Is this normal or is something wrong?

i would not put a double-cardan joint in the driveshaft unless you are planning to rotate the pinion up on your axle.. Keep it with single joints on each end of the shaft, just get it clocked correctly and balanced.
 
Ok, I got the driveshaft inspected and balanced and reinstalled it phased properly. This did stop the shudder when driving with the hubs locked in 2wd.

But I still have the following:

In 4H, hubs unlocked (on stands or street) - at 15mph it starts sounding like gears are skipping or trying to mesh

In 4H, hubs locked (on stands or gravel) - at 30mph it starts sounding like gears are skipping or trying to mesh

In 4L, hubs unlocked (on stands) - at 15mph it starts sounding like gears are skipping or trying to mesh

Did not try 4L with hubs locked as I can't go above 15mph yet.

So with the hubs locked the grinding starts at 30mph, with the hubs unlocked it starts are 15mph. Any other choice then to open the transfer case again?
 
Just guessing at this point now. I'm wondering if the out of phase front shaft wore out the front output bearing enough to cause enough slop to cause the chain to jump under torque. It may not be totally noticable but with a slightly stretched chain and a bad bearing that may be what's happening. It's not totally out of the norm. I've had a NP242 act the exact same way.
 
Well since I have the transfer case open I decided to go ahead and replace the chain. I do see a bit of shiney strips inside the transfer case that may be from the chain rubbing. I didn't want to put it back together with that possibility. I also notice that the drive sprocket teeth appear to be slightly rounded. The teeth usually have a slightly squared off edge with little ribs, the ribs and edge are gone but thats about it. Think the drive sprocket should be replaced? The stupid thing costs too much!
 
If the teeth are worth a couple thousandths of an inch, that only translates to a couple thousandths between gear centers. If every link of the chain has a couple thousandths wear, that could easily translate to 1/2" or more stretch. I'd replace the chain and not mess with the gear unless you are building a racecar, or worried about not having 4wd in 10 years and 50k miles.
 
Well I checked everything in the transfer case and replaced the chain and a few other things. I also raised the transfer case 1/4" when I put it back in.

The sound is not gone but it has changed a bit. I think I'm going to get a new front driveshaft made - I am at a complete loss.
 
midnit said:
Here is a rough video of the sound...video...of...the...sound. Ok, anyway its a video thats all black!
http://youtu.be/n7dIOker6dA
Click to expand...
Hmmm, without seeing it I'm still just guessing. It sounds fairly high frequency so I'm still going to say t-case since doesn't do it in 2wd. The front shaft has been verified as good. I know you've had the case apart and it looks good, but what else is there? I'm still thinking the out of phase shaft has loosened the output bearing. When it gets up to speed it starts to wobble. That's my theory that can only be proven by swapping out the case. I'm out of any other ideas.
 
Here is a better video with it on stands. You can hear there is a noise in the left hub, and a lot of noise seemingly in the transfer case. I have been in that thing 3 times. The only thing I haven't taken apart was the planetaries because it makes no noise in 2wd.

http://youtu.be/EgaZmwSsjFs

I also replaced the u-joints on the front driveshaft but saw no problems with the old ones.

No noise until 15mph, its almost like clockwork, but once the sound starts you have to slow down below around 10mph for the sound to go away and then speed up and boom at 15 it starts again. The noise continues but changes a bit up to 40mph but havent gone above.

Tried it in reverse, the noise was less and started at higher mph.

I am so lost.
 
noise

I had this same noise in my np205. Started at 35mph or so. I know its absolutly nothing like a 231. But my problem was worn out front output bearings. And it sounded like a syncro grinding. Well. Grinding is not right. Maybe. Riding. Buy a rebuild kit. Cames with all the bearings. Or get a new case

Daniel
 
Roscoe77 said:
I had this same noise in my np205. Started at 35mph or so. I know its absolutly nothing like a 231. But my problem was worn out front output bearings. And it sounded like a syncro grinding. Well. Grinding is not right. Maybe. Riding. Buy a rebuild kit. Cames with all the bearings. Or get a new case
Daniel
Click to expand...

Did the noise only happen in 4wd? I know nothing of a 205 :)

I grabbed a transfer case from the salvage yard and the noise remained the same. So either both cases had the exact same problem or its something else. I am betting on something else but...
 
Roscoe77 said:
I had this same noise in my np205. Started at 35mph or so. I know its absolutly nothing like a 231. But my problem was worn out front output bearings. And it sounded like a syncro grinding. Well. Grinding is not right. Maybe. Riding. Buy a rebuild kit. Cames with all the bearings. Or get a new case
Daniel
Click to expand...

I just realized you said front output... But I read input :)
 
231

Well if it did it with two different cases your probly right. Its something else. I would bet bigred is right. You should pull the diff covers and rotate the ring gears till you see the ratio stamped on them and make sure they match. Usually with a chain drive case a 4.10 with a 4:11 would be fine except on pavement. But if they are off more than that like a 4.10 with a 4.56. Disaster will happen. Lol. Hope I helped. Btw. A np 205 is a cast iron gear driven t case. A heavy(150 lbs or so) almost indestructable beast. With a crap crap 1.96 low. (Pic) but they are cool cause you can twin stick them. Independent shift front n rear axles:driver:
 
After hearing that from the front axle i'd be pulling in apart and inspecting it very closely. As far as the problem I have no idea but pulling it apart my lead to a solution.
 
Well front driveshaft was altered so it wont bind. It reduced the noise but it didn't go away...with front hubs unlocked.

I took the truck to uwharrie this weekend and found that with hubs locked on the trails and gravel there was NO noise except when decelerating, then it would sound like some chattering in the front. This is in 4x4 with hubs locked, say braking down a hill.

Any ideas on that?
 
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