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In need of Death Wobble Diagnosis...

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Old 02-10-2018, 09:46 PM
  #11  
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It would seem that several jeepers tend to forget that balancing a 35" (or greater) tires is very difficult. Often the shops doesn't have the manpower to effectively & correctly mount & balance these tires with the use of lesser installation equipment. Although I could go into a full detailed check list here, one of the main culprits would be the balancing of these tires. I would have the tire rebalanced by another shop who has the correct balancing equipment. Worn bushings, would be the next area to address. Then let's test the shocks, onward to the tires PSI, Not to mention the wheels being either hub centric or lug centric, as all of these things can't be ruled out. Inferior installation techniques and poor geometry can all have an effect on the vehicles handling.

Last edited by TrailBadger; 02-10-2018 at 09:51 PM.
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Old 02-13-2018, 04:32 PM
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Ok well I got the front end aligned and had them balance the tires. And remember, right now the tires I'm running are stock. The mechanic that did the alignment had experience with jeeps and said he believes the wobble is a tire issue because the wobble goes away when I am running the 35s. (I thought this was because the wider wheel base would dampen the resonant frequency causing the wobble, but he seemed to think that if the issue was with anything other than the tires, the larger wheels would make the wobble worse).

After aligning and balancing, and airing to about 30 PSI, I still felt a "Shimmy" when going over uneven expansion joints on the highway. Because of this I didn't feel comfortable pushing the speed past 65. I feel like if I hit a joint at 65, it would have went into DW.

Next, I'm going to look into upgrading my steering stabilizer. I know what people say about the stabilizer not FIXING the problem, but if the stabilizer is stabilizing the front end and preventing me from getting a wobble I don't see the issue with it.
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Old 02-14-2018, 10:35 AM
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Originally Posted by NatteyB View Post
Next, I'm going to look into upgrading my steering stabilizer. I know what people say about the stabilizer not FIXING the problem, but if the stabilizer is stabilizing the front end and preventing me from getting a wobble I don't see the issue with it.
Backing all the way up to the OP, let’s see if we can pin down some details and recap things:

Jeep bought in November 2015, at which time RC 3+” lift installed. Stock tires used for a couple months, then switched to 35s.

November 2016 rolls around, you put factory tires back on for the winter. This is when you first noticed signs of a wobble.

March 2017 rolls around, and you put the 35s back on for spring/summer. Wobble appears to have disappeared.

November 2017 comes and the factory tires go back on, and you’re getting a wobble at every big bump ~60mph.

You’ve replaced the track bar with a RC adjustable track bar.
You’ve replaced TREs as the old ones were loose.

No mention of offroading, so presume this is pretty much a pavement rig. No mention of alignment specs….can you post your current caster just so we know (Nthinuf was trying to get this out of you earlier)? Can you post your alignment sheet? No mention of specific build specs in your profile, so I also presume no drag link flip? No mention of ball joints having been replaced in the past, so presume they are factory. These are all just minor details, but helpful to know.

Here’s my 2c. I think you likely have a crap ball joint. Keep in mind that driving with 35s is going to put added stress on all steering components. Those factory ball joints (if that is indeed what you still have), are crap. They have plastic internals and just don’t stand up long to larger tires. If you have a couple years of wear on them with 35s, even if just partial years, that alone could be enough. It is probably the most likely thing. The track bar and ball joints are the most common culprits for a wobble. I think that the issue is really still there when you swap to the 35s, but it’s not as easily triggered, maybe because the 35 is soaking up more of the bump or reaction then the factory tires is….not so sure bout that necessarily, but I don’t believe the wobble itself is due to the tire.

If the wobble was tire related (like an out of balance tire), I would think that driving along on a straight path, a wobble would start to generate/build as speed increased. I have had DW induced by an out of balance wheel after wheeling (wheel caked in mud) myself. Culprit was loose TB bolt and bad BJ, but tire triggered it. Anyhow, it sounds like you are saying it takes a bump in order to trigger this….then things go crazy. That right there makes me think this is NOT an out of balance tire issue. I can also envision this being worse with the smaller tire….lighter tire, less stability, easier wobble around…..even though the 35 has much more mass. I’m no scientist, I’m just thinking out loud trying to make some sense.

Assuming you didn’t have any wallowing at the frame side TB hole when you replaced that, and that every suspension and steering component is torque to spec, I will bet dollars to donuts that you have a BJ issue. You’ve read it 1000x I know, but putting on a new steering stabilizer isn’t going to solve it. It might mask it a bit more, but the underlying issue is still going to be there. If you just want to cover it up even better, install some hydro assist steering. You should be able to drive that jeep with no stabilizer at all and not even notice.

Also, to lead back to the alignment stuff….if your caster is too low, or if you are a good candidate for a DL flip, those things aren’t helping your issue. They aren’t CAUSING the issue, but are probably leading to some bump steer which isn’t helping at all.

Did you test your ball joints with a shovel or something under your wheel?
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Old 02-22-2018, 05:30 PM
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Resharp, thanks for your detailed post and analysis. I appreciate you taking the time.

Everything you summarized is correct. Just to note, I did take the jeep offroading twice around august and september just before swapping back to the stock wheels.

I'll post my alignment specs sometime tomorrow if I remember. I don't have the sheet with me right now.
No Drag Link Flip
Yes, factory BJs

And as I mentioned before, the guy doing my alignment said the 35's would make a wobble worse so he says the issue is with the stock tires, however I tend to agree with you that the 35's being more massive are harder to throw off so the issue is with another steering component (BJs for example). So to me, in a way the 35s are like steering stabilizers in their own way.

I did not test the ball joints with a shovel. I'll be sure to do that. Also, there was no wallowing of the factory TB bolt hole. And yes, everything was torqued with a 400 ft-lb impact wrench so no doubt nothing is loose.

And to add another piece of info, I increased my tire pressure from about 30psi to 40 psi and the bump steer I was getting was noticeably reduced but not entirely eradicated.
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Old 02-22-2018, 06:13 PM
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I dug back up through the thread but don't see a mention of your mileage...but you're a couple years in now, and some of that is on 35s. I really suspect the ball joints, especially since you note they are still factory. Keep in mind that the factory ball joints have plastic internals. New Google changes have made it difficult to easily embed and image, but check this link for pic -

https://goo.gl/images/C4vnAk

That is the big reason that BJ are a common issue on our JKs. One crack in that plastic and they're toast. I typically jack up the front axle till tires are a couple inches off the ground, slide couple jack stands under it to stabilize, then stick a shovel under the tire, stepping on the handle...using it as leverage to force the tire upwards. Shine some good light right there where the knuckle meets the C (both upper and lower) and watch for movement. There shouldn't be much play at all. If you don't have jack stands, you can just jack up one side at a time.
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