Death wobble caused by sway bar? - JeepForum.com
 11Likes
Reply
 
LinkBack Thread Tools
post #1 of 32 Old 09-07-2021, 10:54 AM Thread Starter
86cj7pete622
Registered User
 
86cj7pete622's Avatar
1986 CJ7 
 
Join Date: Sep 2008
Location: New York, NY
Posts: 101
Death wobble caused by sway bar?

Hey guys,

So I took my 86 CJ7 offroading (nothing crazy) for 3-4hrs and when I got back to pavement, I got death wobble within a few miles. I was doing 35-40mph at the time, no bumps/potholes in the road.

I looked underneath and found that my sway bar bushing bracket on the driver side unbolted itself (the bushing bracket that attaches to the frame- picture attached). If this bracket just happen to come off while on pavement, would that have possibly created a jerking jolt to start DW?

My ball joints, beefier drag link, and beefier tie rod are all less than a year old. I drove it again at 60mph and no out of balance 33" tires. I don't see any slop in any of the components. The only obvious thing was that sway bar bracket that came loose.

I had DW about 20yo, but smooth sailing until this weekend.

Thanks.

Attached Thumbnails
20210907_125006_1631033634228.jpg  
86cj7pete622 is offline  
Sponsored Links
Advertisement
 
post #2 of 32 Old 09-07-2021, 11:18 AM
StoneTower
Registered User
1985 CJ7 
 
Join Date: Jan 2015
Location: Fair Oaks
Posts: 2,216
Bolt it back up and see if the problem goes away. It looks in the picture that the sway bar has been pulled back. Did you hit something that bent a spring or something? The sway bar is a spring and if you have it connected properly to one wheel and not the other, the suspension is not going to work properly especially at road speeds.
80cj likes this.
StoneTower is offline  
post #3 of 32 Old 09-07-2021, 01:44 PM
stripperguy
Registered User
2005 LJ Wrangler 
 
Join Date: Mar 2010
Location: Schenectady
Posts: 864
It’s unusual for a leaf sprung vehicle to have a death wobble. the lateral stiffness of the suspension usually keeps the critical frequency of that vibration mode above the frequency of the tires. In addition, there is usually enough damping in the leaf to leaf interface to preclude such motions.
Obviously, your situation is not typical, but that doesn’t help you, since it happened.
I would look at any component that allows lateral motion, spring mounts, spring clamps, shackles,
Also see if you’ve lost any wheels weights. Even though you could drive again at higher speeds, if you pass through that critical frequency quickly enough, a marginally stable system may not go unstable, as there is a time function involved as well
Renegade82, Neuner-9R and Wyo like this.

1977 CJ5 is a CJ build ever really done?
2002 TJ gone
2005 TJ also gone
2005 LJ insurance wreck
stripperguy is online now  
 
post #4 of 32 Old 09-07-2021, 01:48 PM
ECJ-7
Registered User
1976 CJ7 
 
Join Date: Sep 2014
Location: Forestdale
Posts: 776
sway bar shouldn't have anything to do with a wobble. You don't need a sway bar except in hard cornering to keep the vehicle level.
OrangeCJ-5 likes this.
ECJ-7 is offline  
post #5 of 32 Old 09-07-2021, 02:40 PM
StoneTower
Registered User
1985 CJ7 
 
Join Date: Jan 2015
Location: Fair Oaks
Posts: 2,216
A sway bar was never intended to be attached on one side and not the other. I am sure it being disconnected on one side is not helping the problem.

Quote:
Originally Posted by ECJ-7 View Post
sway bar shouldn't have anything to do with a wobble. You don't need a sway bar except in hard cornering to keep the vehicle level.
StoneTower is offline  
post #6 of 32 Old 09-07-2021, 04:08 PM
JEEPFELLER
Registered User
 
JEEPFELLER's Avatar
1977 CJ5 
 
Join Date: Dec 2015
Location: Western
Posts: 1,549
Garage
Look these over

https://www.youtube.com/results?sear...th+wobble+jeep

Some are better than others

Once you neglect it, or it does it intermittently

It's too late!

I complained several times about DW in the van where I used to work.

It was intermittent and hitting a small pothole or a slight uneven spot in the pavement "Could" set it off.

Like everything else you want to show somebody else, it might go days before you hit something just right.

I showed the boss that it was perfectly fine and I was an idiot and my going slow proved that I was just a sniveler after maybe 5 "check this outs!"

I had spread the word, and it got back to him.

While I was performing a task, he stormed over and said this was the last time he was going to test it.

I reckon since he would not let me ride with him this time, The "ONE" person at 60 MPH was all he needed!

Not even out of site, he wobbled a few yards and decided to counter it with by gaining even more yardage sliding the whole driver's side down the road.

That fixed the problem!

I had another van within the week!

------JEEPFELLER
JEEPFELLER is offline  
post #7 of 32 Old 09-07-2021, 09:32 PM
jeepdaddy2000
Registered User
 
jeepdaddy2000's Avatar
1971 CJ5 
 
Join Date: Jan 2002
Location: Eagle Point
Posts: 9,455
Quote:
Originally Posted by ECJ-7 View Post
sway bar shouldn't have anything to do with a wobble. You don't need a sway bar except in hard cornering to keep the vehicle level.
X2
Barring front end damage, DW is usually caused by a caster issue or loose U bolts.

Paperwork will ruin any military force.
Chesty Puller
jeepdaddy2000 is offline  
post #8 of 32 Old 09-10-2021, 04:06 AM
ECJ-7
Registered User
1976 CJ7 
 
Join Date: Sep 2014
Location: Forestdale
Posts: 776
Quote:
Originally Posted by jeepdaddy2000 View Post
X2
Barring front end damage, DW is usually caused by a caster issue or loose U bolts.
I bought a '65 falcon way back with the death wobble and it turned out to be a bad shock and a bald tire. If you hit a bump just right she'd start until you came to a complete stop.
ECJ-7 is offline  
post #9 of 32 Old 09-12-2021, 12:51 PM
80cj
Web Wheeler
 
80cj's Avatar
1980 CJ5 
 
Join Date: May 2002
Location: Hawaii
Posts: 8,753
I drove for a long time with one link on my sway bar disconnected and finally ended up removing it. Problem was that I was getting stuck offroad a lot because the sway bar was seriously limiting articulation. My suspension is firm enough that I feel comfortable driving without the swaybar. Difficult to imagine how the sway bar could affect death wobble. Never made a difference on my Jeep after disconnecting and finally removing it. As was suggested, try reattaching it and see if it takes care of the problem. If it solves the problem, then we all have learned something new.
80cj is online now  
post #10 of 32 Old 09-12-2021, 07:15 PM
jeepdaddy2000
Registered User
 
jeepdaddy2000's Avatar
1971 CJ5 
 
Join Date: Jan 2002
Location: Eagle Point
Posts: 9,455
Quote:
Originally Posted by ECJ-7 View Post
I bought a '65 falcon way back with the death wobble and it turned out to be a bad shock and a bald tire. If you hit a bump just right she'd start until you came to a complete stop.
Apples to oranges. A car's front suspension is completely different than a CJ's.

Paperwork will ruin any military force.
Chesty Puller
jeepdaddy2000 is offline  
post #11 of 32 Old 09-13-2021, 04:29 AM
John Strenk
Moderator
 
John Strenk's Avatar
1976 CJ5 
 
Join Date: Feb 2005
Location: Shalersville Ohio
Posts: 22,663
I always heard about the death wobble but never experienced it until I bought a JK and it was all stock.
My sons JK did the same thing. New steering dampener fixed it.
Never had it in my CJ.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


I drive a Prius to save money and buy more Jeep Parts....
John Strenk is offline  
post #12 of 32 Old 09-13-2021, 07:21 AM
Matt1981CJ7
Registered User
 
Matt1981CJ7's Avatar
1981 CJ7 
 
Join Date: May 2011
Location: Elbert
Posts: 23,035
I've always thought that if you have death wobble at a certain speed, that goes away at different speeds, you have a tire balance problem.

Matt


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Matt1981CJ7 is offline  
post #13 of 32 Old 09-13-2021, 11:30 AM
Renegade82
Registered User
 
Renegade82's Avatar
1982 CJ7 
 
Join Date: Apr 2011
Location: Lewistown
Posts: 5,610
Garage
Quote:
Originally Posted by stripperguy View Post
Itís unusual for a leaf sprung vehicle to have a death wobble. the lateral stiffness of the suspension usually keeps the critical frequency of that vibration mode above the frequency of the tires. In addition, there is usually enough damping in the leaf to leaf interface to preclude such motions.
That's correct as far as everything I've read. Jeeps don't get death wobble. That's more of a Wrangler thing. Jeeps get bump steer, mostly because the drag link and the tie rod are not even close to being parallel. Worn ball joints can also contribute to it.
I've had what is similar to death wobble and it came from having a frozen, or dried out rusted u-joint at the front wheel. I would have never guessed that but I had taken my Jeep to my cousin who was a mechanic. He found it, replaced it, and it was gone.
I suggest putting your front end up on the frame so that your strg. and suspension is loose and unloaded. Then start yanking and pushing on things to see what moves. Use a pry bar under your tires and lift up. Have someone inside cycling the steering back and forth as you watch.
robblue6412 likes this.

The end of a defining era.... JEEP R.I.P. 1941-1986
My frame off Re-Build: (the 4 year saga....)

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Renegade82 is offline  
post #14 of 32 Old 09-13-2021, 02:32 PM
StoneTower
Registered User
1985 CJ7 
 
Join Date: Jan 2015
Location: Fair Oaks
Posts: 2,216
Some CJs do get death wobble. This is an old post from one of our members.

StoneTower is offline  
post #15 of 32 Old 09-13-2021, 03:42 PM
Matt1981CJ7
Registered User
 
Matt1981CJ7's Avatar
1981 CJ7 
 
Join Date: May 2011
Location: Elbert
Posts: 23,035
This excellent article has a good section on death wobble, which can most certainly affect CJs.

https://www.scribd.com/document/1323...pension-Basics

StoneTower, did the owner of the CJ in that video ever figure out what was causing the death wobble? My money is on a tire balance issue.

Matt


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Matt1981CJ7 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome