SELECTING 4x4 ON TAR

I have a Hilux with selectable 4x4 and there has been a lot of debate around the use of all-wheel drive on wet tar roads for safety reasons. Is there any harm in selecting 4H on a wet, tarred road? I understand that 4L locks the central diff? If so, then surely it is not advisable? IAN SHAW Durban

It all depends on the type of 4x4 system that is fitted to your vehicle (please see our technical feature on page 96 explaining the subject and also refer to your owner’s manual). We asked off-road guru and multiple racing champion, Hannes Grobler – now at 4x4 Mega World Zambesi – for further advice:

“A differential on an axle (or transfer case) takes care of the speed difference between the wheels on an axle (or front and rear axles)

during cornering. When driving in 4x4 mode, there must be a mechanism between the drive to the front and rear axles to take up the speed differences between the axles on high-friction surfaces such as tar (even when wet). A differential is the obvious solution, but many part-time 4x4 vehicles also use viscous couplings or multi-plate clutches to engage the non-driven axles (normally rear) when slip is detected on the driven wheels (usually front). Many bakkies (normally rear-wheel drive) with a selectable transfer case have no centre differential, as in the case of the Hilux, but instead lock the drive 50:50 between the front and rear axles when engaged. In these systems, it is not advisable to select 4x4 on high-friction surfaces because it can lead the drivetrain to wind up and get damaged.”