4x4 Dune Driving

[sherqa]

Dune Experts please advise and share your experience Dune Driving, Yesterday I tried Dune Driving, I reduced the Tyre Air to 20 PSI, then change the Gear as Low (the main gear) and L4 the (4x4 Gear), I climbed some dunes but can't climb some, then I change as 2nd (the main Gear) with L4, there was more power and speed after it changes from 1st to 2nd. my Question is will it cause any damage to the Gearbox if use 2nd with L4 or we need to use Low with L4.

 

[Andrew Prince]

Some more details would help - why couldn't you climb some dunes? Not enough power? Tyres digging you in? How soft was the sand? What type/size tyres are using?

20 psi is still relatively high for sand driving, especially if it's soft sand. 12-15 psi is more the mark - just be careful if you go to low pressures that you don't pull the tyre off the rim if you turn sharply under power.
Big strong off-road tyres, particularly MTs do not "flatten" out easily due to their thick sidewalls, so low pressures are needed.
Momentum is all important on dune climbs because you cannot rely on torque and traction to pull you up - sand doesn't offer great traction and torque is sapped by tyres digging in. So you need to choose the right gearing to give you enough speed on the approach to the dune - it sounds like this may have been your problem. If the dunes are big, chances are low range (L4) will be too low to allow you to build significant speed. H4 with centre diff locked is probably better - trial and error will soon show you which combination works best

Your gear selections are unlikely to damage the gearbox - likeliest source of damage would be overheating in dunes!

Cheers,

 

[Toby]

Hi Sherqa,

No you don't have to use L with L4, in fact you certainly won't get enough speed up to climb anything more than a very small dune this way - as Andrew says, momentum is the key. 2, 3 or D would be fine with L4.

Driving for a long time at maximum speed for L4 may risk overheating your transfer case, OTOH, be a little bit cautious about switching to H4 in very soft sand unless you really need the speed - you may risk overheating your automatic transmission fluid and damaging your transmission if the going is very soft for prolonged periods.

All the best,
Toby
1990 HDJ80
1994 HDJ80

 

[scubadec]

Any pictures or videos?

 

[chriscolleman]

As andrew stated 12-15 psi pressure and a little momentum mostly works.
And you can drive at a decent speed.

Just a small question, how do you walk up a dune?
You simply do a charley chaplin and walk up the hill.

If you got the time and aren't driving fast.
Simply let all the air out of the tires and let it idle up the hill everything locked up.
When turning unlock everything and use as much space as possible.

 

[Marius De Kock]

Lot’s of momentum and a bit of speed always helps to get you to the top of the dune. This is the way the guys do it in Namibia. The petrol cruisers always do better at dune climbing over the diesels ones. Keep your tyre pressures very low.

Hope this helps.

 

[Rob Voerman]

With the BFG's I ran .8 - 1.0 bar (12-14psi)

but on the Maxxis I ran at .5 - .8 (7.25 - 12psi) even lower on beach runs ... depending on the sand wetness
the softer and warmer the sand the lower the pressure, avoided sharp turns descending.

tyre pressure is king

 

[sherqa]

Thanks to all of you Friends for your advices, Dear Andrew I couldn't climb only one of the dunes because it was too high, my Tyre Dunlop Size 17", first I tried with Low and L4, so I reached only the middle of the dune and lose the power then I tried 2nd time with 2nd and L4, I almost reached near the top by 2 meters and lose the power, I step off the accelerator before it start digging in the sand and reverse back.

So the momentum is important, I think I will try the next week again with 2nd with H and see how it works.

It is Soft sand here are some pictures of the dunes of Qatar Sealine Beach

http://www.qatarqlick.com/images/storie ... 450013.jpg

http://theqataradventure.blogg.se/image ... 581475.jpg

http://www.pbase.com/archiaston/image/90736493

http://www.pbase.com/archiaston/image/57051661

 

[Graham]

Thats some dune,

I would be rather worried about getting down at that angle and gradient.
It almost looks like the front is ready to tuck itself in deep, and flip over.

Great photos,

Graham

 

[chriscolleman]

Although the landcruiser is a great 4x4 it is designed to wobble through trails with people and gear aboard and even tow a trailer.

For that kind of dune you need to loose all the weight you can, have a tranny that can supplie full hp at every speed, low pressure floatation tyres and a no worries 4x4 system.

For a minimum of gear crunching clutch burning difflock shocking driving and a MAXIMUM of fun you need another kind of vehicle.

google sandrails, Polaris RZR XP 900, Polaris RZR 4, Can-am commander, Polaris XP 850, Can-am Renegade

These vehicle are born from the millitary necessity for a go anywhere fast reconnaissance vehicle.

Our beloved landcruiser is more a United Nations peace keeping and medical supplies delivery vehicle. It wobbles and doesn't break anything inside when driven moderatly.

 

[Andy Harvey]

I did quite a bit of dune driving in the UAE when I lived there in a 4 Litre Jeep Cherokee and the few things I learned are as follows.

1. Power and momentum are key - give it a good run up and keep your foot to the floor - you DON'T want to stop as you will get stuck and not get going again.
2. Air down tyres or use big floaty wide tyres - you want to stay on top of the sand as much as possible.
3. The most important rule - DON'T and I mean really DON'T go across dunes at an angle. Straight up and straight down is the rule. It doesn't take much shift of weight or a bit of a tyre biting on one side to ship the weight and cause you to roll it and once you do, on some of the bigger dunes you won't stop for a long time - a rolling vehicle won't dig in and stop because the sand on the downslope will always give way the moment you hit it.
4. A Petrol LC will be better than a Diesel on Sand - you need more power than Torque to keep you moving at a reasonable speed.

Best truck I ever used on sand was a GMC Yukon with a big block chevy in it and humungous great wide tyres. It might have been heavy but not much more than an LC and the power was amazing, kept that baby floating over the top of the sand nicely.

 

[consigliero]

This something for me . In November we where in Morocco , than we made some dunes trips . Other people give me some advise, when we go alone to Merzouga dune I made 1.8 bar , when we meet French , first what they told is to go down to 1.2 bar (245/75/17 BFG A/T tubeless). Next advise I didn't know if I should run on 4L or 4H , they told for our type of driving we need speed to pass dunes so 4H. Some days later we come to erg Chigaga with another French , we where to long on dunes and we get some problems with his LR . Later I have problem I got stuck than with to much spin I got overheating gearbox , we stay 30 minutes, some stress I got stuck second time . I made pressure down to 1 bar and I drive out . After this I think when you can't make speed enough, is maybe better go for 4L. I think in small areas this tactic can be better . Next day we drove 30 km in the sand but with speed , I made 1,8 bar, because first idea was to go near mountains on stone piste. When we change plan I should made pressure 1.2 then car will drive perfect with 1.8 he drove only because of another big plus which I have , 4.0 l 6V petrol. I always use D
Regards Marek

 

[Andy Harvey]

Yep and you have to factor in different types of sand - wind blown crust, soft fluffy stuff, hard gritty stuff. all takes it's own technique.

In the end the only 100% sure fire rule was the up and down straight, don't go across the fall line at an angle - you may end up very injured and you 4x4 will be a pile of smashed metal. Anything else changes as the sand changes and the length of the hill. Long hills definately require speed and momentum, shorter dunes you may get up in low.

I always think that a good education to dune driving is to watch the guys who do it for a living - those slightly crazy guys who do the 4x4 tours out of Dubai - lots of them in Petrol 80s and 100s. Drive it like you stole it seems to be their motto.