I have a 99xj with a 6in lift and 33x12.5s. Of course just like any xj owner i'm used to some minor vibrations that make for a loud ride at high speeds. I just got my truck out of the shop where i installed new ring and pinion 4.88 gear set and lock right lockers front and rear. since i got my jeep back the vibration has doubled on the front end. if i'm going 50 i cant even see anything in my mirrors the vibration is so bad. at low speeds its not any problem at all though. the guys i had put it in are pros and are known around here for this type of work. what i'm wondering is:

-has anybody had this happen with a new gear set?
-has anybody had this happen with new lockers installed in the front end
-can anybody recommend where the problem may have come from?
-is this a common problem with a new gear set/locker that goes away after some use?
-did my mechanic totally F$%^ up?

i'm at a loss and i am bummed because i thought the 4.88 gears met going faster but i'm stuck at my same old speed of 50mph now. cherokee gods please lend a hand.

 

since you are at 6" lift I'm sure you have a SYE then. Has it been aligned recently? cant see ring and pinion or lockers causing a vibration

 

yes i had the SYE and new drive shaft installed less than a month ago by a pro as well. but the vibration is DEFINITELY coming from the front end. the rear seems the same as before. the only thing that has changed is the gearing/lockers.

 

take it back to the installers then and ask them since they just did the work. maybe the locker is locking up and causing vibes. doubt it but you never know. if it was the ring and pinion would would here a metal on metal chatter. what lockers where installed?

everything tight in the front? trackbar? bushings? balljoints? tires?

 

ya everything should be tight, same as before. all they did was the differential work. they didnt touch anything else. they are powertrax lockrite lockers. the front for sure isnt engaged unless its in 4x4. i took it on some trails just now to make sure. any other ideas? i'm for sure going to take it back to the guys tomorrow to see what they say.

 

sorry I meant that it wasnt unlocking. actually the front will lock up in 2wd usually on tight turns or parking lots.

does the front have any noise coming from it?

 

It does get some of the usual chattering/clicking accociated with lock rites when I'm doing some tight turning, but I thought they engaged when they were given power. If its in 2wd then they shouldnt be getting any power because th front drive shaft isn't spinning right? I could have a misunderstanding about the whole thing. But I can't imagine that them being engaged or not would cause any vibration when I'm going completely straight. I'm thinking more and more they fouled up something during installation, but at the same time she handles better than before at slow speeds. I'm confused.. Please help?

 

Anybody have this problem?

 

Take off your front shaft and drive around....process of elimination.

 

this was going to be my next thought. bad ujoints.

 

Can't imagine this being bad joints if I've never had an issue before but good idea on taking off the shaft to see. If it doesn't vibrate then that means its in my diff right?

 

Rotate and balance tires would be a good start. Ball joints and u joints next.

 

If the double cardigan joint goes out, it will try to shake the vehicle to pieces. Happened to me in the worst state ever, ohio

 

And I bet they just let the front ds hang from the tcase and something happened to the balljoint in the BC joint

 

The gearing could have made your vibes seem worse because you are spinning your driveshafts around 20% faster with 4.88s at any given speed. So your driveshafts are now prolly spinning as fast at 50mph as they used to at 70mph, roughly.

Not sure, but it makes sense to me.

So like was said, take off your front ds try to find where the prob is.