Last week I started having a hight pitch vibe that can be felt in the steering wheel, floor pan, and gas pedal. Had the tires (KM2's w less than 10K on em) reballanced and rotated at Discount Tire. Vibe is still there. Removed the front DS last nite and took a drive. Same vibe still there. I haven't been off-road and has been driven the same 40mi round trip to work and back. When cruzing on the interstate in OD at 70mph, the vibration comes and goes in 2 sec intervals. Any ideas?? Got me stumped. Thanks in advance.

Edit: Did some research and it COULD be the torque converter?? The vibe starts around 40MPH. I took it for a drive and shifted into neutral when the vibe started. The vibe did NOT go away when I did this. Would this rule out the torque converter??

 

It may or may not depending on the load at the time and if the RPM remains the same. On that note is it the same vibes going up a slight hill and down a slight hill? If it is only uphill it is possible a motor mount is the culprit, to verify that open the hood, put the parking brake on, put the tranny in reverse and slowly give is some gas. If the motor mount is bad the motor will lift on one side and it could rub on the hood and the tunnel while your driving under a slight load.

How much lift is on your Jeep? Any chance the vibe is coming from the rear? Any slop at the transfer case input & output shafts? what about putting the front driveshaft on and removing the rear driveshaft to eliminate vibes from the rear too much caster maybe)?

There must be an inspection plate you can remove to check tightness of the torque converter bolts as well as to see if there are any cracks in the flexplate.

My 2 cents from the peanut gallery

 

Good move on the "shift to neutral" test. When you shifted to neutral you let the engine revs drop to around idle, right? That eliminates the engine and all the stuff rotating with the serpentine belt.

When the transmission goes into neutral, it means the TC also drops to idle speed. That leaves everything from the gearbox back to the rear axle.

There's a couple more tests that will isolate parts of the drive train:

Try slipping the xfr case into neutral when its vibrating on the hwy. That will drop the transmission out of the picture and leave part of the xfr case plus the rear driveshaft. (Stop before putting the xfr case back in gear.)

Also, while parked in the driveway you could put the transmission in drive and put the xfr case in neutral, then run the engine speed up to the RPM where it vibrates. Now you have just the engine, TC, transmission, and xfr case input shaft turning.

Keep in mind that some vibration is normal in the drive train. Its usually isolated from the interior by rubber motor mounts, transmission mounts, and exhaust hangers. If something is out of place and causing metal-to-metal contact between the drive train and the chassis, you will feel it big time in the interior.

 

RK 2.5 lift on a JKU. Really doubt it's the rear. Even w the front DS out, the vibe is still felt in the steering wheel ,floor pan, and gas pedal. There is no play in the rear DS while in park. I can rotate the front DS a bit while in park and T-case in 2wd.
Edit: Just put in 4wd and park. No play in front DS

 

I have the same vibration problem on my 2013 2 door Rubi, totally stock.
Very interested to see what you find. I have done tires, checked everything underneath....for run out issues, etc. Have found nothing yet. Was going to start pulling drive shafts but I have a feeling that it isn't them!

 

That kind of suggests there are two or more things vibrating, going into and out of phase.

Could be as simple as tire treads. 10k is certainly enough for the treads to start getting a little feathering on the edges of the tread lugs.

Have you run your hand over the tires in one direction, then the other, to see if the treads feel sharper in one direction?

 

Tires are nice and even. No sharp edges. I felt it was not the tires but had em reballanced and rotated to rule em out due to the fact it might end up at the dealership with this issue. I love Discount Tire where I got my KM2's. Free rotation and ballancing for life of the tires.

 

How long since you've had an alignment check?

 

Been over a yr.

 

I think I will be doing some of these tests in the next few days. It really has me concerned...
Seems like there are more and more new JK's with this issue popping up all over! It's got to be a common factor causing the same vibration.