ok so i just installed my 3.5" RE lift and went for a test drive. I began feeling and hearing a quick grinding noise from under the drivers side seat. i replaced the front u joints and took a look at my driveline and other u joints but nothing seemed wrong. so i thought that maybe i over tightened the shackle bolts on the leaf springs and they were binding.

Does anyone have any idea of what this noise could possibly be?

 

Hmm.... that's the thing about noise questions, I'd have to hear it to really understand. Your rear driveshaft could be on a slight bind at the U-joint, causing it to grind either inside the joint or at the tranny's output shaft. On a 98, chances are you're going to need to lower the t-case to correct your angles a bit. Of course, an SYE and new driveshaft would be best, but who has the money for that?

 

Did you install an adjustable track bar? Did you put any shims in the rear leafs? This grinding noise does it happen when you accelerate or when you decelerate? To me it sounds like you need a tc drop and eventually an SYE and CV shaft like trueblue said.

 

Sounds like the normal driveline vibes/grinding that we're quite prone to after lifting.

Sounds like you could probably get away with a 1" transfer case drop to solve the vibes/grinding.....but as mentioned a SYE would be the best option. Which transfer case do you have?

 

I just installed the same lift and have some vibes as well..I am going to buy one of rusty's 1" tc drop cross members..You lose no ground clearance and you get the drop without the need of removing the old studs and what not..So That's the route I am going till one day I can afford the SYE and TW CV shaft..


http://rustysoffroad.com/mm5/merchan...y_Code=xj_skid

 

Try the t/c drop but it would be better with a SYE.

 

Rear driveshaft angle is off or at it's limits. 97+ xj's are prone to driveline vibes with the slightest lift. At 3.5", you definately need driveline modifications like what was stated above.

 

Yeah if the vibe/grinding is at acceleration then rear shims if it's at deceleration tc drop or SYE.. Also if you get vibe/grinding at deceleration and you don't have a track bar installed to re-center the axle then you need a track bar because then that shifts the driveshaft towards the drivers side as well as the upward angle... I know my axle shifted towards the drivers side quite a bit when I installed the lift and mine measures right at 4.5"...Also mine is really really bouncy on some bumps..lol

 

I have the np231 transfer case. i hear the sound when i slightly press the accelerator or let off it.

thanks for the input!

 

Did you install an adjustable track bar or relocate the mount on the axle end? If not that could be part of it.. but being that your XJ is a newer model you will likely need the tc drop or SYE/CV ....

 

i think i will try the tc drop kit.
this may be a stupid question but what does the track bar do?

 

get a tcase drop. ive still got vibes even with mine but only little ones. then again, im a little higher than you so yeah. but ill be getting an sye too when i get more money.

 

I have the same vibration, been doing it for a year now. I'll correct it at some point.

 

I think it is unrelated to your grinding noise.
The trackbar locates the front axle under the Jeep. When you lift a vehicle the geometry causes the front axle to shift. The adjustable trackbar re-orients the front axle under the center of the Jeep again.

 

Well I installed the same lift on a 91 XJ..Had a similar noise until I put the track bar on..I still have vibes but not the nasty grinding vibe noise fron the front drive shaft..On mine after I installed the lift it shifted the front axle quite a bit off center to a point I didn't have to eye ball it I could just glance and tell it was off.. Although you will still likely need a SYE or tc-drop..I plan on doing a tc drop till I can afford an SYE next year.