post #31 of Old 09-22-2013, 08:56 AM
SLADE
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Originally Posted by JTPhoto View Post
Hmm that's interesting ... So I assume then that shackles introduce enough lateral slop that a Trackbar is required?
Not required but used. It is common practice to remove the trackbars on YJ's and it does not immediately cause death wobble. The leaf springs will still center the axle, but more side to side slop may be noticed. Increasing the shackle length would also increase the side to side slop.

I mentioned shackles being forward on those setups because I'm not aware of any leaf + trackbar setups with shackles behind the front axle.


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In my case the Trackbar had the metric bolt so there was plenty of slop to promote DW. 1 week of driving for me is 600-1000klm.
There is minimal difference between the stock 14mm bolt and the 9/16" upgrade. If the conversion is right, it's only .3mm or .01" difference.

Obviously there wasn't enough slop to cause death wobble and I do not believe you had enough slop to rule out the trackbar a cause for death wobble.


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post #32 of Old 09-22-2013, 08:58 AM
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Originally Posted by HighandLow View Post
Knowing that alot of those vehicles mentioned dont have power steering. I guess then, that power steering is not a factor that may be overlooked or not considered?
If I ever had a DW in my old YJ I would've just jumped out if it!

Those vehicles DO have power steering.

Steering (power or not) is a direct link to death wobble.

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post #33 of Old 09-22-2013, 09:14 AM
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Well my YJ did not have PS and no tractor I've ever driven had it. So just a thought.

Thanks for the thread JTPhoto. And the continuing education from all.
Watching Planmans videos should be a must for all jeep owners.
After watching I did two things, bought bolt upgrade kit from Northridge and bought real torque wrench.

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post #34 of Old 09-22-2013, 09:18 AM
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Originally Posted by SLADE View Post

Not required but used. It is common practice to remove the trackbars on YJ's and it does not immediately cause death wobble. The leaf springs will still center the axle, but more side to side slop may be noticed. Increasing the shackle length would also increase the side to side slop.

I mentioned shackles being forward on those setups because I'm not aware of any leaf + trackbar setups with shackles behind the front axle.

There is minimal difference between the stock 14mm bolt and the 9/16" upgrade. If the conversion is right, it's only .3mm or .01" difference.

Obviously there wasn't enough slop to cause death wobble and I do not believe you had enough slop to rule out the trackbar a cause for death wobble.
It's having a shouldered style bolt that makes all the difference. A fully threaded bolt is like a file inside the mounting hole if and when it loosens.
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post #35 of Old 09-22-2013, 09:36 AM Thread Starter
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As I did mention earlier when I changed my track bar 2 week ago the lower Trackbar mount hole was also wallowed out so there was definitely movement there. Enough that others have experience DW with less.

None the less the track bar is only a piece in the puzzle and is really not the cause but a piece that can either stop or contribute to death wobble in some vehicles. We know that high tire pressure can initiate DW with tire bounce but what other factor continues or stops the continuation to full DW.

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post #36 of Old 09-22-2013, 09:42 AM
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None the less the track bar is only a piece in the puzzle and is really not the cause but a piece that can either stop or contribute to death wobble in some vehicles. We know that high tire pressure can initiate DW with tire bounce but what other factor continues or stops the continuation to full DW.
The trackbar can be the primary cause, not just a piece.

Alignment
Tire balance
Any loose or worn component (both steering and suspension) that allows the front axle or steering/tires to move without control.

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post #37 of Old 09-22-2013, 10:08 AM Thread Starter
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Originally Posted by SLADE
The trackbar can be the primary cause, not just a piece. Alignment Tire balance Any loose or worn component (both steering and suspension) that allows the front axle or steering/tires to move without control.
I buy that, but my point is: Why is the loose trackbar a primary cause on some and not on others even though they are just as loose and worn. And again the vehicles that don't have trackbars. What is the underlying difference that initiates and continues DW. Something between the tire and suspension / steering gear.

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post #38 of Old 09-22-2013, 10:27 AM
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I buy that, but my point is: Why is the loose trackbar a primary cause on some and not on others even though they are just as loose and worn. And again the vehicles that don't have trackbars. What is the underlying difference that initiates and continues DW. Something between the tire and suspension / steering gear.
Because it could be the main cause, all the other little pieces that add up make it have DW. If its just a bad trackbar and everything else is in good shape then you will not have DW.

And for on road vehicles I do not know of one leafsprung vehicle that does not have a front trackbar. Tractors are not a fair comparison for the argument of DW.
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post #39 of Old 09-22-2013, 10:37 AM
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I buy that, but my point is: Why is the loose trackbar a primary cause on some and not on others even though they are just as loose and worn. And again the vehicles that don't have trackbars. What is the underlying difference that initiates and continues DW. Something between the tire and suspension / steering gear.

I would guess that is where the condition of the other components come into play also and it's a combination of worn/loose parts. Your looking at a problem that has more than one trigger.


Leaf sprung vehicles without trackbars have side to side axle movement (what trackbars prevent), so they would have the same issues that a vehicle with a loose/worn trackbar would have.

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post #40 of Old 09-22-2013, 10:48 AM Thread Starter
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Originally Posted by COLOUXJ
I do not know of one leafsprung vehicle that does not have a front trackbar. Tractors are not a fair comparison for the argument of DW.
How about every straight axle vehicle up to at least mid 80s early 90s .. All my dodge and Chevy trucks with leaf spring had no track bar. Tractors are just as fair to compare as any other straight axle. They still get death wobble and backs my point that the Trackbar may be a major contributor but not the cause.

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post #41 of Old 09-22-2013, 01:04 PM
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How about every straight axle vehicle up to at least mid 80s early 90s .. All my dodge and Chevy trucks with leaf spring had no track bar. Tractors are just as fair to compare as any other straight axle. They still get death wobble and backs my point that the Trackbar may be a major contributor but not the cause.
So what is the cause of death wobble? Overinflated tires?

DW is vehicle specific. The harmonics of the system depend on a lot of different points, anything on the front end that rotates, pivots or absorbs shock could be a factor in deathwobble.
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post #42 of Old 09-22-2013, 01:18 PM Thread Starter
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So what is the cause of death wobble? Overinflated tires? DW is vehicle specific. The harmonics of the system depend on a lot of different points, anything on the front end that rotates, pivots or absorbs shock could be a factor in deathwobble.
Exactly, that is the million dollar question. What is the ROOT cause of DW? We already know what can contribute to it. We know that after 1 or 2 bouts of DW so many parts may have compromised that it's hard to tell what part is at fault. But what is the underlying piece that is common on all straight axle vehicles.

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post #43 of Old 09-22-2013, 01:24 PM
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Exactly, that is the million dollar question. What is the ROOT cause of DW?

There is not just 1 root cause of death wobble.

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post #44 of Old 09-22-2013, 01:37 PM
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Originally Posted by JTPhoto
Exactly, that is the million dollar question. What is the ROOT cause of DW? We already know what can contribute to it. We know that after 1 or 2 bouts of DW so many parts may have compromised that it's hard to tell what part is at fault. But what is the underlying piece that is common on all straight axle vehicles.
Sloppy holes cause DW.
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post #45 of Old 09-22-2013, 01:42 PM
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There is not just 1 root cause of death wobble.
Exactly. Its like the swiss cheese model of most accidents. A collection of tiny things that when not lined up correctly do no harm. But if you happen to line those up (get a bunch of air pockets in swiss cheese) bad things happen (like a big hole in your cheese).
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