HELP!! Can't find vibration
 

Need help I have a 99 4x4 auto 2500 cummins and can't find out where this vibration is coming from!!!!!![duhhh] Just above 60 mph and tac reading about 2000 rpm I get this really strong vibration in the floor board just below the brake ped and in the seat. It sound like a Harley is riding in the bed of the truck. I have put in new U-joints removed the front drive shaft and $1500 worth of rims and tires and a front end alinement and still its there.[verymad] I also have a sound like gears whining at both 35 and 45 mph at both speeds tac reads about 1500 rpms let off the throttle and the noise is gone if I'm in nutral or park and tack up to 1500 have no sound. I have flushed out the P/S fluid and replaced the pass hub and lower ball joint and the noise and vibration still there.. The wife is about to kill me this has cost me about $2000 if I have to spend any more I will be living in the truck with the dog!!! Need some help ASAP!! Maybe a tourque converter going bad trans on the way out just need a few ideas or maybe someone has had this problem before I'm lost!!![duhhh] Taking the truck back to have the tire's checked to make sure that I didnt get a bad tire or thrown a weight. Going to change the trans and the diff fluids this weekend might be it I just dont know thanks in advance!!!!

First check the tires lke you said. Look at the driveshaft see if the weight is still on there. Another thing to do to isolate it is to jack up the rear and drive it on jackstands. That will eliminate the whole front end if the noise is still there. Check that stuff and let us know

I did jack the rear end up ran all the way to 70mph and just a very suttle vibration nothing like when driving down the road. Did check the drive shaft all looks good I even rotated the drive shaft 180 just to make sure and vibration still there. Let me know if you have any other ideas..

Its not an engine skip when tc is locked is it? Some times a misfire will cause it to shake when in lock up. Was there a weight on the driveshaft? Is the excessive lash in the rear end? Another thing to look at is the tire. Even though there new I have seen new tires out of round. If its out of round it will give a shake in the air and even worse when its on the ground.

All weights were on the shaft a looks like none are missing. No loss of power or engine misfire or excessive play in the rear end or transfer case. Would the TC be locking in at both 35 and 45 mph?? Driving slow it shift fine no sliping goes into gears just fine and at 60mph tack reading 2000 and at 61mph vibrations starts. Have 156000 miles on truck unsure if bands have ever been tighten or if fluid has been changed I'm going to do a fluid flush this weekend by removing the return on the trans and adding into the fill tube to get rid of all fluid. Fliud not brite red but not to discolored eather. Going to check the TC bolt to make sure they are tight will give up date later..

Is the vibration fast and harmonic or slow and wobbly? Does it follow the speed of the engine?

Ok sounds like you got 410 gears. Converter will lock in 3rd gear also. My truck will lock in 4th at 40mph. So before that your in 3rd locked.

Just got back from the shop and the guy told me that the front wheel hub is bad no play just a knocking/whining sound from the hub... C/K the wheels,lugs and tires a all is good.. The vibration is a very fast hum and letting off the throttle it seems to go away just the mph slow down to fast to tell if its motor or drive line. I guess going to change the drivers hub out this weekend... Will post if its fixed just wondering is the drivers threaded axle nut lefty loosly or righty loosy??? Thanks If this is not it the back seat doesn't look to good to be sleep on after the wife throws me out..... lol

I have this very same issue and heres what Ive done: front ball joints upper lower, track bar, shocks all around, bd diesel steering box stabilizer bar, tie rod end, new rims tires and I still have the same issue when i hit 40 mph it feels like theres a jack hammer in the bed of my truck. So I do know for a fact its not the front end its been checked aligned and rechecked again so its something from ma booty on back somewhere anyone got any ideas? I just think it weird i only get it from 35-40 and thats it, it goes away

try putting a tc lock up switch in don't have to get fancy just something you can use to lock it up and see if its the culprit of your vibration

check your engine mounts

You mentioned that the vibration is fast and not slow so its not wheel/tire related. Doubtful a wheel bearing. If the vibration stops as soon as you get off the throttle then I'd be looking at tranny issues like the torque converter or motor mounts or tranny mounts. If the vibration didnt go away when your off the throttle then I'd be looking at the driveline and driveshafts.

mine does it weather im in or out of the throttle but only between 35-40 mph, and Im not tryin to hijack this post but just seems my problem is almost the same so why start a new thread.

Well it wasn't to long ago that I had the strange "wobble" at around 45 mph. Made the truck kinda hop in the rear. Apparently others were experiencing similar issues because it became a thread topic BUT.....posters seemed to pop in with all kinds of vibration problems which in turn ran the thread off course. I also remember there being some kind of relation to a certain vibration and auto tranny trucks where as us manuals were having a different kind of vibration.

Nonetheless, I looked at lots of possible fixes to get rid of the feeling like my tires were egg shaped at certain speeds only to get new tires later on down the road and find that all the crazy problems went away. Not saying yours is bad tires either.

yea ive narrowed that one too, 3 sets of tires and 2 set of rims and same thing. Im gonna triple check my ujoints and balancing weights on the drive shaft...again but Im stumped