Hi all , have an 05 cummins crew dually 4wd 6spd. purchased new only mods are nelson muffler and bully dog on tow. Tried the core 2 in level kit with mini packs and bilstiens. The truck had a pulsing vib at around 1600 rpm. removed kit and most of vib was gone. This tells me that it was drive shaft angles . The truck still has a very rough feel to it under accel. The vib or rough feel tends to get worse with more wieght and accel. Is very noticable when lugging just a bit. We took out the half inch shims in the rear pac to lower it for our 5ver and it got worse. We put a 4 degree shim in and it got a bit better. dc looked at it and test drove , normal hd truck feel they said . Does not have the 70mph vib ., only under accel. I am so sick of the generally rough feel of this drivetrain that i am looking into new trucks. Have driven several dodge cummins and they all have launch shudder ( ie drive line issue) for 40k i dont think so. smoother under accel though . Test drove a duromax allison and that was one smooth combo. no launch shudder no vibs under accel. I do like my dodge but hate these driveline issues . Does any one have any ideas or know any shops in the mid atlantic region the knows these trucks. If not she , goes. One other note is that it seems to be worse in colder weather than warm.

 

Put a ton and a half in the bed. That cured my shimmies and bounces.

 

I already have 2 transfer tanks that weigh about 1k . bouncing is not my problem, the vibes that come through the pedals shifter wheel and seats when accel. are. I drive truck for a living i know what to expect from a diesel engine and drive train . At idle they will shake your teeth out above idle they smooth out. My DC sends move vibs though the cab under accel. than my Macks do. My cousins auto Dc dually does not fell this rough.

 

Mine does not vibrate at all. Smooth as a car. Wonder if yours has out of balance tires? Also it is not terribly hard to check the balance on driveshafts... but if this is bothering you enough, I'd say get a duramax.
-P

 

The tires are not an issue they were just replaced . It feels a lotlike pinion angle issues but i dont know if it is front or rear. I have a 65 mustang fastback we built that had the seat of your pants hum or roughness under accel. but not decel. We lowered the pinion with a 6 degree shim and it was smooth as silk. Since the vib got a lot worse with the leveling kit , one of the pinions would seem to be the problem. I can't figure why this truck would be so sensitve. We have lifted other trucks 1 to 2 inches and never had a problem with vibes. My dealer said they checked pinion angles and they were within specs , i dont think they even know how to check . I was once pulling a broken down dump truck (about 15 k) and the truck started shaking bad up a hill like ther was a bad universal or bent drivshaft . all have been checked and are ok.