Proper Technique?

[R_Lefebvre]

Ok, total newbie question here...

Two weeks ago I had the truck out on a pretty rough logging road. Well, it had degenerated into a river bed actually. It was the most technical thing I've been on to date. The surface was basically head sized to 12-16" sized field stones. Some of them wet.

I navigated around the biggest rocks. I put the tires on the 12" rocks. I was in low range locked. The truck has decent power, but it was still kinda hard to get it go over a 12" rock. I'd slowly ramp up the power, but then it would want to shoot forward once the wheel is over.

I ended up using my left foot on the brake lightly, and right foot on the gas. I found dragging the brakes a bit sometimes helped with traction, but it also helped control the truck so I didn't come down hard on the other side. I was taking it very easy, not wanting to brake anything.

Is this the right way to drive on this surface? I was mainly concerned about braking an axle or coming down on the rockers which don't have sliders yet.

What about when you're trying to get over something, and various wheels are "ratcheting" as they slip-grab-slip-grab. I'm not talking about hammering on the gas, just gingerly trying to get over something and sometimes the tires "ratchet" is the only way to describe it, sometimes they hop a bit while this is happening. Is this going to break an axle, or is going to be fine with my small tires? (31.5")

Also, what's the best way to cross a small ravine which has gouged a ditch across the road?

The area I'm driving in is full of logging roads that used to have heavy trucks and such, but once they finish logging and area, they quickly fall into disrepair. There are tons of ATV's in the area that use them, and the surface tends to suited to them. An ATV would have no trouble getting across these ditches, but the depth and steepness seemed like it would be impossible for my truck. I'd get hung up on the breakover, or the departure with the long tail of the D2. When I reached this obstacle, I turned around, not having a winch or anything yet.

Is there any trick to getting through something like that? I figure bridging ladders would help. This was too big to span the entire thing, but I've seen them used flatten out the bottoms of these ditches.

 

[jcbrandon]

You're on the right track with the two-footed technique. Controlling your speed is the key to avoiding damage. If you get up on one of those rocks and it rolls over, chances are very good of hearing very expensive noises from underneath the truck.

First step in crossing deep ruts is to approach at an angle. That way three tires are in best contact while only one struggles at a time. But you probably already knew that.

If that technique is not enough, you have to overcome the limits of your approach, departure, and breakover angles. Sometimes, a bit of momentum will do the job. Danger there is that if momemtum is not enough, it is probably the wrong thing and you risk getting stuck bad or damaging the vehicle. So best to practice in a safe spot or with a recovery vehicle nearby.

There is no shame in a bit of roadbuilding. Amazing what a few rocks in the bottom of a gully can do to overcome inadequate geometry. There is almost always something you can stack in the bottom of the rut: rocks and logs are everywhere. Trail protocol in most areas is to unbuild your road after you have finished using it. Leave no trace for the next explorer.

About that ratcheting sensation. Sounds like you are describing a tire just on the edge of the limit of traction. It slips then grabs, then slips again. So you need to increase traction. You do this by reducing tire pressure. Softer tire equals larger contact patch which equals more traction. Downside is slightly reduced ground clearance. Also the necessity to air back up when you return to pavement.

The first time I saw the air down technique I was amazed. An instructor told me to air down the 31 by 10.5s on my 5,000 pound truck from 40 psi to 15 psi. To me that sounded a lot like a flat tire. But I trusted his judgement. And learned quickly. A soft tire will caress a rock like an abalone. It is a thing of beauty. Get yourself some sort of onboard air system and start airing down. You will go places in comfort and security that you cannot get to now.

 

[LC/LR4Life]

One thing I like to do is ease my tires up onto rocks to the point I am not rolling forward or backward, then feather forward, and use the brakes to ease down the other side.

 

[Christophe Noel]

This is also where that little bit of lift helps. The factory stance on my DII had me challenged by even modest sized rocks. The lift doesn't help get on top of the rocks, it just adds a tiny bit more lattitude should you make an error. At least that is what my dented lower door panel tells me.

 

[madizell]

Manual transmission or auto? Technique is similar for either, but responses to throttle input varies between the two and to some extent can account for the buildup and release of motive force.

Also, how low were your tires? Some of the difficulty in climbing over rocks is attributable to too high tire pressure. In rocky terrain as you describe, air down. This allows the tire to acquire the rock you are climbing without actually tracking the rock surface the way a hard tire has to. The softer tread also changes the climb angle getting up the initial face of the rock making it easier to climb over.

Best way to get your technique down is to practice. Drive a stretch, get a feel for it, then air down 5psi and try again. You will see the difference.

For what it is worth, I rarely two-foot any vehicle, but prefer to use controlled momentum to achieve the same result, and probably drive faster as a result, but also work the suspension harder. It is just what you are comfortable with.

 

[stevenmd]

Shift the TC to low so you keep the RPM's high and the power to the wheels constant. While in low you will be able to have instant power to the wheels without the lunging forward that you have when the torque builds up with the TC in high.

Combine that with airing down and a 2" lift, you will go a long ways.

 

[R_Lefebvre]

For the deep ruts... it's not really a rut I'm talking about. It's a large ditch, or ravine. We're talking... probably just wider than the truck, and half as deep. So as you can imagine it's a pretty tricky obstacle. I think there used to be a log bridge on it, but somebody pulled the logs. Probably the logging company to avoid liability after they leave the area. I actually had an old log bridge collapse under me on my motorcycle. Didn't fall too far, but the bike wedged between two logs and I had to hike home... not cool. Anyhow...

For the road building, is it a big deal to leave the improvement if it's on an old logging road that's heavily traveled ATV route now? Seems like... this ain't a pristine wilderness as it is. :roost:

The tire pressure I was using was 25. I could probably go to 20. I'm rolling around on 15 while doing landscaping in my yard, trying to protect the grass, but that would seem too low for these tires on rocks. The sidewalls are really exposed. That's one limitation I have with the 245/75/16 S/T-C's. They really expose the sidewalls.

I'll take a pic with the 15 psi so you guys can tell me if it's ok to drive around in rocks like this.

This truck is a D2 with an auto... I actually really like the auto in this. I prefer manuals in my cars, and understand the desire in the off-road trucks too. But, what they've done with the D2, I think the auto is better now. In low range, you can push a button to be in manual mode. Now whatever gear you put it in is absolutely the gear it stays in. I can leave it in 1st on rocks, I like to leave it in 2nd on softer ground, 3rd on trails and 4th, for dirt roads. Also, the Hill Decent Control replaces the 1st gear engine braking from a manual pretty well. And then the advantage with an auto is, it frees up your left foot, and you never have to worry about stalling. Also, the torque converter at full stall will give you more wheel torque in a gear than you'll ever get in a similarly geared manual.

I have an ARB bumper arriving next week, along with an OME lift, and I already have an EP9 winch waiting to go on.:elkgrin:

I think the only really critical thing I'd like to get on there is diff guards.

The TC was already in low.

 

[jcbrandon]

For the deep ruts... it's not really a rut I'm talking about. It's a large ditch, or ravine. We're talking... probably just wider than the truck, and half as deep.

Depending on the slopes in and out, this might be the limit for your vehicle as it is set up. Down into a ditch and then back out again is a challenge. If the ditch was carved by water, the sides will be pretty steep. All you can do is improve your approach and departure angles.

For the road building, is it a big deal to leave the improvement if it's on an old logging road that's heavily traveled ATV route now? Seems like... this ain't a pristine wilderness as it is.

It is a judgement call. You might ask yourself how you would feel if you came up on an obstacle that had challenged you in the past only to find it had been "improved" by someone else. And, just for the record, the word "wilderness" has a very specific meaning when it comes to off-highway travel. Wilderness areas are off-limits to motorized vehicles. It's a hot button. Using the term accurately contributes to more productive conversations with folks who would like to see all motorized vehicles banished from the backcountry.

The tire pressure I was using was 25. I could probably go to 20. I'm rolling around on 15 while doing landscaping in my yard, trying to protect the grass, but that would seem too low for these tires on rocks. The sidewalls are really exposed. That's one limitation I have with the 245/75/16 S/T-C's. They really expose the sidewalls.

You could probably go lower. My Dakota has 31x10.5x15s. The truck weighs 5,000 pounds. My trail air pressure is 15 psi, compared to 40 psi on pavement. I go to 10psi for deep soft sand. Your Discovery weighs about 4,700 pounds. Your tires are about the same diameter, one inch less wide and on a one-inch larger wheel. And there is a huge difference in contact patch between 25 psi and 20 psi. I suggest experimenting with slightly lower pressures at first. You might try 18 psi to see how it works and feels. A few experiments will help you determine the sweet spot.

Good luck, and let us know how it goes.

 

[R_Lefebvre]

I got some pics I will post up later. I might try 15 front and 20 rear next time, as the rear axle deflects much more than the fronts.

The area I'm talking about... it really isn't wilderness. It's near cottage country and the land is "used". Logging roads running everywhere, not any kind of national park. The trail I was trying to drive on was an old logging road, and then they used it to bring in an old fire watch tower to put on top of a tall hill overlooking the cottage area.

I'm kinda blessed with a cottage in Quebec. The people of Quebec don't seem to get too tree-huggerish. The land has been logged for 400 years. Sustainably. It isn't being harmed long-term and I guess everybody knows it. I dunno, attitudes are different in Quebec and it's hard to pin down why exactly. Maybe because they have SO MUCH land it's nuts.

It's not like in Ontario where the tree huggers are trying to get a county forest near me closed to ORV, even though the forest is actively logged and most of the trails are logging roads.

The biggest problem I have in Quebec is the ATV clubs staking claim to every old logging road or pre-existing trail they can, and blocking access to trucks and motorcycles. Pain in the butt.

 

[Lynn]

My personal feeling on the mini-ravine:

If it is naturally-occurring, leave it alone or remove whatever put in. If it is, as I suspect, an erosion ditch perpetuated by the logging roads, then 'rolling a few rocks into it' and leaving them is fine, and might actually help curb the erosion.

 

[Pskhaat]

A few things people have touched on:

Both brake and throttle application have a slight yet somewhat appreciable effect on the axle open differentials effectively giving them a touch of TBR (bias).

A good technique IMO for any bump-obstacles are to maintain a low-enough gear to put your RPMs higher than your torque curve (why I love low-curved inlined engines) and allow the engine's torque rise to assist you more smoothly over them. The key is to increase climbing torque at the same time slowing down rather than to try and increase your engine in order to climb the same which causes you to rapidly adjust speed when cleared.

Don't allow your truck to hop or your tires to bark like you describe; loss of continuous traction and gigantic force deltas in axle components lead to failure.

 

[sinuhexavier]

The internet is the wrong place to be asking about techniques... You will receive 20 different opinions and boggle your mind. Experience is, of course, the best teacher, so go buy some and take a class and save yourself the headache.

In lieu of a class you should just get out there in as many situations as possible and figure it out. After all, experience is what you get when you don't get what you want.

 

[R_Lefebvre]

Not sure if the Bill Burke thing would work out for me, since I'm in Canada.

But there is one of the Land Rover Experience things nearby, not sure if that is worth the cost?

 

[sinuhexavier]

Unless you have someone with more skills than you that allows you to tag-along, IMHO you are opening yourself up to bad habits.

Canada isn't that far from some of his Eastern locales...

I was fortunate to hook up with some very experienced drivers, Marc Olivares, Steve Rupp and Rob Davison who have taught me everything I know. Although I would still like to take a proper class from Bill Burke, if not for the experience, for the fundamentals that sometimes get passed up in real world events.

 

[R_Lefebvre]

There's a Land Rover club nearby that I'll likely be joining, once I figure out if it's worthwhile. I've also been out with some local Jeepers but I try not to learn from them (using reverse gear and burning the clutch while trying to winch somebody else out of a hole)

:xxrotflma

Are Bill Burke's videos good?