30 December 2008

Four Wheel Drive: A Short Course

Knowing how to operate a 4WD vehicle is important for anyone who likes to hunt, fish, backpack, ski and othewise enjoy the backcountry around a place like Butte, Montana. This post is for those who use a 4WD as a tool to get places--not for those who drive just to drive.

Like many kids growing up in the oilfields of Bradford, Pennsylvania, I learned to drive with a little Willy's Jeep. They were a common utilitarian roustabout and pumper's vehicle, and many -- like Gramps' Jeep -- were military surplus. My sister Kathleen began driving, as I recall, at about age ten. I didn't have her quick reflexes or good attention-span, though, so Gramps didn't trust me behind the wheel until I was twelve or so.

We learned to drive on "lease roads"--two-track paths through the hills that gave a pumper access to the oilwells on a particular lease. Oftentimes, the surface property was owned by one party, and the oil & gas rights by another. Furthermore, the original oil & gas rights owner usually leased out a seven-eighths working interest to the party that actually pumped & maintained the wells. Hence the term "lease" for an oil property.

Older lease roads were built by hand with horses & mules, and more recent roads were cut by a Cletrac "bulldozer" (similar to a Caterpillar). They were seldom well-designed roads: overly steep grades, poor drainage, sharp turns, rocky--what a great place they were to learn to operate a four-wheel drive vehicle!

4WD 101
First off, let's be clear: we're talking 4WD here, not so-called "All Wheel Drive" vehicles such as the Subaru Outback, Honda CR-V, or Toyota RAV. Jan's Subaru is just the ticket for highway travel in all conditions, and the occasinal off-highway foray on a good Forest Service road.

AWDs, however, lack the rugged construction (e.g. they have no frame), ground clearance, and other features of a true 4WD, such as my little '91 Toyota pick-up (only 330,000+ miles):

INTRODUCTION
Do not drive off the highway unless you are prepared with some basic equipment & know-how.

Carry a shovel. Though it's best not to get stuck (see 4WD 401), there are times when you will need to dig out of deep snow or make room for a jack to fit in the mud. A versatile shovel has a semi-spade blade (a bit of a point) and a SHORT handle. You will only try digging out your rig from deep snow once with a long-handled shovel before sawing the handle off. The point helps when you have to chisel your way into hard-packed snow, ice, or rocky ground:

Weight the rear wheels. In deep snow or mud, a light rear-end will climb and lose traction. In my little Toyota Pick-up, I find four 80-pound sandbags (320-pounds) about right--placed directly above the rear axle. This is in addition to a bed-mounted toolbox with a lot of heavy stuff(chains, tire chains, come-along, etc.) in it.

Run good tires. True off-road tires are horribly noisy on the highway and may not perform well on slick, rainy pavement. "M/S" (mud + snow) rated tires are a good compromise. Consider an LT ("light truck") rated tire: LT tires have thicker & more rigid sidewalls for heavier loads and more resistance to rocks in a deeply rutted road:

All four tires MUST be identical. Rotate them every 5,000 miles to insure even wear. Consider studded tires if you spend much time on snowpacked or icy roads:

Carry a full-sized spare tire. Ideally it will match your other four tires, and you will rotate it with them.

Carry a 3/8" chain or nylon snatch strap ("recovery strap"). Either should be at least 20 feet long. They are necessary when you are pulling a stuck rig out with another vehicle, and can also be helpful when you are freeing yourself with a winch/come-along. A snatch strap is safer, and has some elasticity so you can "jerk" out a stuck vehicle. Two straps and chains have no elasticity so take up the slack slowly!

NEVER, EVER drive with 4WD engaged on dry pavement. At the very least, you will wear out tires fast and damage the drive-train. At the very worst, the vehicle will flip over on a turn and kill you. That said, some 4WD vehicles do have a feature that allows them to be operated safely on dry pavement: read your owner's manual.

4WD 201

Carry heavy-duty tire chains (note cross welded pieces on links in pic below). Lightweight chains will break frequently on rocky roads or if you must drive even a short distance on pavement/dry road. Ideally, have a full set of four chains. If you have only one pair, chain the front wheels and go slow especially if you're going downhill--the unchained rear end can break free and swing around very quickly! Carry a pair of gloves just for putting chains on and taking them off: it can be a wet, cold, dirty job. Chains must fit snugly--it can be a problem getting them tight enough. Try driving a short distance, stop, and catch another link to tighten the chains. Rubber tensioner cords (short, thick bungee cords) can help keep chains from slapping around, especially with a broken cross-chain. Carry a few extra links and "monkey links" (repair links):

Know how to put chains on. Practice in the drive-way. Two basic techniques are: (1) lay the chains out in front of the tires, drive mid-way over them, and attach; and (2) jack up a wheel, attach the chain, lower and move on to the next wheel. It should go without saying, but NEVER crawl or reach under a jacked-up vehicle so that you could be pinned or injured if the jack slips.

Chain driving tip: unless you are seeking an adventure, do not use chains to drive into a place where you intend to hunt, fish, or camp etc. Weather conditions can deteriorate (see 4WD 301): if you had trouble driving in with chains, then you might not get out at all. I've seen folks drive in as far as they could, then chain up and drive further--only to get stuck in the next big snow drift or mudhole, sometimes just a few hundred yards from where they chained up!

Carry a heavy-duty bumper jack. It's often called a "handyman" or "hi-lift" jack. If you're high-centered or in a deep rut, you can jack the vehicle up and kick it sideways. Stay clear of the jack when doing this. You can also use a hi-lift jack as a sort of winch or come-along, although this is awkward and it's much easier to use a REAL cable winch or come-along. NEVER leave the handle in the ratchet under tension unless the handle is pinned in place. The jack's cog can break or slip and launch a loose jackhandle through a human skull:

On rough ground when you need to go slow or on steep terrain where you need maximum torque for braking or climbing, shift the transfer case to low range (also called compound low). If you have lock-in front hubs, do not use low range unless the front hubs are engaged. Otherwise, you double toque to the rear wheels and risk breaking an axle shaft.

DO NOT ride the clutch to control speed. Avoid braking where possible. Use the transmission and throttle to control speed. Many 4WD off-road fanatics even start and stop their truck in gear without using the clutch.

If you encounter an obstacle that might be higher than your ground clearance, drive over it by keeping your front & back wheel on it. Know your ground clearance, and how it varies from the front & rear differential toward the suspension. Drive slowly enough so that if you do get hit an obstacle, you don't break anything.

4WD 301

Carry a winch or come-along ("power puller"). Some trucks have a winch mounted on the front bumper, but it can be awkward to use if you have to pull from the rear. Carry a tree protector and strap/chain assortment for maximum flexibility. Inspect the winch cable, use grease or a corrosion-protectant on it, and replace if it's frayed. For maximum torque, carry a snatch block so that you can double the line. The block can also be used as a pulley to change the angle of pull. When using a cable winch or come-along, through an old coat or blanket over the cable--that way, if the cable breaks, it is less likely to whip around and take someone's face off.

Heavy-duty come-along that I carry in the Toyota p.up (pictured with chains):

Manual drum winch that fits to my LandRover's front or rear (pictured with snatch block):

Do not buy a cheap come-along: cheap, thin cables break easily, and I've seen the pressed-metal frames twist apart. These are OK for stretching fence or hoisting an elk.

Lock-in hubs, manual transmission: I'm a traditionalist. I like lock-in hubs that allow the front wheels to "free wheel" when you don't need 4WD. And I like a manual transmission including a manual transfer case, as I've seen a lot of balky electric or push-button 4WD and hi/lo range selectors. "Warn manual locking hubs" can be fitted to most 4WD vehicles:


Carry an air pump. This can be a simple manual pump or an electric-operated version. This not only allows you to inflate a low tire, but -- more importantly -- allows you to let some air OUT of your tires when you need extra traction on loose rock, snow, or mud. At low, off-highway speeds, you can drop tire inflation to 10 - 20 psi. Traction improves greatly.

Scout ahead. Before driving into a mudhole, stream, or snow drift, get out and check the depth with a stick.

Carry a large bow-saw and ax. Sometimes you need to clear the road: remove a low hanging tree, or saw through a large downed tree so that you can then pull it out of the way.

Watch the weather. Warm snow is MUCH slicker than cold snow. Many times I've driven in through deep snow and parked early in the morning, and then had trouble driving out in slick, warm snow. And I've had to chain up to drive out through drifts after a mid-day blizzard all but obliterated the road. Warming temperatures can cause a firm, well-frozen road to turn into a muddy quagmire. Warming temperatures can also increase snow melt, so that the little stream you drove through in the morning is over the floorboards by late afternoon. Most people are fair-weather off-roaders, so you are likely to find yourself alone when you need help the most. Be prepared.

4WD 401

Don't get stuck (unless you are driving to test your rig, or need experience in getting unstuck). Learn the capabilities of your vehicle and do not get high-centered or buried in deep mud or snow unless that is the whole point of your adventure. To me, a 4WD vehicle is a treasure, and though I use it often I also want it to last a long time. Here's my '72 Land Rover Series III that I've owned since 1980:

Here we are, parked near a good cross country skiing area on a very snowy day. I knew the risk, and expected to be stuck when we returned to the truck parked in 20 inches of new snow that became very slick as the day warmed above freezing. Luckily, after just a half-hour of digging, we were free (I could have chained up and drove out, but I did not have far to go):

Conclusion

This blog post is only a brief introduction to the intricacies of 4WD off-highway travel. There are many good books and videos on the subject, and new 4WD owners should study up on them. There are also some EXCELLENT YouTube clips about specific 4WD skills. However, there is no substitute for experience. Put together a good 4WD kit and practice using it.

Have fun. Be safe.

1 comment:

mahesh said...

I really like your site. Will keep checking back here.
Ice Metal and Tires Packages