Engine Vibration at highway rpm/speed
It doesn’t do it in nuetral its no the engine. Pinion angle or driveshaft phasing. You can mark the shaft and pinion yoke then take ot apart and spin it 180 degs. Then see if it changes the vibration. I had the same thrummm. Pinion angle and new/bal shaft took care of most of it. New tailshaft bushing?
yes new tailshaft bushing....completely rebuilt trans.
its a brand new driveshaft, new ujoints, and new trans yoke....all computer balanced. trans has all new seals, bearings, bushing, etc. third member was completely rebuilt and converted from 3.23 to 3.73. pinion yoke is the only thing original on the third member now. Driveshaft should be in phase as it is new and I never took the trans yoke off it. I can disconnect it from the pinion yoke and spin the pinion 180 and reattach, but man you think Dodge would have made it to where the driveshaft would only connect one way and not both if that was really an issue.
i'm really hoping this is related to the rims/tires. if not...i'll take the car over to my cousins automotive repair business and have him check the angles in driveline and pinion. sticking it up on jack stands and running it doesn't bother me any either. I've already done that a few times....but this time I can stick a camera down there to watch the driveshaft spin, etc.
everything is brand new except engine internals, rims and tires, rear axles and rear outer axle bearings.
rear axles look okay and bearings good and greased.
drums/shoes/rotors/calipers/pads/front bearings/driveshaft/flexplate/balancer/converter/trans/trans mount/engine mounts/etc......all new. yes it is a cast crank....and yes the flexplate has the notch taken out....and the balancer has a weight on it. it is setup for external balance, based on the fact that I have cast crank. converter is neutral balanced. the only thing old on the motor is crank, bearings, rods, pistons, rings, block, heads, valves, valve springs, rockers, push rods, cam, and power steering pump. the rest of the outside of the motor is all brand new.
tires and rims being replaced today.....so that leaves pinion angle and engine internals. I can't think of anything else that would make a pulsating droning vibration between 4k-5.5k rpm that changes oscillation with rpm change. letting off the gas changes the oscillation as well. give it gas and it changes again. vrump...........vrump........vrump vs. vrump..vrump..vrump
its not so much that i'm desperate...I'm just tired of it, its been there ever since I was a little kiddo, and I want my dad to finally beable to drive this car for once in his life, and since he bought it in 1989, without feeling that vibration....its a mission. its personal now....I got a big middle finger pointed at that vibration and i'm coming for it.