Getting up to highway speed without shaking apart (05 LJ)

I had the same issue, and rebuilt the entire front end: new upper and lower ball joints, u-joints, wheel hubs and bearings, and bushings where there were any bushings. New ball joints made the biggest difference from a shaking perspective-these were in very poor shape, and new u-joints significantly reduced drivetrain noise.
 
Well if there's one thing I've learned about Jeeps today it's that they aren't trucks, lmao - thanks for the clarification. ;)

Some additional context on the wheels/tires:

When I bought the Jeep it had some pretty ugly 17" mall crawlers that I promptly replaced with brand new steel wheels - while I assume that means they are free from defect I can't truly rule that out. I did transfer over the tires from the old set since they appear to be in pretty good shape. It's possible that they're the source of the shake-up, since the Jeep had issues going over 60 when I was bringing it home; I had just thought it more likely that the OEM steering components and big lift were the culprit. I'll need to try on a set of different wheels/tires to check that out further sine I've done all I can with the existing parts I've got.

Pictures of your driveshaft rear and front. I'm thinking they did a lift without a DC shaft or didn't lower the skid. Pictures would help everyone here. Good luck Buddy!

Attached,
1) skid - looks like the plate was lowered, so that's a plus.
2) rear
3) front - axle side
4) front - tcase side

How do all the joints look while doing the dry steering test? If you put the driver‘s tire up on a ramp ant move the wheel, it the front still, or does it move with the wheel? It could be tires out of balance, or wheels bent/out of round too.
For the steering components, they look pretty solid to me in a wiggle test on the ground, ill have to try the ramp trick and see if that changes anything.
video of a flat-ground steering test linked below:


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I had the same issue, and rebuilt the entire front end: new upper and lower ball joints, u-joints, wheel hubs and bearings, and bushings where there were any bushings. New ball joints made the biggest difference from a shaking perspective-these were in very poor shape, and new u-joints significantly reduced drivetrain noise.

I wouldn't be surprised if they're shot, most of the components that I've taken off thus far have been in pretty sorry shape.

Not related but was the rear pinion seal leak fixed? 🫢

View attachment 472313

Sure doesn't look like it to me 😒👌
The fun never ends.
 
Some places/people fix them and don't clean off the dried-on gear lube. Just did this on my wife's WJ.

I'll wipe that off with some degreaser and see if it shows back up after a couple highway drives, thanks!

Cheapest or free option
Check all 4 tire balancing

next , driveshaft

Tires/wheels have been balanced twice in the last month and are on brand new wheels.

thinking that next step is a driveline pull and see how it feels.
 
Your fixed control arms are placing the pinion too high for the driveshaft. Also you don't have an SYE.

That was the underlying fear from what I've been reading so far, haha - I've been reading that an SYE is pretty much mandatory for a 4" lift - and I'm not terribly surprised that the PO didn't put one on.

I'm also not terribly surprised that the arms that came with that lift didn't put things in the right position, just a "good enough" for driving around the mall parking lot.
 
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That was the underlying fear from what I've been reading so far, haha - I've been reading that an SYE is pretty much mandatory for a 4" lift - and I'm not terribly surprised that the PO didn't put one on.

I'm also not terribly surprised that the arms that came with that lift didn't put things in the right position, just a "good enough" for driving around the mall parking lot.

Common on bottom of the barrel lifts.

If you want to fix it cheap, get stock control arms and see what that does. The tcase drop would have to remain most likely. If you want to do it correctly, then get quality adjustable control arms (rock jock preferred), an SYE (or even an SSYE (JB Conversions)), and a double cardan driveshaft (Tom Wood). This will allow you to place the axle correctly, get rid of the tcase drop, and get rid of the lower shock relocating brackets (which would likely require you to get different shocks).
 
Common on bottom of the barrel lifts.

If you want to fix it cheap, get stock control arms and see what that does. The tcase drop would have to remain most likely. If you want to do it correctly, then get quality adjustable control arms (rock jock preferred), an SYE (or even an SSYE (JB Conversions)), and a double cardan driveshaft (Tom Wood). This will allow you to place the axle correctly, get rid of the tcase drop, and get rid of the lower shock relocating brackets (which would likely require you to get different shocks).

OK this lines up with the little plan I had drawn out, but I had questions surrounding the best way to get it done. Really helpful of you to post out a plan for me, thank you. A few questions if you've got the time:

Regarding the Tcase, are the spacers of the skid plate the same mechanism in which the tcase itself is lowered? IE, is the tcase bolted to the skid an the spacers simply angle the powertrain by a few degrees? Wild.

On the Driveshaft - I'll do some research on the process to install the SYE, I'm no stranger to diving in so unless there are some wild specialty tools required I should be able to handle that, though to confirm, only the rear DS needs to be swapped with a DC because the front already has one, yes?

For for the control arms, would it be sufficient to purchase only lower adjustable arms and leave the top stock ones in place? or would adjustable uppers and keeping the modified lowers be appropriate?

And wow I didn't even notice that those were relocation brackets for the shocks. Those must compensate for the wonky axle angle. I did just purchase a set of Rancho RS5KX's for the appropriate lift height so those should just slot into place, since the ones that came with the lift were completely blown (shocker).

Thanks, I feel like this is likely the true culprit here.
 
I think the dropped pitman arm is assisting to cause the issues... your track bar and drag link aren't parallel..

The rod end on the driver's knuckle looks like it might be moving a little... could be camera aberration though...

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If you want to do it correctly, then get quality adjustable control arms (rock jock preferred), an SYE (or even an SSYE (JB Conversions)), and a double cardan driveshaft (Tom Wood).

Also, any thoughts on the need for an SYE with an LJ? I read the following on Chris' write-up
(https://wranglertjforum.com/threads/the-official-sye-slip-yoke-eliminator-thread.100/)

What if I have an LJ?
Lucky you! The LJ in most cases is fun up to about 4-4.5" of lift without a SYE or double cardan (CV) driveshaft! That's one of the benefits you get from the LJ with it's longer wheel base... much less extreme driveline angles.
 
When I bought the Jeep it had some pretty ugly 17" mall crawlers that I promptly replaced with brand new steel wheels - while I assume that means they are free from defect I can't truly rule that out.
I bought 5 new steel wheels and one was unusably wobbly,two others wobble some but aren't terrible.
 
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I bought 5 new steel wheels and one was unusably wobbly,two others wobble some but aren't terrible.

Well shit - I guess that's what I get for assuming - the tire shop wouldn't have been able to detect this during the balance process and inform me?