Diff lock
makes the difference uit Leisure Wheels; 23; Jul - Aug - Sep 2003
Text by Braham van Zyl
Driving
differential-lock equipped two-wheel drive vehicles off the beaten track or even on
off-road 4x4 routes is a new concept waiting to be explored by adventurous owners of these
vehicles. But there are a few things to keep in mind.
Sales
of raised-body bakkies with the aggressive looks of a four-wheel drive vehicle, but with
two-wheel drive, differential lock and a more attractive price, are on the increase. And
for owners of these vehicles, there are new off-road opportunities opening up.
The
greatest advantage of this new generation of off-road vehicles is perhaps its ability to
handle dirt roads better than sedans. So owners of raised-body 4x2s can get to remote
guests farms much easier than people with low-slung passenger vehicles. And while on the
farm, they could use the opportunity to test a few of the easier 4x4 trails.
By
knowing what a differential-lock is and following a few basic rules, 4x2 drivers are able
to tackle many a route previously rated for 4x4s only.
So, what is a
differential lock, or diff lock for short?
In
layman's terms it is a device that locks the two independent rotating sideshafts of your
vehicle's rear axle into a solid steel bar, allowing both rear wheels to turn at the same
revolutions, for equal traction on each wheel.
The
driver can decide for himself when to engage or disengage the diff lock, but some of the
older models feature a partial locking devise incorporated in the rear axle, called a
limited slip diff, which automatically sends a portion of the torque to the wheel that’s
not spinning.
It
will take you some time to get used to the vehicle's steering action when the diff lock is
engaged, as it tends to understeer somewhat – thus trying to move in a straight line
rather than following the direction you’re trying to steer it in.
The
most important rule in 4x2 off-road driving is not to attempt a trail alone. Always have a
companion vehicle or two along, and be prepared for emergencies.
For
instance, few of today's 4x2s have proper recovery hooks. Fit them to the front and rear
of the chassis before you do any off-road driving. Never attach a tow rope to the ball on
the towbar, however, as many a case has been reported where that recovery rope has snapped
the towball right off.
Do
not be surprised, but the most important recovery tool is a spade. It is surprising to see
what manpower and a spade can achieve when you get stuck. We have recovered many a 4x2
with only a spade, the vehicle's standard jack and lots of commonsense.
The
second important rule in 4x2 off-road driving is to walk a difficult section of the trail
if you aren’t sure if your vehicle will make it. Rather play safe, than get stuck or
damage your vehicle.
The
biggest secret of driving any off-road vehicle is in the grip of the wheels. Deflating the
tyres improves l traction in off-road conditions. You only need to deflate a 4x2’s
rear wheels, as opposed to all four on a 4x4.
It
is not easy to recommend tyre pressures for every occasion, as not all tyres perform the
same at the same pressure. Therefor you will have to experiment to find the best pressure
for your type of tyre.
But
as guideline - in sand the minimum pressure is 0,8 bar. On shale you need at least 1,8 bar
to protect your tyres from the needle-sharp rock ledges that can damage the sidewalls,
while you can go down to 1.2 bar on sandstone terrain.
Extra
weight above the rear axle will also improve grip. It not only prevent excessive wheel
spin, but will also improve vehicle stability while driving off-road. We use sandbags,
which are usually filled at the route we are doing.
By
deflating your 4x2's tyres and adding extra weight on the back you will minimise spinning
of the wheels and your vehicle will be able to climb most of the hills a 4x4 can manage.
As a
4x2 does not have a low-range gearbox, you don’t have the same amount of engine
breaking and cannot go down declines as steep a 4x4 can. The problem is that the front
wheels will lock if the brakes are applied on too steep a decline, sending the vehicle
into a skid.
If
things get tough going down, use the handbrake and apply less pressure to the brake pedal.
However, rather play it safe and stay away from routes with steep downhills.
Trying
to see what’s going on in the road a few meters ahead while concentrating on driving
at the same time take some practice. So you have to decide what to do at an obstacle
before you get there. The eye-feet co-ordination needed on a hiking trail, also applies to
off-road driving, except that your boots are replaced by the vehicle's steering wheel and
foot controls.
Take
your left foot from the clutch pedal as soon as the vehicle starts moving. In off-road
driving you tend to be nervous and normally keep your foot close to, or on the clutch.
Make it a habit to push your left foot back towards the seat instead of keeping it too
close to the foot controls. If your depress the clutch when the vehicle stalls on an
incline or decline, it will start rolling and you could lose control. Rather let it start
with the clutch out. In which case you merely turn the ignition key in first gear until
the vehicle starts moving again.
Two
wheel drive vehicles do not perform too well in sand or mud. Rather avoid soft sand and
deep mud and use the vehicle for exploring the back roads of the countryside where you may
be surprised by many an undiscovered gem.
More
and more travel and off-road magazines nowadays include information about 4x2
opportunities. A Cape Town based tour operator, Eksplôr SA, organises special trips for
these vehicles. Information is available on website www.explore-sa.com,
or phone 021 975 6531.
EDITOR’S
NOTE
Many trail operators discourages two-wheel drive vehicles on their routes, as the rear
wheels tend to dig holes and damage the tracks. The lack of low range also means that some
obstacles have to be tackled at speed to get through, which could mean damage to the
vehicle. Make sure the route is suitable for your vehicle before driving all the way
there, only to be turned away. |
