Nissan Patrol 4x4 (Africa)

Gerrit Loubser wrote:.... but if the vibration is like a growl or rumble that is not specifically felt in the steering wheel, then the source is probably somewhere in the drivetrain.

or you've got a lion trapped somewhere under your car and the higher speeds makes him mad.

Checked for lions... nothing.

The vibration is felt more through the seat than the steering wheel.

Then I would search for the root cause in the drive train. Now the question is whether it is coming from the front or the rear and to help clarify this, you need to establish whether it also happens when the front propshaft, ring & pinion and sideshafts are stationary, i.e. when the front autohubs arw definitely disconnected....

Steve, it is obvious what the problem is since the vibration is more in the seat

Jou gat jeuk vir n 4.8 Patrol

Shalom

Guys, could this not be as simple as a propshaft that needs balancing or which has been refitted out of phase or inverted (iow splines on the wrong side?).

Clem, worn universals oe a worn slip joint can aggravate vibrations, but it should not make a difference which side the splined end is mounted. Phasing of the universals can also play a role, but the bottom line is that the suspension and driveline geometries used at the front in the Y60/Y61 Patrol (and SFA Cruisers with coils) is a recipe for front propshaft vibrations if the suspension is lifted; the radius arms ensure that the front axle and therefore also the diff pinion shaft move on an arc as the suspension is lifted. The universal joint at the transfer case end of the front propshaft is forced to accommodate the lion's share of the angular deflection, while the universal at the front diff end experiences almost no deflection angle. The unequal deflection angles at the two universals mean that they are then unable to cancel the cyclic rotational velocities that are generated by each other (a simple fact of the operation of simple Cardan-type universal joints) and the result is vibration (unless the suspension remains standard or is lifted only very slightly, in which case the angle and the vibrations are both negligible).

Fortunately the Patrol is a part-time 4x4, so the front propshaft only needs to be in play when in 4x4 mode.

Gerrit, thank you for the informative posts, both here and on the load - brake force thread.

I can only add here that I would imagine eliminating the front propshaft as a source of the problem should be fairly easily achieved by ensuring it is not turning (or if absolutely essential, removing it altogether).

Re the slip joint, I understand what you are saying. Possibly the slip joint has been refitted one or two splines out of phase and that could cause the issue? Sometimes these vibrations are hard to trace. My old Disco 1 used to do it also at about 120km/h. It was the rear propshaft rubber coupling. It was directional but Land Rover did not know this (and nor did the workshop manual say anything on the subject) and that was the cause of the problem.