Calling all TJs with 5.13 gearing (or deeper) that had or currently have vibrations at highway speeds

justjake843

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I feel like this needs to be talked about again. A lot of posts on this topic are a couple years or so old and there's not really direct "fix" per set and more or less band-aids to clear the problem, but the problem still exists.

I've been down this rabbit hole before, and the general consensus is to change the front hubs to manual hubs or just ride around without the front driveshaft when around town. If you're like me and went to manual hubs you'll find doing maintinence is a little more tedious as some parts are universal parts that can be got at a parts store, while.some components are made directly by Yukon and that means they have to be ordered.

I want to know what others have done that fixed the issue. Things like caster angle adjustments, tummy tucks and I've even seen a few mentions of upgrading the front driveshaft yoke bearings to high rpm rated bearings, although no posted results from that from what I recall.

I want to know what you all have done and any recommendations. I like my manual hubs and all, but I'm just curious if there's other fixes out there.

For reference I have a 4 inch lift, 5.13s, 42rle, NP231 and and a SYE kit in the rear.
Front driveshaft is stock with a LP Dana 30 and I have had the driveshaft balanced a couple times and adjusted my front control arms a bunch before I just ended up switching to Yukon hubs.
 
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That's a common issue with the 42rle that hasn't been solved. There was a Jeeper on the old forums (Unlimited04) that tried chasing it down and could never find it. And he did EVERYTHING to try and eliminate it. He never had any problems with it, just the ever so slight harmonic vibration.
 
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Following this as well. Also interested whether people with high pinion front axles have the same issues or not.
 
There was a Jeeper on the old forums (Unlimited04) that tried chasing it down and could never find it.
I remember that guy. (y)

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This is the first I've heard of this... harmonic driveline vibes from a specific gear ratio set, and only with a specific transmission? Weird.

I've been running 5.13s with the 6 speed for years now and it's silky smooth.
 
This is the first I've heard of this... harmonic driveline vibes from a specific gear ratio set, and only with a specific transmission? Weird.

I've been running 5.13s with the 6 speed for years now and it's silky smooth.

It has to do with the driveshaft speeds resulting from the lower gears and dumb overdrive ratio.
 
I feel like this needs to be talked about again. A lot of posts on this topic are a couple years or so old and there's not really direct "fix" per se and more or less band-aids to clear the problem, but the problem still exists.

A conversion to manual hubs can hardly be called a band-aid if it eliminates the vibrations. Once eliminated, how does the problem still exist?

And why the need for another thread on the subject? The "couple of years old" threads you mention are perfectly appropriate places to post any new information that may exist.
 
A conversion to manual hubs can hardly be called a band-aid if it eliminates the vibrations. Once eliminated, how does the problem still exist?

And why the need for another thread on the subject? The "couple of years old" threads you mention are perfectly appropriate places to post any new information that may exist.

All I'm saying is that, this issue is almost exclusive to 4spd auto TJs (although there are outliers because every TJ is different in how it reacts to lower gearsets) and it makes a quite a bit more in depth when doing gears on auto TJs. Yes converting to manual hubs does "solve" the problem, but it shouldn't be a solution when other tjs with different transmissions have no issues. I do understand it is unique due to the overdrive gearing.

I'm simply curious to see if anyone has found a better solution over the years
 
That's a common issue with the 42rle that hasn't been solved. There was a Jeeper on the old forums (Unlimited04) that tried chasing it down and could never find it. And he did EVERYTHING to try and eliminate it. He never had any problems with it, just the ever so slight harmonic vibration.

Yeah that's the rabbit hole I went down when I first did gears and discovered that vibration. He seemed super dedicated to tracking down the issue.

Maybe I'll just have to get as crazy as he was and just trial and error everything🤪
 
All I'm saying is that, this issue is almost exclusive to 4spd auto TJs (although there are outliers because every TJ is different in how it reacts to lower gearsets) and it makes a quite a bit more in depth when doing gears on auto TJs. Yes converting to manual hubs does "solve" the problem, but it shouldn't be a solution when other tjs with different transmissions have no issues. I do understand it is unique due to the overdrive gearing.

I'm simply curious to see if anyone has found a better solution over the years

It’s not exclusive to transmissions, it’s exclusive to deep gears and high driveshaft speeds.

Personally, I believe double cardan shafts don’t like high speeds. They survive fine, but seem to put out harmonic vibrations. Many folk swap to the SYE and double cardan rear shaft and then have two of them.

There are also different types of vibrations. There are physical vibrations that feel like you’re driving on the wake up bumps on the side of the highway. Those can be fixed with proper angles and balancing shafts well enough, in most cases. There are also rhythmic vibrations that feel like bass pulsing, in and out, as you drive down the road. Those are harmonic vibrations. They are relatively harmless, but annoying. Harmonic vibes are the ones most folks with 5.38 or 5.13 are complaining about.

I do think every Jeep is different, but I also think every driver is different. Some may not know what harmonic vibes are or maybe their hearing isn’t even good enough to hear them. I’m sure some Jeeps are truly lucky to have no vibes, but I also think some who say they have no vibes, may have them and not know the difference. I didn’t understand I had harmonic vibes for a while. Well, I knew I had them, didn’t know what they were and never put 2 + 2 together that it all happened after I converted to SYE, DC shaft, lift, and heard them bad when the hardtop was on at 85 mph.

Either way, it isn’t transmission specific. What is transmission specific is the gearing many people choose, which is where the issue starts, due to resultant higher driveshaft speeds.

The hub kit puts a halt to the front driveshaft which isn’t really a bandaid fix….it stops the problem.
 
I am dealing with this currently. 04 lj, 42rle,4 inch suspension only lift, 35s, 5.13s limited slips front and rear. Stock rear shaft, new tom woods front , proper length, it did help but not eliminate the harmonics. Pinion angle is 0.3 degrees. The very subtle, but distinct cyclical buzz between 60 and 70. Almost completely goes away above 70.

Also curious about any other options besides a free spin kit.
 
I am dealing with this currently. 04 lj, 42rle,4 inch suspension only lift, 35s, 5.13s limited slips front and rear. Stock rear shaft, new tom woods front , proper length, it did help but not eliminate the harmonics. Pinion angle is 0.3 degrees. The very subtle, but distinct cyclical buzz between 60 and 70. Almost completely goes away above 70.

Also curious about any other options besides a free spin kit.

There's not really any other options. No one in this forum has had them and solved them without the hub kit being part of the recipe.

@machoheadgames posted a theory above about it being related to the double cardan joint. But what reasonable alternative is there? Rzeppa joints don't seem to be as strong or handle the operating angle that a DC joint does, or else newer Jeep drivers wouldn't be tossing theirs in favor of a double cardan.

I've mused about using a larger diameter tube for the shaft to add some rigidity as well as maybe making it easier to balance? This is mostly based on the fact that aftermarket shafts are almost always smaller than OE. But it also introduces manufacturing concerns with the splines in the slip joint so it's not just as easy as "use a 2.5" tube".

I'll tell you this much ..I had a 99 TJ with no vibrations. I took the axles, suspension, transfer case out of it and put them under an LJ with a new rear driveshaft and got vibes that I haven't gotten rid of. I even swapped the LJ from a 6 speed to an AX15 which matches the 99 and they didn't go away.

I considered the possibility that the section of frame behind the skid plate was equal length in 03-06 and unequal in 97-02 which was interesting because the late model seems overrepresented. I added weight to one side of mine and it made no difference. I didn't add much, just equivalent to 3" of frame rail which is how much the difference was in the earlier design.
 
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There's not really any other options. No one in this forum has had them and solved them without the hub kit being part of the recipe.

@machoheadgames posted a theory above about it being related to the double cardan joint. But what reasonable alternative is there? Rzeppa joints don't seem to be as strong or handle the operating angle that a DC joint does, or else newer Jeep drivers wouldn't be tossing theirs in favor of a double cardan.

I've mused about using a larger diameter tube for the shaft to add some rigidity as well as maybe making it easier to balance? This is mostly based on the fact that aftermarket shafts are almost always smaller than OE. But it also introduces manufacturing concerns with the splines in the slip joint so it's not just as easy as "use a 2.5" tube".

I'll tell you this much ..I had a 99 TJ with no vibrations. I took the axles, suspension, transfer case out of it and put them under an LJ with a new rear driveshaft and got vibes that I haven't gotten rid of. I even swapped the LJ from a 6 speed to an AX15 which matches the 99 and they didn't go away.

I considered the possibility that the section of frame behind the skid plate was equal length in 03-06 and unequal in 97-02 which was interesting because the late model seems overrepresented. I added weight to one side of mine and it made no difference. I didn't add much, just equivalent to 3" of frame rail which is how much the difference was in the earlier design.

I think it’s the angle the lift puts the double cardans at. All stock TJs don’t seem to have problems, although maybe there are a few that do. I don’t know for certain though. In his case he’s lifted somewhat tall for a stock shaft although it’s an LJ so I’m not really sure what the deal is on that one.
 
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I think it’s the angle the lift puts the double cardans at. All stock TJs don’t seem to have problems, although maybe there are a few that do. I don’t know for certain though. In his case he’s lifted somewhat tall for a stock shaft although it’s an LJ so I’m not really sure what the deal is on that one.

Blaine has said that he's seen it on a stock one, '04 if I remember correctly. Don't remember the details as to whether it was T or L, manual or auto, 231 or 241.
 
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Interesting. Haven’t seen that but I believe it. I think some of them are just unfortunately quirky. I’m actually reverting my YJ from lifted and double cardan back to bone stock. Tired of the bullshit, and in my case the lift and tires serve no purpose. Back to basically fully stock it goes.

With the hardtop on and stock 3.55 gears (2.5”, AX15, locally built DC), mine would vibe hard at about 85. After 4.10 regear, it of course started at an earlier speed. With the top off I couldn’t hear it enough to care. But when I was completely stock, I never had a single issue and I want it that way again.
 
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There has been mention of people curing driveshaft vibrations with a new set of gears. I wonder if its propagating from there? Or

Unless the engine rpms at a given mph increase over stock I'm just not seeing the argument that regearing is making a driveshaft overspeed condition.if driveshaft speed was so crucial then stock 32rh jeeps would have them more when going fast down the freeway.

Driveshaft speed is tied to engine rpms and transmission gearing at any given speed. Regearing is just a way to compensate for larger tires.

Yes regearing spins the driveshaft faster. But it would need to be faster than stock speeds for that argument to work