Land Rover Repair: Shudder steering at high speed, wheel bearings, steering damper

Question
Dear John,

My 1997 Discovery TDI300 is developing an unconfortable wobble, at around 60/70+ mph if a small bump/pothole is hit and specially on irregular surfaces, it sends a massive shudder through the steering wheel. This rarely happens below 50mph, although it can still send a shudder through the steering wheel. There is no shudder at all and the truck runs perfect on smooth surfaces.

Just for your information, I have checked the swivel pre-load, changed bearings, panhard rods, tyres almost new, wheel balancing, new steering damper, new shock absorvers, wheel bearings, Steering Ball joints, and rubber suspension bushes.

I have also aligned the wheels set them to total toe +0.5mm

There is only one thing I have never changed, the front springs.

Can you please advise on this problem?
Thanks
Mariano

Answer
You seem to have gone down the list
- swivel loading
- alignment
- tie rod end free play
- bushing
- shocks
- wheel balance

Yet it still shakes.   

You ask if springs can cause the problem.  The answer - only if they are sagged badly.  Is the height correct, and even?  If so, the springs are fine.

There are two possibilities I see.  One is that you have a caster problem which is addressed with different front radius arms or bushings
The second is that some of the work you did - is not done right.

Outside that. you are out of options.   It must be one of those things

John