How can I figure out why I have death wobble?

B

bjp

Joined
Apr 11, 2021
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14
Location
Los Angeles, CA
I have a 1993 with death wobble that I've tried to fix and it's still not fully gone. I'm sure there are many things I could blindly try if I had infinite money, but how can I figure out which one is actually likely to fix the issue?

I know this is a bit long, so to encourage responses: I'd be excited to send $50 to whomever first describes a diagnostic procedure which leads to diagnosing an issue that, when fixed, solves the problem. Just throwing out things it could be doesn't count unless accompanied by some test I can perform to confirm or deny whether that thing is actually the main problem before spending money and time addressing it.

When it started
I'm completely new to Land Cruisers and vehicle maintenance in general. I bought this LC in March with 163k miles and I've been baselining it ever since, so I've put less than 1k miles on it. I thought I had the minimum set of stuff done in September so I took it to an offroad picnic about an hour away by paved roads. Just before hitting dirt, I got my first death wobble around 30 mph. I thought "that was crazy", but the pavement was a little rough and I hadn't heard about death wobble before, so I did a bit of light offroading then started home. A fire forced me to take (paved) back roads for 23 miles and I got probably 8 or 9 wobbles. By the end, I was trying to intentionally trigger them to figure out what the trigger was, and I was trying various things to mitigate them instead of just braking hard, but I couldn't find any reliable patterns.

Behavior
The wobbles always started between ~20 and ~55 mph -- I took it carefully on the freeway on the way home after the wobbles on the back roads and got zero wobbles on 28 miles of freeway, then one more wobble on the 1.5 miles between the freeway and my house. The wobbles seem to be more likely to happen while on a slight curve (especially when the curve direction changes), when hitting small bumps (but larger bumps don't seem to do it), and when slightly braking, but even a combination of all these factors doesn't guarantee a wobble, and not all factors are necessary to produce a wobble. Again, I could never figure out when they would or wouldn't happen.

Initial investigation
When I got home, I found the jam nut of my front adjustable panhard rod completely disengaged, so I tightened that jam nut. I could grab the drag link or tie rod and rotate them on their axis by hand fairly easily, but I didn't feel any play. I jacked up each front wheel one at a time and tried to wiggle the wheel while grabbing at 12 and 6 and I didn't feel any play. I tried to wiggle while grabbing at 3 and 9 and did turn the wheels a bit, but didn't notice any play. I took off the mud guard of the driver front wheel and looked at the frame and panhard tower around the steering box and didn't see any cracks. I measured 30.15 PSI in front passenger tire and 30.65 PSI in front driver tire, and both wheels still had balancing weights attached (though I can't rule out some falling off). The two of four knuckle nuts I could easily access with my torque wrench were still torqued to at least 71 ft-lbs and the other two were "tight" (both sides).

After tightening the panhard jam nut, I took it back out on a 45mph street and got 2 more wobbles within 3 miles. A member of my offroad club diagnosed needing new rod ends.

Attempted fixes
I bought the Trail Gear Heavy Duty Steering Kit which includes a new drag link, tie rod, 4 rod ends, and a steering damper. I took off both rods, damper, and the steering box and had the steering box professionally rebuilt. The old steering damper was pretty much entirely done -- spring only, virtually no oil resistance. When reinstalling the steering box, I replaced the high pressure hose with Gates and the low pressure hoses with Gates from phhkit.com. I installed the new tie rod and used two aluminum angles to set 1/8" toe in at 37" wheel diameter, using two laser pointers to center the steering:
AM-JKLV3AsFfm_f_Aep2X7zeCWn3oG4E3Uj6J8k4gFzTSp86yaOr5vxQTSbEwRRchurt5SAQ106R7kd5BSI3YmZnXX08ITylryWDto_gtg9QffLKqVvY2SlYRavUIjidNBMNznuW47E73VtCN3zpOFDlGflNjQ=w2614-h1960-no
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AM-JKLX_NWUZ3X4xIMoJtsIW0m4UzD76wFN2qmzhCvOpPsqmu8zh1aVds2ncGKpXdwUjtMhuGtyHVpVLmyV7XIN0RfGsFwN3vSbwa5Q5lfsvMjQXCWHmbRg_M4TPTSbNQTcoPeQJAXf1NlA8eDwQ8anib9_TGw=w2614-h1960-no
AM-JKLV1UDQuTrv9VWAKorOawU7FmIvASj3OLKrSVSZJCrVJZk1qx-mIcJcAD27STOYL-6bs0RDOxud-CwF85ugeOKuyknlk7hgVFbF8PEQDQ7Fm7vEHxkeErEXafkFDy8KjpT89Hj_gyRmt0T9B5Z2nLCp2nA=w2614-h1960-no
AM-JKLVzqvAdly8XmG6k6WZlyebu-4Mf4S3OMUq710EJ23p7en8czy9OzM9QDlG3oxreue87377VoVbPlOiO2w0mjY7hqWtsBMd7WYAXnQzMrHt_Wm59JAjWveZnjC0aMa_CZP2L-tLm2yiubJMragdQaRTgjg=w2614-h1960-no
AM-JKLXSs77TR621Ruxhqg19VJfm7jJFI14QNHnOfzM38XMxDrnGDBHFCktUdd1OeCcpQlqECBp_6YNlunCWQddMjzIjUJfnEhegMB0lyqPHTupGRlh_m2r1PR215x95C5WMZFJeetwZhnMZnQItkZTeFyVmJQ=w2614-h1960-no
AM-JKLX_zmytYQ20veC3SdlYiQ47tYZKVwXiU1icT1efQwpAalCvQCHfVro13AbeoxJbCYMJEDbpi-BD_jGdLHZBKM8oMDwpubeVk4Z4hi76IBAoA13efwBmCCQ7XCnJ-WgW1JXIeXrP9xY9ttcjt4BYR8UneA=w2614-h1960-no

I installed the new drag link and tried to center the steering wheel as closely as possible using the two laser pointers on my alignment jig shown above. All crown nuts torqued to 67 ft-lbs plus whatever was needed to line up the cotter pin holes. The Trail Gear rods use jam nuts and do not have any indents to put a wrench on (!), so I tightened the tie rod jam nuts to TG's recommendation of 75-85 ft-lbs using a giant 14" set of vice grips and a giant adjustable wrench. I tightened the drag link jam nuts with just the wrench to "medium tight" because I knew I would need to adjust the steering wheel position a bit more. I did NOT install the new steering damper because one of the bolts was missing and Trail Gear has STILL today not delivered that missing bolt (they blame PROcomp, the steering damper manufacturer), but my understanding (which could definitely be wrong!) was that the steering damper just masks the issue and is never the root cause, so it seemed ok to leave it out initially. I also got my front wheels professionally balanced. Unrelated(?) to these fixes, I also installed a new Tom Woods DC front driveshaft.

Results
After these fixes, I drove a 38 mile loop including 23 miles of paved mountain roads like the ones that triggered so many wobbles. Zero wobbles. I did feel some "incipient shimmies" (vibrations like the ones that preceded death wobbles) which worried me a little, but I don't know the truck super well so I figured those may just be normal solid axle stuff. Given that I got 2 wobbles in 3 miles before the fixes, I thought for sure I would see wobbles in the big circuit if they were still a problem. The drag link did come loose from its jam nuts during the circuit because I hadn't done the final tightening yet, but even with the drag link working its way loose, still no wobbles. So, I considered the issue probably fixed and moved onto the next work.

Going to the picnic, I also had the AC shut off from overtemp while climbing a steep freeway grade on a hot day, so I did a bunch of cooling work next including replacing all of the heater hoses, replacing thermostat, replacing fan clutch with new 95F/6500cst-modded clutch, replacing radiator, and adding a temperature sensor to the upper radiator hose.

I went to do a short test drive to also re-set the drag link properly and...got a death wobble a short distance before my house. Well crap. I finished dialing in the drag link length and tightened the jam nuts to basically the gripping limit of the vice grips, then drove the same 38 mile loop. No death wobbles, but still a bunch of "incipient shimmies".

So, I don't really know what to do. I don't think tightening the drag link jam nuts should have made the difference between wobble and no wobble since I wasn't getting wobble on the big circuit even when the drag link was loose. But, it's also now apparently hard to actually reproduce the wobble. I feel like I can't take the LC on trips because I'll probably see wobble at some point since it was still present after all the fixes (not taking it on the trip I'm leaving for today because of this).

Configuration
When I bought the LC, it already had:
  • 37" Cooper Discoverer STT Pro tires with most of their tread life remaining
  • Method 105 beadlock wheels
  • OME 419 Comp Coils in front, unknown OME coils in back, resulting in ~5" lift based on DeltaVS's panhard bolt method when lightly loaded (but still have front & rear bumpers + winch on front + full-size spare on back)
  • Front sway bar removed
  • 5.29 diff gears (net result from 37" tires + 5.29 gears = truck travels 92% as far as speedometer/odometer thinks it went, so slightly lower gearing than stock)
  • Air locker front, Detroit locker rear
Not very many miles before the picnic, I installed new DeltaVS radius arms for a 4" lift. I tried to get before & after caster numbers, but no shop around here will measure alignment on beadlock wheels, and I gave up trying to measure the caster accurately.

I had recently removed all wheels (one at a time), deflated, carefully and progressively torqued all 120 beadlock bolts, reinflated, and reinstalled.

Both the previous owner and the one before that are members of my offroad group (I joined shortly after getting this truck). The previous owner had a bunch of stuff put on the truck (including air locker), but drove it only a few hundred miles over 2 years. The second-previous owner (an experienced amateur mechanic) said the front axle "is basically all new" -- he said he thought he did the rebuild at 13Xk, but based on CarFax, I don't think he owned it until 145k (he works on a lot of cars, so not surprising his memory may not be perfect).

Possible things to try
I can think of a number of things that hypothetically might address the issue:
  1. New non-beadlock wheels + new smaller (35"?) tires
  2. Knuckle rebuild, including new wheel bearings
  3. Install steering damper
  4. Add a front sway bar
  5. Replace some of the front axle components (not sure which ones)
I'd be happy to do any of these to fix the issue, but doing all of them would be very expensive, especially when it seems like there's no guarantee that even doing all of these things would fix it. #2 seems like the leading candidate to address any wheel bearing problems, but it seems like the fact that there's no play in the wheels wiggling at 12 and 6 would suggest that the wheel bearings aren't the issue (plus, the wheel bearings were probably replaced 20k ago). #3 will probably "help", but if it were just hiding the underlying issue, that seems like it would actually make things worse by making the underlying problem harder to find. Could #4 actually affect death wobble? I'm not sure what I would be targeting in #5; are there any components that might be causing the wobble? #1 seems like the most likely solution (but I don't really know what I'm talking about yet), but $3k-$4k is awfully steep for "most likely". I want to get non-beadlock wheels eventually in any case, but I really like the Coopers and would like to keep 37s if I can figure out this death wobble issue.

Thanks for reading; thoughts?
 
gummycarbs

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And, the upper nut was already loose, so that seems like a candidate for contributing cause.
Wait, what? I missed this earlier. That's pretty big.

Has the OP made moves to end the DW? Are we just talk might each other?
I think he's going to swap wheels and get the alignment checked tomorrow, which will give us caster numbers. Until then, we're just, how should I say, engaging in a pointless manual activity while arranged in a circle...?
 
baldilocks

baldilocks

Battle Ground, WA
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Wait, what? I missed this earlier. That's pretty big.


I think he's going to swap wheels and get the alignment checked tomorrow, which will give us caster numbers. Until then, we're just, how should I say, engaging in a pointless manual activity while arranged in a circle...?
More than likely.
 
T

toyotaboy80

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May 24, 2015
Messages
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Has the OP made moves to end the DW? Are we just talk might each other?
Caster was completely disregarded as a concern and wasnt in radar for.... I already have the 1k wrong arms so thats not the issue, lol

May his set up needs 6° caster to handle appropriately. Who knows. Check everything else thats free or cheap, ok I understand
... but replace panhard bushings "just because theyre not rubber" doesnt make sense.
 
T

toyotaboy80

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I alluded to upper nut being loose with my torqued to spec statement. Apparently seemed to already be on the loose sleeve tangent.
 
mudgudgeon

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but replace panhard bushings "just because theyre not rubber" doesnt make sense.

No, replace them because they are cracked, and a visibly loose fit around the centre sleeve.

This may not be the sole cause of the problem, but it's almost certainly a contributor.

Its also why several people said remove and inspect panhard.


Anyway, back to that manual circle thingamajig
 
T

toyotaboy80

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No, replace them because they are cracked, and a visibly loose fit around the centre sleeve.

This may not be the sole cause of the problem, but it's almost certainly a contributor.

Its also why several people said remove and inspect panhard.


Anyway, back to that manual circle thingamajig
They look well within their proper service life to me and without actually having them in my hand I cant say one way or the other if the sleeve or bushing is loose. They just look like theyve been installed, used, and removed...aka not shiny brand new. Beyond the curling at the edge (from being installed and torqued down and then pivoted 1000 times as it drives down the road), I imagine that sleeve to be properly sized throughout. But...I dont have them in my hand and we can only arm chair this out so far based on a pic. How does the saying go... opinions are like...

If nothing else certainly theres enough diagnostic info on these panhard bushings for the owner to draw a conclusion to what he wants to do now. So thats a plus.
 
cruiserdan

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I've skimmed through this and I didn't see a mention of checking for frame cracks. Look carefully at the frame where the panhard rod bracket is attached on the left side. The frame on my wife's 80 was cracked where the bracket and frame were welded togther. We found it by watching that area as the steering wheel was rocked back-and forth. I could see the crack open and close when the steering cycled. I had that welded back up and the wobble stopped.
 
B

bjp

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Los Angeles, CA
For everyone getting antsy, I have new info for after tightening panhard rod bolts, my friends helped me set the preload on the driver wheel bearing, and I now have 35's mounted. Won't have time until at least tomorrow to write about it :)
 
T

toyotaboy80

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So.... loose bolts and loose wheel bearings solved the problem? Thats like... super textbook rookie mistake. chaper 1, page 1, word 1+2 "tighten stuff". How did that happen? Sounds like someone I know that got fired.
 
shocktower

shocktower

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For everyone getting antsy, I have new info for after tightening panhard rod bolts, my friends helped me set the preload on the driver wheel bearing, and I now have 35's mounted. Won't have time until at least tomorrow to write about it :)
When I had the DW I first checked everything and 2 things first was the tires where out of round and then my steering damper
 
B

bjp

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Update:

After removing the panhard rod to inspect the bushings (prior post), I reinstalled the panhard rod and remounted the two front wheels. That pretty much resolved the death wobble (where a shimmy gets bigger and bigger), at least the kind that I was reliably reproducing before -- awesome. It didn't resolve the thing I call the "incipient shimmy" which is how the death wobble starts. Here is what death wobble looks like (green = vertical accelerometer where you can see the knuckle hitting the two 2x6's, purple = knuckle vertical-axis gyro; shows the knuckle rotating about the ~steering axis)
AM-JKLVanmAPw8POphJNjq0O2bamnC4XHW0ycK91cJLFffnhSXStT-xD53zAox1emz8TXMC8WCCqjvYOP-WnYucfyj16mORoRwqtQufFHyHgCarnjJn-2t8hfY42JjuFLVxjNWBHjvUBDLUYs9IqLyfxEvevYg=w2023-h1054-no
AM-JKLXcov7HYG-tcSIgd_3dA3y7MbPfcG81jn9y0Ktw4kD22mvetR8yDiDNIRaLIkCWqReQVq_EXIsFFZVSnf3hvBZSI0K7IvGNYshCOQSgxCtsF03_4G-8U2Pr2tr5oJaExqgzgKGgWVCdFEXUod0B0cBmDQ=w2047-h1051-no

Those are two runs without changing the setup.

Then, I removed and reinstalled the panhard rod and removed and reinstalled the front wheels. After that, the death wobble went away, but the "incipient shimmy" was still there:
AM-JKLVofHdjSA_sxxjEpLIC6zMXT3CPDuVNtHKgUu4wC84fCJEimOFxgBWS0Io60gfNvYQt5aCsroE4lZN7wqA1KtFMnCAV13mFFvNK2UrTeXZz9Z18jcaBfnr4lFdrVUsWdQoa49xZakEgIwue9dbMbYFHrQ=w2050-h1047-no
AM-JKLUhXtvTh5WgeOdX0Kj5pTT13eosqDHB7SzCZ72JMMKfgY5eqN2l3q_Hyh3SUnWPXBJ2mzb-Ecu7XlcnFKFpnU5yjINrrB4isqNB0uwq7KrBw7_LJ2n0tSKh1CUpCXRCmi99WHy228nID6jIkzZkUFDXhw=w2055-h1057-no


Then, I went over to my buddy's house to swap wheels, but first they diagnosed bad preload on the driver wheel bearing, so we (they) set the preload correctly. After that, I drove around with my buddy so he could see the issue and we could see if adjusting the preload helped. It didn't seem to make a difference:
AM-JKLWqeyynb6-oyFcJ71LlrcFtukawW-DH9X8EUUT5zbC3uqp82nHVw7HDzZdMdq8isCedjHxA63ChS9H2pHfjgUhR1faPuazqgaWakg6Z8gxDjExY6ruW3cCjrnDSZo860VqEDbPzfQizw1t12j2IctQtBw=w2050-h1048-no
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After that, we actually did the swap (changing 10 wheels is hard!) and that seemed to pretty much fix the shimmy. Technically, I think the system is still underdamped (you can see a few cycles of resonance), but practically it seemed fine:
AM-JKLWCnh_efIn4rKgxcd9TqfXyRniAJzj6596Go9v_3qRS_mYbnmzKVb0pai60guiSuua7E273Y_Hqj4qAPP963gqwqTMKKXmnAqwhlkHoX7sHby9eSbLoRhg3SBU6VxRv6nN9LI542wCinhtukAU-5NFX6Q=w2052-h1045-no
AM-JKLWtrPrwUU_qBWV6-IHniEdgP37HW4Bal6d-ybzPH_WJlm2zPzCn_fJsig_SCPOsqhB39mAY3I3RXXldY-bwADyBlpNt3Sp50_Ss4kzt7yBO4fnSrJPaenK4fvyiAKfAmAc0UnVApCtHPBYfZL_I29N-eg=w2044-h1045-no


After swapping wheels, I was able to have alignment measured. And, just for good measure, I wasted $100 to have Pep Boys rotate my steering wheel 4.5 degrees.
AM-JKLVmGCroczijUBA4q3fG_jBD_KyBu3vqn1EMIPdgZbK6PMwlc3a_SK7Z9GVyUxzF6_jSW6-mmNsxjva0Y8Hl7b2mH_qe8hS8fEiIBkblSxlhJbSeXezl4cMA5E3MWkjryR_D3Jz9agtyGOG4grCinDWVqg=w2690-h2017-no
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My caster was already surprisingly good; I was expecting it to be lower. Turn the steering wheel 15x 0.3 degrees and both toes were already in the shop-spec'd range of 0.0-0.3 degrees (though I was expecting toe-in of 0.24 degrees on each side since I measured a 1/8" difference between 37/2" in front of the axle and 37/2" in back of the axle).

I bought OEM panhard bushings and was hoping to press them in, but we ran out of time. The reason I was in a hurry to do all of this was to make a trip to the Mojave Road (2x 4-5 hours freeway, ~160 miles dirt). That went well -- adjustable panhard jam nut came loose once, but made kind of a distinctive sound so I think I fixed that pretty quickly. Zero death wobble, and the only worrying shimmies were probably just the arrangement of the rocks we were blowing over. Gratuitous trip pictures:
AM-JKLURY4MMPV-cZHMCyE_ma7kNwpHwtWRfLDBBBTcjpCxpFOMw3vZQIIIBUcWBTAl1H8cNQz4n39egERS-8bLBQmI_G871FDAhNS3ngvKoDs4_Hlb-YoyDC0OyqMT_RVmgdng9uR3nDA9ypOGa9coS6-H5aQ=w3026-h2017-no
AM-JKLWmQmBhxu15vzLoilWESRqjJcaLBv5zZKjpHQ6-ySjCipZs7wp8GbxjojXTTnilQ0FKzOCdk2FHTzy8SUz09PTWksjvpZXmXhAUJZw5rTu6WpkdyqVSk4bWT1wg7LJHwEw9FgEVH16FrGd9vA1xufCs6A=w3026-h2017-no


All of the above was without a steering damper because the frame bolt I received for the ProComp damper from Trail Gear didn't fit the frame mount (frame mount hole tapers from 0.55" to 0.50", old ball joint bolt tapers from 0.55" to 0.50", provided bolt tapers from 0.63" to 0.55").

I left my sensors on the axle/knuckles for the Mojave Road, but the system didn't survive (or else I would measure performance after trying to shake the living daylights out of the truck for tens of miles). I may see if I can easily fix it. I'll be swapping wheels back this weekend, and I turned the steering damper bolt on a lathe so that it fits now, so I hope to put the steering damper on soon as well. I'm hoping between swapping wheels back (will probably reintroduce the shimmy), replacing the panhard bushings (may make the shimmy better), and adding the steering damper, that the issue will continue to stay resolved. I'll try to update this thread in the future with the outcome of those changes.

So.... loose bolts and loose wheel bearings solved the problem? Thats like... super textbook rookie mistake. chaper 1, page 1, word 1+2 "tighten stuff". How did that happen? Sounds like someone I know that got fired.
This is pretty disingenuous. The instructions were to "check the torque on every fastener related to suspension and steering". As I said, "I'm completely new to Land Cruisers and vehicle maintenance in general" so I was careful to explicitly list each fastener I checked because I don't know what "every fastener related to suspension and steering" is. "Tighten stuff" is worthless advice. "Tighten the right stuff" is accurate but also useless.

@alia176 was the first to suggest the actual procedure that ended up primarily solving the issue. @gummycarbs would have won if the panhard bolts were specified explicitly or if he (or someone else) mentioned they were missing from the list of things I said I checked in response to that comment. Thanks to the many other helpful commenters as well!
 
BILT4ME

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Update:

After removing the panhard rod to inspect the bushings (prior post), I reinstalled the panhard rod and remounted the two front wheels. That pretty much resolved the death wobble (where a shimmy gets bigger and bigger), at least the kind that I was reliably reproducing before -- awesome. It didn't resolve the thing I call the "incipient shimmy" which is how the death wobble starts. Here is what death wobble looks like (green = vertical accelerometer where you can see the knuckle hitting the two 2x6's, purple = knuckle vertical-axis gyro; shows the knuckle rotating about the ~steering axis)
AM-JKLVanmAPw8POphJNjq0O2bamnC4XHW0ycK91cJLFffnhSXStT-xD53zAox1emz8TXMC8WCCqjvYOP-WnYucfyj16mORoRwqtQufFHyHgCarnjJn-2t8hfY42JjuFLVxjNWBHjvUBDLUYs9IqLyfxEvevYg=w2023-h1054-no
AM-JKLXcov7HYG-tcSIgd_3dA3y7MbPfcG81jn9y0Ktw4kD22mvetR8yDiDNIRaLIkCWqReQVq_EXIsFFZVSnf3hvBZSI0K7IvGNYshCOQSgxCtsF03_4G-8U2Pr2tr5oJaExqgzgKGgWVCdFEXUod0B0cBmDQ=w2047-h1051-no

Those are two runs without changing the setup.

Then, I removed and reinstalled the panhard rod and removed and reinstalled the front wheels. After that, the death wobble went away, but the "incipient shimmy" was still there:
AM-JKLVofHdjSA_sxxjEpLIC6zMXT3CPDuVNtHKgUu4wC84fCJEimOFxgBWS0Io60gfNvYQt5aCsroE4lZN7wqA1KtFMnCAV13mFFvNK2UrTeXZz9Z18jcaBfnr4lFdrVUsWdQoa49xZakEgIwue9dbMbYFHrQ=w2050-h1047-no
AM-JKLUhXtvTh5WgeOdX0Kj5pTT13eosqDHB7SzCZ72JMMKfgY5eqN2l3q_Hyh3SUnWPXBJ2mzb-Ecu7XlcnFKFpnU5yjINrrB4isqNB0uwq7KrBw7_LJ2n0tSKh1CUpCXRCmi99WHy228nID6jIkzZkUFDXhw=w2055-h1057-no


Then, I went over to my buddy's house to swap wheels, but first they diagnosed bad preload on the driver wheel bearing, so we (they) set the preload correctly. After that, I drove around with my buddy so he could see the issue and we could see if adjusting the preload helped. It didn't seem to make a difference:
AM-JKLWqeyynb6-oyFcJ71LlrcFtukawW-DH9X8EUUT5zbC3uqp82nHVw7HDzZdMdq8isCedjHxA63ChS9H2pHfjgUhR1faPuazqgaWakg6Z8gxDjExY6ruW3cCjrnDSZo860VqEDbPzfQizw1t12j2IctQtBw=w2050-h1048-no
AM-JKLUwuqBsjAovD5KutUqi94tSHAVIXwuwbab96JR2UO-tkvhObBxMpbmNKx6VKbIAhOVUrgnbB_EiB0fRYNkWtj0o61fLTy312ecOc_gAK0crQFQXPJXm6BwTg7qBIe2xWCsslB4joselr2CLDybos7r_Mw=w2047-h1051-no


After that, we actually did the swap (changing 10 wheels is hard!) and that seemed to pretty much fix the shimmy. Technically, I think the system is still underdamped (you can see a few cycles of resonance), but practically it seemed fine:
AM-JKLWCnh_efIn4rKgxcd9TqfXyRniAJzj6596Go9v_3qRS_mYbnmzKVb0pai60guiSuua7E273Y_Hqj4qAPP963gqwqTMKKXmnAqwhlkHoX7sHby9eSbLoRhg3SBU6VxRv6nN9LI542wCinhtukAU-5NFX6Q=w2052-h1045-no
AM-JKLWtrPrwUU_qBWV6-IHniEdgP37HW4Bal6d-ybzPH_WJlm2zPzCn_fJsig_SCPOsqhB39mAY3I3RXXldY-bwADyBlpNt3Sp50_Ss4kzt7yBO4fnSrJPaenK4fvyiAKfAmAc0UnVApCtHPBYfZL_I29N-eg=w2044-h1045-no


After swapping wheels, I was able to have alignment measured. And, just for good measure, I wasted $100 to have Pep Boys rotate my steering wheel 4.5 degrees.
AM-JKLVmGCroczijUBA4q3fG_jBD_KyBu3vqn1EMIPdgZbK6PMwlc3a_SK7Z9GVyUxzF6_jSW6-mmNsxjva0Y8Hl7b2mH_qe8hS8fEiIBkblSxlhJbSeXezl4cMA5E3MWkjryR_D3Jz9agtyGOG4grCinDWVqg=w2690-h2017-no
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My caster was already surprisingly good; I was expecting it to be lower. Turn the steering wheel 15x 0.3 degrees and both toes were already in the shop-spec'd range of 0.0-0.3 degrees (though I was expecting toe-in of 0.24 degrees on each side since I measured a 1/8" difference between 37/2" in front of the axle and 37/2" in back of the axle).

I bought OEM panhard bushings and was hoping to press them in, but we ran out of time. The reason I was in a hurry to do all of this was to make a trip to the Mojave Road (2x 4-5 hours freeway, ~160 miles dirt). That went well -- adjustable panhard jam nut came loose once, but made kind of a distinctive sound so I think I fixed that pretty quickly. Zero death wobble, and the only worrying shimmies were probably just the arrangement of the rocks we were blowing over. Gratuitous trip pictures:
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All of the above was without a steering damper because the frame bolt I received for the ProComp damper from Trail Gear didn't fit the frame mount (frame mount hole tapers from 0.55" to 0.50", old ball joint bolt tapers from 0.55" to 0.50", provided bolt tapers from 0.63" to 0.55").

I left my sensors on the axle/knuckles for the Mojave Road, but the system didn't survive (or else I would measure performance after trying to shake the living daylights out of the truck for tens of miles). I may see if I can easily fix it. I'll be swapping wheels back this weekend, and I turned the steering damper bolt on a lathe so that it fits now, so I hope to put the steering damper on soon as well. I'm hoping between swapping wheels back (will probably reintroduce the shimmy), replacing the panhard bushings (may make the shimmy better), and adding the steering damper, that the issue will continue to stay resolved. I'll try to update this thread in the future with the outcome of those changes.


This is pretty disingenuous. The instructions were to "check the torque on every fastener related to suspension and steering". As I said, "I'm completely new to Land Cruisers and vehicle maintenance in general" so I was careful to explicitly list each fastener I checked because I don't know what "every fastener related to suspension and steering" is. "Tighten stuff" is worthless advice. "Tighten the right stuff" is accurate but also useless.

@alia176 was the first to suggest the actual procedure that ended up primarily solving the issue. @gummycarbs would have won if the panhard bolts were specified explicitly or if he (or someone else) mentioned they were missing from the list of things I said I checked in response to that comment. Thanks to the many other helpful commenters as well!
I'm curious what you do for a living, as you are very smart for building and installing a set of vibration sensors and where to place them, but have little automotive mechanical skills?

Seriously not trying to be a dick, but it probably sounds like I am.

I work in an industry where we deal with large industrial fans and balancing them and vibration sensing is part of it.
 
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bjp

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I'd be interested to see the same test after you fit your new OEM panhard bushings, and again after you fit a damper.
Me too -- I'm hoping to fix the sensors before swapping the wheels back to measure the "after a bunch of usage" as well as the "after panhard bushings" (and "after steering damper"). I give that like a 60% probability of working out (will need to see why the sensors stopped working)

I'm curious what you do for a living, as you are very smart for building and installing a set of vibration sensors and where to place them, but have little automotive mechanical skills?
Yeah, I get it :) I'm basically a software engineer after going to school for electrical engineering way back when (I'm really just an amateur electrical engineer), but my current title is a "standards engineer" because I work on standards and interoperability. I work with commercial drones in my real job. My good friend is a mechanical engineer and the things he would do often seemed like magic to me. I bought this LC March of this year and that was the first time I had ever changed a car's oil myself. Being good at one thing definitely doesn't mean someone is good at everything :)
 
mudgudgeon

mudgudgeon

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Across the pond, and upside down
Being good at one thing definitely doesn't mean someone is good at everything :)

True, but your clearly smart, methodical, curious, analytical and have problem solving mindset.
Apply that to anything, and you'll soon add another string to your bow

You're leaps and bounds ahead of other novice mechanics.
 
baldilocks

baldilocks

Battle Ground, WA
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@bjp - It looks like you run those Bird Dog wheels once sold , but no longer, by Interco tire company. They are basically unobtanium these days. Two valve stems is a cool feature in my opinion.
 
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bjp

Joined
Apr 11, 2021
Messages
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Location
Los Angeles, CA
It looks like you run those Bird Dog wheels once sold , but no longer, by Interco tire company. They are basically unobtanium these days. Two valve stems is a cool feature in my opinion.
Yeah, those are my buddy's wheels that you've correctly identified (he runs them on his 62) and I do like them a lot. But, they're his and this was just a trial swap to diagnose the death wobble so unfortunately they're being swapped back this weekend. The two valve stems initially confused me when I went to air down -- when I noticed the second, I thought I had accidentally aired down an inner beadlock, but you're right that they're just two stems into the same place so it's easy to adjust air even when sunk in mud or something.
 

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