Offroading

Offroading with the 4WD Xterra

These are just some pointers for offroading in the Xterra; some of the tips are general offroading tips that apply to any vehicle that goes offroad and some are things that the Xterra has to look out for specifically.  The Xterra is surprisingly at home offroad, and can do a lot more than you think a “grocery getter” SUV would.  However it can’t do everything, and there are many vehicles that are more capable.  The key is to use your own skill to make the most of what you got; a good driver can get and Xterra over and obstacle that stops a poor driver in a “Built” Wrangler.

Description of “offroading”

By definition anything that isn’t on pavement is offroading but not many 4wheelers will agree that a smooth dirt road counts as going offroad; offroading is usually going over terrain that is impassible to typical street cars.  Many people will say that they’ve been offroad and describe entirely different scenarios and terrain.  Usually all are offroading but different techniques and different equipment is needed to get through different types of terrain.  Sometimes you’ll cross all types of terrain in one trail; but your vehicle may be built for a different type of terrain, in the end you’ll need to rely on your own skill to get you through.

There are four main types of offroading: Back Roads, Mudding, Cross Country (Baja), and Rock-Crawling.  These terms are used to describe the type of obstacles encountered.  There are other types of offroading but they usually all fit into these main categories somehow.

  • Back Roads
    Back Roads or forest roads can be anywhere; a good description of a back road is any unpaved trail that is made to give access to areas that paved roads don’t go.  The terrain can vary from simple graded roads that can be passed in a Toyota Tercel to washed out roads that are barely passable with the best equipment and vehicle.  But generally back roads are in good shape because they are kept up by the BLM, National Forest Service, or other government departments to keep access available to the public.  For an easy back road not much gear or modification is needed but it’s always good to be prepared for problems along the trail like washouts and excessive trail damage (fallen trees).  It’s also good to have some form of 4WD so that impact to the trail is minimal.  Most back roads can be done in passenger cars but a Subaru Outback or more capable All Wheel Drive street vehicle is usually a better choice; of course trucks, SUV’s, and other offroad vehicles are best.
  • Mudding (Muddn’ in the south)
    Mudding is a very simple form of offroading; all it consists of is driving through a mud puddle and trying to get to the other side.  There isn’t much skill needed just aim for the other side and hit the gas.  Equipment however plays a big role in how easy it is to get through the puddle, and for deep thick mud hole you need a specialized vehicle.  For big mud holes a large truck is usually the best choice, modifications are usually lifting the suspension to keep the body from dragging in the mud, large mud tires are needed to paddle through the muck and axle components need to be strong to guard against the mud holding a wheel too much and breaking an axle.  A winch or other extraction equipment is a must; mud holes that look 3 inches deep can easily turn out to be 3 feet deep.  And nothing’s worse than slogging through freezing, knee deep, muck and hiking to the nearest road to find help.
  • Cross Country / Baja
    Cross Country offroading is sometimes also referred to a “Baja” offroading.  It consists of getting from one point to another without the use of trails or roads.  The worst obstacles encountered are usually large rocks and brush.  Unfortunately this type of offroading creates A LOT of damage to otherwise untouched terrain, and for this reason is usually not allowed in most areas and is highly frowned upon by other 4wheelers because of the bad name it gives the sport of offroading.  If you would like to do this make sure you get the proper authorization and permits from the government or avoid this altogether.  Nobody wants to see our beautiful country destroyed by crisscrossing dirt trails.  Vehicles that are best for this type of offroading are high clearance vehicles that have long travel independent suspensions and stiff shocks to cushion jumping; a Hummer is a perfect Cross Country offroader.  Hitting bumps and rocks at high speed causes incredible stress on axles and suspension so most vehicles need reinforced components, and you need to bring replacement parts with you for when things do break.
  • Rock-Crawling
    Rock-crawling is probably the most advanced type of offroading; it involves crossing large rock outcroppings in a vehicle.  It can range from overcoming a 1 foot ledge to crawling up a jagged 20 foot rock “waterfall”.  Rock crawling has the highest probability of damage to the vehicle, in many instances you’re at risk of rolling your vehicle or having it slide into a rock outcropping and doing damage to the body.  Vehicles optimized to this environment are high mobility,  Solid Axle designs like the Land Rover Defender Series. Independent Suspensions are a huge liability on rocks and are the main limiting factor on independently sprung vehicles.  And even though rock damage is a possibility the main cause of damage is ignorance; the rocks can’t hurt you if you know how to get over them without tipping over.

Techniques

Choosing a Line
Choosing a line over broken terrain is one of the most important skills to master, unfortunately its also the hardest to teach, its just a feeling that your develop after getting some experience offroad.  You want to drive a line that will keep all four wheels on the ground so no wheels spin.   And you don’t want the undercarriage to smash against anything in the process, it will do damage at worse and get you hung up and stop your momentum at best.  Also you want to make sure you don’t tip on your side or slide into a large rock.

One way to develop your sense of picking a line is to not look out your window at your driver side tire all the time.  It does help to know where the tire is but if you focus too much on the driver side you lose track of the passenger side.  It’s best to sit back in the seat and visualize where both tires are going as you climb an obstacle.  You can practice knowing where tires are during the winter by driving over clumps of snow that are on the road and looking in the rear view to see if you smashed the snow.

If an obstacle looks too hard for you to get over, get out of the vehicle and walk the obstacle on foot.  See where the high points and low points of the obstacle are, where there’s a chance for damage, and any places you can escape or back off if you can’t make it up.  After you have a feel for the obstacle visualize your line over it, walk the center of the line and imagine where your wheels will be going up, remember where big rocks are and when you have to put your wheels on them.  Now that you know where you need to be hop back in your vehicle and follow the line you walked.  Discuss the line with others that will be going over to get their opinion on the ideal line.

Some obstacles are too complex or you can’t see the line over the hood of your vehicle or you simply get off track and need some help.  This is where a spotter comes in, since you can’t see the area 5 feet in front of your hood a spotter can act as a separate pair of eyes to tell you if you’re on track and guide you over crucial parts of the obstacle.  Be sure to discuss your line with your spotter so they know where you want to be going, and make sure you and your spotter know what hand signals each other are using before you get moving.  Communication with your spotter is the most important thing, I’ve seen some pretty bad rollovers that were caused by lack of communication between the spotter and driver.

The best lines up an obstacle can be pretty treacherous, and even a perfect line may require alot of flex from your vehicle.  In the Xterra the IFS will make it very easy to lift a wheel so the best way to approach an obstacle is to get the two front wheels to go up at the same time; that will keep the front axle from flexing too much, the back axle is solid so it will flex a lot more than the front and you can usually rely on it to follow you up the obstacle.  Just drive the front and the back will follow.  You may have to choose a different line than a solid axle vehicle uses and it usually requires that you spend alot more time turning left and right on the obstacle to line the wheels up with ledges then a solid axle vehicle would.

This doesn’t mean in any way that you should ignore what’s happening behind the front wheels, if you put your front wheels over a big rock then ignore it and make a sharp turn that rock will go right under your undercarriage and can tear through any number of expensive hard to fix components.  When you go over broken terrain where rocks are reaching up high enough to touch the underside of your vehicle you need to be very conscious of where the rocks go under you.  For large rocks its best to put one of your wheels up on it, for one thing it keeps the rock from going under the sensitive components of the vehicle, the other benefit is that it lifts the underside of the vehicle up higher so that other rocks are less of a worry.

Two things you need to remember is that when you come down off the rock you may come down on another sharp rock, the other is that even though the front of the vehicle is past the rock the rest of the vehicle can still be hit if you turn the wrong way.  When one wheel goes over a rock its good to proceed in a straight line till the rear wheel goes over it too.  This can still be a problem for really big sharp rocks though; after the wheel goes over the rock the rock passes under your rocker panels (the panels under your doors) this is one of the most vulnerable parts of the body, luckily its also quite a high clearance part.

Approach, Departure, and Break-over Angles

There are three angles you need to keep in mind when offroading, the approach angle, the departure angle, and the break-over angle, they come into play most when going over ledges and ridges.

  • Approach Angle
    The approach angle is the angle drawn from front of the tires to the front bumper.  The greater the angle the steeper the ledge you can go up to without the bumper hitting the ledge before the tires.  If the front bumper sticks out too far it will hit the rocks before the tires have a chance to crawl up.  And going down steep ledges the nose will bury in the ground before the wheels reach level ground.
  • Departure Angle
    The Departure Angle is measured from the back of the rear wheels to the rear bumper.  If the rear bumper sticks out too much the rear will drag in the dirt when going up ledges and drag against ledges after going down.
  • Break-over angle
    The Break-over angle is the smallest possible angle when measured from the wheels to the underside of the vehicle.  If the break-over angle is too small then as your vehicle crests the top of the ledge the vehicle will bottom out on the edge of the ledge.

The taller the frame of your vehicle is the better it’s angles will be so a suspension lift can improve what kinds of terrain you can handle.  A body lift doesn’t have any effect on the angles because the frame and bumpers stay at the same level as before.  Larger tires also get the frame higher but not by much.  If your tire size is increased by two inches your frame will only be one inch higher.

Ground Clearance

That brings us to the issue of ground clearance.  Ground Clearance is one of the most important aspects of offroading, you NEED high ground clearance to make it almost anywhere offroad.  offroad you may come across alot of things that make curbs and pot holes look like a smooth piece of glass.  That’s why you never see a slammed Civic offroad, it can barely make it over a speed bump without scratching its fiber glass bumper on the pavement.

The Xterra has really good clearance for an SUV; compare it to a Ford Explorer or Chevy Trailblazer you’ll see that the Xterra has a higher stance.  Not only that but all the under body components are tucked up higher than the frame rails and cross members; a very good move by the Nissan engineers.

Unfortunately the underside isn’t a smooth line all the way to the back.  Stand in front of the Xterra and look underneath and you’ll notice it’s low points.  The main one is the Rear differential “Pumpkin”; it dangles down lower than the rest of the undercarriage, luckily it’s also one of the strongest parts of the undercarriage.  If it does happen to come in contact with a rock it’s most likely to slide over the rock rather than get damaged by it (unless you’re going way too fast).  The next lowest point is the front leaf spring hangers, they connect the leaf springs to the frame.  Luckily this one is just as solid as the pumpkin.  The next lowest points are probably the oil pan and the frame cross members; the oil pan is a very vulnerable point but it’s nestled up between the two front wheels so if one wheel is up on a rock or ledge the oil pan will be lifted clear.  The frame rails are pretty sturdy on the rare occurrence of you hitting one they will grind over the rock they hit.

Everything else is tucked really well up in the frame.  Since the Oil Pan and the Rear Differential are on the same line going down the center of the Xterra, straddling a rock right down the middle isn’t a good idea.  You’ll also notice that the lower control arms for the front suspension are at their lowest right before they go into the wheel.  Therefore the best point to straddle a rock is about 1-1.5ft. to the left or right of center.  Since the Gas tank for the Xterra is on the passenger side it’s best to straddle rocks on the driver side.  If you have to straddle a tall rock try to have it go right under your seat while you’re driving.  If the rock looks too big make sure you put your tires over it or drive around it if possible; in all cases make sure that you’re going slow enough that if the rock does reach out and touch you you’re going slow enough that it just brings you to a stop rather than rip off the part it hits.

The most damaged part on a stock Xterra is the step rails, people think that they’re strong enough to use as rock sliders.  THEY’RE NOT!!!!  The step rails are made of aluminum and bend very easily, do yourself a favor and take them off before going offroad.  In fact it’s probably best to sell them and use the money you make to buy real rock sliders.  Rocker Panels see alot of action being behind the tires so it’s only a matter of time before the ground or a rock reaches up to them and bends them.  If you’re lucky the step rails will only bend, if you’re unlucky the rails might bend so much they hit the rocker panels and do body and paint damage.  If you hadn’t had them there in the first place the rock would have passed harmlessly to the rear.

Momentum

You may hear a saying floating around 4-wheeling circles, supposedly it came from Camel Trophy trainers:

“Go as slow as possible, but as fast as necessary.”

Momentum is your friend on the trail but speed is your enemy; unfortunately the two go hand in hand, the trick is to find the right balance of both.  On most trails the ideal speed is 15 MPH or slower but that’s only on flat open trail.  On really hard trails or obstacles you’ll be lucky to go fast enough to have the speedometer register movement, that’s why they call it rock CRAWLING.  Since you’ll be going slower than 20 MPH it’s a good idea to be in 4L most of the time.  On obstacles try to keep forward momentum without stopping, you should be going about walking speed.  If you do stop slowly apply gas to get going again, the wheels will easily break free when stopped in low gear.

If you get going too fast on a rough obstacle however you’ll quickly be in a world of hurt.  The bouncing will be very uncomfortable but also may bump you off of your chosen line and into a body snatching rock.  The suspension also doesn’t like speed, remember that your vehicle is resting on springs, going really fast into a ledge won’t seem so bad the first half second when your suspension absorbs the sudden compression but when the springs react their going to launch your front end into the air.  Your drivetrain also hates speed, when the ground is resisting movement with friction on one end and your engine is pumping in power from the other end something’s got to give.  Usually the yard long, inch and a half wide axle sending power to your wheel.

Another bad thing about speed is that it usually means high wheel RPMs, a spinning and bouncing wheel is ripe for destruction.  I’ve seen people get a little too throttle happy and start bouncing.  In the instant your wheel leaves the ground it begins spinning rapidly with no friction, then the wheel hits the ground again.  The sudden shock of a high RPM wheel from no friction to high friction will snap things in an instant.  Sometimes you’re even amazed that anything happened, a wheel won’t be spinning that fast and won’t bounce that high but when it comes down you hear the familiar “ping” or “pop” of something very expensive and important breaking.

Hills and Gearing

Stay in 4L over any rough terrain, you’ll be going slow anyway and having the transfer case in 4L will give you more power when you need it.  4L has the added benefit of engine braking when going down a steep slope.  Engine Braking is the preferred method of going down steep obstacles, it allows you to go slow without the use of brakes.  That will keep the brake lining from wearing as fast; It will also prevent brakes overheating.  When the brakes overheat they fade and don’t work as well or go out completely.  There was a very famous video shown of a Blazer careening down the Lions Back in Moab because their brakes went out.  If they had shifted into 4L and first gear and just used the brakes to keep the speed from being too great the problem would have been avoided.  Another benefit of using engine braking is that it creates a steady pressure based on angle of decent that lowers the chance of your tires breaking free from the ground.

The strange thing about traction is that as soon as you lose it it’s hard to get it back.  So when you lock up your brakes going downhill and slide you’ll have to release the brakes to get the wheels to grab hold again.  Instead when you get to the top of a steep descent, shift into 4L and put the transmission in 1 (AT or MT) then use the brakes for speed control only (listen to the engine rev as you descend, the compression is absorbing all the speed without wasting gas or brake lining).  Don’t use the e-brake, it only affects the rear wheels and if they break free the rear can slide to the side and as soon as you get sideways on this steep hill you’ll likely roll the rest of the way.  When you get to the bottom shift out of 1st and proceed on your way.

Never go sideways along a steep hill, SUV’s are notoriously top heavy and like to roll, that’s why many people want them banned from the road.  But speeding around a corner and rolling isn’t the only way you can roll; as you cross a hill sideways all the weight shifts to the two downhill tires.  Nobody really knows how far the Xterra can lean before if rolls and nobody wants to do a scientific experiment to find out.  I know from experience that they can lean 40 degrees and some say that its possible they can go as far as 45.  BUT THIS IS NOT A SPECIFIC NUMBER!!!  Your center of gravity will be different depending the load that the Xterra is carrying from the cargo on the roof , to the passengers inside, to the amount of fuel in your gas tank.  So whatever you do try to avoid excess roll as much as possible, when you come across a hill proceed straight up it.  When the Xterra goes straight up or straight down a hill it can go many more degrees then it can going sideways.  I’ve seen a couple Xterras roll on their sides but I’ve never heard of one rolling forward or backward.

Water Crossings

Water crossings are a very unique offroading situation but everybody likes to do it because something in our minds think that water crossings are the ultimate in offroading.  But there are some things you have to be aware of when fording a water in the Xterra.  The main thing to remember is that the Xterra isn’t a boat and water isn’t it’s natural element.  You can cross quite a bit but if you make a mistake you’ll end up soaked.

The best thing to do is to check the water depth before going across, and you need to know what the bottom of the water is like before you cross it in the Xterra, there may be holes big enough to dunk the vehicle, or rocks that can reach up and tear open the oil pan.  So if you’re going to cross water get out and walk the bottom on foot to verify that there are no surprises, and when you cross in the Xterra cross in the same place you walked.  Once you know how deep the water is you have to make the decision whether to cross or not here are some things to keep in mind when deciding if the water is too deep or not.

Anywhere past the hubs is when you have to start worrying. First problems is that if water gets in the hub grease it contaminates it and causes wear. Some people change the grease ASAP but I checked mine after a deep fording and the grease was fine. But if you do it alot you should change the hub grease.  Second problem is water getting into the drivetrain components. Luckily all the vents are mounted up high or they have a valve that closes in water so they’re usually ok for fording.

The real limit is the bottom of the doors, you can close all your windows, turn the ventilation on full fresh air to create a positive cabin pressure but it won’t keep the water out if the water is very far past the bottom of the doors.

Plus there’s a whole mess of problems when the water is up to the body. The Xterra will actually start to float when the water gets too high. It won’t float enough to float over the water but it will be enough to cause your tires to lose traction on the river bottom. And it the water is moving very fast it can wash you downstream.

To sum it all up:

  • Water below the hubs is ok, no problems.
  • Water between the hubs and body you need to be cautious.
  • Water up the side of the doors is a cause for concern.

And in any situation don’t go too fast through the water, you should go fast enough to create a small bow wave in front of the Xterra. You shouldn’t be going fast enough to get the water to wash up over the hood.

Emergencies

When you’re offroad you always need a backup plan if anything goes wrong, it doesn’t matter how easy you think things will be, sometimes bad things just happen.  Follow the boy scout code and “Be Prepared” for any eventuality.  The most important thing to do before you go off road is to tell somebody where you’re going.  If everybody you know is going with you tell a neighbor or co-worker; tell them where you’ll be, when you expect to be back, and how long to wait for an answer before they call the search and rescue.  If anything does happen then you have an idea how long it will be before help comes.  If you don’t tell anybody then help may never come; and even the easiest trails can quickly turn to disasters, and disasters can quickly become life and death situations.  Last of all make sure that the people waiting for you are informed when you get back; you don’t want Search and Rescue looking for you because your neighbor didn’t see you pull into the garage.

If you do get stuck you don’t want to rely on Search and Rescue to be your only way out.  After a few trail runs they’ll be hating you because you’ll get stuck a lot; you should have a way to get out on your own.  The best method of getting unstuck is to have a buddy to pull you out, offroading on your own can be very dangerous.  A very important rule is to never go 4-wheeling alone, however it’s the most broken rule there is.  I know it’s tempting to go 4-wheeling on your own, I do it alot too; but take somebody with you if you’re venturing somewhere unknown, and be more willing to turn back if things get a little tougher than you expected.  If you’re alone and you roll and break your legs Emergency Services is your only chance for help.

However a buddy without a rope to pull you out isn’t much help other than he can give you a ride out and bring you back with some gear to fix the mess you’re in.  That’s why it’s best to bring your extraction gear with you, chains for pulling stuck vehicles are helpful, yank straps are better but a little more dangerous, a winch is probably the best extraction tool there is but it can also be the most dangerous.  Check the extraction page for more info.

Being stuck doesn’t just mean being in a mud pit or dangling over a ledge, it can also be any damage that keeps you from making it back.  There are so many things that can go wrong that it would fill a book and being prepared for every eventuality would mean carrying enough tools and spare parts to fill a semi trailer; hardly what you’ll be taking offroad.  The best bet is to bring a few items that are most important and most likely to break.  For the rest of the things that can break down bring things that you can use to jury rig your vehicle long enough to get it off the trail and to a place it can be towed.  Check the page ofequipment carried in my Xterra for things to quick fix most problems.  Check the Jury Rig Page for ideas on how to use the equipment to get you off the trail.  Remember it doesn’t have to perfect or pretty, all it needs to do is get you off the trail without causing too much more damage in the process.

Keep Things Secure

Not long after venturing off road you’ll realize how smooth paved roads are and how bumpy a dirt road can be.  Anything that’s not tied or strapped down is going to be bouncing all over the place.  First off all passengers should be in seat belts, it may go with out saying but often it goes without doing too.  Many 4-Wheel events not only require seatbelts worn but sometimes they require helmets too.  When you’re offroad you’re more likely to be rolled and thrown from a vehicle than you are if you are driving on road so use that seatbelt.

Any gear you may be carrying should be tied down too, first because if you roll all that stuff is going to be flying all over the passenger compartment, second if you go down a steep incline all that stuff is going to come sliding to the front.  And make sure your vehicle is clean from any junk in the passenger area, the last thing you need is a coke bottle rolling under your brake pedal as you start down a steep incline.

If you keep things secure you’ll be alot happier when you get to you campsite or destination and everything is still where it’s supposed to be and nothing is broken.

Shifting to 4 Wheel Drive

The first thing to do when you get off pavement is to shift into 4WD; I know you’re probably saying “Duh” but not everybody does this, some people go by the idea of leaving their vehicle in 2WD till they need 4WD.

This is WRONG!

The first reason is that it damages the trail.  When you’re in 2WD the rear wheels are pushing but the front aren’t pulling; that way it’s easier for the rear wheels to lose traction and slip, and when the wheels slip they pull up a little bit of the trail and fling it off to the side, physically causing erosion.  It may be just a little bit but it makes a difference, especially when everybody does it.  Plus you keep going till you get stuck and for a few seconds you push the gas and try to push over the obstacle in 2WD, meanwhile your tires are flinging huge chunks of the trail all over the place.  This is why you’ll see holes dug in front of large rocks, they just serve to make the trail more and more impassible besides damaging the trail.  And the more aggressive the tire tread the more damage caused.

The second reason to put the X in 4WD right off the bat it that when you do get stuck and come to a halt you’ve already lost your best friend offroading, Momentum.  If you had been in 4WD from the beginning the obstacle would have been overcome as you went over it because you had momentum and 4WD.  If you were in 2WD and got stopped you shift to 4WD, but now you don’t have any momentum to help you through the obstacle.  So you’re better off putting it in 4WD as soon as your tires hit the dirt.

The third reason is Gas mileage.  It’s well know that you get better mileage in 2WD than in 4WD but most people don’t realize that on a slippery trail that isn’t necessarily true.  being in 2WD on dirt will cause your wheels to slip so much that you’re wasting alot of gas and not getting any forward momentum out of it.  If you’re in 4WD the wheels slip less and more of you expensive gas is spent moving the vehicle rather than spinning the tires.

Shifting into 4WD while still on pavement can be a problem too, the Xterra has differentials on the front and rear axles to keep relieve stress on the axle from left to right along that axle but it does NOT have a differential in the transfer case.  This means that if the rear wheels turn more than the front wheels there will be binding along the front and rear drive axles and the transfer case.  If the wheels cannot slip to relieve this pressure the binding will cause the wheels to stop turning, or worse one of the driveline components will break.

On pavement the traction is so high that the wheels might not be able to slip and if you enter a turn with the transfer case engaged the front and rear axles WILL turn at different rates possible leading to damage.  So don’t drive on pavement with 4WD on, not even if the rain is really bad.  The only time I would shift to 4WD on city streets is when the roads become so snow packed that the wheels are no longer in contact with the road (whiteout).  Some people have mentioned rain so bad that it’s needed but it better be 6in. deep because at surface road speeds there isn’t enough time for the driveline to bind and slow you down, it just snaps.

Another thing is to make sure that the transfer case is out of 4WD when you go from dirt to pavement, if you’re accelerating as you shift the stress of the acceleration on the transfer case will keep it from disengaging.  Usually if you coast a short distance it’ll disengage, but if it doesn’t and you make that sharp turn onto the road you can bind the axles that quick.

The Auto Hubs on the Xterra need to be taken care of as you get off the trail too, if you don’t back up enough one or both may remain engaged and clatter till you reverse again.  When they clatter they are trying to engage but aren’t being allowed to which can cause damage to the hub mechanism.  My experience is that the hubs are pretty resilient when locked but they are very vulnerable when in the process locking or unlocking; when locking or unlocking it only takes one time for permanent damage.  The Xterra owners manual says you can shift at speeds up to 25 MPH but this is much too fast in my experience.  There’s usually no reason for you to remain in constant motion as you shift so slow down to 5 MPH or slower to shift then speed back up after the Transfer Case engages.

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