4 Wheel Drive System

[Guest]

Have just experienced an unusual phenomenon in a 4wd vehicle.

Road was damp and I pulled out of a side road into a gap in the traffic accompanied by a lot of wheelspin from the front wheels. (Landcruiser Prado 3.0 LWB)

How does the normal 4wd system split the power between front and rear?

By moving the 4wd lever into the 4HL setting what will I achieve? Locking of centre diff or equal power split between front and rear or none of these?

Thanks for any info.

Steve H

[Scot]

I cant really answer to acuratly, but here goes:

*How does the normal 4wd system split the power

between front and rear?

On most systems its somthing like 40:60 biased towards the rear.

*By moving the 4wd lever into the 4HL setting what will I

achieve?

This as far as i know changes the ratios, so rather like a bike, if u change the gear, on the pedals, it gives a whole new set of ratios to the ones on the back wheels.

So H is for high ratios, like normal cruising, and L is for low, to go slow down steep declines, or power up inclines in fields and mud etc.

*Locking of centre diff or equal power split between front

and rear or none of these?

When u lock a diff, it stops any slip. When a car corners the inside wheel has less distance to travel as opposed to the out side... like runners on a track (the grids are ofset to make them run the same distance) If the back axle was locked, both wheels would travel at the same speed so youd end up with massive tyre wear because the inside wheel is being forced to travel at the same speed as the outside wheel.

This is why road cars have diffs that only send power to the easiest wheel to spin (ie the outside wheel on a corner). But the flip side of this is that wheel spining is easy, so performance cars are fitted with LSD's with clutchs in the to stop to much slipage.

So a diff lock will send power to each wheel equally. This helps when you are stuck in mud, gravel, and general offroading, but if you used this on the road you would end up not only wearing out the tyres, but reducing fuel consumption, and putting excess stress on all related componants.

Hope this helps, but it all should be in your manual.

Is it permanant 4wd? were you on a slit gradient? its nothing to worry about though.

[Scot]

Oh Steve, please could u put your location on your profile.