Re-geared, now I have a vibration above 50 mph

NHjeeptj said:
I just went from 4.10s in my 04 Jeep Rubicon to 4.56s. Has a 4” teraflex lift and 35” discovery tires. It now has the vibration at 50+ like the core of this thread describes. Prior to that it drove perfect. Has anyone tried going back to 4.10s and if so did that fix the issue? I have many concerns having the shop try and resolve this issue and making too many changes if they can’t fix the issue and it doesn’t sound like anyone has figured this out for sure.

Is it worth letting the driveline shop it’s at keep trying to figure this out or cut my losses and go back to the way it was? I just worry the vibration will now still be there going back to 4.10s since things have already been messed around with.

Thoughts?
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4.56 is still a pretty uncommon ratio to get the kind of unsolvable vibrations that @bobthetj03 has (though I believe that’s his ratio too). Start by going over your driveshaft u joints and make sure they are good. Check pinion angles. The faster the driveshaft spins the more sensitive to pinion angle it becomes.

You mentioned a 4” lift. Do you have a double cardon driveshaft? TJ Rubicons almost require that (and adjustable upper control arms, minimum) to handle 4” of lift. LJs, with their longer wheel base, get away with more.
 
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Mike_H said:
4.56 is still a pretty uncommon ratio to get the kind of unsolvable vibrations that @bobthetj03 has (though I believe that’s his ratio too). Start by going over your driveshaft u joints and make sure they are good. Check pinion angles. The faster the driveshaft spins the more sensitive to pinion angle it becomes.

You mentioned a 4” lift. Do you have a double cardon driveshaft? TJ Rubicons almost require that (and adjustable upper control arms, minimum) to handle 4” of lift. LJs, with their longer wheel base, get away with more.
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I do have adjustable upper and lower control arms. I am unsure what driveshaft I have but here is a photo of the rear driveshaft. I don’t have a pic of the front one but looks similar to me. Maybe you can tell me what it is:

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NHjeeptj said:
I do have adjustable upper and lower control arms. I am unsure what driveshaft I have but here is a photo of the rear driveshaft. I don’t have a pic of the front one but looks similar to me. Maybe you can tell me what it is:

View attachment 347935

View attachment 347936

View attachment 347937
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Have you driven it with the front shaft removed? If not, that's the first thing to try.

If the vibes go away with the front shaft out, then it's a result of the interaction between the two shafts and will go away with a locking hub conversion that allows you to run unlocked, and the front shaft won't spin. This is generally much less expensive than a regear.

If the vibes are still there, try to get rid of them by fine tuning your pinion angle. The cases of having a rear shaft only vibration that doesn't seem to go away is pretty rare. I have one but it doesn't set in until 75mph and it's still a lot weaker with the front shaft out.

I'm not aware of anyone who's picked up these vibes without increasing their driveshaft speed by regearing. That suggests going back to 4.10 should fix it. However, I'm also not aware of anyone who has tried solving them that way.
 
Unbolt the front DS at the front pinion and strap it up to the frame securely, then drive. If they go away you are pretty much screwed into a hub kit, or re-gearing back to 4.10's. You can try and fiddle with the front pinion, but unless your pinion angle is totally jacked up, you'll be adjusting in vein. If it drove vibe free before the re-gear, then your front pinion is probably just fine.
I've considered re-gearing to 4.10's, but I'm not a betting man, and I'm tired of throwing money at my turd. I have not heard of anyone re-gearing back, so if you decide to go that route let us know how it worked out. FYI, I've tried 3 different brand new front drive shafts, including the latest one by JE Reel, who high speed balanced it. No improvement. Mine kicks in about 60 mph.
 
bobthetj03 said:
Unbolt the front DS at the front pinion and strap it up to the frame securely, then drive. and then reattach it or pull the shaft completely before you forget it's tied up and put it in 4wd.
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FIFY

I promise I haven't done that, but I came really close once, only remembering it was still disconnected and tied to the frame as I grabbed the TC shifter about to pull up on it, while already moving.
 
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bobthetj03 said:
Unbolt the front DS at the front pinion and strap it up to the frame securely, then drive. If they go away you are pretty much screwed into a hub kit, or re-gearing back to 4.10's. You can try and fiddle with the front pinion, but unless your pinion angle is totally jacked up, you'll be adjusting in vein. If it drove vibe free before the re-gear, then your front pinion is probably just fine.
I've considered re-gearing to 4.10's, but I'm not a betting man, and I'm tired of throwing money at my turd. I have not heard of anyone re-gearing back, so if you decide to go that route let us know how it worked out. FYI, I've tried 3 different brand new front drive shafts, including the latest one by JE Reel, who high speed balanced it. No improvement. Mine kicks in about 60 mph.
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I admit that I for some reason didn’t think about the option of just disconnecting the front driveshaft from pinion and attaching it to the frame for experimenting purposes.
I have also installed new Dana 30 HP with 4.56 gears (replaced my 3.73), and I do get vibrations after like ~63MPH. Before new axle, it was not vibrating like this even at 70MPH.
My pinion angles are not ideal, as if is HP Dana 30 with maybe 1 inch of actual lift.
My front driveshaft angle is 2.6 degrees and pinion angle is 4.6 degrees.

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bobthetj03 said:
Unbolt the front DS at the front pinion and strap it up to the frame securely, then drive. If they go away you are pretty much screwed into a hub kit, or re-gearing back to 4.10's. You can try and fiddle with the front pinion, but unless your pinion angle is totally jacked up, you'll be adjusting in vein. If it drove vibe free before the re-gear, then your front pinion is probably just fine.
I've considered re-gearing to 4.10's, but I'm not a betting man, and I'm tired of throwing money at my turd. I have not heard of anyone re-gearing back, so if you decide to go that route let us know how it worked out. FYI, I've tried 3 different brand new front drive shafts, including the latest one by JE Reel, who high speed balanced it. No improvement. Mine kicks in about 60 mph.
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I’m having the front driveshaft replaced. That’s their best guess. I’m nervous this won’t make any difference based on the other posts I’ve read that have tried that in vein. I’m also concerned how many people have had to have a 2nd or even 3rd Adams driveshaft since the ones they ordered weren’t correct. I thought Adams was good? That’s the driveshaft they ordered. I’ll report back on how that goes. I do know all vibrations go away when front driveshaft is disconnected. I’m really conflicted. If this doesn’t work, and reading no one has had much luck, and I don’t have the funds to go manual locking hubs and honestly it defeats the purpose in my mind of having shift on the fly 4 wheel drive. I have two options if this doesn’t work. Either allow the new shop working on my jeep to try to regear the front diff with another set of 4.56 (or Same ones with new rebuild kit) or just cut my losses and go back to 4.10s. It didn’t drive terrible on 35s it just wasn’t ideal or what I wanted. This is such a dumb problem and I can’t believe there is no actual solution or explanation. I’ll report back on how it goes
 
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NHjeeptj said:
I’m having the front driveshaft replaced. That’s their best guess. I’m nervous this won’t make any difference based on the other posts I’ve read that have tried that in vein. I’m also concerned how many people have had to have a 2nd or even 3rd Adams driveshaft since the ones they ordered weren’t correct. I thought Adams was good? That’s the driveshaft they ordered. I’ll report back on how that goes. I do know all vibrations go away when front driveshaft is disconnected. I’m really conflicted. If this doesn’t work, and reading no one has had much luck, and I don’t have the funds to go manual locking hubs and honestly it defeats the purpose in my mind of having shift on the fly 4 wheel drive. I have two options if this doesn’t work. Either allow the new shop working on my jeep to try to regear the front diff with another set of 4.56 (or Same ones with new rebuild kit) or just cut my losses and go back to 4.10s. It didn’t drive terrible on 35s it just wasn’t ideal or what I wanted. This is such a dumb problem and I can’t believe there is no actual solution or explanation. I’ll report back on how it goes
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Usually when this happens (with new and multiple driveshafts) it's not a problem with the shaft exactly, it's that driveshaft balancing equipment peaks at 3300rpm and almost all of us target 3000rpm (engine) at 75mph. Divide that by your OD ratio to get your driveshaft rpm and a regeared TJ ends up 3600-4400 driveshaft rpm at that speed. Forces the machine can't even pick up at 3300 become significant when run 25% or more above that.

I hope it fixes it for you, but know that once you've replaced it once, there's no point in trying that again.
 
Somewhere, a long time ago on one of the TJ boards, someone referenced a front output bearing that would fit the NV241OR transfer case that is designed for greater rpms than the factory installed front output bearing. The theory was that the factory bearing turning 25% over its design speed was responsible for vibrations after re-gearing to deep axle ratios thus a bearing designed for greater rpms might be the fix. The post even had a part number.

I promptly lost the link and the scrap of paper with the manufacturer and part number.

If anyone would like to play detective, those are your leads.
 
Mr. Bills said:
Somewhere, a long time ago on one of the TJ boards, someone referenced a front output bearing that would fit the NV241OR transfer case that is designed for greater rpms than the factory installed front output bearing. The theory was that the factory bearing turning 25% over its design speed was responsible for vibrations after re-gearing to deep axle ratios thus a bearing designed for greater rpms might be the fix. The post even had a part number.

I promptly lost the link and the scrap of paper with the manufacturer and part number.

If anyone would like to play detective, those are your leads.
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This is a 231 but it sounds like the same solution.
https://wranglertjforum.com/threads...-after-re-gear-to-4-88-or-deeper.12218/page-5
This parts list shows that inner needle bearing is shared between the 231 & 241OR.
https://www.quadratec.com/jeep-replacement-parts/wrangler-tj/tj-nv241or.php
 
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Ok, I wanted to report back on my jeep vibration. It’s fixed!!! The second shop I brought it to figured it out in a week unlike the first place that couldn’t get it figured out in 7 weeks. The first place balanced my front driveshaft and it made no difference. After going over everything, and because the vibration stopped when the front driveshaft was disconnected they felt relatively confident the issue was with my front drive shaft. They replaced it with an Adams one. This did not fix it alone. They placed the jeep on jack stands under the axles and got it up to speed. At speed they noticed the front pinion yoke began to give movement due to being lightly bent. They replaced that too and bam, no more vibration at 50+. They did recommend I do an alignment by adjusting my upper and lower control arms on the front to adjust the axle and pinion angle to get a better steering feel (always been like that) but I’m hesitant because honestly the steering feel isn’t that bad to me and I worry it could induce a vibration. They seem confident it won’t. Maybe I’ll let them try so long as they remember how it is all set up now. Anyways, I wanted to report back in case this is the issue for any of you.
 
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I'm currently dealing with the exact same shit. Light vibration comes on right at 60MPH. I have 4.88 with most of the parts that you all have and I have been dialing in the damn pinion for 2 days and I cannot get it to stop. I even tried taking the pinion up higher but my shocks smash into the rear lower coil buckets preventing it from going any higher but that was really high haha
 
Nutro said:
I'm currently dealing with the exact same shit. Light vibration comes on right at 60MPH. I have 4.88 with most of the parts that you all have and I have been dialing in the damn pinion for 2 days and I cannot get it to stop. I even tried taking the pinion up higher but my shocks smash into the rear lower coil buckets preventing it from going any higher but that was really high haha
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Remove front drive shaft. Adjust rear pinion where it ideally should be. Go for a drive and report back.
 
When I bought this Jeep 4 months ago it had 35's and I don't remember any vibes. Now that I am doing all of this suspension work and now on 33's is vibes. I'm reading now that 4.88 gears and 33s is a vibrating combo? The only other thing I realized is, it has a stock front track-bar on the 4" lift. Maybe I need a front track-bar and upper adjustable arms to help dial shit in.
 
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