Death Wobble: A 21 month saga. FIXED!

[Devilfrog]

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

snapped some pics of the bracket/bracing. The new paint is where extra metal was added. the whole bracket was actually twisting on the crossframe brace before this.





this one is fully boxed and gusseted now, it used to open on the inside and was a simple chunk of tube (open back like a C ). All gaps are filled (between bracket and frame) and it's braced pretty heavily, we could probably add more but we'd be getting into overkill (the option is there if needed though). I am happy to say my own journey is over for now ... and today I measured my axle and realized it's sitting an inch back on the passenger side, yet she still runs perfect on the road and highway ... have to sort that next shift home.

hopefully that bearing makes a world of difference for you. I used to cringe when I hopped in the XJ for a while, now I'm just all grins again.

 

[nosigma]

Re: Death Wobble: An 18 month saga: ALMOST CURED

Finally some REAL TANGIBLE PROGRESS.

Last night I Installed the new unit bearing. While doing that I found some slop in the tie rod, just a little play in the threads of the TRE inside the tie rod. The Goodyear shop didnt tighten the clamps beyond just snug on one side.

Took it out for the usual depressing run down the relatively smooth road that is Dolley Madison (RT123) past CIA HQ, where at 40-45 mph it starts to shake itself to death. Guess what? No shaking. No vibration. Feels GREAT. I run that route a couple more times hitting all the manhole covers swales and patches in the road. No DW. Time to pick it up notch. Head West the GW Parkway. Hit 60 then 65 mph. Lots of rough spots. All good. Finally I hit a stretch of patched road about 25yds long (still at 65) and I get is bit of a shimmy. NOT DW. Back off to 50mph and it stops. Speed back up, turn around in a park and run back home. No shimmy, no DW feels good.

Not perfect but its getting close, real close.

Here is the task list:
1) Get it aligned (check the clamps). Toe is out, wheel is off center and it pulls mildly to the left.
2) Doing a tire swap with a guy that has brand new 31x10.50 this weekend.
3) Pull the motor mounts and plate the full inside of the frame rails and finish the bottom off from the firewall up to the motor mount. Read most of the Advanced Fab threads and everything I could find on this. I am sold.
4) Run a pair of gussets from the inside of the frame rail down onto the shelf that the track bar bracket bolts to.
5) Add some section thickness to the outside of the track bar bracket to stop any bending. The RE HD bracket is just a big flat plate on the outside the frame rail.

Lots of work to be done but now success seems very very close.

Devilfrog:
Thank you for posting the pics. The RE bracket is well braced underneath but its got nothing on the outside, just a big flat plate going up the side. Sort of the opposite problem you had. I could use some section thickness on the outside (like your bracket has) so I will add it.

My persistence seems to be paying off and all your suggestions have been incredibly helpful. Not done yet, but very very close.

John

 

[blondejoncherokee]

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

Love the plating . Post more pics once you get the rest of the stuff done

 

[nosigma]

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

Not sure I would call it progress but I picked up a 3'x6' 10 gauge sheet of steel today after work. I will start pulling the motor mount brackets tonight and get on with the extra plating. When I get some real progress on the plating I will post some pics. In suspension news there is still something thats not exactly right in the steering gear. I can feel a catch/thump in the drag link when someone turns the wheel just as the tires change direction. Change out the drag link TRE but no improvement in DW. I notices a very small amount of free motion in the pitman arm when the drag link was off. The arm moves between 1/16th and a bit less than1/8 of an inch at its end. It would not surprise me if I needed to replace the steering box with all the hammering it took. I will probably survey boxes in the JY instead of going back to crap auto or ordering a $400 new box from the dealership.

Video from the last drive after replacing the TRE on the pitman arm.

John

http://www.youtube.com/watch?v=ha9ywNVyUIE

 

[Devilfrog]

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

In my journey I replaced the stock box with one from a TJ I picked up with pump and hoses for $150 ... that alone made a world of difference. The flexing trac bar bracket was only a problem if I found just the right pothole, at just the right depth, at just the right speed, at just the right angle of attack.
And I still need an alignment, but now I cruise over stuff that used to scare the piss out of me before.

 

[rockclimber]

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

if you do get a TJ steering box, make sure it is pre 03. they changed to a POS mercedes box in 03 with a different bolt pattern.

 

[Devilfrog]

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

Yeah, was just about to type that part as well.

Was thinking ... tie both sides of the bracket together (box it) and maybe add the gusset from the front of the bracket to the brace bar. Your bracket still seems to be doing a lot of moving, mine is just bolted in with the four stock bolts an shows less movement (it's also longer so should place more force on the frame). I'm not sure how the brace attaches (can't see the back side) but it does attach considerably higher than the actual trac bar (so it creates less controlling force than the tracbar creates moving force). My brace attaches using the same bolt the bar is attached with and goes directly to that bolt ... the passenger side mount looks pretty much the same as mine. Another thing ... when I attach my brace I have to pull the brace to the bracket just as the bolt pops through in a dance of bolting. If the bolts come through too soon, no way that brace is going on without lots of pry bar (but there is no room ... I tried).
Just throwing thoughts, I feel your pain bud, it's a crappy journey I know.

 

[nosigma]

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

Devilfrog,
I like the way your brace attaches, being centered on the bolt that secures the track bar itself. Much better than the location that the RE brace attaches. Finally settled on how to stiffen the bracket so it wont flex. Pics when I get it welded up.

Devilfrog & Rockclimber,
Thanks for the hint on the TJ box. I will go that route.

All,
I think I found part of the reason the bracket was moving. When I pulled the motor mount to frame bracket (it supports the actual motor mount) I had to remove the two bolts that run up through the TB bracket on the inside of the frame. The when the rear bolt came out I heard a clunk, like something fell out, but it wasnt the bolt.

The rear corner of the track bar bracket had broken off. The picuture below shows the damage. Its a real bad angle to get a picture from but you can see that it failed right around the bolt hole. You can also see a part of the broken corner lodged into the hole. Need to drive that out.

I remember thinking that it was a weak design when I put it in. The distance from the edge of the TB bracket to the edge of the hole was less than a fastener diameter. Good design calls for at least a full diameter and best is 1-1/2 diameters. Of course I didnt make things any better when I had to offset the hole 3/16ths of an inch to make up for the plating on the outside of the frame which offset the hole so it would line up with the bolt holes going up through the bottom of the TB bracket and frame into the motor mount bracket.

Its a nasty little tear. Corrosion, flexing, lots stress right there. Its fixable and I can make it a lot stronger. I do need to change the load path, which I did about a year ago with the TB bracket brace, but it was probably way to late by then. A gusset form the TB bracket to the brace will help tremendously. Need to be careful to spread the load out on the tubular brace, I dont want to collapse it so its going to be a LONG gusset where it attaches to the brace.

 

[markw]

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

Let me guess, you had big tires and wheeled it some before doing all the frame plating right? Seems that everone who's cracked the frame around the steering box/drop bracket did so without having a steering box brace or other re-enforcements there.

 

[nosigma]

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

Been on 31's since I got it in 2004. Plated the frame in late 2008. But I run it way beyond what most people would consider 31's suitable for. I like to pick my way through, do a lot of self spotting and plan my routes carefully. Didnt do anything to radical when I was in SoCal (Rubicon) with few bypasses (Little Sluice was definitely bypassed). Most of the difficult stuff came when I moved East. Crozet Blacks and little Red where safe for no cage and then The Cove, particularly Corum Special which is a 35's minimum trail. How I love Corum.

John

 

[nosigma]

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

With work, travel and family it takes a while but I finally go the inside and underside frame plating started. I finished the driver side last night. Plan on cutting the plates for the passenger side today. Its snowing this morning with freezing rain expected this afternoon and this evening so I dont think much welding done. Overhead in the cold is one thing, overhead in the cold with freezing rain is something else.

The bottom plate under the engine mount was put on about 4 years ago. I put the inside front plate on a couple months ago. The inside rear plate does not go all the way back to the firewall and the back edge is curved with two extensions to try and distribute the loads smoothly and vertically along the frame rail to minimize stress concentrations that start cracks.

I also fixed the broken edge of the track bar bracket where the bolts go through to the engine mount (see 2 posts back). I cut a 1/4 inch plate to replace the broken off parts and extend the bracket further inboard so it sat under the frame rail for one side to the other. With both outside and inside frame plates the bolt holes dont line up so lots of grinding with a burr and a little metal to strengthen the bracket was required.

Progress continues.....

John

 

[nosigma]

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

Made some progress on this over the rainy weekend. It rained and sleeted here all Saturday afternoon and night. Working outside under a tarp lean-to. I finally had to quit around 9pm when the welder started to "tickle me" despite my being dry and insulated from the damp ground.

Passenger side and lower plating from under the engine mount back to the fire wall done. The lower is now complete from bumper back. I need to add a forward plate from the engine mount to the bumper. Side plates are tied into the bottom.

Started on the steering box brace/cross member (modified copy of NCCherokee's design). I am carrying the side plates up to the top of the frame rail to capture all three of the steering box bolts on the driver side and the passenger side (holes are there) along with the sway bar bolts. I am hoping that this brace along with the frame plating will both stiffen the front end considerably as well as eliminate any steering box motions.

Need to finish the pax side front inner plate, install eng mount on pax side, install oil filter boss, tighten up mounts on both sides and then complete the cross member before it goes on the road for a test drive. Taking a couple weeks off work so unless it gets just nasty stupid cold and wet I should get it done before the first of the year.

John

 

[nosigma]

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

ITS FIXED ITS FIXED ITS FIXED

Thank you NC Cherokee for posting the steering box support work you did.

Thank you: Devilfrog, rockclimber, cal, blondejoncherokee and cracker

You convinced me to take on the long, cold, wet, dirty and electrifying (you get shocked welding in wet conditions you know) task of plating the rest of my front frame rails. I darn near trashed the rig out of frustration a couple times in the last 21 months but I stuck with it and now it is finally fixed.

Success is so sweet. 21 months to get the DW fixed.

After finishing putting the axle back in tonight I took it for drive. Hit all the rough spots, swales, pot holes, gutter drains and choppy patched concrete I could find, all of which caused DW previously. Steady as rock with not hint of shudder to vibration. I can happily proclaim the the DW I have had for so long is now FIXED !!!!!!!!!!!!!!!!!!!!!!!!!

The last steps to resolving it involved welding 10 gauge plate to the inside of the front frame rails from the front bumper back to the fire wall. Welding 10 gauge plate to the bottom of the frame rails where it was not already plated and tying it all together as best I could where it butted up, a big job in and of itself, adding a new 1/8 inch wall 2x2 cross member just forward of the sway bar mounts that captures the sway bar mounts and sandwiches the frame rail grabbing the three steering box bolts on each side (pax side is only used on RHD vehicles). The cross member also supports a pillow block bearing that supports the bottom the steering box (extended nut from PSC) which puts the steering box shaft into double shear.

Maybe the frame plating alone would have done it, maybe the cross member and steerig shaft support bearing alone would have done it. I really dont care at this point ITS FIXED!!!!!!!





Now I need to cut off the camera mounts (tube welded to the frame rails), reinstall the bumper and then figure out a way to mount the sway bar so I can get through inspection but these tasks pale in comparison to what I have just completed.

I am so outrageously happy to have my rig back.

Huge thanks to everyone who assisted me in chasing this down and ecouraging me not to give up!!!!!!!!

John

 

[cracker]

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

Good job john!

 

[highspeed]

I just read this whole thing. Congrats on a long fought battle

Glad to see it all welded up and fixed

Ive been to McLean a few times. ��

 

[yossarian19]

So, the lessons seem to be
1 It's probably something you've already looked at
2 wheel bearings. Check them.
3 If it's been flogged , it might be cracked. Weld things and add steel in direct proportion to your doubts.

 

[PahlMc]

First: RIGHT ON! Second: Damn I wanted to know the cause. So it may be the sector shaft or frame flex.

 

[NCCherokee]

Glad it worked out. Wonder how much the sector shaft slop played into this

 

[nosigma]

yossarian19: right on. Triple check that which you have already checked if the problem persists because you WILL break the new parts.

PahlMc & NCCherokee:

If I find that I am bored this weekend I will pull the bearing off and take it for a drive. The question of frame or sector shaft will be answered if the DW comes back.

The video I shot (link below) shows the dw kick in at full and 1/4 frame rate. you first see movement in the end of the pitman arm before the dw kicks in hard. Not sure if that is just a reaction to the onset of dw or the cause since I had no audio marker of when it actually started. I can not see any side to side motion in the sector shaft initially. After the dw gets violent the whole front end is shaking so badly that it is impossible to sort out what is moving relative to what else.

http://www.youtube.com/watch?v=ha9ywNVyUIE

I am betting it was frame. Remember this all started AFTER and uneventful drive home of 200 miles from a running some harsh rock trails (V-trail and Corum at the Cove) and let it sit parked for two weeks. Next time I drove it, to work on a nice smooth road DW set in. I am betting there was frame damage/loosening and after sitting for two weeks it just sagged, weakened and got worse.

At test w/wo the bearing will tell.

John

 

[NCCherokee]

Wow that video is awesome. I'd love to see my trackbar, used to have a pretty good knock from it that was resolved with the RE brace. Kinda makes you realize how much the frame can flex. I bet that was your issue. I'm thinking if the brace did anything for you, It may have been to limit frame flex at the steering box.