00 Xj NP231, Auto, 5'' coil front, 3.5'' AAL rear, 1'' Tcase drop. I am experiencing a slight PULSATING vibration only between 60-70mph. If I engage neutral or let off the gas, it goes away. This started after I replaced my 4'' front coil with 5'' coils (for my winch). My tires are halfway worn and become loud and vibrate the floor in a different way. QUESTION: are my tires (which are worn evenly) acting upon my vibrations or.....is it time I FINALLY do an SYE??? Thank you in advanced.

 

What are your pinion angles like?

Max

 

There is never a bad time to do an SYE always a good idea so you can lose that TC drop kit. See if the engine and trans mounts have been trashed by the drop kit.


Have you checked the factory leafs to see if they have given out, happens often when trying to use AAL's instead of full leaf packs for the lift.

 

how are mounts checked, just examining the rubber to look for wear or damages?

 

^ This. Specifically the front pinion.

After you installed the taller coils did you adjust the caster, then toe, priority going to correct pinion angle (close to zero)?
You changed the caster and toe considerably with that 1"
Also, are you running short arms?

 

I installed IRO adjustable upper and lower control arms.

 

And had an alignment

 

Did the alignment shop have experience with lifted setups and know to correct the pinion angle as well as the other three alignment stats?

 

I too have the pulsing vibration. I had it before I lifted the Jeep, and now at 4" I still have it but not as bad. This after replacing every single U-joint, bearing hubs, rear outer axle bearings, balancing rear drive shaft.

Sure like to identify the problem & get it sorted out.

 

Tough one to diagnose through the web. Cannot rule out tires.
How are motor and tranny mounts?
Did you also replace the centering ball in driveshafts?
Guess you could remove the front driveshaft and drive it, see if there is any change. Same with the rear shaft, remove it and run in 4 Part Time. Will have a bit of torque steer but still drives nice. I suggest this as a process of elimination.

 

Tried all that. Problem has remained on this vehicle since purchase, and any change I make seems to make no difference. Had 3 sets of tire on this thing, latest are new Duratracs w/new aluminum wheels. New eng/trans mounts. New ball joints, hubs, axle brgs, etc. No lift, then 3", now 4". TC drop, then pinion shims, then both, then none. Throughout all of it I get "wub wub wub" at highway speed.

Frustrating. Wondering if maybe there is a bearing going out on trans or Xfer case.

 

You will need to start a new thread for your specific issue. Here we are trying to help Danbizzle2009, the owner of this thread. Assisting another will get confusing.

 

Not trying to hijack, but it seems the OP and I might just be experiencing the same problem. If so, it might be beneficial to collaborate and identify the stupid thing, no?

 

Your other thread regarding the lift, (that Unidentifedbomb and I hijacked) has some very knowledgeable folks that replied. Perhaps just post there and we can continue with their assistance. I understand your point but there are usually so many variables that it helps to keep details separated.

 

AA SYE and full leaf packs are on the way! I will first install the SYE as it has been my fault cheaping out and not doing it. I will post afterwards to share if it fixed the problem. If it doesn't I will check into getting some Cooper AT3s as suggested by another forum member. Thank you all!