Rebuilding/servicing GM NR3 single-speed transfer case

[i6pwr]

I have this in my 2012 Yukon Denali wwith 123K miles. There is noticeable driveline slack when engaging drive or reverse, maybe that's just the nature of this AWD system but I don't know that for sure as I didn't purchase one new.

I also have some vertical movement of the rear output shaft, probably a good .020".




Maybe it's only a bushing, but if I open it up, I figure I may as well replace the chain also.

What else could I replace if I dive into this? Never been inside of one.

 

[Jim_Truett]

Put a bearing and chain kit in it. It's not hard. You just need a special driver for the front output shaft seal. I did mine a few years ago. No change in the driveline slack. There's just too many splined connections throughout and loose tolerances stack.....

 

[i6pwr]

I spoke to a couple shops including one who rebuilds these, and they said some play is normal.

I do need to get a gauge on it to see exactly how much movement I have.

I will look into the bearing and chain kit. If I open it up, I will definitely replace them.



What tool is used for the front seal?

 

[D60]

No help exactly but with such things I often just wait 'til I have the parts in hand and improvise. Of course having a couple lathes is what allows me to do that. Here I had to just open up the ID of some gas patch pipe to clear the front flared lip. Front output on NP241

I understand a lot of seal drivers also insert into the seal to keep the spring in place, but with caution this is rarely an issue for occasional use....IME at least

 

[Jim_Truett]

What tool is used for the front seal?

Kent Moore J-43484​

It's basically two seals in one, so the inner seal needs to be driven in to a specific depth.

 

[D60]

If it's a BW4485 apparently you have to time the planetary??


This one at ~9:40 is hilarious!! Seal installer? What seal installer? He drives it in w a ball peen and keep watching for the "Huh?" moment on the second part of the seal.

 

[i6pwr]

I wanted to revisit this as I just finished the rear diff rebuild and quieted that noise.

Now I only have a very slight noise under load, and I believe it's the front diff which had the same noises as the rear but not as bad.

However, yesterday I put chassis ears on the front diff and transfer case, as well as tailshaft of trans.

For the front diff, I did the LF output, pinion, and RF output. I also clamped the tailshaft of the trans, input of transfer case, and front output of transfer case.

The front pinion was noisy, as well as LF output, but pinion had more noise.

The noise at the transfer case input, was the same as tailshaft of trans, I want to assume that since they are bolted together, the noise will be hard to pinpoint....but it kinda sounded louder at the trans which was concerning.

The sound the transfer case/trans tailshaft made... did sound like it could be the chain, and maybe the sound is just traveling into the trans.

Where I clamped the transfer case input, was more towards the center and that might have more air between the case and chain sprocket as opposed to the closer proximity of the trans tailshaft and housing.

Trans shifts great, fluid looks good, but I'm curious if the 6L80E has any known rear bearing issues.

I do want to open the transfer case now.

I'll get a video tomorrow.