Driving on gravel roads, use 2wd or 4wd ?

[klahanie]

Searched a bit but didn't find this covered.

Curious on what others are using and why. Specifically on gravel fsr, haul roads, resource roads and just plain old unpaved roads. These being the roads found just after turning off pavement, mostly decent surfaces, decent speeds and chance of meeting other traffic - not 4x4 only stuff.

If you have the 4wd option do you use it here or stay in 2wd ? Use it because you have it or save it until ... ??

I know often "it depends" but I'm wondering with all the experience on this board if anyone wants to share their reasons for doing what they do and when. Perhaps food for thought for the rest of us.

~David

 

[pvstoy]

Roads as you ask travel in 2 wheel drive where 4 wheel drive is not nessacery. It is when the road gets a bit ruff and has some hill climbs or grade drops where the tires need more tourqe to keep momentum. That is where you will find ruts and wood-to-doos and road erosion is likely. To keep road damage to a minimum 4 wheel drive will help.

 

[Cayuse]

Most of the time keep it in 2WD until 4WD is required. Exception is if I haven't used 4WD in awhile I might shift into it just to get things moving around and keep the pieces/parts lubricated.

 

[12valve]

I ALWAYS use 4wd for these reasons. The front wheels turn easier, far better steering, far better response. Often if the dirt is loose, the front wheels get pushed forward and the front end is not responsive. When power is applied to the front wheels, they "pull" themselves over bumps instead of being "pushed" by the back wheels over bumps. Much easier on the suspension, far better ride. You will have much better braking. With pushbutton on demand 4wd nowadays, there is no reason not to use it. I do not have push button 4wd, I have to get out and manually engage the hubs, and I still think it is worth it.

 

[DavidGraves]

Hi David

In our part of the world we generally do use 4WD high if forrest roads are steep...even more so coming down for better engine braking.

It would not be absolutely needed but it does seem to minimize road damage.

David Graves

 

[craig333]

2wd unless I feel the need for low range. There are exceptions of course.

 

[OutToLunch]

I drive forest service roads every day in 2WD. Most of my driving is on gravel or dirt. Only change to 4WD when conditions necessitate it, which means deep mud or water obstacle or wet clay surface or six inches of snow or steep climb or similar. I have seen and pulled out too many people who think 4WD will save them or will let them drive fast on dirt, snow, mud, etc. Mostly, it just gets them into trouble. IMHO I think it is more about how you drive and less about what you drive.

 

[Advmoto18]

2x when driving slowly and sight seeing.

4 High if making fast tracks. Much better control on sketchy surfaces. If you begin to slide, much easier to counter steer with 4 High engaged.

Regardless of mode, think about airing down. I air down about 20 psi from 65 psi for long stretches of FS gravel roads. Makes a world difference.

 

[Backroad Joe]

Like 12valve says. I've heard lots of discussion along those lines. Tried both ways. However my Dodge does not like to make u-turns in 4wd. My '68 jeep doesn't even like mild turns as there is a locker up front. Just wants to keep going straight.

Yea, airing down. Now that is what you should be paying attention to.

 

[klahanie]

Thanks all for the comments.

For uphill sections, I'll add that I was told directly that possible, unnoticed wheel slip in 2wd was contributing to my tire wear and chipping - an important cost consideration for me - so now I try to remember for even modest slopes.

4wd for faster driving I understand. And wondered if 4wd always for always having a margin safety would be mentioned in a reply, for that unexpected patch of deep loose, gravel or reactive pull over for that sudden appearance of a industrial truck. I do usually slip into 4wd for an approaching private vehicle - just in case.

I admit to finding it difficult to break my old habit of '2wd until 4wd is necessary' but I have expanded necessary to cautiously prudent. Still not driving 4wd full time, not sure why ... maybe fuel economy or wear ... OTOH I have it, why not use it. That's why I started this.

For downhill, regular speeds not 4lo, I'm usually 2wd, thinking that would save the front drive train from some the jarring. Am I wrong here ??

And what do we think about 4wd for pot hole fields. Helpful or not ??

Thanks,

 

[PackRat]

Hmm...if you are on a familiar road and you know it has no washouts or muddy sections or creeks of an as-yet undetermined depth of water I suppose you can go with 2WD as outlined above. If you are going 25-35 MPH on known roads, sure, why not?

However...if you are in uncharted territory and you are on a less than stellar road surface, maybe some ruts, muddy sections, water crossing or pooling on the surface and it has some ups and downs you expect ahead according to you map....and you don't feel comfortable doing 35 MPH on it....you may choose to chug along at 25 MPH and I see no reason under the circumstances to NOT use the 4WD because those are the very conditions it was designed to help give you traction on.

Then there is the snow factor...which may hide some of the obstacles I mentioned above....that sounds like you need to proceed with caution anyway unless you really do KNOW the road well! In that event, the 4WD will be a good idea as well since you won't be going 45 MPH there either.

The toss-up I think is also affected by how your rig is loaded....heavy on the rear axle? Near the GVWR for the truck? I agree that 4WD may give some people a false sense of security, but you have to use some degree of common sense in any situation based on your truck, the load and the road.

Always better to err on the side of good judgement and SLOW DOWN to begin with and using 4WD is beneficial (read your truck owners manual about it) and when all else fails, time to chain up!

 

[klahanie]

Thx PR.

Just to clarify some pics of the type of road I'm referring to. These might be main lines originally for log hauling or a haul road to a shuttered mine or an active power facility or even a country road. Typically recently maintained, wide, reasonable sight lines, present but infrequent other traffic etc. I know they don't require 4wd because they are often linked to small communities and have seen locals drive them in 2wd cars and vans - prob in all kinds of weather...

But I mean driving in good, dry, warm weather.

ON EDIT: I get it that these a good roads, we've all driven worse. Was just wondering if there was any compelling reason to be driving these, as described, in 4wd if it was available. With the exception of 12valve, it seems most would usually be using 2wd, at least part time.

 

[ntsqd]

Roads like those I'd be in 2WD. Where I make the transition to 4WD depends on a lot of things, not the least of which is my mood. When doing the 40 part of a 4-40 road and its washboard our CTD prefers 4WD, but both my old '84 Xcab yota and our current '88 4rnnr prefer 2wd.

 

[slash2]

My Dad once told me "it takes 4wd to get really stuck" so as a young man I often got really stuck, I figured if you didn't get stuck once in awhile you weren't trying hard enough.

After I "grew up" I would only use 4wd after 2wd was no longer cutting it, then switch back to 2wd as conditions improved.

Now, as an old guy, if the road is level and smooth I leave it it in 2wd, but if it starts to get any washboard I'll air down and switch to 4x4, I feel it improves the ride and I've heard that it helps to keep the washboard from getting worst. If there is loose sand or gravel, steep inclines or just about any condition much beyond smooth and flat I'll just leave it 4wd, I mean why not? It doesn't hurt the car, and I'll never drive enough miles in 4x4 where I'd be concerned about causing premature wear on the drive train, maybe a little worst gas mileage, but come on, a small price to pay for the added control should something jump up and surprise you.

/2

 

[cwdtmmrs]

I do not want to derail this thread, but I've never seen a good explanation of what actually causes "washboard". I've heard tire slip, wheel hop, wind, water and gremlins, but nothing explains (to me) the almost perfectly spaced ridges that go completely across the road for such long stretches,sometimes for miles.

cwd

 

[Vic Harder]

2wd on those kinds of roads. Engage 4x4 to lube all the 4x4 parts occasionally.

 

[rando]

Washboard is caused by the 'skipping' of tires over the road surface in combination with a granular road bed that can be pushed around by tires:
https://phys.org/news/2009-07-scientists-explore-physics-bumpy-roads.html

 

[DavidGraves]

The regularity of washboard is because of the regular and equal energy of the tire, shock and vehicle impact then rebound to and from the maleable surface.

Semi trucks sometimes form "washboard" on asphalt where an initial fault in the road bed is echoed afterwards.

The best vehicle for washboard is a beat 63 Caddy ....let er rip !

One can actally acheive a "float" effect where the vehicle stabilizes and the suspension takes all the action.

I think the very best washboard vehicle ever mass produced is the Citroen 2CV......huge long suspension travel designed for coblestone roads and streets.

David Graves

 

[cwdtmmrs]

Washboard is caused by the 'skipping' of tires over the road surface in combination with a granular road bed that can be pushed around by tires:
https://phys.org/news/2009-07-scientists-explore-physics-bumpy-roads.html

Interesting. How come it is usually seen across the entire roadway? Is it because driver's are always moving over a notch to avoid the ruts that are already there and creating new ones?

 

[DavidGraves]

I think so....that is what I do.

Klahanie...sorry we stole the thread....washboard isn't allowed in the great north, is it ?

David Graves

PS See PM