Driving FJs in sand
There's a lot of discussion in various posts regarding driving FJs in sand.
It's something I've done once or twice, so I thought I could share some advice, and consolidate the discussion.
All about sand...
Sand isn't really that difficult once you understand it, but of course there are a lot of different factors:
- Grain Size
- Moisture Content
- Pack Density
Let's start with grain size. Sand can range from a talcum powder like dust to gravel, and there is always a mix of grain sizes in any one location, and they can vary wildly within a couple of meters depending on deposition (wind, water, gravity).
Moisture content - from bone dry to waterlogged. Generally, the finer the grain, the more effect the moisture content has on its drivability.
Temperature mostly affects moisture content. Hot desert sand is dry, and has very little adhesion. Even if the sand is packed hard, it will loosen up very easily.
Gradient - the steeper, the harder it is to drive on it, but gravity can also be your friend.
Topography - from flat sabkha to beaches, to gatch tracks, to small technical dunes to monster dunes, bowls, slip faces.. the list is endless, and so are the techniques for driving.
Pack density is like snow and is affected by grain size mix, temperature, moisture content, and deposition method. E.g. hot, fine grain wind blown dust in the bottom of a bowl or on the Lee of a dune will drag you down to your floor pan in a nanosecond if you're not switched on mentally (or inexperienced).
On sand, weight may be a major success factor, depending on the conditions, but in general, a light vehicle will perform a lot better than the same vehicle with an extra tonne of crap in / on it.
Weight distribution. This is not unique to driving on sand, but excessive weight up high is not ideal. The lower your centre of gravity the better. If you must carry additional water, etc, put it in the footwells rather than the roof rack. Roof top tents are not ideal for dune bashing.
Suspension. When doing a suspension lift, only lift it as much as you need to stop the tires rubbing the inside of the wheel arches on compression. The height you need to lift will vary depending on spring rates, weight, etc. On sand, it is my experience that softer springs & shocks are better than super stiff, but the damping still needs to be effective - the vehicle shouldn't bounce after compression - you'll get seasick and your axles will bounce under power, which is no good.
Tires. These are an integral part of your suspension. The most important parts to consider are sidewall height & sidewall stiffness. Some brands are better than others on sand. The generally accepted kings of sand are Yokohama Geolandar AT, and Cooper Discoverer AT3. LT grade tires have stiffer sidewalls for greater weight, and generally aren't needed for our types of vehicles. P rating is better in sand. MT tires are usually super stiff, and not as good as AT.
Remember the width of the tire is not what helps flotation, it's the length of the contact patch that's more important. Think tank v steam roller. On the FJ, 285/70R17 or 285/75R16 (a shade under 33") is a good size - balancing diameter, and minimal rub, and on road performance. Pressure will vary based on the sand conditions, but 20PSI is a good starting point. You can safely go as low as 12 PSI on the front before risking a pop-off depending on your driving style. The rear tires can go a few pounds lower if necessary.
Armour. Less is more. On the FJ, the main vulnerability is from the radiator to the first crossmember after the engine. There is no need for transmission skids or fuel tank skids or rear diff skids beyond the stock items. The front skid will get fairly battered, so 10mm aluminium or equivalent steel. My last front skid was 8mm aluminium, and it had to be replaced after 3 years of use. Most of the damage was done in the year before I lifted the suspension & fitted larger tires.
Front, rear bull bars, sliders - not needed. My plastic bumpers covers are still fine(ish).
I had factory side steps on the vehicle when I bought it - they just grabbed the sand and made it harder to dig under the vehicle during recovery, so they went the way of my stock rubber & suspension.
You may have a need for a steel ARB bull bar (animal strikes mostly), but sand isn't a reason for it. There's not much risk of animal strikes here (If I hit a camel, then I'll need more than a bull bar. Those things are massive), and I don't have a winch, so stock works fine for me.
Long handled shovel
Snatch strap & selection of steel & soft shackles
Hilift jack with offroad base and lift mate
If you're on your own, the above would be the minimum and doesn't include safety equipment. The snatch strap can even be used without another vehicle if you're careful!
When stuck in sand, stop before you bog yourself to the frame rails. Get out and have a look around before proceeding.
Are you hung up on something? Are you fighting gravity? How's your tire pressure?
If you still have downward pressure on your tires, dig the sand out from in front and behind ALL tires. Drop your tire pressure to around 15 PSI in front and 10-12 in the rear. Lay the maxtrax out in the direction of travel (Downhill. always downhill. Gravity always wins), and kick them down under the tire.
select low range & lock everything that can be locked (centre diff, rear diff, ATRAC on), then have a go at driving out. If you bog again, repeat unless you're on the frame rails. Then it's time to bring out the big guns...
If the sand is touching the bottom of the vehicle/frame rails, then unleash the Hilift...
To be continued...
Last edited by amaclach; 07-11-2019 at 08:23 AM.