Sure glad you're here to do the scientific stuff. I'll be standing by.
Is this most common in TJ or TJUR or no difference?
I don't think there's enough data to say. We hear about it a lot more in TJ's, but there are a lot more of them out there.
The Official Jeep Wrangler TJ "Vibrations After Re-Gear" Thread
- Thread starter Chris
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I don't think there's enough data to say. We hear about it a lot more in TJ's, but there are a lot more of them out there.
I also have vibes with the 6-speed. I tried all this stuff, ended up rebuilding the front shaft, trying every pinion angle front and rear. It doesn’t matter what I do. It doesn’t change. With 33’s they came on at 64. With 35’s they come on at 70.I LOVE the hubs on my XJ and had pondered doing them on the LJ until I saw the price tag these days (upwards of $2k I've read here). But, if after experimentation, first up will be drop the front DS, I'll spend the coin and get it done.
Of course, I have to be part of the outlier group sporting the 6spd that 'less likely' to have this experience.
It IS good to hear that hubs might be the cure.
Hub kit is the answer, but $1400!
Or go to 37’s and they’ll move to 76! 
Where you finding them for $1400? Brand please? I'll do it if it comes to that. Haven't yet removed either DS, too buy wheelin' the XJ. I haven't even documented where they start. Do they go away at a higher speed or once they start they stay?
I probably won't live long enough to wear out my brand new 35s.
I don’t know. What’s the story with an HP30? How does that help vibes by raising the pinion output on the differential? So far with the LP30, no matter the pinion angle the vibes are the same.
IDK guys. I only NEED them. I don’t HAVE them.
I think they are plug-n-play unless you are doing a BBK.
Dunno TJ but my XJ has Warn hubs, Dana 30, and needed 1" spacers in the rear to match the track. Works fine but don't know if I want 1" less backspacing on the TJUR. Good question, tho', probably better than mine.
The HP30 upgrade is a crap shoot. It might help with the front pinion angle, maybe. I wouldn't do it just to try and solve the vibes, unless you just want the added clearance that a HP30 gives you, plus a tiny bit more strength, going forward, that is.
The front driveshaft is a mile long compared to the rear. I wouldn't put much effort into decreasing that driveshaft angle or expect any change resulting from an Hp30.
I had a 99 TJ without vibes, took the transfer case, front hp30, rear Dana 44, shocks, and control arms out of it, put them with the same wheels and tires under an LJ, and got vibes. The only thing that changed was the rear driveshaft and the rig that sits on top of it all. And the driveshaft got rebalanced with no change.
I had a 99 TJ without vibes, took the transfer case, front hp30, rear Dana 44, shocks, and control arms out of it, put them with the same wheels and tires under an LJ, and got vibes. The only thing that changed was the rear driveshaft and the rig that sits on top of it all. And the driveshaft got rebalanced with no change.
Sorry just saw this while heading out to the Bay Area for the week but I can get a measurement Friday when I get back.
My previous axle was a LP30 with the same (more or less) lift and I didn’t have any vibes with it and it’s been on 35’s and 4.5” of lift since it was new.
Leads you to believe that Jeep engineers built the TJ on the edge of acceptance. Why else would you need a harmonic balancer at both ends of the jeep? Ugh!
I checked this today, 10.3 degrees, 5” of lift, Atlas clocked at 7 degrees, and tucked. The engine skid is lower than the DS.
Wow. Mines not clocked so its not apples to apples but I'm at 14.7.
Ok, here's my proof of concept. Definitely not a permanent way to do this or even an efficient one, but very temporary and one that required as much welding as possible, because I'm trying to accumulate arc time before I start doing things that matter like welding on a bumper or mini skids.
It just goes around the frame, with a other strap that bolts into the tabs to hold it on. I used about the length in 1/8x1.25" to be equivalent to the 3" of extra frame length that was behind the skid on the 97-02 models that don't seem as affected by this phenomenon.
Going to put it on the frame between the skid and the rear most body mount. I'll let you guys know if it changes anything.
It just goes around the frame, with a other strap that bolts into the tabs to hold it on. I used about the length in 1/8x1.25" to be equivalent to the 3" of extra frame length that was behind the skid on the 97-02 models that don't seem as affected by this phenomenon.
Going to put it on the frame between the skid and the rear most body mount. I'll let you guys know if it changes anything.
Now I'm curious what the difference between the two are; like from center of front output to bottom of frame.