Please help me solve the oscillating vibration crisis by providing some basic info on your Jeep

srimes said:
um... don't you need lift height too? Seems critical here...
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freedom_in_4low said:
Oddly enough, from my research to this point lift height and driveline angle seem to not really be major contributors.
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to go more into this, I have not found one single example of someone picking up this vibration after a lift. There are plenty of examples of people installing a lift and tires without regearing and none with this problem.

While the operating angle does increase the amplitude of the angular velocity waveform of the double cardan assembly or the main shaft body if a single cardan shaft, but that's a second order vibration which would be double the characteristic frequency of this phenomenon. If my understanding of NVH is correct, a vibration can excite second and third order harmonics of itself, but it can't excite a vibration of half itself.

Lastly, I think pretty much everybody in the affected group is gonna be running about a 4" lift because everybody with vibes (so far) has at least 33" tires. It would be nice to find some people that regeared with no lift, but I don't expect them to show up.
 
freedom_in_4low said:
Oddly enough, from my research to this point lift height and driveline angle seem to not really be major contributors.
Click to expand...

Nonsense. You can get by using tire size as an analog for lift as they're well correlated, but suspension lift is the dominate factor. Unless you're proposing that larger tires themselves are inducing vibes.

And even if the suspected lift wasn't a major factor you'd still be better off gathering that data in the survey and calculating effect. Surely it's way more important than the gas tank skid.
 
1. Not now. Yes w/ bad u joints and wrong pinion angles (bent stock skid, new barnes skid before adjusting). 45 mph.
2. Yes. No w/ rear shaft pulled.
3. 99 tj
4. HP30/44. 4.88
5. 35/12.5/15
6. ax15
7. 231 sye
8. barnes 4wd bolt on.
9. stock
10. none
11. 1" MM lift
12. 6" springs
 
srimes said:
Nonsense. You can get by using tire size as an analog for lift as they're well correlated, but suspension lift is the dominate factor. Unless you're proposing that larger tires themselves are inducing vibes.

And even if the suspected lift wasn't a major factor you'd still be better off gathering that data in the survey and calculating effect. Surely it's way more important than the gas tank skid.
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@Artsifrtsi @06lj @Apparition can you guys give us your suspension lift heights?

I got everybody else's from their profiles.
 
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1. no
2. n/a
3. 2006 LJ
4. Dana 44 and 5.13
5. 35x12.50/15
6. NSG370
7. 241
8. Savvy
9. stock
10. 4ish"
11. midarm, shock outboard
 
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1. No
2. No
3. 05 LJ
4. LP30/44 3.73
5. 35x12.5x15
6. NSG370
7. 231 JB SSYE
8. stock
9. Savvy GTS
10. n/a

This is current configuration but if need data points you here are previous configurations along the way. I really want to share different setup but parts in a pile waiting for others before they go on the Jeep just cause frustration not vibration 😢

1. No
2. No
3. 05 LJ
4. LP30/44 3.73
5. 33x12.5x15
6. NSG370
7. 231
8. stock
9. stock
10. n/a

1. No
2. No
3. 05 LJ
4. LP30/44 3.73
5. 35x12.5x15
6. NSG370
7. 231
8. stock
9. stock
10. n/a
 
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freedom_in_4low said:
@psrivats hoping not to trigger a PTSD episode for you by bringing you into this, but I have most of your info already figured out except for speed at onset, and what specific skids you're running, and couldn't remember if you have frame mods like a midarm or an outboard. I fiogured I'd enter yours once with 5.38, no vibes and a rubicrawler, and once with 4.88, vibes and no rubicrawler.
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Front hubs are only thing that fixed the problem. Other things do not matter. You have the right information otherwise. Please add that to the "5.38, no vibes and a rubicrawler" entry.

I do have frame mods (Dave's midarm + outboard). But those are irrelevant for this vibration issue. They were there both before the mods and after the mods.

FYI - don't expect much to come out of the pivot table analysis. You will see that some jeeps just have this problem and some don't and there really isn't a pattern. There are enitrely stock vehicles with the problem too.
 
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freedom_in_4low said:
they don't list this skid on their website, do you know about how much it lifts the transfer case?
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All but about .5". It's nearly flush with the frame. Catching a fight home, so I'll try to grab a couple specific pics tomorrow, but you may be able to get an idea via some of the pics under images on my profile.
 
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psrivats said:
Front hubs are only thing that fixed the problem. Other things do not matter. You have the right information otherwise. Please add that to the "5.38, no vibes and a rubicrawler" entry.
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I'm trying to get to a point that the rubicrawler got you to...where the vibrations were at least gone with the hubs, where as before the rubicrawler you could have got hubs and still had the vibration.

psrivats said:
FYI - don't expect much to come out of the pivot table analysis. You will see that some jeeps just have this problem and some don't and there really isn't a pattern. There are enitrely stock vehicles with the problem too.
Click to expand...

Unfortunately I think you'll prove right because the sample size is gonna be too small to identify a pattern. As far as I know, there's only 3 of us that still had the problem even with the front shaft out, and only 2 of us left.

psrivats said:
I do have frame mods (Dave's midarm + outboard). But those are irrelevant for this vibration issue. They were there both before the mods and after the mods.
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good info (y)
 
1. Yes, 55-65
2. TBD
3. 2003 TJ Rubicon
4. Stock F/R 44, 4.10
5. 265/75R16 currently, also present with previous 245/75R16
6. NV3550 5-speed
7. 241
8. Stock transfer case skid
9. Stock gas tank skid
10. No lift
11. None, stock driveshafts, both rebuilt, Centramatics
 
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srimes said:
Nonsense.
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That is a strong statement, which begs me to question how much time have you invested into this issue.
How many times have you moved both pinions + and - 4 degree in 0.25 increments just to realize that only thing that changes is frequency of the vibration? How about changing the lift from 2" to 4 " in 1" increments, and redoing + - 4 degree pinion angles at each lift? When you changing pinion angles, what do you think that simulates?
 
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Wow, i was literally about to start gather this info for exact same reason. (y)

1.Yes, 60 mph
2. No
3. 2006 Sport
4. 4.56 Dana 30 front, Dana 35 rear which now swapped to D489
5. 265/70 R17 and 33x10.5 R15
6. NSG 370
7. 231, 3 and 6 pinion planetary, Advanced and JB
8. stock transfer skid
9.stock gas tank skid
10. 2" , 2.75", 3" and 4"
11. No mods
 
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TRE3TOP said:
Can you explain this oscillating vibration issue?
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Activate pulsating vibration mode on your phone, and put it on the table. Feel it? Now imagine same thing going through your entire Jeep and you feel it in every corner. It can range from continuous to pulsating consistently at the same interval like 2 seconds on and 2 seconds off.
Regearing triggers it, don't confuse it with bad tire balance.
 
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1. Do you have the oscillating vibration issue and at what speed does it start? - Thankfully No
2. does it persist even with the front driveshaft removed? - N/A
3. Model year and TJ or LJ - 2004 TJ
4. Axles and Gear ratio (and if you have a Rubicon, did you keep thick cut gears or did you get a 3.92+ carrier and go to standard gears?) - Stock Rubicon Axles with Factory Lockers and 4.10 gears
5. Tire size - 35 x 12.5 - 17 Also running Centramatics.
6. transmission - NV2550
7. transfer case, and if 231, is it SYE'd - NP241OR
8. stock or aftermarket transfer case skid, and if aftermarket, which skid (please include brand, tuck height, and material) - UCF Extra Clearance Aluminum Skid, Approximately 2.5" tuck
9. stock or aftermarket gas tank skid, and if aftermarket, which skid? - Savvy G/T skid
10. suspension lift height, if any - 4"
11. any other mods that might change the way the frame is constrained, such as a stretch, midarm, rear frame raise, crossmember deletions, spring perch relocations, shock outboard, etc. - Raised Rear Crossmember, Relocated rear upper spring perch.
 
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1. No
2. No
3. 2005 LJ
4. Dana 30, Dana 44 3.73
5. 35x12.5R15 Maxxis Razr
6. NSG370
7. NP241OR with 1310 yoke Stock lj Rubicon shaft without stock flange
8. Stock skid, stock height
9. Stock skid
10. 3" teraflex springs 1.25" savvy body lift
11. 1" MORE rubber mounts, swayloc
 
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