Thread: D3, D4 & RRS Simpson Dune Driving technique with Auto.

Rich
We traveled through the Simpson last year as far as Poeppel Corner and back to Dalhousie as Eyre Ck was closed. Traveled the French Line, Rig Road and WAA line.
We used both high and low range but considered the D3 gave better fuel economy in low (saw 23 L/100Ks at one stage).
In high range found it was often nessesary to use command shift to maintain the revs and momentem. In low range the auto did the job.
Tyre pressures also come into it, but thats a never ending conversation.
Reading the track ahead is also important but nothing beats actually doing it.

Ivan

Even in winter sand conditions can very a lot. The softest and most difficult part of the crossing is the French Line from Poeppel (K1) to Lindsay Junction heading west. This is the only section that may need low range. I have always used high low tyre pressures.

After my experience this weekend climbing the calcup sand dune below Pemberton, when they are steep as this, high range is completely useless. These are pretty big and soft dunes.

I have only ever been over these dunes in previous cars in high range and low pressures.....around 10-12 psi.

Sand mode, dsc off, high range made me furious with the D4's poor sand climbing performance (I actually thought i was going to have to leave it at the beach and wait for the tide to write t it off.....was pretty angry).. First part of the climb no probs, but then it would kick into second, then lose power, then back to first and would rooster tail, then back to second and lose power again, and so on. Basically as soon as it went to second, it did not matter how hard your push the throttle through the firewall, it would not kick back and would not pick up rpm. Putting it into manual shift made no different at all....it still changed up, and down at the wrong time.

It took me four attempts before I decided to use low range and once i did i then had to brake at the top. The car did what it was supposed to do, and no shifting of gears all over the place at very illogical times.

I became happy again with my D4.....realised again that it need to be driven differently.

This was also the case for a fellow D4 driver. He described it as loosing power.....and it certainly felt that way.

Small dunes no probs in high, but longer ones in low.

Brett.....

I have driven heaps ( no pun intended) on Stockton beach in many 4wds and found the best one was a 79 manual Rangie / modded V8 and 10 psi worked wonders.
I have driven the D3 up there too without any issues.
What I'm really trying to find out is what is the most economical use of the Auto box for fuel economy.

Ensure the use of Sand mode whilst in sand with DSC off?
Use special programs off as much as possible with DSC off? ( Standard)
Yes it all depends on how the conditions are and tyre pressure too.

General rule of 4WDing - if you're going slowly enough to comfortably use low range then use low range. Applies to sand dunes too.

Low pressures really help, and by low I mean 15psi not 25 or 20. The last few psi really do help.

The D3 auto box is a bit indecisve on hills and really needs to have its gear selected for it by the time you reach the hill base.

Last July we spent an afternoon playing on a big dune on a shot line north west of Poepells corner with the D3. After much playing with settings etc I learned a bit about how the truck behaves in sand. I didnt manage to get up on the dune and needed a little tug to get out once on the crest. After having about 8 attempts the most successful method seemed to be to get as much momentum as possible in low range with traction control set to rock crawl, DSC off. Auto or manual didnt make a lot of difference and what defeated me was a loss of power at the top of the dune. I'm still not sure if the power loss was in some part caused by the engine management/traction control or simply not having enough torque off boost but the end result was a stall near the top of the dune on most occasions.
The thing that irked me most was the the 100 series poverty pack made it up in two goes with 7.50-16 tyres.
My pressures were only down to about 18psi and arguably I could have gone lower but we ran out of time for another go once I was at the top and did have to keep an eye on how much fuel we used.

On reflection we didnt try 1st gear high range which might have given some more speed but from my other experience in the sand the traction control seems to work differently in high range and the stalling problem is more pronounced.












Regards,
Tote

The Discoverys do seem to limit engine power in extremis. I have found this on sand, and in mud. Non-electronic vehicles tend not to have this problem and can power through.

I do not believe it is a lack of power, it is the electronics not letting you use it for fear of breaking something.

I found this in a slippery climb recently where the D3 simply wouldn't let me power up the hill, and it wasn't a DSC issue either.

We tend to spend more time teaching people how to drive in sand in these vehicles, than in any other conditions. Success is more dependent on technique than on other terrains, where you can virtually just "point and shoot" to conquer obstacles.

To the OP, if optimising fuel consumption is the primary concern (we were in a similar position when doing the CSR - 1080km on one fill of diesel), then use high range, normal (on-road) TR as much as possible, DSC off and command shift for dune traversals. We ran at 23psi (cold) for most of the sand-dunes on the CSR, which can be steep, but not particularly long. For longer or softer steep dunes, switch to low-range as you approach (you can do it whilst moving at less than 40kph) and auto + sand mode will get you over most. Fight the temptation to bury the throttle in the carpet - the car will NOT respond as you might think. Feeding a smooth progressive increase up to about 3/4 throttle will get you a lot further and avoid triggering the DSC - which will cut in otherwise, even if you have switched it "off".

Cheers,

Gordon