Thread: High Speed Vibration 93 Disco and RR Classic

Have you checked the simple things like out of balance or out of round tyres?

Sure have BJ.......
All the logical stuff have been checked and or changed and or adjusted.
Problem still the same.
It seems to be coming from the front axle assy but the speed of the vibration is similar to that of a bad universal or two... All are new in the rangie and in top condition in the Disco.

Shirl..

Next to check is the swivel bearing preload. A common problem.

Hi Langy,
We had the swivel pin preload adjusted on the Disco only about 6 months ago as it was shaking wildly in the steering and several shims were removed, howver this has not stopped the vibration, which feels to have a frequency far greater than that of the axle.
The vibration seems to be a fast as the rotation of the prop shaft, possibly making the problem ether related to the differentail or even the transfer case components.
If I remove the front propeller shaft, the vibration ceases (in the Range Rover) as it has a viscous Differential in the transfer case.
Do you think that this could be damaged?
Regards,
Shirley..

It sure sounds like uni-joints.

When the joints were changed on the rangie drive-shaft, is there any chance the someone re-aligned the front and rear yokes?

They are supposed to be out of phase to compensate for the un-equal operating angle (due to front diff pinion not being parallel with t/case output shaft.

Edit: When the viscous coupling fails, it is usually to mode that doesn't give slip. This will give wind-up - I'm not aware of this causing vibrations like you described - others will know more about this than me.

The disco has an LT230, which has common bevel gears in the centre diff - these are reasonably reliable, but excessive wear of the taper roller bearings on output shafts could lead to vibrations.

And if you raised trhe Disco's suspension by 2" the front shaft (with narrower unis than the RR) will be at the limit of it's useful deflection.

Means lowering it again, or getting on to www.tomwoods.com.

As for the RR, dunno. Might just be old.

One thing to try, is spin up the wheels to see if they are out of round. Used to have to do this with early Magnas. The damn tyres would balance up fine on the balancer, but put 'em on the car and it would drive like crap. But be damned careful when doing this. Use vehicle stands on both ends (no wheels on the ground) and engage the park brake to lock off the back wheels. Do not lock the centre diff and start the test VEEERRRY slowly..........

No, that's not it.

No John, that's not it.
We replaced the entire shafts with new factory parts, even replaced the nuts and bolts.
Just running out of ideas.
Thanks anyway,
Shirley.