Disco 1 Death Wobble - Please Help

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J

JaseSG

New Member
Posts
8
Location
Volksrust, South Africa
Hi All,


I've googled high and low around this problem. I've probably read all the threads on it but I'm still struggling (for the better part of a year now).


I have:

  • replaced all tie rod ends
  • replaced all shocks
  • installed poly bushes all around (and re-checked them)
  • replaced panhard rod bushed twice since
  • Checked wheel bearings
  • Done wheel balancing and alignment (at this point the rear rims are slightly bent and need straightening - I don't think this should impact it? There's no vibration from them whilst driving at speed)
  • checked the swivel bearing preloads. They read 6.5kgs each side with the seal in place
  • Rebuilt the steering box (it was leaking and had some wear on the sector shaft)
I was hoping that after the steering box rebuild the death wobble would be gone. It is definitely better since, with spots in the road that normally trigger no longer doing so. I drove it to my work and back on Tuesday last week with no issues (80km round trip on a freeway at 120km/h). Then on Wednesday on the same trip coming down a hill I hit a slight bump in the road and the death wobble was triggered again.


I then got my daughter to shake the steering while I looked at the front axle. When doing so I can see some movement on the Panhard Rod and the chassis moves side to side over the axle (watch carefully on the attached video). Does this look normal? Is there an issue with the Panhard rod or it's bushes or mounting points?


Please, any other ideas?!?!
 

Attachments

  • Disco 1 Front Axle movement.gif
    Disco 1 Front Axle movement.gif
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Not watched the video but the panhard rod is supposed to stop that.
Remove the rod and illI wager the mounting holes are worn in the axle end.
 
Ok, I'm going to remove the panhard rod this Friday. I'll check the holes and weld on washers if needed. So, should there be no visible movement in the panhard rod at all (compared to the chassis and axle mountings)?
 
Sounds like the parnhard rod is your problem to me but have you checked the a frame ballpoint and did the bushes get done. They sometimes get overlooked when doing bushes
 
If you look at the axle hole you will see that landrover fitted a washer there to beef it up. I found the bolts wouldn't be long enough if I just welded a washer over the top.
It's not a bad job to weaken a couple of the welds with a grinder and then knock it off with a chisel,they are only tacked on.
You can use a decent thick repair piece then.
If you put an unworn bolt through your axle you'll be able to see how worn it is, mine looked slightly worn but the bolt showed it was a lot worse than it looked, both sides may need doing. I've had to do both sides of my rear trailing arms too for the same reason.
 
JaseSG said:
Ok, I'm going to remove the panhard rod this Friday. I'll check the holes and weld on washers if needed. So, should there be no visible movement in the panhard rod at all (compared to the chassis and axle mountings)?
Click to expand...
The panhard rod bolts could be worn down in diameter where they fit through the steel eye of the rubber bush in each end of the rod, on my 300Tdi the bolt at the steering box end was near 3mm worn undersize the chassis end about 1.5mm undersize. The wear was from the bolts not being tight enough to clamp the ends of the bushes, I've replaced the bolts and had to repair the mounts on the vehicle by welding and re-boring the 14mm dia bolt holes.
My 300Tdi exhibited the speed wobble symptoms on roads at speed with slight undulations, repair fixed the problem.
 
Gazbo said:
The panhard rod bolts could be worn down in diameter where they fit through the steel eye of the rubber bush in each end of the rod, on my 300Tdi the bolt at the steering box end was near 3mm worn undersize the chassis end about 1.5mm undersize. The wear was from the bolts not being tight enough to clamp the ends of the bushes, I've replaced the bolts and had to repair the mounts on the vehicle by welding and re-boring the 14mm dia bolt holes.
My 300Tdi exhibited the speed wobble symptoms on roads at speed with slight undulations, repair fixed the problem.
Click to expand...
Ok, so if I understand correctly, the brackets on the chassis and axle should touch the outside edges of the steel sleeves of the bushes so that once tightened the brackets clamp the steel sleeves? And this should be done at 88NM torque setting? (It might be that my torque wrench is out but 88NM always seemed to be a bit low/light to me...)
 
JaseSG said:
Ok, so if I understand correctly, the brackets on the chassis and axle should touch the outside edges of the steel sleeves of the bushes so that once tightened the brackets clamp the steel sleeves? And this should be done at 88NM torque setting? (It might be that my torque wrench is out but 88NM always seemed to be a bit low/light to me...)
Click to expand...
You understand correct, what had happened on mine because the bolts had lost their clamping tension long ago the steel centre sleeves had worn into the inner steel faces of both brackets inner surfaces, so tightening only produced bending /distortion of the brackets, totally useless, so the inner surfaces needed restoration to allow correct "clamping" of the panhard rod bushes within the brackets. And when replacing the bolts I used new M14 high tensile grade 10.9 fine threads with nyloc nuts tightened to 95 ft/lb.
Surprising what a difference it made to the steering/stability of the Disco, I would not have believed that so little transverse movement of the axle would be such a problem.
 
Gazbo said:
You understand correct, what had happened on mine because the bolts had lost their clamping tension long ago the steel centre sleeves had worn into the inner steel faces of both brackets inner surfaces, so tightening only produced bending /distortion of the brackets, totally useless, so the inner surfaces needed restoration to allow correct "clamping" of the panhard rod bushes within the brackets. And when replacing the bolts I used new M14 high tensile grade 10.9 fine threads with nyloc nuts tightened to 95 ft/lb.
Surprising what a difference it made to the steering/stability of the Disco, I would not have believed that so little transverse movement of the axle would be such a problem.
Click to expand...
Thanks. I think(and hope) this is where my problem is also. You say you tightened yours to 128Nm. That's more what I would expect. The workshop manual says 88Nm which doesn't seem tight enough...
 
I'm not convinced the panhard rod is your problem. I would take another look at your swivel pins and bearings. Long time ago since I had a D1 but had a similar problem and rebuilding the pins solved it.
 
Nig43 said:
I'm not convinced the panhard rod is your problem. I would take another look at your swivel pins and bearings. Long time ago since I had a D1 but had a similar problem and rebuilding the pins solved it.
Click to expand...
I did check the preload on the pins last year and removed some shims in the process. While the vehicle was off the road for the steering box rebuild I removed the front wheels, took off the steering rods and measured the resistance of the swivels as 6.5kgs. The swivels were moving smoothly from lock to lock. There's also no play at all when checking with the wheel on with a crowbar lifting under the wheel.

Perhaps others can comment if this was the right way to go about it?
 
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