Death Wobble: A 21 month saga. FIXED!

Wheeled it hard. Drove home 120 miles no problems. Parked it for two weeks. Drove to work and all heck broke loose. Terrible, dive for the ditch cant drive over 45 mph death wobble that could even kick in as low as 30 mph given the right bumps.

That was 18 months ago. I still have it and here is what has been done.

Welded RE HD track bar mount to the frame. Frame already had 3/16th plate sides and bottom. Welds are not broken.
CROK steering box plate. Bolts are tight.
Installed an RE track bar brace I had laying around.
Installed new Johnny Joint on the frame side and new larger bushing and bolt on the axle side.
All control arm bolts fit tight in the mounting ear holes and in the bushings/bearings.
New (rebuilt) steering box
New drag link (Moog)
New TRE's on the tie rod (Moog)
New Unit bearings
New ball joints (Dana Spicer)
New rubber bushings on lower control arm (Moog)
New upper rubber bushings (Moog)
Rebuilt the chassis side of the Rustys control arms (upper and lower) using new balls and delrin washers.
Control arm bolts fit tight in all the holes.
New rims run true
New tires run true and balance
New steering intermediate shaft. Steering is tight as it should be, no slop.

Here are the alignment settings:
Camber L 0.3 deg R -0.2 deg
Caster L 6.9 deg R 6.5 deg
Toe L 0.01 deg R 0.00

So I still drive down the road and I can feel the front end getting unstable at around 45-50 mph. Hit even the slightest bump or pot hole patch seam and the rig immediately goes into death wobble.

I have driven this rig with bent wheels, a missing control arm, toe all screwed up from a bent tie rod, a bad ball joint, cupped tires, bad TRE's, bad unit bearings, bad axle bushings and a sloppy steering box at different times and it never went into death wobble on me. It was very robust. Now I have installed all new stuff and front end is as tight as a tick but I get death wobble at the slightest bump.

The rig has had a hard life. I cant find any frame cracks but could the chassis be so loose that it cant hold the axle under it? Hard to believe because it is so much stiffer after I plated it 3 years ago (RTI score even dropped 75 points after plating).

Could I have too much caster in it?

Suggestions welcome.

John

Death Wobble: An 18 month saga. Need help still

Since you didn't mention these, I'll suggest them.
Try swapping wheels front to back.
Check your shocks and get your wheels balanced.
What size tires are you running?
I'm not a fan of them but have you tried a steering stabilizer?
Did any of the parts you replaced look worn or bad?

Your caster looks in spec.
Didn't give us any other specs on your rig like brands and lift height. That might help. After chasing my death wabble for ages and swapped axles it ended up being the track bar axle bushing. I found a really hard poly bushing and it fixed the problem.

Re: Death Wobble: An 18 month saga. Need help still

GordoSmasho said:

Since you didn't mention these, I'll suggest them.
Try swapping wheels front to back.
Check your shocks and get your wheels balanced.
What size tires are you running?
I'm not a fan of them but have you tried a steering stabilizer?
Did any of the parts you replaced look worn or bad?

Your caster looks in spec.
Didn't give us any other specs on your rig like brands and lift height. That might help. After chasing my death wabble for ages and swapped axles it ended up being the track bar axle bushing. I found a really hard poly bushing and it fixed the problem.

Click to expand...

Right.

How much lift? Long or short arm? Tire and wheel size?

Re: Death Wobble: An 18 month saga. Need help still

Check your angles - are the track bar and drag link parallel?
Read this link
Alignment looks good - well within factory specs.
Have somebody in the driver's seat start the engine and throw the wheel back and forth quickly. Watch your hands, but grab the track bar's threaded section(s) and feel for any movement at all. If threads are galled, they may seem tight but allow some movement. This applies to any similar linkage - if it has threaded adjustment, those threads need to be in good shape to avoid slop / dw / etc.
And, yeah, what is your exact suspension / tire setup?

Re: Death Wobble: An 18 month saga. Need help still

i've found that when you have every component tight as can be, everything is new, and nothing looks worn and its all in spec... you have a bad piece of chassis somewhere. something might be cracked somewhere and you just dont see it.

Re: Death Wobble: An 18 month saga. Need help still

I fixed a broken frame rail at the steering box the other day that resulted in the elimination of a bad death wobble situation

Re: Death Wobble: An 18 month saga. Need help still

if you are 100% sure there is no play in the trackbar at both ends and the mount is tight. Even though my trackbar frame side mount was partially welded, it would still get DW when it came loose at the bolts. weird. Now its all fully welded with about 10 extra bolts and the frame is all plated in 1/4" in the entire front area.

Id consider plating the front area in 1/4" if you havent just because its a pretty solid upgrade in general.

whats youre exact steering setup up front? Pics?

Re: Death Wobble: An 18 month saga. Need help still

Control arms are Rustys, rebuilt joints and new axle end bushings.
Short arms, adjustable uppers and lowers.
Tires are 31x10.50's
Track bar, track bar brace and HD track bar mount are Rubicon Express New bushing and joint.
Steering linkage is all stock. TRE's are Moog, Ball joints are Dana Spicer
Steering box plate is C-ROCK
Lift is 4-1/2 inches. Springs are from a T-Bird
Shocks are Monroe from an F-150,
Steering dampener is Monroe (if its right I shouldn need this)

Tire swap front to rear has been done to no effect. I will be swapping tires with a friend this weekend.

Plating the inside of the frame rail and tying in the track bar braket better is not a bad idea.

Multiple attempts at finding something loose underneath by moving the steering wheel and feeling for slop with different people underneath. Nothing loose that any of us can sense.

The link that yossarian19 posted raises some interesting points once you study it:
Since I am on 31x10.50's using stock wheels the tire contact patch has not moved inboard or outboard from stock. However since these are taller tires the point where the KPI (King Pin Inclination) intersects the ground has moved FORWARD of the contact patch compared to a stock tire diameter Jeep and it has move OUTBOARD. Both of these increase steering forces on Jeep from tire drag and from bumps.

To correct this I need to REDUCE caster, moving the KPI ground intersection point back closer to the tire contact patch AND space the tires outboard just a little bit, 1/4 to 1/2 inch to start.

Before doing anything else I will space the front wheels out a little and then reduce caster to 5 then 4 degrees and see what happens.

Great suggustions. Welder at the ready, spacers on the way.

John

Re: Death Wobble: An 18 month saga. Need help still

The frame rail I rebuilt had a c-rok plate on it....pos.

Use only the jks weld on style and add material continuing down the framerail (past the track bar bracket) AND plate the bottom of the framerail welding it to the outside plates

Re: Death Wobble: An 18 month saga. Need help still

cracker said:

The frame rail I rebuilt had a c-rok plate on it....pos.

Use only the jks weld on style and add material continuing down the framerail (past the track bar bracket) AND plate the bottom of the framerail welding it to the outside plates

Click to expand...

yup. all those plates do is create pressure points onto the stock framerails.

Re: Death Wobble: An 18 month saga. Need help still

The outside and bottom are covered in 3/16ths from the front of the frame horns back to the front spring perch. The inside is bare up front other than the C-Rock plate. Plating the inside back to the track bar bracket and tieing into the bottome would be fairly easy.

Back on geometry. I have run the same lift and tire set up since 2006. The geometry has not been changed since I first had this lift/tire set up in 06 but the death wobble is new. Suggests strongly that the geometry, while not correct, did not cause the problem, rather a weakening of the chassis did, which now allows the geometry problems to manifest themselves.

Plating the inside of the frame on both sides should stiffen it up some (the track bar brace spreads the track bar loads out to both sides). I would think that a similar brace running across the Jeep up front near the steering box (if there is room for it) would also help. Not sure if a steering box brace is what I want as much as I need to tie the two frame rails together up front.

John

Edit: There is room to run a box tube (say 1x3 or 1x4) across between the frame rails where the sway bar mount is. I would have to move the sway bar mounts to the bottom of tube (needed to pass inspection).

Death Wobble: An 18 month saga. Need help still

Can you get a picture straight on from the front. Just so we get a good look at the steering geometry. Im intrested why you are running completely stock steering. You said you run it hard but you use the week stock setup. Especially at 4.5" if lift. At ride height you are pretty much maxing out the travel of the tre at the pitman arm.

Re: Death Wobble: An 18 month saga. Need help still

so TREs, rebuildable joints, and ball joints can wear faster than you think 18 months is along time if you wheel frequently.

My money is on the 4 18mm bolts holding the trackbar mount being loose, or the 2 joints, or the rebuildable joint at the frame side being fubar.

so as of today, you checked since you posted this up, that you are 100% the TREs are good, ball joints, etc?

All of those parts can wear easily in 18 months. thats a very long time.


please post pics.

Re: Death Wobble: An 18 month saga. Need help still

It hasn't been wheeled at all in the last 18 months. Just driven around to see if various fixes solve the problem, nothing has made much difference.

I pulled the bumper, steering box and C-Rock plate (cut it out very carefully) tonight in preparation for reinforcing the inside of the frame rail. The bottom and outside already have 3/16ths plate on them in case you didnt read the earlier posts.

I did not see any cracks in the unibody or any broken welds in the frame plating.

Since I just pulled the steering box its not possible to get a picture that shows the track bar relative to the drag link. The best I can do right now is the picture below. The tie rod is a stock tie rod that has had a solid bar inserted into it and then rosette welded in place. Over that I welded some angle to beef it up a bit more. Never bent this tie rod though I have bent several TRE's. It DW'd with that tie rod in it. I put a stock tie rod back in just to see would happen and re aligned it, no better, no worse.

Re: Death Wobble: An 18 month saga. Need help still

I cut the 3/16ths plate to go onto the inner frame rail tonight. Going TDY for a long day then running a Jeep event at the local Jeep dealership Fri-Sat so I wont make any more progress til Sunday. Need to break out the carbide bit to drill the steel for bolts and rossette welds since its HY120 (used in subs) and is pretty hard.

I did notice that there are tears in the metal between the bottom edge of the front valance/radiator support and one of the small lightening holes in it. The panel is also bowed in/out a bit so it has been flexing quite a bit. This may have happened before I added the front frame stiffeners in 2010 since back then the rig creaked and groaned something awful when steering at low speeds. The noise stopped with the stiffeners and I also lost about 75 point on my RTI scores. It also turned in at corner entry a LOT better at high speed after stiffening.

I will also be addding additonal welds to the existing plating. I skip welded the plate perimeters 1" weld, 3" space, 1" weld. I can put an extra inch of weld inbetween to tie it to the unibody a bit better. Below is a picutre of the front frame horn plates I put in back in 2010 before installation. Note the large number of holes, the vast majority were for rosettes, the rest for bolts.

John

Re: Death Wobble: An 18 month saga. Need help still

plating looks very legitimate man. That should really stiffen up the front and if you find major cracks when you start getting in there that should fix it.

Re: Death Wobble: An 18 month saga. Need help still

blondejoncherokee said:

plating looks very legitimate man. That should really stiffen up the front and if you find major cracks when you start getting in there that should fix it.

Click to expand...

The plates in the picture above were installed back in 2010. Tonight I just added the plate for the inside of the driver side frame rail. Shown below. I tacked the C-Rock plate over this, not for the reinforcement but for the stand offs used to support the steering box. 4 3/4 inch rosettes and then skip welded the top and bottom to the unibody as well. Note greatest welds in a few places (but most turned out acceptable. 110V MIG on at 15 amp line. I get about 10 seconds of welding before the breaker pops so lots of starts and stops (need to stop renting).

I need to hook up the PS lines and steering, which I wont get to til next weekend due to work this week.

John

Re: Death Wobble: An 18 month saga. Need help still

Took it for a test drive a few minutes ago. I still have DW. It comes on at 40 to 45 mph with slight road undulations which is about the same as before. There is no doubt that the chassis is stiffer. The rise and fall times of the steering wheel impacts are much sharper and the frequency is up (time between impacts is shorter). Amplitude of the force is pretty much unchanged. Interestingly I dont have to slow down to 15 or 20 to get it back under control now. The DW ends at 30 to 35mph now.

John

Re: Death Wobble: An 18 month saga. Need help still

As requested earlier:

Below is a picture of the front of the Jeep showing the angles of the track bar and drag link. They are about as close to parallel as I can imagine them being. The wet stains are from R&R of the lower hose to get easier access to the PS lines when I hooked them back up plus a little PS fluid from disconnecting the hoses.

John

Re: Death Wobble: An 18 month saga. Need help still

Control arm mounts cracked, possibly?
Bad-from-the-box steering gear?
I'm grasping for straws here.