Just wrapped up changing out the output shaft bearings on the transfer case, both front and rear, and found the process super straightforward. I used this as an overall starting point for the method, though I did it with the transfer case still on the truck. Keep in mind too, this video is on a Defender's transfer case, which uses a little wheel that interfaces with that spiral cut sleeve to feed the speedometer. The disco doesn't have that since it's electronic.


Couple notes on tools and some photos that might help the next person...

SLIDE HAMMER
I used this slide hammer from OTC: https://amzn.to/3K4DbH3
I then got these two adapters to attach the slide hammer to the output shaft threads. Worked like a charm: https://amzn.to/3K9Zb3u and https://amzn.to/3bXNWP2
There was plenty of room to use the slide hammer under the truck. It basically just rides in the space previously occupied by the driveshafts.
The threads on the output shafts are M20 2.50.

CIRCLIP
There's a big circlip that holds the bearing in place that needs to be removed in order to slide the output shaft out. I'm super partial to Knipex things, and if you're looking for incredible circlip pliers, this pair here is the correct one that will accomplish this task perfectly: https://amzn.to/3pq8zGn

SEAL PULLER
If you don't have one yet, I highly recommend one for this. Makes removing them a breeze. You'll use it for other things like axle seals, front main seal, differential seals, etc. Again, OTC to the rescue: https://amzn.to/3dsyNp0

BEARINGS
The replacement bearings I got were these from Rover's North: https://www.roversnorth.com/parts/pl...ia_rear_output
They weren't even in the Disco section. They were in the Series 2A part of the store since they're used in that too.

 

Nice! Did you get it back in the truck yet to see if that was the cause of the whine?

 

Not yet. I'm waiting on puller set to replace the little bushing in the rear driveshaft. Comes on Friday. Also replacing a leaking front diff seal tomorrow. Hoping to have it back on the road by Friday eve. Even if they weren't the cause, it was a fun project and wasn't too involved. The OG's have 190K on them, couldn't hurt replacing them. If it's not the cause, then I'm not sure where to look next yet.

The original bearings didn't feel too bad. The new ones spun way more freely, but could also be because they weren't saturated in gear oil yet. The old ones didn't make any noise on the bench, but doesn't necessarily mean they weren't bad under load or at higher speeds than I can test them at by hand.

 

Ah nice! Fingers crossed that's the culprit! Hopefully your parts arrive on time so you can finish up. I've been having a heck of a time with another project and parts being delayed in transit or just plain lost.

 

Excellent write up. I have a post-driveshaft failure vibration that goes away when the front driveshaft is removed so I’m assuming a bad output shaft bearing. You’ve made me reconsider my plan to swap out the trans/TC and try this first. Thanks especially for all the part numbers and links provided.

 

Reporting back - no change whatsoever in the rumbling noise above 73, not in the whine I was hoping this would resolve. All good though, it was a fun project and I needed to replace the output shaft seal anyway. Also glad I was able to take some time and really give the transfer case a good scrub. Never has it ever been so clean.

 

Bummer, wonder what the whine is. I replaced a T-case in an '04 I had due to a very loud whining noise. That fixed it but then I had an occasional whine from my steering box. I don't think my current whine is that but who knows...Hopefully someone on here can pinpoint some other culprits.

 

Not sure. Definitely not engine related - it increases with speed not RPM, which rules out what it sounds most similar to, which is the alternator whine. It's not the most annoying thing; I actually didn't even notice it until I got the 2004 Disco with only 70K miles which was nearly silent. If it wasn't for something to compare it to, I probably would've still been oblivious to it.

 

That makes sense. I used to just turn up the radio or roll down the windows in my last 2 '04s so I couldn't hear the ticks and noises. That seemed to work pretty well! With my current truck, I want it to be whisper quiet at 90k miles...I've got a small exhaust leak and some ticking lifters though...

 

I'm trying to sort out a whine on my 2003 Discovery. It's similar to what you describe in the sense that It doesn't match the RPM just the speed. I just purchased it and checked all fluids. T case fluid was extremely low, if not dry. So I filled it up to see if the noise would change, It didn't.