So I've been having really bad vibes above 45 mph or so. Basically violent shaking on the floor that goes up to the steering wheel. It's less in 4wd but still present.

First culprit is driveshaft u joints, correct? I looked down there today and have found 0 play in both driveshafts. Does this mean anything or are they still most likely the cause?

If they are, which U joints would you guys recommend getting? I've done a little searching but I figured I would just make my own thread to get more direct answers.

1999 sport, 4.5 in rubicon lift, 242 with hack n tap sye. Thanks for any help

 

Another to add is that I can hear a rotational thump when I'm coasting somtimes. Does this lead to ujoint's more than anything else?

 

When did it start? (What modification)

Tires balanced?

What driveshafts are you using?

Does it matter if you are on or off the gas?

 

I've had it since I bought the vehicle so I don't know when- lift & sye installed before

Haven't had them balanced personally- PO said they were but we all know how that goes. Should I look at doing this first? Would it really be the cause of that violent of vibration only above 45?

2 stock front driveshafts

And once the vibration begins, it does not matter if I have my foot on the gas or not. Still vibes when coasting.

Thanks for the reply

 

Tires

 

I'm gonna be ordering brand new KM2's in a few weeks so I guess we'll see if that's really the cause. But the tread/wear on the tires all seem pretty even. Should I just go get them balanced to be 100%?

 

There are plenty of things that can cause vibrations... I try to start with the easiest and go from there with my problems. I would start with balancing... Mine will vibrate terribly after about 50 when the rims are stuffed with mud or snow. You said there is no play in the driveshaft joints so that is good. Might jack up the front end and see if your hubs/axle ujoint have any play in them. Also possible that your drive shaft is out of balance. More than likely a tire balance will fix.