Death Wobble

[cmb396]

Just checked air pressure and they are 26-27 psi.. Airing them up now and see what happens..

Mine were around 28 when I got it on a bump in a straight stretch that I hit several times a day and never had DW before. It was cold that day too, around 20.
Aired mine up and hit stuff purposely to try to get it to wobble, and it's been fine.

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[XJADDICTION]

With that much lift you should have long arms or geometry short arm correction brackets to lower control arms to more horizontal to ground position. Your caster is way off if you haven’t done this and everything will cause DW. DW is not fixed permanently by anything other than correct caster AND, trac bar.

check the 19mm bolt at the axle end of track bar.

 

[Punkn_Gladiator]

Make sure everything is tight on the front end bolt/nut wise. Check tire pressure. My front end was getting "loose", and got DW the other day for the first time too, noticed my psi had dropped down with the colder weather more than i realized. Aired up to 38psi from 34psi on my 39's and made all the difference.

Aired tires up to 38 psi after checking everything else which nothing was loose.. Went for a short drive then drove to work with no issues but I am still not convinced air pressure is the issue.. Just have to see if it does the wobble again on my way home.. Planning on triple checking all bolts, ball joints, end links, etc once again tonight..

 

[Punkn_Gladiator]

With that much lift you should have long arms or geometry short arm correction brackets to lower control arms to more horizontal to ground position. Your caster is way off if you haven’t done this and everything will cause DW. DW is not fixed permanently by anything other than correct caster AND, trac bar.

check the 19mm bolt at the axle end of track bar.

I have the drop brackets installed.. I am planning on triple checking everything again tonight when I get home.. I also want to have the alignment shop verify Caster is good since they just aligned it 2 weeks ago

 

[XJADDICTION]

Check that bolt on the axle side of track-bar. 19mm and it should have the factory bolt on there that includes the retainer/tightener metal wing. I also use lock-tite on the threads… I know most don’t recommend but I’ve used it in the track-bar for over 20 years. My first DW experience was in 1997 on a 6.5” lifted XJ Cherokee. None of the 4x4 shops knew what it was… or what caused it… but the Dodge truck dealer knew exactly what it was! Only took me 1 year to get to them.

steering stabilizers, wheel balance, loose CAs, bad tires, bent wheel … etc. all of this shouldn’t cause real DW on its own. DW is directly related to Caster change while driving due to improper orientation of the front control arms relative to the front axle. This IS the primary cause of DW.

So… even if your Jeep’s caster is perfect statically (as in stationary not moving)… AT SPEED if the axle is allowed to rotate enough to reach a caster angle that starts the harmonic cycle then you will have DW. So, control arm length and position are critical to stop this from happening. This is why long arms are so effective at stoping DW. Drop brackets are second best way to do so.

All the other things just make it more susceptible to happening. DW is also usually occurring around 50mph with some sort of uneven surface bump from one front tire to the other to get it started. Real DW is a harmonic event that continues until you do something to change or stop the cycle.

I have done all of these to stop DW when it occurs (DO ALL OF THESE AT YOUR OWN RISK. I AM NOT SUGGESTING FOR YOU TO DO THIS, THIS IS JUST WHAT HAS WORKED FOR ME)
1- hit the brakes hard and get below 35mph (not always safe on the road)
2- immediate and powerful increase in speed…. if your Jeep has enough power to do so, I only could do this in my 6” lifted 5.9L 4:56 geared GC(again acceleration changes the load on the front axle and also wheel speed which strengthens IMOP a gyro effect that seems to stop the DW harmonics)
3- put the T-case in 4H and accelerate slightly (do this at under 60mph).
4- turn the wheel to the right… this can be dangerous as you can easily loose control of Jeep.

after one 7+ inch lift on an XJ Cherokee, I had DW at 35 mph and above. This was all related to caster changes (as it always is) from control arms being to short and when front end unloaded just a little from a bump or acceleration, the CAs allowed the axle to rotate up. This changed the caster and the short arms were essentially not keeping the axle located in position. the only thing that fixed it were newly released… at the time… Rubicon Express beefy drop brackets for the XJ. After I put those on I never had DW in that Jeep again.

 

[Punkn_Gladiator]

Check that bolt on the axle side of track-bar. 19mm and it should have the factory bolt on there that includes the retainer/tightener metal wing. I also use lock-tite on the threads… I know most don’t recommend but I’ve used it in the track-bar for over 20 years. My first DW experience was in 1997 on a 6.5” lifted XJ Cherokee. None of the 4x4 shops knew what it was… or what caused it… but the Dodge truck dealer knew exactly what it was! Only took me 1 year to get to them.

steering stabilizers, wheel balance, loose CAs, bad tires, bent wheel … etc. all of this shouldn’t cause real DW on its own. DW is directly related to Caster change while driving due to improper orientation of the front control arms relative to the front axle. This IS the primary cause of DW.

So… even if your Jeep’s caster is perfect statically (as in stationary not moving)… AT SPEED if the axle is allowed to rotate enough to reach a caster angle that starts the harmonic cycle then you will have DW. So, control arm length and position are critical to stop this from happening. This is why long arms are so effective at stoping DW. Drop brackets are second best way to do so.

All the other things just make it more susceptible to happening. DW is also usually occurring around 50mph with some sort of uneven surface bump from one front tire to the other to get it started. Real DW is a harmonic event that continues until you do something to change or stop the cycle.

I have done all of these to stop DW when it occurs (DO ALL OF THESE AT YOUR OWN RISK. I AM NOT SUGGESTING FOR YOU TO DO THIS, THIS IS JUST WHAT HAS WORKED FOR ME)
1- hit the brakes hard and get below 35mph (not always safe on the road)
2- immediate and powerful increase in speed…. if your Jeep has enough power to do so, I only could do this in my 6” lifted 5.9L 4:56 geared GC(again acceleration changes the load on the front axle and also wheel speed which strengthens IMOP a gyro effect that seems to stop the DW harmonics)
3- put the T-case in 4H and accelerate slightly (do this at under 60mph).
4- turn the wheel to the right… this can be dangerous as you can easily loose control of Jeep.

after one 7+ inch lift on an XJ Cherokee, I had DW at 35 mph and above. This was all related to caster changes (as it always is) from control arms being to short and when front end unloaded just a little from a bump or acceleration, the CAs allowed the axle to rotate up. This changed the caster and the short arms were essentially not keeping the axle located in position. the only thing that fixed it were newly released… at the time… Rubicon Express beefy drop brackets for the XJ. After I put those on I never had DW in that Jeep again.

Great info! Thanks

 

[Punkn_Gladiator]

With that much lift you should have long arms or geometry short arm correction brackets to lower control arms to more horizontal to ground position. Your caster is way off if you haven’t done this and everything will cause DW. DW is not fixed permanently by anything other than correct caster AND, trac bar.

check the 19mm bolt at the axle end of track bar.

Rough Country gave me these specs to stay within so tomorrow morning I am going up to the alignment shop to get a print out of my alignment they did.. Compare them if something is wrong they will fix it.. If all is within specs then I am taking it to Rough Country(1hr away) for them to find the issue..

 

[ShadowsPapa]

6"lift? But no mention of the geometry correction? That track bar is sitting at a crazy angle unless you've done something about that.

What caster is this running at? Have the control arms been relocated to make things sit proper again? OK, looked at your last posts - 38 psi is way up there on those huge tires. Mine stock was 38 with skinny Overland tires. The bigger the tire, the lower the pressure. You shouldn't be running anything in the mid-30s even.
And caster? Those are low numbers. Don't get down as far as 4 or 3. Even JTs with less lift need more caster than 4 degrees. Some are running in the 6s. I'd be happy with mine in the 5s, I'm running upper 4s now and want some more.

 

[Punkn_Gladiator]

6"lift? But no mention of the geometry correction? That track bar is sitting at a crazy angle unless you've done something about that.

What caster is this running at? Have the control arms been relocated to make things sit proper again? OK, looked at your last posts - 38 psi is way up there on those huge tires. Mine stock was 38 with skinny Overland tires. The bigger the tire, the lower the pressure. You shouldn't be running anything in the mid-30s even.
And caster? Those are low numbers. Don't get down as far as 4 or 3. Even JTs with less lift need more caster than 4 degrees. Some are running in the 6s. I'd be happy with mine in the 5s, I'm running upper 4s now and want some more.

Adjustable Trac bar with relocation bracket and control arm relocation brackets for the 6" lift.. Thing is I have been driving this setup for 1 year not a single issue until the tire shop did the alignment 3/4 weeks ago.. Tires are at 35psi..

 

[XJADDICTION]

Rough Country gave me these specs to stay within so tomorrow morning I am going up to the alignment shop to get a print out of my alignment they did.. Compare them if something is wrong they will fix it.. If all is within specs then I am taking it to Rough Country(1hr away) for them to find the issue..

Camber can be is spec with most any solid axle lift, caster can be in spec in a static measurement (as in at the shop on alignment rack)… but with short arms and that much lift I’ll bet the caster easily goes beyond spec when you drive it. Once the front pinion is allowed to rotate up, caster goes extreme and the only thing controlling that back and forth rotation is your drive-shaft… and that has a joint in it so does not stop that rotation. This is why a proper (or notorious) bump at about 50mph+ will always cause DW if caster is allowed to go out if spec (I.e. the front end of the vehicle is weighted in down travel, pinion angles down, then unweighted on up travel the pinion will swing up, opposite of what you might think but Drive-shaft at high speed rotation and compression/extension at slip plays in). Sometimes… good shocks and springs that are progressively rated (Rough Country has notoriously stiff ride due to spring rate (one size fits all) and their shocks are very basic dampers. They can’t handle those sudden changes like a high end shock can).

Drop brackets, long arms will get rid of your troubles with the RC lift. Better shocks and springs will make it ride soooooo much better! Your weight (vehicle weight that is) and application are huge when you purchase a lift for your vehicle. Cheaper (less expensive) lift kits are less expensive for a reason.

trac-bar and drag link have to be in parallel. Shadow mentioned, those Are also important though not causing DW they will cause bump steer if not set up correctly.

Just for the heck of it, go put a 19mm socket with extension and a good torque wrench on there and see if that tracks bar is loose at the axle. Personally I do this by feel with a long ass socket breaker bar. I drive my JT a lot right now with 3.5” RE lift and can tell right away if the trac-bar is loose. I’ll Stop at gas station, tighten up and smooth as silk afterwards.

 

[Punkn_Gladiator]

Camber can be is spec with most any solid axle lift, caster can be in spec in a static measurement (as in at the shop on alignment rack)… but with short arms and that much lift I’ll bet the caster easily goes beyond spec when you drive it. Once the front pinion is allowed to rotate up, caster goes extreme and the only th isn’t controlling that back and forth rotation is your drive-shaft… and that has a joint in it so does not stop that rotation. This is why a proper (or notorious) bump at about 50mph+ will always cause DW if caster is allowed to go out if spec (I.e. the front end of the vehicle is weighted in down travel, pinion angles down, then unweighted on up travel the pinion will swing up. Sometimes… good shocks and springs that are progressively rated (Rough Country has notoriously stiff ride due to spring rate (one size fits all) and their shocks are very basic dampers. They can’t handle those sudden changes like a high end shock can).

Drop brackets, long arms will get rid of your troubles with the RC lift. Better shocks and springs will make it ride soooooo much better! Your weight and application are huge when you purchase a lift for your vehicle.

trac-bar and drag link have to be in parallel. Shadow mentioned those Are also important though not causing DW they will cause bump steer if not set up correctly.

Just for the heck of it, go put a 19mm socket with extension and a good torque wrench on there and see that tracks bar is loose. Personally I do this by feel with a long ass socket breaker bar. I drive my JT a lot right now with 3.5” RE lift and can tell right away if the travel-bar is loose. Stop at gas station, tighten up and smooth as silk afterwards.

I installed 4 new Fox reservoir shocks, new Falcon adjustable stabilizer then put a torque wrench on every suspension and front end piece yesterday..

 

[Pcasp3]

welp, i fall into the unique category of DW now... 14k miles is when it occurred dealer has checked all torque on components. replaced track bar, replaced steering arm to pittman arm which was worn. put on 0 mile brand new wheels and tires to verify still has it... now they are recommending a drop bracket on the factory mopar lift.. like wtf? isnt is engineered to have the correct geometry... to me a drop bracket sounds like hanging another random ass part on it to hopefully mitigate the underlying issue just like a dual steering stabilizer which i only have the factory single from the lift. will report back whenever solution is found on my end...

 

[ShadowsPapa]

like wtf? isnt is engineered to have the correct geometry..

Uh, no. Not unless you dropped the frame end of the control arms to keep them level, more parallel with the ground. Most low lift kits won't do that, in fact, many over 3" won't do that.
Any time you lift a truck - you change geometry.
Maybe you don't realize - that lift kit is lower control arms (to regain some caster), springs, shocks, etc. - nothing else to it.

 

[bgenlvtex]

Uh, no. Not unless you dropped the frame end of the control arms to keep them level, more parallel with the ground. Most low lift kits won't do that, in fact, many over 3" won't do that.
Any time you lift a truck - you change geometry.
Maybe you don't realize - that lift kit is lower control arms (to regain some caster), springs, shocks, etc. - nothing else to it.

2" Mopar comes with slightly longer LCA to correct geometry.


Who installed this lift?

 

[Pcasp3]

2" Mopar comes with slightly longer LCA to correct geometry.


Who installed this lift?

dealer... my thoughts exactly on kit comes with proper geometry... which is why im reluctant to accept the repair with an aftermarket part on it, also. i doubt itll fix it.

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