4×4 Basics

Source: http://www.jeep.com

With a few guidelines and some good old-fashioned common sense, almost anyone can drive off-road in a Jeep vehicle.

Be Prepared

Always check your vehicle before going off-road. Make sure your battery is fastened, all hoses are in good condition and oil and fluids are topped off, including fuel. Also be sure that all four tires are in good condition and have the proper tire pressure. Avoid travelling alone, especially into unfamiliar territory. Even with a caravan of two, there’s always a tow vehicle.

Be on the Lookout

Once off-road, put your vehicle in 4WD whenever you anticipate a situation that will demand the additional traction. It’s difficult to engage 4WD after you get stuck. You’ll also want to get into the habit of looking over your hood, scanning left to right so you can clearly see what you’re approaching on the trail. If you’re just watching the left tire, there’s a good chance you’ll get the right tire in trouble. Avoid putting your head outside the vehicle to see what’s coming (that’s what Wrangler’s folding windshield is for!). Also, many trail masters recommend keeping your thumbs up and out of the way of the steering wheel spokes in rough terrain. For example, if your tire suddenly falls off a rock, your steering wheel could quickly rotate and catch your thumb with a spoke – ouch! Generally, vehicles with power steering, like all Jeep® vehicles, lessen the chance of sudden steering wheel rotation.

Take It Easy

Speed and power are not required in rough off-road driving. In low-range 4WD, the low gearing and low speed of Jeep® vehicles at idle will generally pull you over obstacles. In many cases, with manual transmissions, letting the clutch out slowly and allowing the vehicle to crawl over obstacles in the lowest-gear is the best scenario. As a matter of fact, on the Rubicon Trail, the average speed is a mere 3-5 miles per hour.

Snow and Mud

Generally, when snow or mud is present on the driving surface, it is the right time to engage your on-demand or part-time 4WD system. If you have an all-time system like Quadra-Trac I®, there is no input required from you. In heavy snow, when pulling a load, or for additional control at slower speeds, shift the transmission to a low gear and shift the transfer case to 4-LO if necessary (Quadra-Trac I does not offer a low range). Don’t shift to a lower gear than necessary to maintain momentum. Over-revving the engine can spin the wheels and traction will be lost. If you begin to lose traction in snow or mud, turn your steering wheel back and forth rapidly. This will generally help the wheels bite into fresh terrain and pull you through. If traction is lost, STOP. Wheel spinning will just dig you in deeper. The key is to maintain forward momentum.

Sand

For better traction in sand, drop air pressure 10-12 pounds below normal pressure on conventional tires. (Return to normal pressure after use in these conditions). Try high-range 4WD to maintain forward momentum. Depending on the condition of the sand, low-range 4WD and alternative gear selections may be necessary. Also try to make wider turns if at all possible. Tight turning slows the vehicle abruptly and can get you stuck. Again, maintaining forward momentum is key.

Dune Bashing (Source: dubaitouristvisaonline.com)

Hill

When climbing hills ALWAYS go straight up or down. It’s also smart to know what’s on the other side before going up. At the base of the hill you should apply more power. Ease up on the power as you approach the top and before going over the crest. If you stall on the ascent, back straight down the hill in reverse. For downhill travel, always use the lowest gear with a manual transmission. When descending a hill in low-range, do not disengage the clutch and allow the vehicle to coast. Severe damage to your clutch disc may result. Allow the gears and engine compression to slow you down, using the brakes only to fine-tune your speed. If equipped with an automatic transmission, use low-range and the lowest drive setting. NOTE: NEVER drive a hill at an angle. If the hill is very steep and you don’t feel confident that you or your vehicle can make it up, then don’t attempt it.

Crawling

We call it “crawling” for a reason. Use a low gear and low-range 4WD and just let the vehicle crawl and idle (with as little throttle as needed) when going over obstacles like rocks or logs. Never straddle rocks. A vehicle with 10 inches of ground clearance will not go over a 12-inch rock! Maneuver the tire on top of the rocks and crawl over them slowly. If you hear scraping, don’t panic. Your Jeep® vehicle’s skid plates and rock rails (this equipment varies depending on what Jeep® vehicle and packages have been purchased or leased) will take the brunt of the beating. Dropping tire pressure 3-5 pounds improves traction and helps avoid tire punctures. (Return to normal pressure after use in these conditions). Remember, the ideal speed for rock crawling is 1-3 miles per hour.

Tread Lightly

Leave it better than you found it. Observe posted signs and stay on trails and recreation areas approved for off-roading. Use your good judgment in protecting the beauty and solitude of the area. Don’t leave anything behind and, better yet, pick up and remove any trash that others have discarded. And if the terrain looks especially fragile, take an alternate route. For more information on how to Tread Lightly click here http://www.treadlightly.org

ENGINEERING FAQs

What is the difference between Full-Time 4WD and Part-Time 4WD systems?

Full-Time 4WD systems utilize a center differential, which enables the front and rear driveshafts to turn at different speeds, thereby allowing engagement on dry surfaces for normal driving conditions. A Part-Time system does not employ a center differential and locks the front and rear driveshafts together. With a Part-Time system, 2WD mode should be used during normal driving conditions and 4WD mode is to be used only when off-road or on wet or slippery surfaces

Why can’t you use Part-Time 4WD on dry surfaces?

Part-Time 4WD systems effectively lock the front and rear driveshafts together, forming a single driving unit that does not allow for differential action between the front and rear driveshafts. Driveline noise and binding (Crow Hop) may occur when operated excessively on dry surfaces or in turns. This binding can lead to heat buildup and early part failure

Why does “Crow Hop” occur?

When a vehicle turns, each wheel rotates on a different radius to the turning circle, thus traveling at different distances and speeds. If the vehicle’s front and rear axles are locked together and are turning on dry surfaces, the difference in wheel speed sometimes results in driveline binding that is released with a “bang” or vehicle “shudder” when one of the tires loses traction

Can I shift into 4WD High Range at any speed?

Shifting into 4WD High Range can be made with the vehicle stopped or in motion. If the vehicle is in motion, shifts can be made up to 55 mph (88km/h).

How long can I drive in 4WD High Range?

With a Part-Time system, prolonged driving in 4WD High Range is recommended only for wet, loose, or slippery road surfaces. With a Full-Time system, you need not worry about switching to 2WD mode when road surfaces improve

How fast can I drive in 4WD High Range?

You should not go faster than road conditions permit

What is 4WD Low Range?

4WD Low Range is a mode specifically designed for temporary use when additional traction and maximum pulling power is desired. Front and rear driveshafts are locked together and engine power is sent through another set of gears to multiply torque. Avoid attempting to engage or disengage Low Range with the vehicle moving faster than 2 to 3 mph (3 to 5 km/h) and do not use this mode for normal driving

Can I shift into 4WD Low Range at any speed?

No. With the vehicle rolling at 2 to 3 mph (3 to 5 km/h), shift an automatic transmission to Neutral or depress the clutch pedal on a manual transmission. While the vehicle is coasting at to 3 mph (3 to 5 km/h), shift the transfer case lever firmly through Neutral and into the Low Range position

How fast can I drive in 4WD Low Range?

Do not exceed 25 mph (40 km/h).

Can I shift into 4WD Low Range when stopped?

Shifting into or out of 4WD Low Range is possible with the vehicle completely stopped, however, difficulty may occur due to the teeth of the gears not being properly aligned. Several attempts may be required for clutch teeth alignment and shift completion to occur. The preferred method is with the vehicle rolling at 2 to 3 mph (3 to 5 km/h). Avoid attempting to engage or disengage 4 Low Range with the vehicle moving faster than 2 to 3 mph (3 to 5 km/h).

Glossary

http://www.jeep.com/en/4×4/glossary/

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