Hola, amigos! I've been trying to chase this down for a while, but can't really find anything to really help me out, so here I am. My '93 get a really harsh vibration at speed over 60mph. It starts right around 60, then quickly gets much worse as I speed up.

A quick rundown of things we've done to this thing:

-3" Rough Country lift (stock trackbar)
-JUST replaced both front wheel bearings, along with driver side upper ball joint. It came apart when I had to pull the steering knuckle off to drill a broken caliper bolt out.
-Passenger front tire had nail removed this morning

So, there's a few things to consider....I'm really starting to think it's worn steering or suspension components because of the ball joint separating. The stud came out of the upper portion pressed into the knuckle.

My next thought would be either the tires or one of the driveshafts out of balance, but since I don't have a SYE yet, can't remove the rear to check without losing T-Case fluid. Any other ideas would sure be helpful!

 

did this problem happen after you installed the lift or?

 

I believe so. We installed it about four years ago, if that makes any difference. Just rotated the tires around, but no change. Does feel like it rides a bit better, though!

 

so stock no vibrations.. then install lift and get vibrations? or install lift then 4 years later get vibrations

 

Wish I could remember....I think it was right after we put the lift in is when it started. Got a T-Case drop, but that didn't solve it.

 

Got a NP213J?
This...

http://www.seriousoffroadproducts.co...it-87-06-XJ-TJ

And these...

http://www.seriousoffroadproducts.co...2-STEEL-RE1464

 

I don't know if mine an NP231J....All I know is NP231. Is there a difference? And what do the shim things do exactly?

 

Shims rotate the rear axle upwards so that the drive line is in as straight of a line as possible . the idea is to have little to no angle in the Ujoints.... even so, if you have not done the driveshaft swap the slip joint will cause a vibration because the lift is causing it to pull out. also you made no mention of ever having the tires balanced. the fact that you said it changed a little when you rotated the tires confirms my theory that your tires are probably way out of whack. If they end up requiring far to much weight it may be time for new tires and likely some new rims. but usually you can balance them out to near zero if you have the patience although if the tires have a shifted belt no amount of balancing will help it... this will likely require you bring the car in for service at a tire shop. or bring the four tires in by themselves and have them balanced. .... may be cheaper if you do that. may also want to have an alignment performed if that has not been done recently(last couple of years). start by balancing the tires though and report back. I am confident you will notice a change. after that we can start chasing down the inevitable drive line vibrations

 

Just another option it could be is a worn axle shaft. Check your axle seals and see one is bad. I had the same problem on a lifted Chevy 4x4 back in the day..... the seal was bad so crud got in and wore a groove/dip into the short axle shaft causing a bad vibration. Once I replaced the axle shaft and race/ bearings and seal that truck would fly at high speeds with no vibration at all.

RIZ

 

Okay, so I think I've got it narrowed down to something with the front half of the drive line. First thing I did today was a driveway alignment following a guide from JeepForum and got the toe within spec. Took it for a drive and vibration was lessened, but still there.

Pulled the front driveshaft and now it's WAY better! Hardly any vibe at 65 when it used to very extremely harsh to the point I was afraid to go over 60. Still a little vibration, but I have a feeling that's from worn suspension or steering components because of that ball joint we had to replace.

I will point out I believe there was too much play in the front DS. I could turn it by hand about a full inch in either direction. Is this normal, or something that should be addressed?

 

Anyone?

 

When was the last time you replaced the U-Joints?

 

Uhh....Crud, can't remember! Just by that, you know it's been a while....

 

Pump some grease in your U-Joints first and see if that helps, if not replace them.