"Death Wobble" HZJ78, modified (1 Viewer)

[RTWbyBUSCHTAXI]

Hello @ ALL,

I got a problem with my Troopy, first here is the data:

HZJ78, Year 2001

180.000km

Modifications (5 month ago):

OME leaf Springs (+600kg) on the back and normal Springs in the front

Adjustable Shocks from Tough Dogs all around (+50mm)

New Wheel bearings 8.000km ago, 5000km ago check and tightened

New Breaks 8000km ago

Steering Damper OME new 8.000km ago

(new ARB Bar, new PopUp Roof from Alucab Hercules but this doesn’t matter).



Out of the workshop after all these mods, everything was fine. 7.000km through the Balkans and Greece and suddenly the “DEATH WOBBLE” started. Off road, of course, no problems. But when returning to Asphalt it started to “wobble” dramatically, only hard breaking worked to keep control. OK, adjusted the Tough Dogs to very hard setting and the way home over the “Autobahn” (highway) was not a problem. Now, TD still on “hard”, riding asphalt is not a real problem, but at 80 km/h the wobble starts, not so dramatic but still.

If I got a load change at low speeds I feel a “klack” in the steering wheel.





First measure, balancing of the wheels, will try to find an workshop today, winter is coming so all super busy… but let’s see…

Anyone an idea of what it could be? (Keep in mind all the new stuff ^^, ‘I doubt that anything of the new parts is already worn by now, we didn’t do reaaaal hard core stuff, some river beads (slow), but nothing real bad…).



So what your "Glass Sphere" says?

 

[pithicus]

Have a gander at this HJ75 inconsistent driveline vibration - https://forum.ih8mud.com/threads/hj75-inconsistent-driveline-vibration.1263213/

It's often tyres that are the culprit. In my case the death wobbles were caused by ovaled [out of round] tyres.

 

[RTWbyBUSCHTAXI]

Have a gander at this HJ75 inconsistent driveline vibration - https://forum.ih8mud.com/threads/hj75-inconsistent-driveline-vibration.1263213/

It's often tyres that are the culprit. In my case the death wobbles were caused by ovaled [out of round] tyres.

SOme great stuff in there... will try some of the easy fixes first (like rotating the tires...) Thank you!

 

[AussieHJCruza]

I'd check the wheel bearings again, and following that, we often see death wobble being caused by Panhard bushes

 

[RTWbyBUSCHTAXI]

I'd check the wheel bearings again, and following that, we often see death wobble being caused by Panhard bushes

The wheel bearings have been replaced 8000km and tested (and one tightened) 5000km ago... The "Panhard bushes" are the last I want to change, cause they are the most expensive and I would need a hydraulic press to change them, I think... so I try to rule out all the rest b4...

 

[roscoFJ73]

Caster out of adjustment is one of the most common reasons for the wobble. And your new suspension settles in , it alters the angles etc

 

[AussieHJCruza]

The wheel bearings have been replaced 8000km and tested (and one tightened) 5000km ago... The "Panhard bushes" are the last I want to change, cause they are the most expensive and I would need a hydraulic press to change them, I think... so I try to rule out all the rest b4...

If the bearings needed to be retightened after 3,000 km they weren't set up correctly in my opinion, hence my suggestion to check them again.

The Panhard bushes are a bit of a pain to change but have always sorted out the problem.

 

[RTWbyBUSCHTAXI]

One more idea (although not really the point maybe), while in the Balkans I have been on a forest track and there was a piercing noise from the right front tire, was very muddy so I had to continue for some meters... after finding an even spot I could take of the wheel, there was a very tiny stone between the brake disk and the disk protection, so I removed it... fixed the wheel again and off I went... (the reason I say that is that I didnt had a tork wrensh with me and "just" fittet the wheel with the board tools. Cant be that I over tightened the screws right? (I think it is 208nM for the screws on the steel rims according to the book)

 

[Rigster]

You do not mention anything about tire size or width, etc... but I have found that the more oversize the tires, the more likely this is to occur. I would start with getting them balanced again. Ask them while they are balancing them if they notice any issues with out of round, rims possibly damaged/warped. It is also an easy check once it is jacked up to see if there is any play in the wheel bearings or not. Good luck! Post back with results and what fixes it for you! Thanks!

 

[RTWbyBUSCHTAXI]

You do not mention anything about tire size or width, etc... but I have found that the more oversize the tires, the more likely this is to occur. I would start with getting them balanced again. Ask them while they are balancing them if they notice any issues with out of round, rims possibly damaged/warped. It is also an easy check once it is jacked up to see if there is any play in the wheel bearings or not. Good luck! Post back with results and what fixes it for you! Thanks!

Of course I will post what it fixed, will be very happy to do so. 'About the tire sizes, I got the standard, narrow tires, 235/85. BFG. (with no plan to change them, unless they are broken... will get the same if...)

It can take a little while till I get an result, all workshops booked out for this year, winter is coming and everyone is changing to winter tires...) but I will get back!!

 

[RTWbyBUSCHTAXI]

 

[pithicus]

Another thing. Rotating the tyres didn't help with my truck. The tyre resonance that sets off the death wobble seems to happen with the dodgy tyres on the front or back.
Balancing all the wheels didn't help either. New tyres 100% fixed it and it's never re-occurred . Also some tyre shops have shaving machines for tyre runout [out of round tyres], if that's your problem. Only good for tyres with plenty of tread left though.

 

[RTWbyBUSCHTAXI]

Another thing. Rotating the tyres didn't help with my truck. The tyre resonance that sets off the death wobble seems to happen with the dodgy tyres on the front or back.
Balancing all the wheels didn't help either. New tyres 100% fixed it and it's never re-occurred . Also some tyre shops have shaving machines for tyre runout [out of round tyres], if that's your problem. Only good for tyres with plenty of tread left though.

Thx Mate, reshaping is not an option, I dont even think thats legal here in Germany...

 

[roscoFJ73]

Thx Mate, reshaping is not an option, I dont even think thats legal here in Germany...

Same here. They tyre shop told me if they cant balance a tyre, its defective, and wont sell it to you.

 

[mt72]

If the bearings needed to be retightened after 3,000 km they weren't set up correctly in my opinion, hence my suggestion to check them again.

The Panhard bushes are a bit of a pain to change but have always sorted out the problem.

I am with the Aussie on this bearing on the side of the noise...

 

[RTWbyBUSCHTAXI]

Update: I rotated the tires, front to back, no effect. Balancing appointment was a Desaster, “THIS ARE SPECIAL OFF-ROAD TIRES, we can’t do that”, got a new appointment end of next week at a “specialist shop” let’s see….

 

[roscoFJ73]

Update: I rotated the tires, front to back, no effect. Balancing appointment was a Desaster, “THIS ARE SPECIAL OFF-ROAD TIRES, we can’t do that”, got a new appointment end of next week at a “specialist shop” let’s see….

Was the castor checked?

 

[RTWbyBUSCHTAXI]

Was the castor checked?

HAd to look that up... So we are talking about the "Wheel alignment" (for reference if sbdy is just me and dont have a clue: ")

Yes this was checked some time ago, now on Friday first the balancing and after, if it doesn't help, all the rest.

Question, do 'I really have to balance the tires on the back as well? Does it make a difference?

 

[pithicus]

Question, do 'I really have to balance the tires on the back as well? Does it make a difference?

It's advisable. I believe a vibration from a tyre will set off the wobble no matter where it is on the truck

 

[roscoFJ73]

HAd to look that up... So we are talking about the "Wheel alignment" (for reference if sbdy is just me and dont have a clue: ")

Yes this was checked some time ago, now on Friday first the balancing and after, if it doesn't help, all the rest.

Question, do 'I really have to balance the tires on the back as well? Does it make a difference?

Yes. The reason I asked is because my suspension shop told me that is the most common reason for the death wobble on the 60 and 7* series . It maybe ok when the suspension is new, but as it settles in, the death wobble can appear.
I had my FJ73 in there some years back, the suspension was a few years old and sagged about a centimetre. At first the wobble was occasionally, then one day towing a trailer witha 1it got real bad on the freeway as I slowed down
To diagnose it, they make the death wobble worse then dial it back till it goes away.

Its like a shopping trolley with a bent wheel, it flops about all over the place.
The shop I use is the biggest Dobinson dealer in the world and the biggest suspension shop in Western Australia

I mentioned "castor" in post #6