Another Death Wobble

[the74bronco]

I will see if I can get some more videos this weekend. I will check the preload as well.

 

[the74bronco]

And I am back. Looks like my tie rod is bending. Could this be my death wobble? Also looks like the upper trac bar mount is solid, but there is movement between the trac bar and the mount. Could I just extend the trac bar a bit? Bushing is brand new.


https://flic.kr/p/2rkfVP7
https://flic.kr/p/2rkfVLS
https://flic.kr/p/2rkfVNF

 

[DirtDonk]

For that size tire you always need to beef up your tie rod.
But with that steep of an angle, the drag link is always going to exert excess force on the tie rod. You can beef it up enough to stop the flex, but it’s still putting a lot of force on different things, including the rod end itself.

Extending the track bar won’t stop excess play in the upper mount.
Even if the bushings and sleeves and bolts are new, any movement in the eye is indicative of an improper fit at least. Yes, there can be flex in the polyurethane bushing. But it shouldn’t be very much.
So at least double check the fit of the bolt inside the eye sleeve, and make sure that the holes have not elongated where the bolt passes through the drop bracket.
I couldn’t really see from my small screen, but from your description it sounds like it’s not the bolt holes, but perhaps the sleeve itself. But still worth checking.
Is it a new bolt? Or an old rusty one?

Is any of this the cause of your Death Wobble? No.
But any one of the above issues can certainly contribute to, or cause a simple oscillation to turn into a Death Wobble.
But in my opinion, and nothing has ever occurred to convince me otherwise, it always starts at the tires.

So while yours may be a factor of many things, and you may never get rid of it completely because of the tires and their influence on the rest of the system (due to their size), it wouldn’t hurt for you to play with air pressures, but more importantly to rotate the tires front to back on one side at a time.
See if the Death Wobble changes or goes away with any of those rotations.

 

[DirtDonk]

And in your first post, you asked about some things for that amount of lift. The answer to most things is… Yes.
For anything over 3 1/2 inches of lift, you have to mock up different steering linkage scenarios. Usually including tie-rod over, sometimes along with the dropped Pitman Arm. Track bar riser, in addition to the drop bracket. And perhaps even other things.
You always want to reduce the angle on the track bar and drag link as much as possible.

 

[Broncobowsher]

I'm really amazed at how much that drag link flexes the tie rod, given it is just tires on concrete garage floor.
If changing that (I would after seeing that video) it is going to play with the angles and arcs.
I had a hodge podge of suspension and steering. When I went to heim joint steering I ended up mounting the drag link to the TOP of a drop pitman arm. Think about that for a moment. Drop pitman was too much, stock wasn't right either. Needed in the middle. Drop pitman, but top of it, so not as much drop. Sometimes you have to get creative.

For that original description of death wobble, sounds like a more severe than normal version. But there isn't a smoking gun in pictures and videos. The wrongest thing I see is the tie rod flex.

 

[ksagis]

My thoughts are the amount of bending in tie rod is totally out family, even considering the angles. Yeah, its a steep force going in, but that degree of bending under fairly light load is certainly concerning.

I can also see the track bar emd moving where it connects to the drop bracket, but can’t see the track bar bracket moving. I can’t reconcile how that would happen though.

I would still jack tires off ground and repeat the test. If that flexes tie rod, something very wrong is happening.

 

[DirtDonk]

My thoughts are that it’s totally normal for a stock type tie rod, pushing 37 inch tires on the ground.
They will bend under much less force than that.
The steering system is extremely powerful, even when the engine is not running. If the engine was running during those tests, the effort to turn, the wheel is minimal, but the force exerted is astounding. Hydraulic assist, trying to push super heavy tires through a wimpy-ish tie rod, is a recipe for bending and flexing.

My guess is that you would see a slight amount of it happen even during driving. I’ve taken Off Road, the flex would be as much or more. Both from Steering input, from Tire leverage input go in the other direction.
I agree that it could be tested by lifting the wheels off the ground, but if all else is relatively normal, you shouldn’t see any flexing under those conditions.

 

[micon]

And I am back. Looks like my tie rod is bending. Could this be my death wobble? Also looks like the upper trac bar mount is solid, but there is movement between the trac bar and the mount. Could I just extend the trac bar a bit? Bushing is brand new.


https://flic.kr/p/2rkfVP7
https://flic.kr/p/2rkfVLS
https://flic.kr/p/2rkfVNF

My 73 did same. Turned out having incorrect pitman arm. Had the curved one for lifts.my truck is not lifted so I put straight arm for unlifted on.Solved problem.curved pitman is for lifts.

 

[garberz]

And I am back. Looks like my tie rod is bending. Could this be my death wobble? Also looks like the upper trac bar mount is solid, but there is movement between the trac bar and the mount. Could I just extend the trac bar a bit? Bushing is brand new.

The movement with the track bar in the frame end mount is the source of your Death Wobble. Get a new bolt with the proper amount of shank, meaning no threads inside of the sleeve or the mount. Make sure the holes in the mount are not ovalized. Back them up with weld washers if you need to.
It doesn't take must movement there to initiate that oscillation.

Mark

 

[the74bronco]

Thank you everyone for the input. I am going to order a heim steer/ TRO kit this week.

I noticed my trac bar jam nut didn’t seem very tight. I pulled the upper trac bar bolt and checked the holes (they looked good), but the bar seemed to have some slack. I adjusted it out one turn and put the bolt back in. I made it to 90ft lbs and stripped the castle nut. I am going to get a new bolt and run a couple washers. I am hoping this helps. It looks like if I go to TRO, I might have to switch my track bar mount to stay parallel?

https://flic.kr/p/2rkpCHx

 

[the74bronco]

For that size tire you always need to bead up your tie rod.
But with that steep of an angle, the drag link is always going to exert excess force on the tie rod. You can beef it up enough to stop the flex, but it’s still putting a lot of force on different things, including the rod end itself.

Extending the track bar won’t stop excess play in the upper mount.
Even if the bushings and sleeves and bolts are new, any movement in the eye is indicative of an improper fit at least. Yes, there can be flex in the polyurethane bushing. But it shouldn’t be very much.
So at least double check the fit of the bolt inside the eye sleeve, and make sure that the holes have not elongated where the bolt passes through the drop bracket.
I couldn’t really see from my small screen, but from your description it sounds like it’s not the bolt holes, but perhaps the sleeve itself. But still worth checking.
Is it a new bolt? Or an old rusty one?

Is any of this the cause of your Death Wobble? No.
But any one of the above issues can certainly contribute to, or cause a simple oscillation to turn into a Death Wobble.
But in my opinion, and nothing has ever occurred to convince me otherwise, it always starts at the tires.

So while yours may be a factor of many things, and you may never get rid of it completely because of the tires and their influence on the rest of the system (due to their size), it wouldn’t hurt for you to play with air pressures, but more importantly to rotate the tires front to back on one side at a time.
See if the Death Wobble changes or goes away with any of those rotations.

I am realizing suspension/steering is a lot of tweaking to get things working as it should. Even though this is my second set of tires. I think I need to switch front to back. I appreciate you input.

 

[1973bronco1973]

The movement with the track bar in the frame end mount is the source of your Death Wobble. Get a new bolt with the proper amount of shank, meaning no threads inside of the sleeve or the mount. Make sure the holes in the mount are not ovalized. Back them up with weld washers if you need to.
It doesn't take must movement there to initiate that oscillation.

Mark

This is exactly what mine was but at the lower track bar mount. 3 1/2” lift and 35” tires. Went from can’t drive it above 35 to good at 75. Wouldn’t have believed it if I didn’t experience it firsthand.

 

[ksagis]

garberz’s comment could easily explain what I thought I saw at frame side of track bar. Worth pulling that bolt and checking hardware up there.

The bending is a separate issue.

Edit: the view on frame side of track bar on this video isn’t as good as previous but I don’t see the movement which would be expected since we eliminated the reaction point. Mainly adding to the value of my suggestion above.

Edit 2: I just noticed this in your post above: “I pulled the upper trac bar bolt and checked the holes (they looked good), but the bar seemed to have some slack.” Maybe ignore my post if it is verified.

Also, only getting to 90 ft-lbs on that size bolt is concerning. What grade hardware do you have and what how did threads on both sides look when you pulled it?

 

[the74bronco]

Should there always be tension in the track bar or will it have a slight wiggle when turning one direction? If there is a slight wiggle when turning one direction, should I lengthen the bar to keep constant pressure?

 

[Oldtimer]

If you lengthen the track bar, the front axle will move toward the passenger side, shorter will move axle toward the driver side.
There needs to be NO movement of track bar in mount at either end, which is why rubber bushings are replaced with polyurethane.

 

[ksagis]

That movement is likely a problem and you need to understand why it is moving. It's either wallowed holes or shot bushings. Adjusting length of track bar isn't the solution.

 

[Grey owl]

Wow those angles are pretty extreme. The death wobble will start when something that is not supposed to move , moves. My guess is that beefier parts will be the solution.

 

[the74bronco]

I just got all my heim steer and TRO parts in this week. I will hopefully get it thrown on this weekend. I did get a grade 8 bolt/washers/locknut for the trackbar as well. I could not find a drilled bolt. Will I be okay with a locknut or a regular nut and lock tight?

Should I lock tight the jam nut on the adjustable track bar or just tighten it down?

 

[rjrobin2002]

Look for egg shaped track bar bolt holes where the bolt has worn the hole oval shaped. When this happens, new bolts and bushing don't help you. It causes death wobble that new bushings don't cure.

 

[DirtDonk]

I did get a grade 8 bolt/washers/locknut for the trackbar as well. I could not find a drilled bolt. Will I be okay with a locknut or a regular nut and lock tight?

I would personally prefer a lock nut, over a regular one with thread locker.
And pants you can always drill a hole of your own through a bolt. If you have a castle/castellated type nut.

Should I lock tight the jam nut on the adjustable track bar or just tighten it down?

Nothing wrong with that idea. Personally though, I would wait until you are certain that you have the axle centered in the frame, while at ride height. Once there you should have no reason to adjust it again any time soon. So a little thread locker there are certainly wouldn’t hurt.