What you might do with five more gears

KENYA HAS AN exceptionally high proportion of 4WD cars – possibly among the highest in the world.

Many of these are SUVs – fundamentally conventional “cars” designed primarily for on-road use, but with slightly better ground clearance and 4WD grip.  Sometimes handy qualities even in town, never mind on safari.

A fair number of the 4WDs in our national fleet are purpose-built to have fully-fledged off-road capacity – much more ground clearance, more suspension travel,  heavier duty components, bigger wheels with chunkier tyres, 4WD, and “transfer boxes” offering optional selection of very low gearing ratios.

Few owners use these attributes to anywhere near their full potential, but they are generally well understood and they deliver the degree of capacity required by each individual user.  Passively.  Automatically.

On most models, for most users, the low-ratio option is a notable exception.   It does nothing passively.  It requires the driver’s “active” choice and it profoundly changes the vehicle’s behaviour.   Letters, conversations and observations in my purview suggest it is not widely nor well understood.  For those not familiar with this technology, third gear in low range is about the same as a normal first gear, so you can imagine how low  the transfer box makes second, first and reverse! 

SMOOTH DRIVE

Few owners use low ratio at the right time for the right reasons and in the right way.   Many don’t use it at all! 

The most common mailbag question is “what is it for?”  A common notion is that its purpose is to enable a vehicle climb slopes that are so steep that normal first gear does not have the grunt to haul the vehicle up.

Certainly low-ratio will solve that, if the gradient is very steep and too long or too rough to take a run at, and if the ground surface is not so loose or so slippery that the extra force simply makes the wheels spin.   But that is far from the only, or most frequent, or most useful attribute of very low gearing. 

Perhaps above all and most often, low ratio allows you to negotiate all manner of severe obstacles more gently.   Gentler on the engine, the clutch, the transmission, the tyres, the suspension, the bodywork and the occupants.

Even owners who do a lot of motoring in severe off-road (or on-rough-track) conditions rarely encounter situations that physically cannot be managed by their 4WD in high-range (normal gearing).  Yet they frequently use low-range so they can pick their way through or up or down or over problems more surely, more safely, more smoothly because they can overcome the obstacle at less than half the speed.  No revving, roaring, charging, bouncing, scrabbling, jerking, clutch slipping, or stalling.

They know when to use it to crawl over football-size boulders, or ease through a ditch, or scale a near-cliff, or ford very deep water, or ease a car down a slippery bank without using the brakes, or pull a massive load, all in the middle of the rev range, without stress or strain, in the controlled slow-motion that super low gearing allows.

Off-road driving is a balance between power and grip and sometimes momentum.  Low range gearing (in all five gears) offers a whole extra dimension of tools in that quest.  It’s worth learning when and how to use it.  And when not to.