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OilHammer
07-23-2012, 04:49 PM
I've read about it for years, but never actually experienced it fully. I had been getting a weird steering vibration ever since the ride home from Moab this year, and had been gradually tracing it down.
I found a loose pitman arm, loose knuckle studs on one side, and one wheel bearing was slightly loose. My guess is that several years of pounding the truck on these Maze trips has taken its toll on the hardware.

I thought I had it all fixed, but the problem was still there. At highway speeds, I would hit a bump and it felt like a tire was out of balance for a second or two after. Not a huge deal, but weird. I took the truck by Robbie one day at lunch and in about 5 minutes he diagnosed shot TRE and trunion bearings. Funny part is that the TRE's were replaced 5 years ago or so.

On the ride home that day, I watched a Cherokee nearly wipe out on the interstate from this problem. Bump and then violent wheel shakes and he barely kept it under control to pull over. Friday on the way back from the Boulder, the same thing happened to me. Had to nearly clean my shorts after that experience!

All that said, I will be planning a full on knuckle rebuild along with a lot of other stuff that's overdue.

The tech part of this, is has anyone else with five five five TRE's had similar early failure of these parts? I think the main problem I'm feeling right now is more TRE than trunion, but it all has to go.

rover67
07-23-2012, 05:05 PM
My TRE's have had to be replaced every 50k or so. I use the 555 brand.

I think we beat the **** out of that kid of stuff.

Oh, and if you figure out the DW, let me know. I still have a hint of it after replacing everything but my axle. Driveable, but you can feel it.

Jacket
07-23-2012, 05:08 PM
The 555's on my 40 are 3-4 years old and seem fine - no issues. But I don't drive my 40 nearly as much as you.

OilHammer
07-23-2012, 05:43 PM
Driveable, but you can feel it.

And that is exactly why I posted this. I felt the same way. The wear in the TRE was only apparent when Robbie used a huge prybar on the joint to press it away from the knuckle arm. When he did that, you could just barely see it move. The Trunions have a slight "spot" in them that you can only feel when both tires are lifted off the ground and you turn the tires side to side by hand. I NEVER would have guessed that amount of wear would have produced the situation I had on the freeway. It was some scary stuff that I never want to experience again, especially in a SWB at speed. In fact, I may very well escalate doing the 450 to sooner rather than later because I suspect it also needs this maintenance.

The only other thing I can think of that may cause the DW might be slop in the steering box? Marco, I think both of us had our steering boxes rebuilt by the same guy...:bolt:

Corbet
07-23-2012, 08:40 PM
good timing on this tread. I've developed an intermitant DW on the 80. I have not had a chance to really look into it but suspect TRE's as I replaced all the bearings last year during the knuckle service.

It was really bad over the Friday in Silverton and Ouray however only while braking. Not as bad in a corner. But Sunday driving to Pagosa and today around town nothing?

rover67
07-23-2012, 10:10 PM
You know, I keep going back to the steering box, but I went through mine twice since the time I built it first. It sure seems tight, but maybe I am missing something?

I'll research the subject more...

nakman
07-23-2012, 10:28 PM
Sure you don't just have hot brakes Corbet? My 80 would always shake about midway down Monarch Pass... but once on the flats again would be good for another year.

AxleIke
07-24-2012, 12:32 AM
Granted, I've only read about death wobble, but I've read a lot. And talked a lot. That being said, take this with a grain of salt

You guys hit the common issues, but caster is often the root cause. A lifted truck without a cut and turn done often has it's caster out of spec, or just on the edge of spec. Combine that with worn parts, and death wobble ensues. Poor caster is very common on most leaf spring trucks. Especially if the axle has been turned at all for driveline correction.

Also, I know Marco has replaced everything, but look into the bushings on both ends of your springs.

On my buddies 87 4Runner with a SAS, he still had death wobble, even after brand new TRE's and new bushings in the leaf springs. Much of the issue can come from a lack of inner sleeve on the bushings. Some lift kits don't come with an inner steel sleeve in the bushings which is necessary for proper driving and keeping the spring immobile. Without the bushing, you just mash the bushings together, and they get destroyed quickly, and there is no support in the bushing for the spring to ride against.

And, be glad you guys have the 555 stuff. I used to burn IFS TRE's in a few months, and that was on 33's. 35's, and I lost a new one within 3 weeks.

OilHammer
07-25-2012, 10:30 AM
Robbie was quick to mention the spring bushings as well, and I have never had mine out. The lift came on the truck when I bought it, and I hate it, so I had planned on swapping to something else. Coilovers would be my choice (ala TLC Icon style) but I have mixed feelings about continuing to modify my 40. Meh, it's parked now for a while, so I have time to pull it all down and find the issues.

Corbet
07-25-2012, 08:40 PM
Sure you don't just have hot brakes Corbet? My 80 would always shake about midway down Monarch Pass... but once on the flats again would be good for another year.

Could be but I don't think so. The rotors are only a year old and DBA slotted units. The worst wobble was right after exiting a trail that was mostly uphill. Then I climbed up the rest of the way to the top of Molas pass before descending into Silverton. So the brakes should have been cool going into my wobble.

I've tried to recreate the DW on my way to work this week. I drop about 1500' into Durango on my morning commute. Even riding the brakes I can't get it to wobble again.

I think the beating on the trail might be shifting a worn TRE? But I need to get the pry bar out this weekend and take a closer look.

Corbet
07-31-2012, 09:14 AM
Well I'm somewhat stumped as I could not find anything obvious over the weekend with the pry bar. TRE's seem fine. I did not put a wrench on the steering arm bolts but visually they looked good and I did tighten them back up post CM12. I guess I need to pull the wheels and do a complete inspection on jack stands this weekend.

Its still hard for me to accept I may have overheated the brakes. After many trips with an un-braked trailer behind me I have never got them hot. A casual trip to Silverton should not have worked them that hard. :confused:

TonkaToy
08-08-2012, 10:09 PM
I had a serious DW issue last year. Turned out to be loose spring ubolt nuts. I found them when I was tearing it apart to put shims in, because I thought that might have been the problem. Added the shims and tightened the nuts down good and no problems since. Sometimes it's the simple things.

OilHammer
08-08-2012, 10:56 PM
Or a combination of simple things that add up. Ever wonder why troops break march over bridges? ;)
Good reminder to tighten mine as part of the troubleshooting. Mine have been loose in the past, and I'm pretty sure that creaking I get in the front end under flex is related to that.

Corbet
08-13-2012, 06:29 PM
Well this might explain a few things. Bad phone pic but the LCA hanger is cracked to the point of 90wt leaking out. :eek:

Edit: Replaced photo

Old40Dog
08-13-2012, 07:18 PM
And discovering this on your birthday none the less! Ouch! :doh: Think its repairable?

Corbet
08-14-2012, 08:05 AM
And discovering this on your birthday none the less! Ouch! :doh: Think its repairable?

I think to determine if I can weld this back together would require complete disassembly. I don't think I want to tear it down to that point without a housing on hand for re-assembly. I don't have the garage space for long term storage of an immobile vehicle.

rover67
08-16-2012, 10:41 AM
The only other thing I can think of that may cause the DW might be slop in the steering box? Marco, I think both of us had our steering boxes rebuilt by the same guy...:bolt:

So I thought about this and I am sending a spare box (cardinal's actually... I hope he approves) off to west texas offroad to get rebuilt. They get good reviews on mud and I am thinking maybe I might be missing something in the steering box. I'll get it back in a few weeks and put it in the 60 and see if there is any improvement.

I feel like I have checked everything on my rig. I even actually put two power steering gear boxes on it, one good used one not rebuilt by me or anybody.. Some had slop and the rebuilt ones didn't. Still they all had a "pulsing" feeling when turning slowly. I think that may be contributing. Also, just FYI I have been through 3 power steering pumps seeing if it was that. none made a change, but my super fancy one from PSC groaned really loudly and I replaced it with a NAPA one after sending it back to PSC twice with no improvement.

CardinalFJ60
08-16-2012, 11:14 AM
Yep...you have my blessing. :thumb:

OilHammer
05-14-2013, 05:11 PM
It's back! My trip to Moab last month was sketchy at best. I hit a diagonal expansion joint coming through Vail that nearly tossed me into the guardrail.
Truck is now down until I can rebuild a number of systems, not the least of which is replacing the lift. (I did a knuckle job, apparently wasn't the full problem)

My springs are now severly sagged on the driver side and I suspect that is pushing the truck out of alignment enough that I'm wearing my tires oddly. Couple that with spent bushings (likely) and you might have an explanation for the DW.

So, what springs to get? I really wanted to pop the 80 arms under there and put some coilovers in, but I think I have talked myself out of it.

OME- I have had OME leafs on a 40 before. Not bad, but not too much lift, and they sagged quickly IIRC. Also stupid expensive now for some reason.
BDS- I had these on my otherwise stock 60. Rode like garbage, even after years of use.
OME coils- Had these on my 80. Not impressed. I think progressives would have been better. In general, I think OME is set up for mild heavy trucks.

What I do: 90% is daily driver to Boulder and back. 10% expo style wheeling with just a little crawling mixed in. Nothing too extreme but my current lift has ZERO rear articulation and rode like crap to boot. Only heavily loaded did it ever smooth out.

Mods: I have a PTO up front, a diesel, and a hardtop, all running on 33's. Nothing too crazy. Ideally, smooth ride with some whoop travel would be nice.

Thoughts? (Retire it and buy an 04 taco you say? lol)

PabloCruise
05-14-2013, 05:13 PM
I've read about it for years, but never actually experienced it fully. I had been getting a weird steering vibration ever since the ride home from Moab this year, and had been gradually tracing it down.
I found a loose pitman arm, loose knuckle studs on one side, and one wheel bearing was slightly loose. My guess is that several years of pounding the truck on these Maze trips has taken its toll on the hardware.

I thought I had it all fixed, but the problem was still there. At highway speeds, I would hit a bump and it felt like a tire was out of balance for a second or two after. Not a huge deal, but weird. I took the truck by Robbie one day at lunch and in about 5 minutes he diagnosed shot TRE and trunion bearings. Funny part is that the TRE's were replaced 5 years ago or so.

On the ride home that day, I watched a Cherokee nearly wipe out on the interstate from this problem. Bump and then violent wheel shakes and he barely kept it under control to pull over. Friday on the way back from the Boulder, the same thing happened to me. Had to nearly clean my shorts after that experience!

All that said, I will be planning a full on knuckle rebuild along with a lot of other stuff that's overdue.

The tech part of this, is has anyone else with five five five TRE's had similar early failure of these parts? I think the main problem I'm feeling right now is more TRE than trunion, but it all has to go.

Just to clarify, you had not replaced trunion bearings before experiencing the death wobble?

OilHammer
05-14-2013, 05:18 PM
No. I put used 70 series axles under it with unknown mileage. As far as I can recall, all I did was put new rotors and hub seals on it. Pretty sure all bearings remained stock. I replaced the TRE's when I did the swap back in 05.

Back in January, I replaced the trunions, TRE's, and tightened loads of stuff. Better, but still had the occasional "tire out of balance" feel on bumps right up until this trip. This trip was a nightmare on any uneven road surface, even dirt.

I rotated the tires and adjusted the toe out a little while out there. Helped but didn't fix it. On the way home, i noticed it pulls HARD to the right. Left springs are flat, so that kind of makes sense it would pull right. I need to pull a tape, but I'm guessing I have 1/2" more between axles on left than on the right.

PabloCruise
05-14-2013, 05:27 PM
Wow. Just noticing the time lapse in this thread.
I am interested because I have had some wobble issues w/ my 40.
I have tightened U-bolts, replaced U-bolt plates, added caster shims, replaced TREs, tightened shackle bolts and finally rotated tires and that seemed to help. I probably should replace bushings, have not done that in a while...

OilHammer
05-14-2013, 05:31 PM
[QUOTE=PabloCruise;232672]Wow. Just noticing the time lapse in this thread.
QUOTE]

Yeah, I didn't get around to the major repairs on it until Christmas and hadn't seen the symptoms really come back until early this month.

PabloCruise
05-14-2013, 06:45 PM
I'll look for your updates.
I think Death Wobble would be a great dynamics class project for mechanical engineering students...

Corbet
05-14-2013, 07:20 PM
I'm guessing I have 1/2" more between axles on left than on the right.

I think a trip to the alignment rack would be worth the money. You've been chasing something for a while now. A print out may display the smoking gun. Or at least point to the wheel in question.

If one side is sagging that bad it could be the problem. But has this always been the case or just recently?

Anyway I have OME springs on my 40 that worked very well. Well up until my engine fire anyway. I drove it daily for over a year on them. Speed tested to 100+. The front end has a SR as well. The truck was light. SBC, 2.5" OME with 33's. Stock front bumper, rear is custom by Cruiser Outfitters, no winch, did have a sub tank. Drove like a Caddy after the lift. Mine are older springs before they moved production. Maybe some things have changed?

PabloCruise
05-14-2013, 07:32 PM
I think a trip to the alignment rack would be worth the money. You've been chasing something for a while now. A print out may display the smoking gun. Or at least point to the wheel in question.

If one side is sagging that bad it could be the problem. But has this always been the case or just recently?

Anyway I have OEM springs on my 40 that worked very well. Well up until my engine fire anyway. I drove it daily for over a year on them. Speed tested to 100+. The front end has a SR as well. The truck was light. SBC, 2.5" OME with 33's. Stock front bumper, rear is custom by Cruiser Outfitters, no winch, did have a sub tank. Drove like a Caddy after the lift. Mine are older springs before they moved production. Maybe some things have changed?

Do you mean OME springs? Sorry, not familiar with your rig...

Shotshell
05-14-2013, 10:23 PM
You'll have to ignore my ignorance. But what are these TRE's you guys keep talking about?

OilHammer
05-14-2013, 10:37 PM
Tie Rod Ends (TRE)
I have replaced mine twice, but the first one's I think were shorted on grease. Doh.
Spring sag: I made this theory years ago and nobody on mud agreed with me that it would be substantial enough. I disagree. Jack up the rear frame so the rear axle droops all the way down. Measure the horizontal distance from the axle to the door. Now fully compress one side of the rear suspension (ramp) and measure again. You'll find the axle "moved" backwards a good bit. To me, it's not too far of a stretch to say that cruiser lean has an effect on alignment. My lean is now severe, last year was bad, and 3 years ago was almost non existent.

nakman
05-14-2013, 11:42 PM
Thinking through your logic Barry, if lean contributed to alignment then with cruiser lean your rear axle would stick out towards the right as you drove down the highway, in a more crab-like stance. So you'd have to turn to the right just a little bit to compensate... have you notice you need to hold the wheel to the right a little more? Also how accurately could you measure wheelbase? If your theory holds it should be shorter on the DS.

rover67
05-15-2013, 12:35 AM
i know it's a band-aid........ BUT


do you have a good steering stabilizer on there?

i went through everything on my rig including taking it to a place that measured the frame and verified it was good and nothing fixed it for me. I am talking every component was touched and replaced. axle housing is the only thing I didn't touch, but the frame shop said it was good.

A new steering stabilizer fixed it. band aid i know, but i was ready to sell the truck. My old one had a dead spot in it where it ran 99% of the time.

DaveInDenver
05-15-2013, 06:46 AM
Internet wisdom says a steering stabilizer is a band-aid and that may be true in a way. But their job is to damp oscillations and so that argument would have to be made about the rest of your shocks, too. Maybe needing two of them is a band-aid, but upgrading or changing the way yours works is just dialing in your steering IMHO. We don't think twice about matching the suspension springs and shocks, but we believe that lifting the suspension, adding a bunch of unsprung and sprung weight should not have an effect on the steering?

treerootCO
05-15-2013, 07:26 AM
This is the best video I have found of the forces involved. In the first part of the video you can see what moves prior to the impact.

mDSIfFhWau8

I had a wheel spacer that wasn't true and it was enough to get everything shaking. On the Jeeps, the most common cause is the panhard rod mount on the frame side gets worn out (after a little wheeling). There are quite a few videos that show that factory stock has issues though.

Corbet
05-15-2013, 07:34 AM
Do you mean OME springs? Sorry, not familiar with your rig...

Sorry, yes and I edited the typo in my post.

OilHammer
05-15-2013, 09:47 AM
Thinking through your logic Barry, if lean contributed to alignment then with cruiser lean your rear axle would stick out towards the right as you drove down the highway, in a more crab-like stance. So you'd have to turn to the right just a little bit to compensate... have you notice you need to hold the wheel to the right a little more? Also how accurately could you measure wheelbase? If your theory holds it should be shorter on the DS.

Other way around. A lean left (drivers) pushes the axles away from center on that side. So driver's side would be something like 91" and passenger side would be 90". Just for fun, I'll put a tape on it tonight and see where it really is.

What I will never understand, is why the cruiser lean starts in the first place, and defies opposite lean when you swap springs R to L. I have read all the threads on various theories. The lean, is the whole reason I considered coilovers in the first place. We all know it will come back, so being able to dial "up" the driver side as it sags seems like a huge bonus.

Marco, I don't have a steering stabilizer. I haven't run one since I did the axle swap and never had an issue until last May. It's a total band-aid, but I agree I need to figure out a way to add one when I fix this.

Jacket
05-15-2013, 09:56 AM
On the Jeeps, the most common cause is the panhard rod mount on the frame side gets worn out (after a little wheeling). There are quite a few videos that show that factory stock has issues though.

This was the issue I had on my 80 - not so much a worn out mount but an under-tightened bolt instead. The result was the same, and the death wobble was severe. Once I got the bolt tightened to spec, I haven't seen it since. But this is not relevant for an FJ40 discussion...

Data point: My 40 has a pretty severe case of Cruiser lean, but I don't have any death wobble to speak of. Other than a very slight shutter around 30mph (which I think is pinion related), I can hit pretty much any speed on my 40 without feeling like the steering is off. It wanders and there's a bit of bump steer, but nothing shaky. OME springs and shocks and OME steering stabilizer - all about 5 years old.

OilHammer
05-15-2013, 09:57 AM
This is the best video I have found of the forces involved. In the first part of the video you can see what moves prior to the impact.


That's pretty much it. I suspect that if I mounted a gopro, I would see the same kind of stuff. I can tell you I don't have the balls to keep driving it knowing that problem will happen again though. It violently shakes the truck, and actually causes my throttle linkage to smack the master cylinder. I may or may not have a motor mount issue as well. Need to verify that when I pull the thing apart. I keep looking for a frame crack at the springs mounts, especially because I have that strange popping noise when my front springs articulate. I should have time to pull the springs this weekend so I can get a good look for worn bushings or broken leaves/hangers.

OilHammer
05-15-2013, 10:01 AM
Data point: My 40 has a pretty severe case of Cruiser lean, OME springs 5 years old.

Bingo! And that's why I hate dropping $1,300 for a "fix" that only lasts a couple years. My OME did the same thing, and it was extremely frustrating that the only fix was to lower the high side with a shim.

rover67
05-15-2013, 10:11 AM
Dave has a point.... maybe not so much of a band aid.

What I noticed was that when i went through every component and took all teh slop out o it the situation got better, but it never was resolved. that stabilizer made it so the wobble wouldn't resonate which "fixed" it.

Maybe the reason it didn't do it before is because everything was "perfect" now that it's not it can start then quickly runs out of control. maybe add one and just see? I wouldn't say it was worth my effort to rebuild everything only to find that 99% of the crap i went through was perfectly servicable and within specified wear limits.

They did come with steering stabilizers from the factory..

subzali
05-15-2013, 10:35 AM
...They did come with steering stabilizers from the factory..

Bingo. I don't think it's as much of a Band-Aid as internet wisdom would have us believe...having said that mine seems fine so far after my power steering conversion.

OilHammer
05-15-2013, 11:35 AM
Internet wisdom says a steering stabilizer is a band-aid and that may be true in a way. But their job is to damp oscillations and so that argument would have to be made about the rest of your shocks, too. Maybe needing two of them is a band-aid, but upgrading or changing the way yours works is just dialing in your steering IMHO. We don't think twice about matching the suspension springs and shocks, but we believe that lifting the suspension, adding a bunch of unsprung and sprung weight should not have an effect on the steering?

I plan to add one back in when I can figure out the correct length so that it IS dialed in. I have a 40 frame, 60 box, 70 axle, and hybrid link. Standard one won't work, I don't think.

Now, to the second part of your point, this truck has been built like this since 2006. I haven't been monkeying with unsprung weight or altering lift. I have driven it from NC to CO twice...never had an issue like this develop until last year. Only thing that has changed is wear, and sag. Logic would say take wear and sag back out, and damper is not "needed" but still desired for off-road dampening.

DaveInDenver
05-15-2013, 11:48 AM
Who knows? The need for steering damping is directly related to scrub radius, so it would seem that should be independent of sag at least. Wear will always change the dynamics though, in the sense that less friction in the components means there is more force available for oscillation. If it was easy to design a truck suspension and steering not to need damping then you better believe all the manufacturers would do anything they could not to use them, but yet most trucks come with them from the factory. It could very well be that they put them on for belt-and-suspenders, so that the truck does not become a death trap when the ball joints and TREs are no longer factory fresh and the whole system is no longer exactly like it was engineered originally, when might not have been a need for the damper.

PabloCruise
05-15-2013, 12:58 PM
I plan to add one back in when I can figure out the correct length so that it IS dialed in. I have a 40 frame, 60 box, 70 axle, and hybrid link. Standard one won't work, I don't think.



Sounding similar to mine, minus the 70 series axles, but I did go with 70 series relay rod to complete the PS set-up.
I'd like to see what you come up with for an ideal stabilizer and mount, as I will probably look to that for a starting place on mine. Last time I looked it was going to be a challenge to fit a stabilizer to the frame mount and the PS TRE...

Corbet
05-15-2013, 01:24 PM
I'd be looking hard for a cracked spring or shackle hanger worn bushing spring perch etc... The description is pretty much exactly like what my 80 did when the LCA hanger broke. I drove it for a month until it started leaking 90 wt and I noticed the damage.

OilHammer
05-15-2013, 08:18 PM
Theory confirmed. Left side is 91.25" wheel base, Right side is .75" shorter. I also have a FULL 2" lean to the driver side. Wow.
I looked at the pins in the perches...they are both pushed forward, so the axle is "centered" on the leaves and not cocked sideways.

Looking at the perches, it's clear I should have narrowed them years ago. So, if the torch and welder are coming out, I'm going coils. I held up the 80 arms, and they look like they are perfect for what I'm thinking. I'm going to leave the leaf springs in the rear...basically troopie 70 style. So, I need some 80 parts. I need a front or rear panhard rod, The axle mounts for the arms, and the two frame side mounts for the arms. The rest I plan on fabbing, and I can fab those parts too if necessary, but prefer to start from something just to make it quicker.

No hurry either, this is going to take a while.

Corbet
05-15-2013, 09:18 PM
I have OEM panhards in Durango as I just replaced mine with adjustable units. But I'm willing to bet you can find some locally. I still have my OEM coils too.

subzali
05-16-2013, 08:31 AM
Theory confirmed. Left side is 91.25" wheel base, Right side is .75" shorter. I also have a FULL 2" lean to the driver side. Wow.
I looked at the pins in the perches...they are both pushed forward, so the axle is "centered" on the leaves and not cocked sideways.

Looking at the perches, it's clear I should have narrowed them years ago. So, if the torch and welder are coming out, I'm going coils. I held up the 80 arms, and they look like they are perfect for what I'm thinking. I'm going to leave the leaf springs in the rear...basically troopie 70 style. So, I need some 80 parts. I need a front or rear panhard rod, The axle mounts for the arms, and the two frame side mounts for the arms. The rest I plan on fabbing, and I can fab those parts too if necessary, but prefer to start from something just to make it quicker.

No hurry either, this is going to take a while.

This sounds fun!

Have you (or has anyone) considered TJ/JK coils etc. on a 40? Yeah I know it's J**P parts but similar in wheelbase and vehicle weight...

OilHammer
05-16-2013, 03:12 PM
The issue is mostly space. By going with the 2" coilovers, you are reducing the size of the coil and also the need for a whole extra tower for the shock. My plan with mods is always to be largely reversible, so the coilover tower can actually fit through the stock shock cutouts in the fenders. If I design it right, the tower on the driver side will incorporate the panhard mount as well. Been thinking this design out for 5 years. lol

Certainly cheaper to go used jeep stuff, but it also lacks the tunability. I will be able to change ride height pretty easily to compensate for lean, and if the spring wears out or I need more load capacity, the coil itself is about $70.

Jacket
05-17-2013, 10:25 AM
I've got stock 80 front and rear panhards if you want them.

OilHammer
05-17-2013, 11:02 AM
Great! I figured Slee probably has a scrap bin full of that stuff too.