Truck hood at 35-40

[Josh Morlock]

I have an 05 ram 1500, lifted on 35’s. It has a weird hop when I get to about 35 mph and it goes away at about 40, happens when I’m speeding up or slowing down, always in that speed range and not in any other speed range. I’m on my second set of tires with the truck and it hasn’t changed at all. Not sure if it’s just a side effect of having a lifted truck or not, I bought the truck 2 years ago with the lift already installed and it’s hopped since I had it. Also does not have anything to do with the front end, it is definitely a rear end hop, can’t feel it in the steering wheel or anything, just in the seat. Could it be a driveshaft balance issue? Or has anyone else had a similar problem?

 

[Smokeybear01]

If you've checked your U-joints then I would suspect driveline balance. You're getting a harmonic from something either loose or out of balance. I wouldn't rule out the output shaft bearing either. Crawl back under there and try wiggling things with your hands. Make sure the brake is set and you put the trans in nuetral on flat surface. Good luck