bender9406

I have an 01 Cherokee Sport 4.0. It has a slgiht hum/vib at 30MPH and it gets really bad at 60-65MPH.

It has been in the shop for 2 months and they have no idea what to replace next. The checks the u-joints, replaced the transfer case, replaced the drive shaft, checked wheel bearings, the tires are only a month old and have been balanced twice.

Any obvious "Jeep" repairs we didn't look at??

builtnotbought89'

do u have a lift on it??? Any dings in ur drive lines throwing them outta balance maybe!?!?

bender9406

There is a 2" spacer and add-a-leaf, but rest assure, it did this prior to the lift...

DEVILSTOY

wheres it coming from ? front ? back ? can you feel it in the floor ? be a little more specific

superxj

that happended to my buddys truck to the point where it looked ltke his box was going to jump off of his truck and it was a bad idler arm or something

jd2311900

i would check if there is any play in the front drive shaft. make sure is is no play up or down. i had the same problem and it was the drive shaft.

1jeepman

Does it track itself going down the road? Front drive shaft in the caden joint?

RENIXBEAST

Check the centering ball in the front driveshaft, it is between the two u-joints inside the carden joint. people sometimes forget its there. I had a bad vibe from mine and I narrowed it to the front drive shaft. All of the u-joints were good but I took the shaft apart anyways and when I seperated the carden joint the centering ball was toast. I just couldn't se it till it was out and apart. Just giving my experience . Good Luck.

bender9406

What do you mean by tracking itself down the road?

I just found out the hum gets better with the 4WD on? It is still there but not at severe. It really sounds like it is coming from the rearend.

bender9406

bump... it sounds like it is coming from the front. Any ideas?

Does this narrow down what the possibilities could be?

Jamie57

A real simple CHEAP test is to take the front drivehsaft off. Drive it around till you get to where the vibration happened before.
If the vibration has stopped you've found your problem.
If it hasn't, replace front shaft and remove rear shaft. put it in 4W and try again.
Still Vibrating? Then at least you've eliminated 2 possible sources for NO money and just a half hour in time.

bender9406

I'm pretty sure the front shaft was taken out, and it still had a pulsing hum. The rear shaft was def. replaced.

Where do you go from here?

Jamie57

Was it driven while the shaft was out?
Were the tires balanced both times by the same machine?
Was the "New" transfer case a rebuild or JY find?
It's obvious the vibration is rotational.
You have to eleminate every thing that rotates at speed.
And remember just because something is new or has been replaced DOES NOT mean it was done right or is as good as new. Sometimes you do get a NEW piece of crap and your problem has not been fixed. Double check that new rear driveshaft.
I still stand by my previous post. Remove drive shafts one at a time. IT"S FREE!!

bender9406

Alright, I'm calling the shop now. Thanks!

bender9406

I just got off the phone with the garage. They said they pulled the rear drive shaft and drove it in 4wd and the vib went away...

They put a JY rear drive shaft in it and the vibs came back, just like before...

Any thoughts?

(Keep in mind, the rear drive shaft, u-joints, transfer case, rear-end, tires, etc. are all new or rebuilt/replaced.)