It's not like it needs to have the wheels balanced. It's intermitent and starts at 55 vibrating and not vibrating (about the pace of the blinker) and goes on in a faster rithm as the speed increases. For example if you count 4 seconds, seconds 2 and 4 vibrates. Can someone explain this to me? I've never heard of it. Weird. Thanks.
ESH. 1992 Cherokee Limited 4.0L

 

that is wierd, if i had to guess to start somewhere i would say either your engine is cutting out or sputtering at high rpm's or maybe something with your rear end, like maybe one of your spiders has a tooth knocked off.

 

actually i second thought that one, id deffiantly check rear end, open it up and look at ring gear and spiders, if nothing broken the great! replace the fluid and see if that helps. probably time for a change anyways right?

 

Another idea might be to check the U-joints and wheel bearings.

 

My 96 did the same thing after I put my 3" lift on, after the TC drop it stopped, do you have a lift on yours?

 

your drive shaft is messed up and check your u joints and your back axle and check your lug nuts make sure there all tight

 

tires! either ware or balence.. the reason it's on and off like a blinker is cause no two tires are exaclt the same diemater (they are turning at different rpm) when the uneven balenc/ware is in sync you don't get vibration, when it's out of synch you hear it..

the freequency will prolly change in a right or left turn (above 55)

 

U joint
or tire out of balance

 

I had the same issue, and had me perplexed for some time, and my problem ended up being the slip joint in the front axle, i grease the fitting and it went away for a while, came back then i replaced the driveshaft and the problem seased. if it's not that, i would lay money on the driveshaft yokes, there only 8.99 or something like that, but i would still check out that drive shaft, my noise didn't sound like it was coming from there, i kept thinking it was in the rearend after checking out all that i just started replacing everything to no aval until i did that front shaft, sounds weird but I guess the noise was travelin throught the drivetrain, hopefully it's not the begining of "the death wobble" good luck

 

what he said check u joints make sure your lugs are tight and make sure the tires are balanced

 

I've thought of almost all of it so far. Wheels are balanced, lugnuts are tight, rear axle is good, gears and bearings OK, U joints are good (just little play).
I didn't think about the driveshaft though. How can I check the driveshaft? I've heard that sometimes you have to get it balanced, but if that's the problem, the symptoms would be like an unbalanced whell woudn't it?
Another thing I came to realize are the tire sizes. I had to replace one front wheel and got it from the junkyard with a tire that is slightly smaller than the other ones. Would it be the problem even if I'm on 2WD?

 

your u joints should have zero play in them

grab the yokes on each side and try to move them back and forth side to side

its OK if the yoke it self moves a little at the tranny
and the pinion yoke should have no movement or just the very slightest hardly detectable

but any movement of the u joint in the cap its bad

 

well check that to and well when is the last time your drive shaft got a lube job like take the u joint covers off and had new grease in her

 

what you are feeling is called "straight line harmonic resinence" look closely at your drive shafts. like what was mensioned before. you should have to movement in the u-joints at all. as well a u-joint can go dry and not move smoothly causing this.