fuel economy than their AWD and 4WD counterparts. They also weigh less. These benefits make the RWD platform a good one for towing and hauling in areas with good traction. While not comparable to AWD or 4WD, many RWD pickups are offered with a limited-slip rear differential; this helps improve traction at a fraction of the cost of an AWD or 4WD truck.

All-Wheel Drive

AWD is offered in a variety of forms. It can be a part-time system that only engages when slip is detected or when the driver engages the system. A part-time system reduces fuel consumption; however, it may take a moment for the system to fully engage or the driver may forget to engage it. Full-time systems are engaged and ready for action all the time. These systems are easy to use and hard to damage. Full-time AWD means extra traction is always available, but it comes at the expense of fuel economy.

Four-Wheel Drive

Four-wheel drive differs from AWD in that the center differential, typically inside the transfer case, can be manually or automatically locked. Many 4WD vehicles also have a transfer case allowing the vehicle to be placed into Low Range. Low Range usually has at least a 2-1 gear-reduction ratio, making slow-speed maneuvers and/or pulling tree stumps out of the ground much easier. Some 4WD systems also have an AWD-type setting in which the center differential isn't locked, but traction can get to all four wheels if the surface allows. Conversely, many have a gear-driven or alternative-style limited-slip center differential that is engaged when the system is manually placed in 4WD. This is great for driving in the rain or on roads that are mostly clear with some slick spots. Four-High usually locks the center differential and can be engaged while the transmission is in gear and the vehicle is in motion.

Being able to engage 4-High while the vehicle is moving is great for rapidly changing road conditions where it isn't safe or practical for the driver to stop to engage 4WD. If not properly engaged, the transfer case and other driveline components may be damaged. To protect the system, 4-High should only be engaged when all four wheels are moving at the same speed. There are also limitations on how fast a vehicle can go when engaging or using some 4WD systems. Be sure to read the owner's manual for your vehicle.

The problem with having the center differential locked is that in high-traction situations (like on pavement), the drivelines can bind and cause the tires to "scrub" or "crow hop," damaging the drivetrain. To shift into 4-Low, the transmission must be placed in Neutral and the vehicle must be moving at a low speed or stopped — between 1 and 5 mph is often recommended. Low Range is great for slow-speed driving when off-road or towing on slick boat ramps. The lower gearing increases the engine braking performance for descending steep slopes, and increases the torque at the wheels for easier climbing. This also can be useful for towing a trailer, but it does take extra time to stop and shift into 4-Low. If the center differential is locked, 4-Low shouldn't be used on high-traction surfaces.

The most versatile 4WD systems provide the driver with the ability to choose when to lock the center differential. This means that the vehicle can be placed into Low Range for backing a trailer up a steep hill or for pulling a boat out of the lake without having the tires scrub and the drivelines bind from the center differential being locked. It also allows the pickup to act like an AWD vehicle when placed in 4-High with the center differential unlocked.

Making a Choice

Four-wheel-drive systems add cost, increase vehicle weight and lower the fuel efficiency of a pickup compared to 2WD systems. Although you must decide for yourself, the positives typically exceed the negatives when vehicle pickup is used in situations where the extra traction may be needed.

[Photo: 4WD and Center Diff Buttons image.]

When shopping for a new pickup truck, evaluate the situations in which your pickup will be used. With all other variables being equal, a 4WD or AWD vehicle will likely outperform a similarly equipped FWD or RWD in heavy rain, snow, ice or off-road. Unfortunately, 4WD and AWD vehicles cost more to purchase, to run and to maintain, but they also have a higher resale value in areas where they're popular. photos by Evan Sears, Angela Conners, Matthew Barnes




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