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'pants 10-04-2017 11:15 PM

invisible railroad-ties
 
Twice in the last three weeks, I've been getting off or on the freeway, gone over some rough pavement, and abruptly BAM-BAM-BAM-BAM!..then I'm working my way over to the shoulder, the truck is bouncing violently, I have to brake carefully because god knows what will happen if I lock up bouncing tires, my coffee is spattering all over...it's much like I'm driving on railroad ties at, say, 30MPH. The bouncing doesn't stop until I've got the speed reduced to like 10mph.

I pull over, see nothing wrong, drive on, but with a little cold-sweat and adrenaline rush.

In the aftermath, I've:
  • torqued the hell out of all lug-nuts
  • jacked up front and verified I don't have any obvious loose-bearing/ball-joint issues (left front can 'click' in the camber plane by a millimeter or so, but it's been that way for a long time)
  • spun the wheels and did a ghetto-run-out measurement that came up somewhere near the spec (one or two mm)
  • got beneath it and checked U-joints for looseness (right front outer 4WD joint is loose, but not the worst ever)

Pertinent confession: I've got Ford rims on it...long story, but this isn't new - they've been on it for more than a year. I mention this because they're not easily set to concentric with hubs - but there's no obvious new problem with them.

As to checking wheel-bearings - it occurs to me now that I think I read in one of these forums that someone reported NOT immediately discovering that his front wheel bearing was bad - as it was later found to be - because the brake-pads/caliper kept it in more or less the right orientation, making it seem like there wasn't really much slop. It wasn't until he noticed that stepping on the brakes had some impact on steering that he really dug into it...or something like that. So is that really a thing? Or can I adequately test it just by manually hauling on it to test for play in that 'camber plane'?

So ***?

dave

AlpineRAM 10-05-2017 03:01 AM

Let a helper turn the steering wheel with the axle on the ground and take a look at what's moving there.
I would bet that the track bar balljoint on the frame or the track bar bushing in the axle has a lot of play...

Death wobble works like this- axle goes to the right, the tie rods are pulled to the left (relative to the axle), wheels turn left, axle steps to the left, tie rods go to the right etc.. fun fun fun.

'pants 10-05-2017 07:49 AM

Thanks Alpine, I will get some help checking. It will probably make more sense to me when I'm under the truck next.

Confirming - you're saying to check this without jacking anything up, yes? Engine off/ no power-steering?

I'm wondering if the play you're describing wouldn't be something I'd feel while steering, esp maneuvering to park, say?

MAC702 10-05-2017 10:00 AM

Death Wobble.

Every time I've experienced it in my 96, it was remedied with new tires on the front. The tires would still look good, but maybe lost balance or something. All I know is new tires made the problem go away.

If I didn't address it, it would start to happen a lot more frequently, almost to the point where I could make it happen on purpose by hitting a bump while braking. This was before I figured out to just put new tires on it every time.

One time it was caused by the brake system needing a complete overhaul. But while it still was a "Death Wobble-like" experience, I could feel it was a different one.

'pants 10-05-2017 10:41 AM

Thanks Mac - I've only just discovered that, indeed, the Death Wobble is a thing. Lots of forum reading to do, but at this point I have the sense that it's primarily (but not exclusively) a 3rd-gen thing.

Since I need to get back to rims that actually fit the truck right anyway (just for peace of mind if nothing else), I'm getting close to pulling the trigger on some alloy duallies. I don't like that I'll have to run them with my old nasty-rusty OEM steelies inboard in the rear...but anyway, assuming I can make that swap before the Death Wobble takes me as a victim, it'll test the idea that tire (and rim) swapping does the trick.

patdaly 10-05-2017 05:31 PM

Oh nay, DW is endemic to any solid axle front end.......... I ran into it for the first time with Greenie, at first I did all the front end and put a new set of Bilstein shocks on there and that helped, but ultimately it was past due for a set of tires and that fixed it, until it was time for another set of tires......which fixed it again.

If you try everything and still have a tendency to DW, have your front end guy dial in the maximum Caster, usually helps a bunch as it tries to keep the tires straight.

'pants 10-06-2017 03:51 PM

Thanks, Pat. I need a front-end guy. And front tires, too.

I was about to write that I'd ordered aluminum duallies and was confident that all my problems would thus be solved, but the only 16" dually alloys I'm aware of (Ion Alloy 167-6681) have a different front/rear wheel - ergo rotating tires will be a *****. Since I've no reason to expect that my tires will last any longer on the alloys vs the steelies, I'm about to scrap that whole approach.

But if I ditch the 16" rims altogether and go with something larger, is there a tried-and-true alloy wheel & tire combination that's not going to result in serious hardware-intensive clearance-problems?

AlpineRAM 10-07-2017 11:22 AM

Quote:

Originally Posted by 'pants (Post 3336244)
Thanks Alpine, I will get some help checking. It will probably make more sense to me when I'm under the truck next.

Confirming - you're saying to check this without jacking anything up, yes? Engine off/ no power-steering?

I'm wondering if the play you're describing wouldn't be something I'd feel while steering, esp maneuvering to park, say?

You can do this with the engine running for power steering, just be careful because of the moving parts there.
The helper should repeatedly turn the steering wheel rapidly about 1/4 turn left and then 1/4 turn right from center.
The truck needs to be on the ground so you can have the forces act on the track bar as if you were driving down the road.

Bad wheels and tires, misalignment etc can also cause death wobble, even with the track bar OK. In my experience a shot trackbar is a sure fire cause for death wobble, and the check takes less than a minute.


shows it perfectly, even though it's not a diesel [laugh]

Lary Ellis (Top) 10-08-2017 10:35 AM

My 96 had death wobble, sure enough the tracbar was shot. VERY common occurrence but certainly not the only possible cause.

I was at the dealership having a recall done and asked the service manager if they get many in for worn tracbars, he said "NO we haven't seen any issues with those."

I laughed because the reason I asked him is he was standing next to a drum with a bunch sticking out of it [laugh]

'pants 10-08-2017 02:19 PM

Quote:

Originally Posted by Lary Ellis (Top) (Post 3336393)
My 96 had death wobble, sure enough the tracbar was shot. VERY common occurrence but certainly not the only possible cause.

I was at the dealership having a recall done and asked the service manager if they get many in for worn tracbars, he said "NO we haven't seen any issues with those."

I laughed because the reason I asked him is he was standing next to a drum with a bunch sticking out of it [laugh]

HAH! I can totally picture that.

I've never pursued a recall to the point of getting a fix done, so I don't know the basics. So there was one for '96, which could extend to '97? If so, do they generally have to make good on them for the life of the vehicle - eg, if I showed up with my '97 now -- of which I'm at least the second owner --
would they deal with it?

Also not sure what wrath I'd suffer for having Ford duallies on the Dodge. And I have a vague memory of actually replacing track-rod end/s at some point, and if so, I'd probably be told to take my non-OEM joints and shove off, right?

AlpineRAM:

Thanks, that all seems familiar, though perhaps from another vehicle. My maintenance-logging is erratic at best; when the weather turns bad I am a lot more willing to add text to those docs.

I have yet to be able to get truck on level surface with helper (er...complaining wife) on hand to wiggle the wheel...but thanks for the added explanation. Maybe today I can get eyes on the joints & take inventory.

Lary Ellis (Top) 10-08-2017 05:24 PM

The recall I was in for was the throttle cable they replaced...I knew about the trac bar issue so naturally had to see if he would lie to me about the barrel full ;) to my knowledge there was never a recall on the 2nd gen trac bar.

arroyojim 10-11-2017 04:31 PM

I had bad DW in my '97 CTD... was the trackbar
Had it with my '85 Toyota p/u too... fixed with alignment.

HMX-1 10-11-2017 06:02 PM

We had DW with our '06 .... the solution was new tires (BFG's were about 40% left) and new Bilstein shocks.

The missus told me about it so I had her drive my truck while I was overseas, came home and forced it to do the DW just to make sure.

Warrantied the tires and put Discoverer AT/3's on, and found an online deal for the Bilstein's.

Problem solved.



-Kris

'pants 10-18-2017 09:27 PM

I'm status-quo on this - been waiting for things to worsen, I guess, but no new incidents to report...'cept it seems to be pulling to the right, ever more.

Looking up at the various joints with my diminutive wife struggling to wobble the steering wheel to and fro, I didn't see any "oh, my GOD, I can't drive it until I change THAT"-type play. There were certainly some joints that need changing.

Another probable contributor is the driver's side control-arm bushing being soaked nearly constantly with ATF from another chronic problem: leaking hydroboost. It's looking pretty soft and squishy, and I'm wondering if that's also tending to make my brake-pedal pulse at wheel-speed frequency, but only sometimes...it's pretty scary-feeling when it happens, feeling like if I panic-stopped under those conditions, something would end up breaking loose from the eccentric loading.

Problems, problems.

So is there somewhere I can look up a complete list of front-end suspension-components that I should order up? Idea being that I'll get in and out of it in one session, of course. RockAuto seems to have SOME complete kits for this and that realm of suspension components, but thus far I've not seen much for 4WD. I'm especially interested in polyurethane bushings/seals, what with the likelihood that oil-drippage isn't going to cease to be a problem for me, even after I get around to dealing with that leaky hydroboost - and in the interest of longevity.

AlpineRAM 10-24-2017 04:16 AM

I got a PU bushing kit from Energy Suspension.
The joints I did always order as needed, no complete kit because there always were too many good ones on and only 2-3 defective ones.


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