Nissan Patrol 4x4 (Africa)

My Patrol has a OME lift and approaching 100km/h there is a high frequency vibration that suddenly smooths out at 100km/h. I still need to have wheel balancing checked but I doubt it is that as I have run slightly different tyre pressures and the speed that it occurs is exactly the same.

Is that a symptom of drive shaft angles with the lift or is it an unbalanced shaft?

Biggles, is this with the front hubs engaged (i.e. front propshaft spinning)? The Patrols often have a bit of a front propshaft rumble, when lifted. At low speeds in the rough when 4x4 mode is engaged one does not really notice it, but on the tar at higher speeds it is noticeable. This is due to the fact that the radius arm front suspension rotates the front axle when it is lifted and this means that the front propshaft does not meet the flanges on the transfer box and front diff at equal angles.

Matters can probably be improved by resetting the front axle angle after lifting (by using different radius arms, castor correction bushes or by modifying the radius arm mountings on the front axle) or by fitting a double Cardan joint to the front propshaft at the transfer case end, but it is probably not worth it, as you normally run in 2H at high speed on tar in any case.

The classic scenario where the front propshaft vibration is felt is driving back home in 2H after using 4H for a bit. The autohubs engage the first time 4H is selected and then remain engaged until the vehicle is reversed in 2H, so unless this is done, the wheels are still connected to the front side shafts, crown wheel, pinion and front propshaft and the whole lot spins (being driven by the wheels despite being in 2H) and generate vibrations all the way.

PS. When driving a trail, always ensure the front-hubs are in the locked position (use a wheel spanner) this will prevent the drive-train from temporarily unlocking when you reverse/roll back

Yes, the AUTO position of the hubs is fine for light duty use, but when the going gets tougher, it is best to select the LOCK position to prevent the generation of shock loads due to unlocking and relocking when torque reversals are experienced.

Hubs are def on auto. I did not lock them when on the trail. To be honest I wanted too but forgot and then i remebered it was going so well i did not bother, I did not feel that they unlocked at any point.

So eliminating the front propshaft would leave rear propshaft balance?

Me thinks it could be a bearing setup problem . Wheels wabble a bit . Take for balance check bearing set up ....

biggles wrote:My Patrol has a OME lift and approaching 100km/h there is a high frequency vibration that suddenly smooths out at 100km/h. I still need to have wheel balancing checked but I doubt it is that as I have run slightly different tyre pressures and the speed that it occurs is exactly the same.

Is that a symptom of drive shaft angles with the lift or is it an unbalanced shaft?

Hi Biggles, First of all did the OME suspension lift give you more then a 40mm lift, I know on some cruisers if you do a lift and it is between 40-75mm lift you wil expierrience a vibration on +- 100km/h and there for you have to replace the caster bushes wit a caster correction kit, we do find these problems on 1 ot of 5 cruiser, you can also let someone look at the universal bushes on the front propshaft , as soon as you change angles on the front propshaft the universal bushes take a lot of strain and due to the angle of the propshaft the universal bushes don't last,

Kind Regards
Riaan Harding

Me thinks it could be a bearing setup problem . Wheels wabble a bit . Take for balance check bearing set up ....

biggles wrote:Hubs are def on auto. I did not lock them when on the trail. To be honest I wanted too but forgot and then i remebered it was going so well i did not bother, I did not feel that they unlocked at any point.

So eliminating the front propshaft would leave rear propshaft balance?

Are you sure that the front propshaft can be eliminated? As I said, the front propshaft is spun by the wheels, even in 2H if the autohubs are locked, as they would be if 4H had been engaged and the vehicle had not been reversed since disengaging 4H.

Is the vibration felt at all times and specifically also when you are positively sure that the hubs are disengaged? If so, then the front propshaft is probably off the hook.

Tinus lotz wrote:Me thinks it could be a bearing setup problem . Wheels wabble a bit . Take for balance check bearing set up ....

Biggles, can you feel the vibration in the steering? If so, it might have something to do with the wheel bearings or king pin pivots, 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.