AH64ID

Okay...I have a 95 with 5" of rear lift and 0 vibrations...so its not the fault of the lift. Like you are doing check the u-joints, mine are greasable...have you greased them lately there is more room for movement in greasable one than sealed ones....also make sure your front driveshaft isnt enagage (i.e. ADD not disconnecting) you can do this by just rotating it with your had...if it rotates no problem, and since you feel the vibration through the t-case this will eliminate any front CV questions.

I find it hard to beleice a u-joint has gone bad...I have original ones (125k) and 35K with a lift, and never a vibration or u-joint issue...g/l

AH64ID

Have the toyo's checked for out of round...this happened to one on my moms runner...balancing doesnt always catch a out of round tire....

I dont think its tire related..since giving gas increases the vibration...

Oh yeah..one more thing check you 4-link setup...espically the upper links. I had one go bad and I would get a helacious vibration under acceleration....FIXED THAT ASAP

TStango

Well, I have a friend with 98 4Runner. Maybe I can swap some of his tires with mine for a test drive just to be sure. If it turns out to be the Toyo's after all of this, I'll freak out.
I really appreciate all the feedback and advice from personal experience. Thanks! I really hope to fix this once and for all, this weekend.

Del

If the vibration increases when you give it gas, it could be tire related...

...More gas = more speed = more rotation of the tires = more vibration.

Eighty7ToyTruck

Okay...I have a 95 with 5" of rear lift and 0 vibrations...so its not the fault of the lift.
^^ARE YOU CRAZY?^^ That's like saying, every lift is the same, and every truck is the same... it could VERY WELL be the fault of the lift... anyways

Also check out your motor and tranny mounts... had bad motor mounts on a 99-S-Blazer, caused a hellacious vibration at highway speeds, moreso with acceleration...

TStango

Okay, here is another observation. The vibrations are not immediately present when I initially reach 55+ mph. Its not until I've driven a mile or two that they appear and progressively get worse. Maybe that's why they are called progressive springs?

Another thing, when the vibes show up, I can very faintly detect them in the steering wheel. In the past, I have experienced vibrations caused by improperly balanced tires. However, the frequency of these vibes is faster.

Did I mention that this all started immediately after the spring install, which in turn caused my CV boots to leak from the shaft clamps? I have since fixed this with a tighter clamping method.
Could the small amount of grease that was lost be the cause of this vibration?
AGAIN, I'm sorry for the long saga. But I do value all the feedback. It stops me from chasing my tail for at least a short while.

AH64ID

That was meant to explain that you can run lift and not have problems...he is trying to find the ultimate cause of the vibration..not the proximate.

if its a motor mount, or driveshaft, or u-joint its not gonna go away if you remove the lift...

AH64ID

If you are feeling the vibration more in the x-case shifter than in the steering wheel..my guesses lean away from the front end..Is speed a factor? try rotating your tires and see if the vibration location changes. How much lift are you running up front, from the pics it doesnt look like much...

the reason you saw grease around the boot after putting the lift on is that the volume of the boot decreased with the lift, and the grease had to go somewhere..I dont think that would cause much vibration. In our 93 chevy P/U we got a piece of sagebrush inside the boot and you could really feel that when it would go through the CV...

there are so many things it could be...you could have a bad CV that is the result of a new operating angle, but I dont think returning to stock would eliminate that...

Because it only appears when it 'warms' up I would really look at your tires...But its also hard to wager a guess without feeling the vibration.