Any ideas why my steering still shakes?

[DrT]

For some time now I've had a problem where if I drive my Discovery over 60mph and I hit a bump (even a cat's eye) the steering seems to go into some sort of resonance and shakes violently. I can still steer and brake but the shaking is horrendous. If I let the Disco slow down of its own accord then at some speed around 40 mph it suddenly stops shaking and returns to normal.
I've replaced the steering damper, replaced the swivel hubs and all the bearings in them. Checked the preload. It still does the shakes.
Any ideas?
Tim

[Snagger]

Dampers and suspension bushes? Wheel bearings, maybe? Or even a bent wheel?

[william_maxwell]

Try changing your wheels around from front to back to eliminate wheel balance etc.

[kevinrbeech]

It is the drag link ball joints. Replace them and it'll be fine.

[DrT]

It is the drag link ball joints. Replace them and it'll be fine.

They are brand new and we've tried putting the old ones back on and it makes no difference unfortunately.

Thanks to everyone for the other suggestions I'll start working through the ideas.

[Batwie]

DrT,
I have exactly the same problem on my 1998 Discovery - have you found the cause yet?

[HPLP]

I suggest readjusting the swivels.
H

[DrT]

No solution yet, we have rebushed everything, swapped the wheels around, changed the steering damper, changed the swivel bearings, swapped the wheels around and it still has the shakes if you hit a bump at over 60mph.

[JimGNR]

I had a similar problem but not as bad as yours, it occurred after fitting a new steering damper, I bought another 2 and still the same problem. Refitted the old one and the problem as good as went.

After advice on here, I primed the damper by cycling it about 20 times in and out before fitting it, that seemed to do the trick even though I had primed it a few times before originally fitting.

[BushMech]

I seen horrendous wobble occur suddenly on a defender and it was due to worn panhard bushes, certain speed, slight bump and the wheels start to resonate until it becomes violent. Ask Toppa he is experienced in this wobble.
If the disco have panhard bushes, then look for cause there.

[jetfiremuck]

Panhard bushes can indeed cause wobble.Unless they are poly they get ruined by oil and flex the axle over and back effecting the steering geometry. Also make sure that all the freeplay in the steering box is taken up.

[camel film unit]

Have you checked the small u/j`s on the steering -- between the steering box and bulkhead??