4x4 Vibrations

Was Coming Back from work today and decided to take a back road since it was raining and road was a mud pit, threw it in 4x4 to have a little fun! Got off the road onto main roads and got up to between 55-60 mph and forgot to turn 4x4 off, when I went to let off the gas and deaccelerate the truck startded making a whining noise and a huge vibration emmitted from what felt like right below my ass, which would be the propellor shaft, trasnfer case area, at visual inspection everything seems fine, just did my last fluid change about a month ago, opened the trasnfer case checked oil, which was fine, spun the prop shaft, spun freely, only noticed a slight turning of gears sound when spinning it. I have a regular cab so with my back sliding window open I can hear the sound echoing up between the cab and bed! The only time this happens is between 55-60mph and I have to been in 5th gear, if I'm in 4th doing the same speed I'm fine no noise or nothing, same with 3rd (although truck was extremely loud at this point). Any tips befor I go to mechanic, I've read through many related posts!

 

Do you have mud stuck somewhere throwing the balance off?

I know after an evening of playing in the snow, I had snow/ice caked in a wheel, and it made the steering wheel shake like no other. I didn't have far to go, so I just kept driving. It melted off that day and everything was back to normal.

Just a thought.

 

No defintately not mud, the truck wasnt even that muddy after I went through, went under it when I got home, I have been out a few more times today after taking the grease gun to both the drive and prop shaft and it still happens!

Although I know what you are talking about I live in Canada eh, so I go through a lot of snow my self and know what you mean about the steering wheel goining insane!
No when this happens my steering is fine, drives straight as a whistle, shifts on the fly into 4x4 smooth as could, its never clunked!

 

check the u joints.grab the driveshaft at the rear and see if u can move it.use your muscles.then go to the front of shaft by the end of the tranny and repeat.should be nice and tight,maybe just a little play not alot.sounds like maybe one is shot.

 

yeah there isnt any noticeable play, maybe slightest bit of movement if I pull real hard!

 

BUMP, Still looking for any insight, truck will be going in to mechanic tomorrow, unless I can figure out what the hell is going on!

 

Go through the same road again, only put it in reverse and go backwards, starting at the place you finished before. Should take care of any issues that came up while driving through it the first time.

In all seriousness, good luck troubleshooting the problem. I'm not the most knowledgeable with vehicles, but I do good with regular maintenance and day to day stuff. Having said that, I'm interested to hear what you find out is causing the issue.

Good luck.

 

Its probably fine, just the front drive shaft fighting the pavement when you were in 4*4 and you were underpowered in 5th

 

That had crossed my mind, truth be told the only other times I ever had the truck at those speeds in 4x4 have been during winther months on snow/ice covered roads. Although I like to be throurough!! It will still be going to a proffesional mechanic, guys a friend so he wont charge me nothing for checking it, just dont wana waste his time on the long weekend!