I have a new to me 2018 JK Sahara with 33000kms, standard trans. There is a "fluttering" sound that sometimes occures under acceleration but not all the time. Travelling at 60 mph/100kph this sound does not occure under acceleration. The dealer said that a torn boot between the tramsmission and the transmission hump was part of the cause of this sound and although after replacing it the sound was still there. The dealership did state that some 2018's had this sound but there is nothing that can be done.
My mechanic has checked the u-joints, engine mounts and transmission mounts and all are good. The sound does not seen to effect the performance of the JK and it runs well. Any suggestions as to what is happening, just getting tired of the apparent run around from the dealer.

I appreciate any and all comments.

 

There are a lot of parts rotating on 4WD drive vehicle under acceleration and your post doesn't give much to go on (not even what direction the sound is coming from?). I'd start by checking fluids. What the heck, replace them all, and especially look at the diff fluid for any evidence of metal fragments (beyond the normal sludge on the magnetic drain plug). Also look at the unit bearings up front, and all four brake calipers and rotors. Might also try rotating tires. Better yet, swap each tire off one at a time with the spare. Might even go to the extreme of pulling the front driveshaft and drive around town. And if that doesn't isolate it, pull the rear driveshaft and drive around town in FWD. Good luck!

 

High speeds only, or also at low speed? The first thing I think of when I read 'flutter' is hood flutter.