I have a 2009 SRT8 with 14000 miles. I have a strong vibration occurring in 6th gear at 80+mph. If I put it in 5th gear the vibration is eliminated so I don't think its a problem with balance or alignment. Anyone have some thoughts on what it is?
No answer for you unfortunatley. I have a 2010 SRT8 and I have also noticed the same shake/vibration at exactly 80 on the highway. I checked to see if I maybe threw a weight off on one of the front rims. I didnt see any missing weights just by looking, but that doesnt mean the tire shop balanced them properly either. My next step is to go have the balance checked and an alignment check done and see if its off for some reason. Mine isnt consistent though ...so that makes it a little harde to really pin point. I will keep looking into it and let you know if I figure anything out. If you find something out please share what you found as well! Thanks in advance!
I really don't think its alignment because it would do it in 5th gear too but it doesn't. I saw some older threads and someone mentioned it could be the synchros. I'm not sure how that works but you never know.