4WD selection issue 96 Cherokke

[robbo]

Hi, My son has a 96 Cherokee that he has never had off road he bought it off a family friend who has never had it off road.
We tried to engage 4WD and in Part Time it will NOT turn corners well, slow or fast The whole front end shudders (sounds like the diff is not diffing). In full time it seems to be OK. When selecting Low Range it goes back to part time and violently shudders on corners, but it does seam to be Low Range.

Any suggestions or a Jeep Specialist in Sutherland
Thanks Neal

[glend]

That's normal in Part-time. What he is experiencing is binding. When you turn a corner in a vehicle the outside wheel must travel faster than the inside wheel, this is not a problem in a two wheel (rear) drive as the front wheels are freewheeling. When in Part-time the fronts are trying to drive and the front engaged diff makes the wheels travel at the same speed. In situations where the ground is slippery, wet, snow covered, muddy etc (where Part-time is useful) the wheels will not bind). He should not be using part-time on pavement or hard surfaces it can damage the driveline (full-time is preferred if needed).

[sbadman]

As glend said. Do not use the part time options on sealed surfaces as it will eventually end in a loud bang. Part time locks the centre differential, meaning the front and rear drive shafts are locked together.

In a turn the front drive shaft is trying to turn at a different speed to the rear due to the front wheels following a track with a lesser radius than the rear. Even in a straight line the variations in tyre pressure/wear on each corner can cause problems. On loose surfaces this isn't a problem, as the wheels can 'slip' over the surface. On tarmac the tyres are unable to slip, with the forces being transferred to the uni joints, axles, drive shafts, and transfer case. It then becomes Russian Roulette as to which part is the weakest and goes bang first.

In short, only the green selector positions (2WD and 4WD Full-time) are suitable for use on road.

[robbo]

Thanks, I wasn't on tar or hard road, but a paddock....Maybe not slippery enough. Hopefully no damage

[sbadman]

Thanks, I wasn't on tar or hard road, but a paddock....Maybe not slippery enough. Hopefully no damage

A dry paddock can have surprisingly high grip, especially if the Jeep is fitted with off-road tyres. Our paddocks seem to be perpetually dry and compacted dirt

You son should come along to one of the planned day trips, he'll definitely get a chance to use 4 low then When I bought my XJ it had never even been taken out of 2WD. But they are surprisingly capable machines, it's a shame not to use them off-road!