None of this post involves rock crawling. That is for well modified vehicles and their drivers who anticipate and plan for equipment and body damage. Think Moab or the Rubicon Trail. Also, perhaps confusingly, horsepower isn’t usually as important as gearing.
A Rockhounding Vehicle
Most rockhounds end up with a purpose-built four-wheel drive vehicle. They may start with a passenger car for rock shop trips or for paved roads to some collecting sites, but as the hobby takes hold they wind up with 4WD. Some drive crossovers and SUVs to remote off-pavement collecting sites but they risk their tires, their vehicles, and sometimes themselves. What follows is not a criticism of any vehicle a rockhound may have now, but a review of practicalities.
Four-wheel drive means differently applied power to all four wheels at the same time. Think about a vehicle making a complete circle or a turn on dry pavement. The inside wheels travel a shorter distance than the outside ones. 4WD vehicles adjust for this difference, operating all wheels with the correct power and play. Without this adjustment, a vehicle would stagger around the circle, perhaps leaving chunks of tire behind. That’s because all tires would be locked together, all turning the same rate over the different distance of the circle. Many vehicles, though, have locking differentials which force the wheels to turn together. They’re used when a vehicle threatens to bog under extremely loose or slippery conditions. More on lockers later.
What to Choose?
Every vehicle is a compromise. A stock jeep offers great maneuverability but carries fewer people and less gear than a full-size pickup. A pickup holds more gear but needs a tonneau cover, a tool box, or a camper shell to protect bed items. A camper shell in turn reduces visibility to the rear and sides. Work arounds are possible. Jeep accessories allow more gear by hanging items off the rear bumper or on top of the rig. A truck with a camper shell can have better side mirrors fitted to reduce blinds spots and a rearview camera to help with reversing.
A short wheelbase Jeep takes turns other vehicles can’t or with effort. Imagine a hard-left turn at the bottom of a steep hill. The Jeep may make that turn without backing up. A truck, on the other hand, may be forced to back up the hill to make the turn with another try. As mentioned before, larger trucks offer greater carrying capacity and a driver may wish to sacrifice some nimbleness for that virtue. Every vehicle is a compromise.
What Should a 4WD Vehicle Include?
Two-speed transfer case
All four wheel or all-wheel drive vehicles are not created equal. At a minimum, a rockhounding vehicle needs a two-speed transfer case providing what’s called high range four-wheel drive (4H) and low range four-wheel drive (4L). This drivetrain component operates off the vehicle’s transmission. The 4L setting increases torque or pulling power tremendously, keeping a vehicle going through thick mud or sand that would bog a rig operating in normal four-wheel drive or 4H.
Engage four-wheel drive only when needed, preferably, just before needed. That includes steep hills, snowy roads, deep sand, or mud. Anytime a road surface is loose or slippery. Which is often off pavement. Don’t underestimate the need for 4WD. A slight hill with wet grass defeats most 2WD vehicles. Engaging 4L means conditions have deteriorated substantially. Reduce speed to no more than fifteen to twenty-five miles an hour and let gearing do the work. A reminder. Ice defeats everything including 4WD. And some silt hills like those above Bakersfield, California, will fill the treads of any tire, making even 4WD useless. Wet clay on a paved road will cause problems. Still, get a 4WD, exceptions or not.
Vehicles lacking a two-speed transfer case
Many crossovers and SUVs feature all-wheel drive (AWD) but lack a two-speed transfer case, the defining element of 4WD. The Honda Ridgeline, the Ford Escape, the Hyundai Tucson, the Subaru Forester and others send power to all four wheels but they cannot gear down the same way as 4WD.
Skid plates cover some or all of a vehicle’s underbody. Especially important is a skid plate protecting the oil pan. These must be metal. Some vehicles have plastic plates underneath their frames for better air flow. These are not skid plates. Factory skid plates are better than none. Aftermarket companies like Hefty Fabworks manufacture 3/16” thick steel skid plates, which can armor a vehicle’s entire underbody. They are heavy, expensive, and require a lift to install. Most rockhounds can happily do with factory plates.
A vehicle needs frame mounted tow hook at front and back. These hooks permit a cable or tow strap to recover the vehicle once bogged. Without a hook there must be some other point on the frame to pull from. Consult the vehicle’s owner’s manual. A bumper or its facia will be torn off if used instead of a frame mounted hook. Lacking a tow hook at the back, a recovery point can be had using a D-ring shackle attached to a frame mounted hitch receiver. Never put a tow strap around a hitch ball. The ball may break loose and fly like a cannon ball into the window of the pulling vehicle. Never use chains. Never.
Picture above shows a D-ring shackle which fits into the truck’s frame mounted receiver tube. Also shown by the red arrow is a lockable hitch pin which deters would be accessory and trailer thieves. The pin goes through the hole in the receiver tube to secure the accessory. The yellow arrow marks this hole location.
Picture above shows a standard trailer ball which for most trucks is 2″ in diameter. Avoid non-standard hitches and accessories. Shown again is the locking hitch pin along with a standard pin.
A Locking Differential (or two)
Many 4WD vehicles have a locking differential on the rear axle. Some have a locker on the front axle as well. As the name suggests, a locking differential forces both tires on an axle to move at the same speed. The lockers are engaged only when 4L no longer helps and the vehicle is at risk of getting bogged. Locked up, the vehicle will want to travel straight ahead, as there is no longer play between tires. Only the most treacherous and slippery conditions warrant engaging lockers and they must be disengaged as soon as firmer ground is reached.
Every vehicle needs a fire extinguisher fixed to a secure mounting bracket. Every vehicle.
A factory installed tow package is worth the cost, even with no towing contemplated. A truck so fitted gets a greater capacity engine radiator and a larger transmission radiator. Possibly an oil radiator. The battery, suspension, alternator and charging system are all upgraded to handle towing’s greater demands. A truck with a tow package should run cooler under all conditions that a truck without.
Batteries die quickly from heat and off-roading, expect no more than two years from a conventional battery.
Before going off-pavement with a conventional battery, make sure the battery top shows no undue discharge. Remove any discharge with diluted baking soda and a stiff brush.
Positive and negative cable terminals must be corrosion free and secure. If not, brush and clean the inside of a wire’s terminal lug and the post. A vehicle may not start simply due to corrosion buildup. Start by removing the negative terminal. Use a proper wrench and not a pliers. Once rounded over by a bad tool, the nut securing the lug will continue to break down when taken off again.
Go slowly if the lug resists removal. Pry if necessary but do not break the battery’s plastic top. Use a thin piece of wood on top of the battery to pry down on rather than the top of the battery itself. After cleaning the inside of the lug, clean or scrape the entire battery post. Make bright and shiny. Do not scrape so much that you distort the shape of the post, making the connection to the lug forever less certain.
Add distilled water to low battery cells. A turkey baster helps as well as a small flashlight.
Replace a battery cable if corrosion extends well into the wire, a job for a mechanic.
A battery must fit its battery tray exactly and be extremely secure. Check it. Never buy a battery that cannot be mounted correctly. A battery mustn’t thrash about the engine compartment. This is important!
Many off-roader’s favor spiral wound absorbed glass mat batteries or AGMs. Optima makes them as well as others. AGMS are made in a radically different way than a conventional battery. AGMs are sealed and require no maintenance. No filling, no leaking, no corrosion build-up. Upgrade to an AGM once an old battery fails. I’ve had my Optima for two years and it works.
Learn to jump start a vehicle and bring heavy duty jumper cables. Black goes to ground on the vehicle being jumped. Locate a good grounding point on the frame or find the vehicle’s approved connecting point. A vehicle won’t start without a solid connection for black. Hand held battery jumpers are a fine idea. Even AAA uses them. No fussing with cables running vehicle to vehicle. The handheld’s positive and negative cables are hooked directly to the problem vehicle.
Some vehicles go into an anti-theft mode when their battery dies, this may prevent jump starting without following a certain procedure. Check the owner’s manual. Replacing the battery or removing the cables will impact a vehicle’s electronics.
A spare battery or a handheld portable car jumper is mandatory when traveling solo. Or bring a lithium-ion smart battery like the kinds Goal Zero, Midland, or Suaoki produces. These can charge a dead battery as well as a rockhound’s electronics. Some smart batteries like the Suakoi will jump start a vehicle, others may only charge. Check.
Automatic Transmission or Manual?
Most off-roaders favor manual shifting. Manual shifting offers better flexibility over changing conditions than an automatic. Stick shift vehicles get better mileage. It’s easier for recovery services to tow manual transmission vehicles. Automatics, though, are easier to drive. If a driver becomes incapacitated, it’s important that any person in the party can drive back to pavement. Every driver can manage an automatic. But many people don’t know how to drive a stick.
What is High Clearance?
Rock clubs will advise or require a high clearance vehicle on certain field trips. But what does high clearance mean?
A vehicle’s lowest point is usually measured at the rear differential or what off-roaders call the pumpkin. The distance from the bottom of the rear diff to the ground is the clearance. A base Jeep, the Wrangler Sport edition, has 8.4” of ground clearance. A Subaru Outback has 8.7” and a base Ford 150 has 8.8”. These are minimums for rockhounding vehicles. (I have a page on this subject here.)
Larger tires and a lift kit increase clearance and void any vehicle warranty unless modifications are factory approved. They pose other problems as well. Unless fording creeks, increasing a vehicle’s height with a lift kit or tires does little if the rear differential remains at or about the same height.
Tough Talk on Tires
The National Park Service, in discussing Death Valley driving, puts the problem well, “Flat tires are a common problem for backcountry visitors due to rough road conditions or from having unsuitable tires. Make sure your vehicle is equipped with ‘off-road’ tires rather than highway or street tires. Carry at least one inflated spare tire (preferably two), a can of fix-a-flat or tire plug kit, a 12-volt air-compressor, a lug wrench, and be sure all parts of your jack are on hand. Know how to use your equipment before you head out.”
The only useful off-road tires are light truck tires, designated on the sidewall as “LT.” These tires are much thicker than passenger tires and have stronger sidewall construction. Using obsolete but familiar terminology, a passenger tire may have four plies, an LT tire six to ten. It doesn’t matter what the rugged sounding name a tire may have, only the designation LT counts. Within the world of LT tires is a huge selection. But, first, recognize “P” tires and avoid them.
Mark of The Beast
Some new 4WD pickups come with passenger tires. Reject them when buying a vehicle or get credit for LT tires. Most Crossovers or SUVs cannot be fitted with LT tires. Reconsider the vehicle purchase. No vehicle with passenger tires should leave pavement unless driving well graded, rock-free roads. Subaru rally vehicles on TV do not represent how their passenger cars are fitted.
Any driver using passenger tires on sketchy roads should anticipate flats and have a plan to recover from them. Do not count on assistance, even on a club outing. Members coming a long distance for a special outing may be unwilling to cancel their day by helping you out. Don’t blame them, blame you.
A donut spare or a temporary tire must be substituted for a full-size spare before going off-road. Many rockhounds carry two full size spares.
If a small leak is discovered, take the easiest approach to recovery first.
A can of Fix-a-Flat for large tires should be carried in any vehicle. Once Fix-a-Flat has been used, a decent size air compressor should fill the tire back to its normal operating pressure after a few miles of travel. (A compressor also helps with airing down and airing up tires in extremely sandy conditions.) In case of a flat, any rockhound with only one spare or those making a Fix-a-Flat repair must immediately return to pavement. Tire shops don’t like Fix-a-Flat but that is their problem.
Quick Note on Air Compressors
VIAIR and others make excellent air compressors for off-road use. Any compressor must run off the vehicle’s battery. Air compressors using a cigarette lighter adaptor are totally unacceptable. They are painfully slow and will burn out or overheat long before they can air up four off-road tires. Even when filling a single tire, small compressors will overheat and shut down, refusing to start again until cool.
Power must be drawn from the battery with the cables provided and the vehicle must be running the entire time of airing up. If not, the battery will drain immediately and die. The sliding hose couplers VIAIR uses demands great hand strength, look at other options if you have any disability. Or get a teenager in your group to connect the hoses for you. Expect to pay at least $200. Someone owning a quality air compressor and good LT tires won’t often need their expensive purchase. But someone in their group will. Count on it.
Picture above shows a VIAR air compressor that runs off of a vehicle’s battery. Note the arrows pointing to the sliding hose couplers. A more elegant and expensive solution is to have onboard air, in which an air compressor is fitted into the engine bay. It is then switched on by a switch mounted to the dash or by a remote control.
Back to Tires
Off-road tires and wheels are big and heavy. A complete tire and rim may be a yard wide and weigh 40 pounds. No rockhound should drive off-pavement by themselves without being able to change a tire on their own.
Sidewall flats are the worst. Tire dealers never fix a sidewall flat. Instead, they replace the entire tire. Tire repair kits exist for field repairs but not for sidewall flats. Repair as best as one can. Driving on a flat gets one further down the road but risks damage to the wheel. Driving on a flat is warranted, though, when getting a vehicle to a level spot for changing a tire. Drive slow. Better to do this than attempt a tire change on badly uneven ground that might cause the vehicle to slide off a jack. And on to you.
Avoid hazards one controls. Keep from cactus, of course, but creosote branches broken at the right angle can puncture quality off-road tires. Stay fully on the route being driven. Avoid camping spots with fire rings where scrap wood may have been burned. Scrap wood leaves nails that are never picked up. A ten year old camp site like that will have nails everywhere. And stay on road in old mining districts, with hidden iron trash over every foot of ground.
Reduce speed. A rocky road at 15 MPH may not puncture tires but it may easily do so at 30 MPH. Some roads are so rocky the driver may not realize a flat has occurred for some time. Unfortunately, too many trip leaders drive too fast, leading group members racing to keep up with break downs resulting. Other than getting the leader to slow down, be prepared with a vehicle that can take extra pounding from time to time.
AWD vehicles like Subarus have a special tire problem. All four tires must have equal tread wear or the AWD system will not work correctly or will break down. If a non-repairable flat is suffered when the vehicle is under warranty, it may be necessary to replace all four tires. If out of warranty, a used tire might be bought or a new tire shaved down to the right depth. Any of these steps means delaying or cancelling an adventure. Especially when broken down in a rural community without a tire store.
Many vehicles carry spares underneath their rigs, especially SUVs. A driver must know how to release them while on their back in mud or rain. A better solution is a swing-out carrier above the back bumper. Or a spare stowed inside the vehicle. This writer’s truck came with a spare mounted underneath. That is now the second spare. The first spare is carried in the truck bed, easily rolled out.
Take advice from a tire dealer familiar with off-roading. Develop a relation with this expert and their store. They will advise on tread depth and design, mileage expected, road noise, and a dozen other details.
–The Hi Lift Jack
The Hi Lift Jack is everywhere in the Jeep Community but of limited use for most other vehicles. It’s mainly used to get a rig going that has high centered, one stuck on a rock or a ledge that puts a wheel or two off the ground. This jack utilizes lifting points close to the frame which most non-Jeep vehicles do not have. It needs a base plate when in sand or mud. A Hi Lift can injure if used improperly. Before practicing, ask someone who knows the jack for one- on-one instructions. The Hi Lift isn’t meant for changing tires but if one does, chock the wheels and use jack stands.
–Off Highway Vehicle Jack
Pro Eagle sells off-pavement jacks that operate like conventional floor jacks. These are for high clearance vehicles, though not necessarily lifted. Check underbody height for compatibility before buying. These jacks may weigh fifty pounds. Despite weight, bulk, and cost, they make a good investment because they work in sand and can go under a vehicle to hit a variety of lifting points. There is a joy in using a jack that is dead simple, needs little instruction, and can be counted to work every time. Again, chock at least one opposite wheel.
–The Bushranger X-Jack
Far lighter than any jack is this Bushranger product. It is a balloon like device that lifts a vehicle for chores like changing a tire. Jack stands must be placed before a spare is installed but that’s good practice with any repair. The X-Jack weighs less than twenty pounds and is inflated by the vehicle’s exhaust pipe or by the air compressor every rockhound must have in their rig. Many inexpensive copies exist. Avoid them.
Solo drivers must have self-recovery plans. A long-handled shovel is mandatory as well as a tow strap should another vehicle come along. Maxtrax recovery boards are excellent. They permit a 4WD vehicle with off-road tires to get moving by first driving onto the boards, enabling momentum which is the key to getting unstuck. You’ll have to shovel first, however, when in sand or mud to place the boards. Recovery boards are far better than sticks or rocks shoved under a tire to give it traction.
A Last Note
A liberating force of a 4WD with heavy duty tires is to splash into pullouts one would never attempt with a passenger car. Every rockhound sees fascinating things on paved roads at 50 MPH, the question is, where can one pull over? Too many things are passed by because there is no where to turn out. After having a passenger car, it is a delight to bounce into pullouts that are within walking distance of a find. The world opens up as you confidently go off the road despite a good drop in grade or surface. Try it.
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