Roaring noise while driving, not from front end
 

Hey guys, I have a 99 Cummins 4x4. Noticed a very loud grinding/roaring noise while driving, was positive it was a wheel bearing. It sounded like every other wheel bearing I have ever heard. Jacked the front end up, sure enough, drivers front wheel hub assembly was shot. Changed it, still have the roar while driving.

I changed the hub yesterday, this morning, I blocked the front wheels, jacked up the back, and brought the speedo up to about 40 mph. The roar is still there. Fluid level in transfer case is fine, as is the fluid in the rear diff. U joints on driveshaft seem tight.

The only thing I can see that may be a problem is when I grab a back tire when jacked up, and rotate back and forth, a loud clunk is heard from the shaft that runs from the driveshaft into the transfer case. I know there is bearing in there that the snapring can go bad on, could this be it?

Any help would be greatly appreciated!

i had a similar problem. u joint of front drive shaft from driveshaft to front axle was bad, made a nasty roaring noise over 55mph

I just changed that joint because it had over a half inch of play in it, but it never made a sound. My rear did right before my rear diff permanently locked itself though. It did it at any speed though, not just over 55.

the reason you may not have heard a sound is because the 2001 and older have a center axle disconnect that makes it so your drive shaft doesnt spin until 4wd engaged. i have a 2002 no cad so spins all the time

Drive shaft still spins with cad. Cad just disconnects the passenger wheel from the differential.

Yeah, mine turns. When I saw how loose it was I couldn't believe I didn't hear/feel anything, so I rolled across the parking lot hanging out of the truck looking underneath. It definitely still turned. Not to mention, I plowed a whole snowstorm with it before I changed it, and most of that was in 4WD. It gave a little clunk on the starts, but that's it.

wow, yea mine had a small amount of play and you could visually see that it was shot. but wow when i got above 55 it vibrated pretty good. im surprised plowing didnt rip it right out! haha

You should have seen the aftershock panic attack I had when I serviced my truck right after that storm and happened to notice it!
Imagine having the front joint on the front shaft blow out while cruising down the highway in the snow... it wouldn't have been pretty. Of course it's a lot more likely to go while pushing a pile through a parking lot, but still. 0_0

Thanks for the responses guys, I will tackling this in the next few days...stuck with the wife's car for now......

Just one more thing to look at... I have had the same issue over the last few months. However, the roaring was only when I let off the throttle. Yesterday the roar got worse and I climbed under the beast looking for a bad U joint. What I found, by grabbing the U joint directly behind the transfer case and pushing up on it, was the transfer case mounting bolts were coming loose! Very little, but it was just enough to cause some wicked vibration in the cab. I'm happy to report a very smooth running truck today. I'm so glad this fix was this easy. I hope you sort your problem out quick.
Cheers:tu: