Death Wobble (1 Viewer)

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Drove on my new (to me) 38.5" SX's tonight for the first time.

Immediatly got death wobble around 45-50 mph (no speedo).

Took a little air out of the front tires, played around with the toe in- everywhere from 1/16" to 3/8".

Still getting it but around 40 mph, and I can drive through it.

SX's are balanced with 3000 airsoft pellets each.

Checked caster tonight, got ~1.5 degrees. (has 2 degree shims to correct 4" lift)

It would seem to me that more caster (thinking about 5 degree shims) would be the ticket? Agree/disagree?

I don't want to put the effort and money into shims and a new set of u-bolts if I don't have to.

Thanks for any input. :cheers:
 

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air the tires down to under 10 psi, and run em....


15x42x15 swampers....I run the fronts less than 10 psi all the time...no death wobble....no crazy wear..no nothing...they are swampers, they can take it.


Multiple road trips, over 250+ miles, no issues.


Good luck!



-Steve
 

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trying to balance a tire that does not want to do so....


I have a few golf balls in my beadlocked 42" swampers...I do not notice any difference with them in, compared to tires that I have ran that were supposedly balanced with lead, that was then knocked off in the rocks....



They are a bias-ply tire, that is not going to ride smooth, NO MATTER WHAT YOU DO!



We are A LONG WAY FROM 33" radials Toto....




Welcome to the world of large Swampers.




Lower your air pressure(10psi or under), heat them up, and they will be fine...


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Hydro Assist was my cure for death wobble.

My hydro assist saved me. My wore out 39.5" would start about 30 and you couldn't drive through it. You couldn't hold on to the steering wheel.

It's ok now. You just can't drive over 60. My vision gets blurry from all the vibration.

J.R.
 
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I would move up to 5 or 6* of caster. Also check the knuckle bering preload (fish scale) which im sure you know how to do. When I did my SOA w/ mini knuckles I ended up w/ about 15-25 pounds on the scale. I think 12lbs is spec? It is a little higher than spec but I havent had and Wobble problems since I got the SOA done. My truck doenst get driven enough for me to worry about wearing out the knuckle berings prematurely and caster set to 6*.

My tires are balanced w/ BBs as well but they aren't quite as gnarly as yours however. Ditto on the 8-10psi in the tires as well. w/ a 40 you could probably run those tires at 0psi and not get too much sidewall flex.

P.S. We need pictures
 
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Swap in 5* shims and make sure the ubolts are super tight. Test run.
If it is still there, swap your rear tires to the front. They may be more evenly balanced than the fronts. Test run.
If it persists after that, experiment with alignment and tire pressures.

Thought you might enjoy this thread on DW from an engineering perspective:
http://www.colorado4x4.org/vbb/showthread.php?t=50775
 
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Thanks for the replys.

I dropped the fronts down to 7.5 psi, the rears to 12 psi, and retorqued the knuckle studs. Definatly made a difference, wobble only occurs at what seems like one specific speed, and it is easy to drive through.

Steve- I sure don't expect these tires to ride like my 33" TSL radials did, but it seems as though I should be able to expect to not have any death wobble.

wait, WHAT are the airsoft pellets for?
It's for balancing the tires, as the tire spins the airsoft pellets distribute themselves inside the tire to balance it. Another advantage is that if the tire spins on the rim, you don't lose your balancing like with traditional rim mounted weights. You can also use BB's or golf balls, or a liquid like antifreeze.

My hydro assist saved me. My wore out 39.5" would start about 30 and you couldn't drive through it. You couldn't hold on to the steering wheel.

It's ok now. You just can't drive over 60. My vision gets blurry from all the vibration.
My next P/S setup will include hydro assist. (the minitruck P/S ain't cuttin it) The assist on my buddies' ZJ in the pic below is saving him from his previously chronic death wobble problem.

Michael- If I want to continue to flat tow, I think I will need to increase caster. Problem is, on my truck it will require more work than normal, and worsen my already steep pinion angle. I might wait until I can cut n turn before I bother with caster.
 

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wesintl said:
Being a swamper man.. I'd say give the tires a few hundred miles to wear in :)


Swamper guy to the bone here......it will not make a difference...



They are a large, bias ply tire, that is not perfectly round or even when new, will run hotter and not wear as well on the road as a radial, and will not wear even....



Just like everything else my friend, it comes down to compromises. You will be hard pressed to find a tire that will out crawl, outlast and take the abuse that the SX will off road, but you are going to give something up for that…and on-road durability/longevity and drivability are not strong suits for a large bias-ply, aggressive tread, off road tire.



Address your steering sooner than later.



You will love these tires and be absolutely amazed how well they work off road aired down to about 5psi, and at the abuse they can take.


Good luck!


-Steve
 

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CruisinGA said:
...If I want to continue to flat tow....


Just get a trailer, and be done with it. ;)


Oh, and get your butt to the Hills next year!


Even in your poor pictures, your truck is looking great Bailey!


:beer:
 
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wesintl said:
Being a swamper man.. I'd say give the tires a few hundred miles to wear in :)

They're already worn- only about 40% tread left.. ;)

Steve- I don't think my 80 can handle a trailer and the 40.. :eek:
I'm starting to ready myself to drive this thing to Tellico (5 hrs in this rig), as much as I don't want too. I'll pack some spare rear axles, and few other bits, and hope I don't break anything. ;)

I never see any pics of your truck 'cept that one or two in the snow.. :flipoff2:
 
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Poser said:
Swamper guy to the bone here......it will not make a difference...
I guess my experiences differ from others.. not suprising though..

I've never run bigger than 36's but ALL my bias ply tires took a few hundred street miles to wear in. I ran new ones and ones that were so beat they had rope plugs in them. All the ones I ever had bounced the truck around had bad wobble spots til they had some miles on the truck they were on.

I only balanced my swampers 1 time with lead inside the rim. Some got ripped out and I took the rest off. All sets since then I don't use gold balls, BB's or whatever, they get mounted and worn in. That's what I found works for me is drive on them til the wear in. I guess maybe your taking that to literally. ;)

Been a while since I've been on swampers though my 8 ply bias jeep serivce tires are about as close as you can come and the BFG Baja terrians (old style like swampers) on my sprung over 40 were necessary when i installed new old springs. I was hoping to run some on my 70 but I gotta turbo first or I will need a truck and trailer :D
 
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I run 36" tsl's and have the same problem. I had them balenced everytime after I went wheeling and it helped but gets expensive. I ended up putting a after market steering stabilzer (Rauncho) and almost eliminated the death wobble. It still has the problem until the tires warm up and the flat spots go away. Good luck Tom
 
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CruisinGA said:
My next P/S setup will include hydro assist. (the minitruck P/S ain't cuttin it) The assist on my buddies' ZJ in the pic below is saving him from his previously chronic death wobble problem.

Michael- If I want to continue to flat tow, I think I will need to increase caster. Problem is, on my truck it will require more work than normal, and worsen my already steep pinion angle. I might wait until I can cut n turn before I bother with caster.
If I had to guess I would bet that your next round of mods will look something like:

4x4 Labs or some other high steer.
Hydro assist (redneck ram or similar)
Cut and turn (nescessary even w/ a SUA rig in the right situations)

Once you finaly do the cut and turn you will realise why everyone that has already done it recomends it so highly as well as why the people who haven't try and aviod it. It is a big job but it makes seting up the front axle so much easier it isnt even funny.
 

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