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Death Wobble - choices

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bigdaddy13 View Drop Down
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    Posted: 10 July 2018 at 5:07pm
My rig is very streetable currently, but recently i got my speed up to about 30mph and the wobble started.

Sooo, with a fairly complete, compliant Ross system, where do i begin troubleshooting?

Also, in looking at parts prices for tie rod ends, etc, i’m looking at $100-200.00 easily, if i’m replacing all possible rod ends, and other “wear items”.

When does it become feasible to consider an upgrade to a manual saginaw box? 
This is a restomod rig that has disc brakes, an f-head, and will likely end up with toyota mini-truck or narrow track D44 axles, eventually, but not for a few years.

Does anyone have a ballpark price for the conversion assuming that i can handle most of the fab work myself, using used parts?


Edited by bigdaddy13 - 11 July 2018 at 9:55am
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Terry Fairchild View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Terry Fairchild Quote  Post ReplyReply Direct Link To This Post Posted: 10 July 2018 at 6:11pm
First thing to check are the trunnion bearings on the front axles. Remove the bearing caps and check for shims. My bet is there are shims there and you could remove a few from each side, tightening the clearance on the bearings and eliminating the wobble. The bearings are probably worn some or brinneled and decreasing the clearance may give some improvement. 
Cheap, easy and down and dirty.
Ideally, you replace these bearings, remove the tie rods and knuckle seals and set the tension on the steering knuckle (with new bearings )with a fish scale.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote PackRat Quote  Post ReplyReply Direct Link To This Post Posted: 10 July 2018 at 6:12pm
If you are going to pull out the axles in the immediate future, getting spendy with parts before you have truly diagnosed the problem is not what I would suggest. Have you determined if it is something as simple as a bent rim that is the issue here? I had lousy steering in my GPW until I rebuilt the draglink and found the spring was broken and with a rebuild kit from RFJP I eliminated that wandering when at certain speeds and took out 80% of the looseness in the steering wheel when parked.

I drove it at about 30 MPH with a friend sitting in the back seat looking at the tires to see if they wobbled and then the front right and I could check the left front myself...bottom line was two were not running straight and true and one of those was REALLY wobbly. I fixed one and now have the other as a spare and that helped some more.

Bottom line is, maybe there are some minor cost items or adjustments to your steering system that will eliminate that Death Wobble or at least mitigate it somewhat until your future modifications are at hand.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rus Curtis Quote  Post ReplyReply Direct Link To This Post Posted: 10 July 2018 at 7:51pm
It is time to troubleshoot.  Wobble can be anywhere between the tire (balance/pressure or wear) to the steering box and include combinations of anything in between.  You could replace everything but one part and still not fix it.  Even a steering dampener won't "fix" it.
 
Crawl underneath and have a friend or family turn the wheel side -to-side.  Just enough to make the wheels twitch and then note everything that moves more than it should: tie rod ends, bell crank, connecting rod and even the steering gear arm attached to the shaft coming out of the steering box.  Something is moving and worn. 
 
Then jack up the front and wiggle the wheels up and down.  That will check for loose/worn bearings.  As mentioned you may have to open the knuckle to inspect the pivot bearings.
 
This is all covered in the Service Manual, under Steering, Troubleshooting (mine is para O-17), and will help with systematically working through to find the worn parts.
 
Once you know what is worn, you can order the correct parts.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote srlbotanical Quote  Post ReplyReply Direct Link To This Post Posted: 10 July 2018 at 9:53pm
I've also found it helpful to park on level concrete and have someone sit in the front seat, cranking the wheel from 9 to 3 and back again over and over. you can then get under the jeep and look at every rod end and link connection to check for excessive movement. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Joe Friday Quote  Post ReplyReply Direct Link To This Post Posted: 10 July 2018 at 10:54pm
I usually start with the knuckle bearings and work my way out. I've always replaced upper and lower bearings and races, but they are getting pricey. I just bought a batch of the races only from Rock Auto for bout 7 bucks each. This time if I don't see any cracked rollers, just brinnelled races, I think I'll do races only.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bigdaddy13 Quote  Post ReplyReply Direct Link To This Post Posted: 11 July 2018 at 10:04am
Like, i said, a swap is several years off.

Rims are in good shape, but good thought there...

Going to troubleshoot in the next few days. Had my wife turn the wheels back and forth a bit and the only movement i saw was upstream of the bell crank connection at the tie rod. No noticable slop at each of the four tie rod ends.

By “draglink”, do you mean the connecting rod from the steering arm/box to the bell crank?  If so, that’s exactly what i was thinking i might focus on, once i double check what i saw last night. Gonna remove it and take a closer look first, of course.


Originally posted by PackRat PackRat wrote:

If you are going to pull out the axles in the immediate future, getting spendy with parts before you have truly diagnosed the problem is not what I would suggest. Have you determined if it is something as simple as a bent rim that is the issue here? I had lousy steering in my GPW until I rebuilt the draglink and found the spring was broken and with a rebuild kit from RFJP I eliminated that wandering when at certain speeds and took out 80% of the looseness in the steering wheel when parked.

I drove it at about 30 MPH with a friend sitting in the back seat looking at the tires to see if they wobbled and then the front right and I could check the left front myself...bottom line was two were not running straight and true and one of those was REALLY wobbly. I fixed one and now have the other as a spare and that helped some more.

Bottom line is, maybe there are some minor cost items or adjustments to your steering system that will eliminate that Death Wobble or at least mitigate it somewhat until your future modifications are at hand.


Edited by bigdaddy13 - 11 July 2018 at 10:22am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bigdaddy13 Quote  Post ReplyReply Direct Link To This Post Posted: 11 July 2018 at 10:09am
Originally posted by srlbotanical srlbotanical wrote:

I've also found it helpful to park on level concrete and have someone sit in the front seat, cranking the wheel from 9 to 3 and back again over and over. you can then get under the jeep and look at every rod end and link connection to check for excessive movement. 

Yup, thanks...this is exactly where i started. Seeing slop from the bell crank on the connecting rod end, and at the steering gear arm. 

Also feeling at least an inch or so of slop in the steering wheel before i see wheel movement, but i can honestly feel/see the steering gear arm move in unison, so it makes me think the gear box is fairly healthy. 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote bigdaddy13 Quote  Post ReplyReply Direct Link To This Post Posted: 11 July 2018 at 10:16am
Originally posted by Terry Fairchild Terry Fairchild wrote:

First thing to check are the trunnion bearings on the front axles. Remove the bearing caps and check for shims. My bet is there are shims there and you could remove a few from each side, tightening the clearance on the bearings and eliminating the wobble. The bearings are probably worn some or brinneled and decreasing the clearance may give some improvement. 
Cheap, easy and down and dirty.
Ideally, you replace these bearings, remove the tie rods and knuckle seals and set the tension on the steering knuckle (with new bearings )with a fish scale.


Thx for the suggestion, my dad and i serviced the wheel bearings when i installed my disc brakes, but you’re right, i dont think we assessed the king pin bearings (i’m assuming that is what was meant by trunnion bearings?)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote athawk11 Quote  Post ReplyReply Direct Link To This Post Posted: 11 July 2018 at 10:19am
King Pin bearings in the knuckle are often neglected, but fairly easy to replace.  Don't be surprised to find them in poor condition...

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Post Options Post Options   Thanks (0) Thanks(0)   Quote bigdaddy13 Quote  Post ReplyReply Direct Link To This Post Posted: 11 July 2018 at 12:07pm
Originally posted by athawk11 athawk11 wrote:

King Pin bearings in the knuckle are often neglected, but fairly easy to replace.  Don't be surprised to find them in poor condition...



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Post Options Post Options   Thanks (0) Thanks(0)   Quote LesBerg Quote  Post ReplyReply Direct Link To This Post Posted: 11 July 2018 at 3:39pm
I was diagnosing wandering at highway speeds and couldn't figure it out.

My wife is an amateur mechanic (maybe not amateur, she can do drum brakes without help) and I brought her out for a fresh set of eyes. She noticed that the bellcrank was moving even after replacing the bearings.

It turned out that the pivot shaft was deflecting under load. I built a tube brace for it and it's pretty solid now. The brace mounts under the right side radiator bolt and just under the bellcrank nut.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote smfulle Quote  Post ReplyReply Direct Link To This Post Posted: 11 July 2018 at 4:52pm
Originally posted by LesBerg LesBerg wrote:

I was diagnosing wandering at highway speeds and couldn't figure it out.

My wife is an amateur mechanic (maybe not amateur, she can do drum brakes without help) and I brought her out for a fresh set of eyes. She noticed that the bellcrank was moving even after replacing the bearings.

It turned out that the pivot shaft was deflecting under load. I built a tube brace for it and it's pretty solid now. The brace mounts under the right side radiator bolt and just under the bellcrank nut.

Got any pics of this brace?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cal.bar Quote  Post ReplyReply Direct Link To This Post Posted: 11 July 2018 at 10:09pm
Originally posted by smfulle smfulle wrote:

Originally posted by LesBerg LesBerg wrote:

I was diagnosing wandering at highway speeds and couldn't figure it out.

My wife is an amateur mechanic (maybe not amateur, she can do drum brakes without help) and I brought her out for a fresh set of eyes. She noticed that the bellcrank was moving even after replacing the bearings.

It turned out that the pivot shaft was deflecting under load. I built a tube brace for it and it's pretty solid now. The brace mounts under the right side radiator bolt and just under the bellcrank nut.

Got any pics of this brace?
 
Never mind the brace, got any pics of the WIFE!  (a woman who can fix her own car is truly a unicorn)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SE Kansas 46 CJ-2A Quote  Post ReplyReply Direct Link To This Post Posted: 12 July 2018 at 1:28pm
My experience in working on death wobble problems is that most of the time the king pin bearings are worn out. Just removing shims from the bearing caps does little good if the bearings are worn or brinelled. The closed knuckle design of the Dana 25 contributes to the problem. especially if the front axle has been submerged in water or mud and the knuckle seal is worn. Once a bearing begins to rust from exposure to water or mud it is just a matter of time until wears accelerates and causes preload problems on a close tolerance design. The lack of preload on the kingpin bearings in my opinion is a major factor (but not the only factor) in the death wobble scenario.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bigdaddy13 Quote  Post ReplyReply Direct Link To This Post Posted: 12 July 2018 at 2:05pm
On closer inspection here's what I've found so far(only spent an hour or so, poking around last night after work)

1. Bell crank castle nut was only finger tight and there was a roofing nail pinning it in...lol. So I tightened it and put a fresh cotter pin in.

2. Drag link/connecting rod from gear box to bell crank actually is only allowing a small amount of movement. I'm actually seeing a bit of wiggle from the gearbox arm, which might mean, what? Sector shaft is worn/loose? going to clean some grime away and take a closer look.

3. I still need to dig into the kingpin bearings, but I reconfirmed that the tie rod ends seem fairly healthy/snug.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote cal.bar Quote  Post ReplyReply Direct Link To This Post Posted: 12 July 2018 at 2:54pm
Bell crank drag link and steering rod slop will not usually cause death wobble. As others have posted before it's almost certainly inside your axles
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Post Options Post Options   Thanks (0) Thanks(0)   Quote athawk11 Quote  Post ReplyReply Direct Link To This Post Posted: 12 July 2018 at 3:17pm
Originally posted by bigdaddy13 bigdaddy13 wrote:



3. I still need to dig into the kingpin bearings, but I reconfirmed that the tie rod ends seem fairly healthy/snug.


This isn’t fool proof, but you can jack a wheel off the ground, then pull/push on the top, then bottom of the wheel/tire.  If you have any significant in and out movement, you’ll want to remove the king pin and inspect the bearings more closely.  The only other thing that would cause movement when pulling/pushing on the wheel like this would be the actual wheel bearing.  If the preload isn’t set right, or the wheel bearings are shot, you may feel some looseness, but you’ll be able to feel/see this difference inside the hub if you remove your drive flanges or locking hubs, if so equipped.


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