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What’s wrong with my nv4500s?

If the rear axle wheel bearings were packed with grease, dark oil is ok. If not then that diff is dirty. I'd look at the vent hose location, maybe move it to a less dirt gathering location.

The arrow in the picture is pointing at the face or crown of the tooth?
 
Wes Harden said:
If the rear axle wheel bearings were packed with grease, dark oil is ok. If not then that diff is dirty. I'd look at the vent hose location, maybe move it to a less dirt gathering location.
Click to expand...
Bearings were packed with grease, will double check vent hose location.

Wes Harden said:
The arrow in the picture is pointing at the face or crown of the tooth?
Click to expand...

At the face, here’s a close up. There appears to be some serration going on. Thoughts?

IMG_8363.jpeg
 
Wes Harden said:
If the rear axle wheel bearings were packed with grease, dark oil is ok. If not then that diff is dirty. I'd look at the vent hose location, maybe move it to a less dirt gathering location….
Click to expand...
joshuak said:
Bearings were packed with grease, will double check vent hose location....
Click to expand...

Breather hose and end were clear of obstructions and terminate behind the exhaust shield with the breather for the fuel tank.

IMG_8385.jpeg

With the rear in the air, I noticed DS wheel had more resistance to rotation, I plan on pulling the shaft and seeing if it’s bearings or brakes that’s doing this.

After that, I was planning on filling the diff up with oil and going for a road test

I’ve looked over the area checking for a heat shield or something else contacting on trans/transfer case as suggested by Zoomad and nothing stuck out so to speak.

When/if starts knocking again, is there anything I can do to try an isolate the noise while going down the road?
 
Should probably try to find a poly trans mount. So they all 3 vibrate the same. I think a rubber trans, with poly engine mounts is better than other way around
 
I’ve run poly engine mounts with a rubber trans mount on both the 5.3 and the 8.1. Never have had an ounce of problem with vibration or anything.

Going back to the noise… What do the Driveshaft angles look like for the rear? If the noise/vibration was angle related it would have to be way out of line.
 
ZooMad75 said:
Going back to the noise… What do the Driveshaft angles look like for the rear? If the noise/vibration was angle related it would have to be way out of line.
Click to expand...

Measured with frame level side to side with a -1* front to back tilt.
- 5* @ transfer case
-5* @ pinion
-10* @ DS

IMG_8408.jpeg

IMG_8418.jpeg
 
joshuak said:
Measured with frame level side to side with a -1* front to back tilt.
- 5* @ transfer case
-5* @ pinion
-10* @ DS

View attachment 458865

View attachment 458866
Click to expand...
Whilst looks like you're good on angles, unless your suspension is linked and your pinion will not lift up under power you need a couple of degrees down on the pinion.
Under load that will make noise.
 
Not to split hairs, but I don't measure the angles off the diff housing like that or off the t-case. Ideally, you orient the u-joint cap on the diff side yoke is on the top and bottom, measuring off the bottom. Then the same way on the t-case side, with the trans side yoke up/down, measuring off the top side. The angles should be equal, but opposing, like -5 degrees on the trans side and +5 degrees up on the diff side.

But based on the numbers you have you've got working angles at each end of 5 degrees. Usually I like to see that number closer to a 2 degree working angle at each joint. To me those numbers would be off enough to cause vibration issues. A quick way to isolate it would be to pull the rear shaft (plug the slip yoke on the t-case side), lock the hubs and drive around in 4hi. If the rear shaft angles are the problem the vibration and noise should be gone.

Here's a very handy calculator to figure the shaft working angles.

spicerparts.com

Spicer Driveline Operating Angle Calculator

Measure the angles of each component in your drivetrain, then use the Spicer Driveline Operating Angle Calculator to find the operating angle of each u-joint in your drivetrain.
spicerparts.com spicerparts.com

Click on the "show diagrams" button for a better visual to the calculator.
 
ZooMad75 said:
Not to split hairs, but I don't measure the angles off the diff housing like that or off the t-case. ...
Click to expand...

I don't mind splitting hairs, actually I enjoy knowing I did things the best way I can.

Thank you for taking the time to type that out. Let me measure one more time and I'll come back with better data.


And not to beat a dead horse, but thanks to all that have shared their help. Was a great drive this morning.

IMG_8421.jpeg
 
ZooMad75 said:
Usually I like to see that number closer to a 2 degree working angle at each joint.
Click to expand...
It's almost impossible, though, unless you have a dually with no lift or something. IIRC, I had more than 12 degrees before I went SYE and CV. Yes, it vibrated a little. With this long driveshaft, I think there's a good chance for it to be acceptable.
 
Blue85 said:
It's almost impossible, though, unless you have a dually with no lift or something. IIRC, I had more than 12 degrees before I went SYE and CV. Yes, it vibrated a little. With this long driveshaft, I think there's a good chance for it to be acceptable.
Click to expand...
Id have to look back at my notes but I had working angles at 5 to 7 degrees on mine. Mine made noise on decel. Rumbled like knobby tires. Made 20 miles before it spit out the rear joint on the shaft.

I thought it was not off by much but the truck told me otherwise.
 
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