Technical > Four Wheel Finesse
The Art of Retreat
by Jim Allen
Most of us have heard and groaned at the ominous, “Okay, everybody back up,” call on the C.B. Fate usually dictates it’ll happen in a tight place like this.
“Retreat hell!” you say in the best John Wayne tradition. Okay, we’ll all chuckle and change the channel back to the “Real World.” Face it — there will be times when you can’t make it over an obstacle. No, you don’t need to think about hari-kari with a buck knife when it happens. Backing out can provide more than enough challenge to assuage an injured ego.
A grizzled driving instructor I once worked with used to say, “You should be able to reverse out of anything you can drive forward into.” That’s a useful observation and a good driving skill to master. At some point, all of us will run up a narrow trail, find it blocked, and have to back a ways — sometimes a long ways to get to a turn-around point. Backing out of trouble is what this installment of “Finesse” is all about.
Rear-Wheel Steer
Backing up turns a rig into a rear-steer rig, just like a forklift. Most of us have experienced how twitchy the steering gets when going backwards, which dictates extra care on the steering input. The old sailor’s adage applies here, “Steer small.” It’s easy to over-control and weave like a drunk walking the white line at a sobriety checkpoint. Deliberately making small steering adjustments will minimize this effect. Going slow also will make it easier to control.
Assume the Position
You’re not going to get by using mirrors alone. It doesn’t hurt to aim the mirrors low (some sophisticated SUVs do that automatically in reverse) and use them to check out the ground at the rear tires, but you should turn around in the seat, drape your right arm on the seatback, and look out the back as if it were the front — unless the direct rear-view is blocked by a camper or gear (more on this in a minute).
Being twisted around and steering behind you will result in a certain amount of disorientation in tricky situations. The connection between eyes and steering arm is reversed until the body adjusts. You may steer opposite of what you intend. This is another reason to steer small.
Hand position on the steering wheel also may help or hinder you. Most people instinctively reach for the top of the wheel. That may make control harder for some, depending on body type and the general position of the seat and steering wheel. Try putting a hand at the bottom of the wheel. Some drivers find it easier, as it reduces the tendency to over-correct.
The view is going to be restricted, as if looking out over a really long hood. Stick your head out the window in tight places and steer closest to things on that side for better judgment of distances.
Spotters and Backing Blind
If direct rear vision is blocked, you’ll have to rely on mirrors, which will make reversing slower and a lot more hairy. If you have a complex maneuvering situation, the best and safest course is to use a spotter. Even if rear vision is clear, a spotter is good insurance in difficult situations.
The usual spotting rules apply here. Use mostly hand signals. The spotter should stay in view of the driver, a task made more difficult if the driver is using only mirrors. Because the spotter will be following a backwards course, he should take care with his footing. Better to stop the vehicle periodically to find a sturdy position rather than trying to walk backwards on rough terrain.
Sometimes backing up can be dangerous. Italian Shelf in Colorado is one such place. Back up slowly. Best put a spotter to work as well. With limited space, it’s easy to get a wheel off the edge, especially if the driver is on the side opposite the edge as shown here.
Backing in Really Tough Stuff
Call it “Extreme Reversing.” Someday you may be called upon to back over something that would be a challenge going forward. It will change your vehicle’s performance characteristics, and there are many issues to be concerned with here, the steering stuff we already spoke about being one.
First, any weight bias will be reversed. That’s more of an issue for climbing something backwards. If you have a rear locker and an open front and try to back up on a slope or an obstacle, special problems will arise. The locked end will be the most lightly loaded end and won’t be much help. The open front axle will be doing most of the pushing and, of course, is limited to the amount of traction the tire with the least grip can deliver. There also are axle-strength issues discussed later.
Gearing choices in reverse are limited to two: reverse high range and reverse low range. That will limit the amount of available momentum because reverse is often among the lowest ratio gear in the tranny, if not the lowest. High range may be too high. Momentum is not easy to use in reverse, so, overall, crawling is inevitable — or taking a strap.
Vehicle Issues
Backing up reverses the normal drivetrain strength bias. Most front axles are weaker than the rears, if not via ring gear and axle shaft size, then by the weak u-joints or front hubs. That’s okay because, normally, they have the least amount of traction load. The situation is opposite in reverse, especially for backing up a slope.
The hubs are often the weakest link; the best ones are able to handle about 5,400 pound-feet (big axle or premium aftermarket), with many or most at or below 4,000 pound-feet (OE and standard aftermarket). In the latter case, that’s at least 15 percent less than a good half-ton-style rear axle and much less than a three-quarter-ton axle. With significant weight transfer, you could be applying a whole lot more traction torque than the axle can handle. The bottom line is that backing up a tough obstacle may end up in a snap-crackle-pop-Rice-Crispies scenario.
Another drivetrain issue is pulling on the weaker coast side of the ring gear on the back axle. Ditto for a reverse cut axle up front, though a standard cut front axle will be working on its stronger side.
Group Backing
Backing a string of vehicles can be tricky in tight quarters. Teamwork is the key. Having watched people back into each other in this situation, I’d suggest several spotters outside to keep an eye on things. Make the move in succession, starting with the rig farthest from what was the front.
Treading Lightly in Reverse
When faced with a long reverse, you might be tempted to turn around on a patch of easy-to-crush brush that could be mowed down. Avoid the impulse. If faced with brush-crushing or a dangerous situation, the brush will probably forgive you (the park ranger might not), but don’t be a lazy dog and tear up foliage or virgin ground just to avoid backing another 20 feet.
Backing Downhill
Otherwise known as the “Failed Climb Maneuver.” To recap, the steering wheels are unloaded and steering effect more reduced and unpredictable. Also, the brakes are more prone to locking up when the wheels are unloaded and locked tires will reduce steering effect. Keep the speed as low as possible, keep the wheels rolling for control, put the vehicle in reverse, and watch the steering carefully.
No Shame
Believe me, after backing down three-quarter miles of shelf road with a thousand-foot drop on the left, there is no shame in moving away from something. To practice the retreating arts, build an obstacle course of empty boxes in a parking lot and back through them without hitting anything.