Help with drivetrain vibration

[thegreatjustino]

I recently swapped out my stock three speed and D20 for an NP435 and a different D20. Periodically while driving, I will get a very audible vibration/whooshing sound coming from the drive train. I have removed the rear drive shaft and driven around in just front wheel drive and still have the problem. I don't know if it is the transmission, the transfer case, or possibly even the clutch. What are the symptoms of a pilot bushing going out? The vibration doesn't affect me being able to accelerate and it will continue even if I shift into neutral and coast. The vibration does slow down as I slow down. Really hoping to figure out what the heck this is without climbing back under there and swapping out transmissions and transfer cases until I find ones that work.......

A couple of other symptoms: If cruising on the highway without any problems, it will sometimes start. If I let it go without pulling over, it will go away, so it is just periodically happening.

 

[bax]

Any of the bolts too long that go into the back 435? A long bolt can touch the gears.

 

[rednck21]

The vibration doesn't affect me being able to accelerate and it will continue even if I shift into neutral and coast. The vibration does slow down as I slow down.

that tells me its probably not the 435. i would check the adapter or tcase. sounds to me like a bearing...

 

[bax]

Could the u joints be out of phase? I know you are smarter than that but just thinking out loud.

 

[justinoshea]

...The vibration doesn't affect me being able to accelerate and it will continue even if I shift into neutral and coast. The vibration does slow down as I slow down.....

So the vibration is proportional to wheel speed and not engine speed?

if so that should rule out the clutch, pilot bearing, and 435 input shaft/bearings.

try asking for an Atlas for Christmas, that may fix your problem.

 

[thegreatjustino]

So the vibration is proportional to wheel speed and not engine speed?
.

Yes that's correct. It sounds like from the posts I am going to swap my old transfer case back in for the used one that came with the 435. I was thinking about doing that when I swapped everything the first time, but figured I'd save myself a step. What a shocker I ended up creating more work for myself %)

 

[thegreatjustino]

Could the u joints be out of phase? I know you are smarter than that but just thinking out loud.

What do you mean by out of phase? I've never heard that term. The fact that the same vibration is there with just the rear driveshaft in as well as with just the front one in leads me to believe it is not a ujoint problem.

 

[bax]

Good point. Is it a rotating noise? One that get slower with MPH. Did you try shifting the t case into netural and coasting? Any noise doing that?