driveline clunk - worn transfer case output bearing

chris_kucia · June 23, 2014

2000 Sierra SLE 5.3 4wd Z71 extended cab

Been chasing a driveline clunk. U-joints and slip yoke (I have the nickel replacement) check out OK, but the output shaft out of the transfer case has a lot of play.

I'm guessing the bearing is bad.

Anyone change out one of these and have any tips? Anything else I should change in the t-case, like the chain? (I have 200k+ miles on her).

How do I tell what model transfer case is in there? It's the one with the pushbutton control and the Auto 4wd option.

chris_kucia · June 24, 2014

If I had ruled out any worn parts, I'd live with it. But there's obvious play on the rear output shaft. Letting it go is just going to cause more and more internal parts to wear if they haven't already.

Looks like I have a NP246. Have the bushing/bearings on order and a seal kit. Once they arrive, I'll pull the t-case and get it apart to see if it needs anything else. Watched a series of vids and it looks pretty straightforward to work on - lots easier than a transmission.

gmtech4 · June 24, 2014

2000 Sierra SLE 5.3 4wd Z71 extended cab

Been chasing a driveline clunk. U-joints and slip yoke (I have the nickel replacement) check out OK, but the output shaft out of the transfer case has a lot of play.

I'm guessing the bearing is bad.

Anyone change out one of these and have any tips? Anything else I should change in the t-case, like the chain? (I have 200k+ miles on her).

How do I tell what model transfer case is in there? It's the one with the pushbutton control and the Auto 4wd option.

was the output seal leaking ?

chris_kucia · June 24, 2014

Output seal doesn't seem to be leaking, but it's difficult to tell for certain as I have a rear main seal leak and oil gets spread everywhere.

chris_kucia · July 1, 2014

So I pulled the case last week, ordered a bearing and seal kit, a new chain, replacement clutches and steels, and the special tool to set the clutch height, along with a pack of shims.

Got it all apart over the weekend and the parts showed up yesterday.

The output bearing was a little sloppy as were some of the other bearings.

With the new clutches, it ended up that the new shim was the same size as the one on the old clutch pack so I really wouldn't have needed the tool and the shim pack. I don't know how often that happens.

Anyhow, one snag in the project is the tail housing bushing that bushes the driveshaft yoke. It can be put in after the case is assembled but you need a special tool. With the case half off, you can put it in with a standard bearing driver. So I had the case halves all ready to go with the sealant on when I realized that the tail bushing didn't come in the bearing/seal kit. Had to wipe off the RTV and set it all aside.

Looking at pics of various bearing/seal kits, it seems this bushing is missing in a lot of them, so heads up if anyone goes down this road.

On the plus side, this particular bushing is used in a lot of transfer cases and some Muncie transmissions. The universal p/n is WT297-62.

As it happens, Summit Racing carries it for $5 and I live close enough to them that I can drive over there tonight and pick one up and then wrap up the assembly this evening. Might even get the case back in the truck tonight.