So today i was in my 1996 Disco and i hopped on the interstate to hhead over to the pull a part. But once i started to get over 60to mph it started violently shaking and only got worse as my speed increased, i took it off the interstate and it was fine under 60full mph. What could cause this problem? Thank you

 

Rear flex coupler ?

 

Front end shake? Felt like you were going to crash? Was fine until you hit a bump?
Death wobble.
Search the forum for it.
A drive shaft vibration will not make the whole truck shake so bad you have to get off the road.
Severe tire out of balance will.
My bet is on the death wobble.

 

When I had the Death Wobble, it showed up when braking at freeway speed, very bad on a tight turn exit ramp. But just driving on flat ground I did not see it. I suspect that the oscillation (wobble) might be triggered at any point by something small. I ended up changing wheel bearings, sticking caliper, and tie rod ends.

 

Searching is good, but keep in mind, if you find a post saying to replace the steering damper to fix death wobble, ignore that post.

 

X2 on that, the damper might mask worn parts for a while, until they wear more, but it basically is there to protect your thumbs and wrists when truck hits a Jersey-rated pothole or a big rock on the trail. You can drive truck without it for testing. Of course, you could have bent wheel, out of balanced tire, bent drive shaft from SWMBO running over parking lot curb while fighting for the last mall parking spot, etc.

BTW, here's a pix of the coupling I mentioned. The correct term for it is "rotoflex", it is at one end of rear drive shaft.

 

It was my U-joints when this happened to me...it would really not be death wobble..since it is speed related on a highway going straight

 

It happened to me. For me it was just the wrong toe setting after I changed the tie rod ends. Set the wheels about straight and measure the distance from rim to rim at the front of the rim and rear of the rim. Set the toe so the front is about 1/16th of an inch or so farther apart than the rear. If you're like half and inch in or out then you'll have problems.

I can't explain why a toe setting resulted in very violent shaking at about 55-60mph when hitting small bump or something, but it did and setting it right fixed it. Normally I think bad toe just results in tire edge wear, but in my case it must have been toed way in or out, I don't know, I didn't check it I just re-did the tie rod. The violent shaking was very repeatable before and has never happened since.

 

Ok I will check everything out today. Im thinking the tires are off balance because Ive put 3,000 miles on them without balancing them, Thanks guys

 

Seriously...why would you install new tires without a balance...sorry but thats just dumb