98 D1 stock setup. I have been chasing massive death wobble for some time now. Replaced the track bar, panhard bar, new shocks all the way around, new power, steering gearbox, swivel preload checked, new front wheel bearings, and I’m still having an awful problem. It is so violent that it breaks the poly bushings on the panhard bar in half when it happens. Here is a video I took, it seems like there’s still a lot of lateral movement. Radius arm bushings?

 

It's usually the Johnson Rod

 

wish it was that simple!

 

You need to replace your front radius arm bushings. you can purchase them from lucky8. Front Radius Arm Bushing Set x4 – Lucky8 Off Road

 

Sounds stupid, but check tire pressure. too much air will make it shake, stay around 30-35 psi

 

Not stupid at all..in fact it got somewhat better when I lowered it..but it’s still there. It is violent when it happens. White knuckle time.. and like I said, it’s violent enough to split the poly bushings on the pan hard bar

 

I'm sure you tried the switch tires front to back routine, but I gotta say it.
fought this on my 1st D! and I even swapped out the front axle and found out lowering the tire pressure did the trick. Tire shop put 45 PSI in the tires, made it ride like it had solid steel tires.

 

That sucks! You've done a lot. I'll list some things below...but they may/may not apply since you may have done more than you listed.

Wheel bearing play? How much bearing free-play is there when wiggling the whee/tire, after you installed the new bearings? I go tighter than L/R suggests...with a very small amt of bearing play.

New Shocks: Just curious what you installed? And have you re-checked the bushings to be ensure recent shaking hasn't damaged them?

Wheels/Tires: Have you put it up on jackstands and run it in drive....and observed the wheels/tires? Make sure there isn't a bent rim, or out-of-round tire? Feel the tread surface with your flat hand to make sure there isn't a bulge or broken cord? Or some other issue like a warped mounting flange which might make a wheel wobble in/out as it rotates? For example I have a car and for whatever reason, the Front Driver's side wheel mounting hub flange has always been a little warped. Needs to be changed. I bought a replacement bearing/hub for my H3 a couple years ago and it came pre-warped out of the box from OReilly's. I understand Land Rover's use a different system, but at this point try to run the wheels (on jackstands) and watch closely for wheel in/out deflection.

Balance: Have you had your tires checked with a Hunter Road Force Balancer? That machine can detect tire imperfections and anomolies which other balancers miss.

Tie Rod Ends: Have you gone back and double-checked the 'tightess' of the tie rods ...and the spindle pre-load, since you've done your work? Just in case? Never know..a defective product could bite a guy in the butt.

I'm assuming your steering is 'tight' as you are going down the road ...at speeds *under* the death wobble conditions, right?

That's about all I got. You kind of know what you're doing it sounds like. I'm just thinking out-loud, and re-asking questions you've probably already asked yourself.

 

Yeah tire pressure. If you check in your manual, L/R actually suggests running front tire pressure at something like 24 lbs, and rear at like 32 (going off memory). That's too low for safety at the front, but as JimVW57 pointed out, too much air pressure can cause it on L/R's. Dial the fronts down to his recommendations and see if that helps. Even 35 on the fronts might be on the high side for these vehicles.

 

You've covered most of the main issues. Swivel pre-load and strut bushings are the big ones.

Have you check the steering stabilizer?