Technical > Four Wheel Finesse
The Honeymoon
Making The First Time Special
by Jim Allen
The suspension type can make a big difference in the way you ‘wheel a rig. Going from a solid axle rig to something like this Hummer (dontcha wish!?) can make for a big change in driving style. Notice how the front right is airborne. That’s not an unusual situation for a Hummer or any other fully independent suspension.
That first time is a special, never-to-be-forgotten moment. It doesn’t matter if you and your partner have prior experience or not, it’s the first time you two have been together in that very special way. It’ll be magical, revealing and perhaps a little awkward. Yep, taking your new 4x4 out onto the trail the first time is special all right. What did you think I was talking about?
While the basic principles of four-wheeling don’t change, the application of those principles may vary widely from vehicle to vehicle. There are many different ways four-wheel drive has been applied and each variation, no matter how minute, needs a slightly different touch. The technique will change somewhat when you modify your 4x4 as well so, in essence, a freshly built rig is another type of honeymoon cruise. Ultimately, it’s the driver’s job to learn the special techniques and maximize the experience.
Be Gentle
Your new, or new to you, rig should be tried out gently at first. That means easy trails and easy driving. If the new rig has any quirks, you don’t want to find out in some hell-bent-for-leather situation. With new 4x4s, despite what you might hear elsewhere, it’s better to break them in easy. A used rig may have hidden faults not apparent when you checked it out for purchase. Either scenario is reason enough to go easy the first few times.
Driver Adjustments
From the driver education perspective, you may need some time to adjust to the controls, the equipment and the general characteristics. The truck will respond differently than your previous rig. A lot depends on how similar or dissimilar the new rig is from the old one. If you think of it in aviation terms, it might make more sense.
Say you’re a transport pilot trained to fly lumbering, four-engine behemoths. Suddenly, the Air Force decides you’ll make a better fighter pilot and sends you to fly F-16s. Sure, both are aircraft and use the same principles of operation, but they are completely different in detail. If they just toss you the keys to the F-16, the odds are good they will be scraping you out of a smoking crater real soon, even if you were the best four-engine pilot around. That’s why they have transition training to move pilots from one aircraft to another and no sane pilot would reject it. Jumping from one plane to a similar one might not take much training at all, but going from one that radically different takes a good deal more.
Driving Position and POV (point of view)
Unless you’ve moved to a very similar rig, the POV, i.e. blind spots and visual cues, will be completely different. Dents, scratches and dings usually happen the first few times a rig is ‘wheeled because you don’t have a “feel” for the four corners of the vehicle. Given time, you will instinctively know just how close you can get to something. Early on, that sense is very underdeveloped.
Pickups are traditionally heavy up front and light in back. This can make for less traction in the back and, on downhills, a greater tendency to change ends. It just takes a little getting used to.
Throttle and Brake Sensitivity
Some rigs have a very touchy throttle. Ditto for the brakes. Especially where a light throttle is concerned, acquiring a feel is conducive to safe and non damaging four-wheeling.
Bump and Droop Steer
Almost all rigs are somewhat vulnerable to unwanted steering changes when the suspension is compressed, drooped or articulated. The rig might pull right or left depending on which part of the suspension is being worked. Better to find out how the rig is effected in a more controlled situation.
Short wheelbase rigs may pose the biggest transition problems. They are the sports cars of the wheeling world and require the best drivers to remain safe.
Noises
Every rig will make noises when four-wheeling They might seem unnatural at first and you really won’t know “normal” from “uh-oh” until you get more familiar.
Balance
Every rig is balanced differently. Some are more nose heavy, others more balanced or even tail heavy. People seem to have the most trouble going from an SUV or bobtail, which generally carry more weight on the rear tires, to a pickup, which is very light in back. The balance effects traction and handling off road and you want to have that feel in the bag before you start hard-core wheeling. Some rigs have a higher center of gravity, so the new rig may not sidehill like the old one. Try not to learn that lesson the hard way!
Suspension & Axle Types
There are stark differences between a rig with independent suspension versus one with solid axles. The rigs with composite systems, IFS front and leaf spring rear, are most difficult to master.
- With all-independent rigs, such as the Hummer H1, Ford Explorers, Expeditions, VW Touaregs, Porsche Cayennes, etc, you will have great center clearance and do a lot of tire lifts in rough terrain. Both are situations that you have to take into account. Use all that center clearance to good effect and spend extra time picking lines that keep the tires on the ground as much as possible to maximize traction. You’ll need all that extra clearance because when one tire hits an obstacle, the suspension compresses on that one corner, thus lowering the center somewhat.
- With solid axle rigs, you will have more articulation front and rear, meaning your tires will stay on the ground better, but you have less clearance; the lowest point being under the diffs. When you hit obstacles with one tire, it will tend to lift the axle and the vehicle. If the rig has one centered and one offset diff, you have to keep in mind those two areas of maximum clearance.
- The rigs with mixed suspensions will be the most difficult. The rear suspension has lots of articulation and the front, being independent, has none. That can make for some extra instability in certain types of terrain, namely rockcrawling. You will have a high clearance area in the center up front... blocked by a centered diff in the rear.
Lockers, Limited Slips and Open Diffs
You will drive a rig with open diffs completely differently that one with a LS or a locker.
- An open diff requires that you try to maintain equal traction side to side (on at least one axle) as much as possible. If not, the torque will flow to the side with the least traction. You will need to use more momentum to substitute for less traction.
- With a low bias limited slip, you will find the most help on low traction surfaces like mud, sand, snow, etc, where the loss of traction is equal on both sides. The low bias LS will be less useful where there is a great disparity from side to side, such as two widely different ground surfaces or one unloaded (or lifted) tire.
- Lockers split the traction evenly, but can make maneuvering difficult... especially if a front locker is used. With automatic lockers, vehicle weight and weight bias can affect how they engage and disengage.