Nashville TJ's Build - Continued

[hosejockey61]

Ever have one of those days when you wake up to sunshine, in a great mood, looking forward to life, excited for your next project - and then a GM 14 bolt destroys it all???

Yup. I buttoned it all up this morning and took it out for a test drive. The noise is still there. Exactly as it was before.

View attachment 667635

I wish one of you boys had told me to go ahead and install the new ring and pinion...

Oh, wait...





To double check, I got under there once again with a mechanics stethoscope, and the only place I hear the noise is at the diff. The transfer case is fine. The spindles are fine. Also, since it's crazy easy to do on a sissy 14 bolt, on a whim I pulled the passenger side axle shaft and installed my spare shaft. No difference there either.

So I guess the R&P is my next step. At this point I can't imagine what else it could be.

Did you use new bearings with the carrier or the old bearings? That's my guess.

Adding on, I know you like the backlash tight, but if it's too tight it could be the teeth making some noise. Just a shot in the dark.

You might try posting up your question on FB to the Gear Install Technical Group. Lots of experience and expertise there.

 

[NashvilleTJ]

Did you use new bearings with the carrier or the old bearings? That's my guess.

Adding on, I know you like the backlash tight, but if it's too tight it could be the teeth making some noise. Just a shot in the dark.

You might try posting up your question on FB to the Gear Install Technical Group. Lots of experience and expertise there.

New bearings. I thought about the backlash, but I don't think that's it. It's still in spec - which is 3 to 12 - just on the low side. When I set it up last year it was 5 thou, compared to the 4 I did this time. I would think if it were too tight on a good R&P, the noise would be more even, and not pulse perfectly with the rotation of the axle - as if there is a bad spot on the ring gear. But again, I'm just guessing.

When I say the noise is exactly the same - I mean it sounds exactly like it did before swapping the locker. No change at all. I know because I paid so much attention to the noise before. The only thing that is left is either R&P - or the axle housing is bent. And on a trussed 14 bolt that's unlikely, but possible. I'll check it again when I pull it out. There was so much slop in there from the failed bearing journal, I can see it damaging the ring gear. Again, just guessing though.

In all honesty it's not a lot of wasted work. The carrier clearly needed to be addressed, so no wasted effort or expense there. And given how easy it is to pull and reinstall a carrier on the 14 bolt, it really wasn't too bad.

 

[hosejockey61]

New bearings. I thought about the backlash, but I don't think that's it. It's still in spec - which is 3 to 12 - just on the low side. When I set it up last year it was 5 thou, compared to the 4 I did this time. I would think if it were too tight on a good R&P, the noise would be more even, and not pulse perfectly with the rotation of the axle - as if there is a bad spot on the ring gear. But again, I'm just guessing.

When I say the noise is exactly the same - I mean it sounds exactly like it did before swapping the locker. No change at all. I know because I paid so much attention to the noise before. The only thing that is left is either R&P - or the axle housing is bent. And on a trussed 14 bolt that's unlikely, but possible. I'll check it again when I pull it out. There was so much slop in there from the failed bearing journal, I can see it damaging the ring gear. Again, just guessing though.

In all honesty it's not a lot of wasted work. The carrier clearly needed to be addressed, so no wasted effort or expense there. And given how easy it is to pull and reinstall a carrier on the 14 bolt, it really wasn't too bad.

Looks like R&P it is then.

 

[NashvilleTJ]

And once more back into the breach…

 

[blay127]

if you havent already, be sure to check both the backlash and the gear contact pattern at 4 spots, 90 degrees out, on the ring gear. I've had yukon gears, and others, that were not consistent all the way around and would cause noise while running. If you see the contact pattern walking in and out over the 4 spots, that would be a clear sign to me. and 4 thou backlash on used gears is awfully tight. i didnt read the whole thread so i am just assuming theyre used from the last few posts. i know thats technically in spec, but since its easy on the 14 bolt to adjust, dial it out to 10 and see if the noise goes away.

 

[NashvilleTJ]

Well, the easy part is done:

Now for the fun…

 

[NashvilleTJ]

if you havent already, be sure to check both the backlash and the gear contact pattern at 4 spots, 90 degrees out, on the ring gear. I've had yukon gears, and others, that were not consistent all the way around and would cause noise while running. If you see the contact pattern walking in and out over the 4 spots, that would be a clear sign to me. and 4 thou backlash on used gears is awfully tight. i didnt read the whole thread so i am just assuming theyre used from the last few posts. i know thats technically in spec, but since its easy on the 14 bolt to adjust, dial it out to 10 and see if the noise goes away.

Thanks for the input.

There is definitely a lot of history behind getting to this point. The Yukon gearset is definitely going bye-bye.

 

[NashvilleTJ]

So fooling with this thing out of the rig, rotating the pinion I can definitely feel a subtle rough / binding area at the exact same spot on the ring gear with each rotation. The ring gear must have been tweaked after all.

 

[hosejockey61]

So fooling with this thing out of the rig, rotating the pinion I can definitely feel a subtle rough / binding area at the exact same spot on the ring gear with each rotation. The ring gear must have been tweaked after all.

View attachment 669280

Do that with the shafts out and compare.

 

[NashvilleTJ]

Do that with the shafts out and compare.

Thanks Mike. I did just that:

I actually marked the ring gear opposite the pinion gear where it was binding - if you look closely at this photo you can see the punch mark.

And the bind was in the exact same place. And without the shafts it was actually much more pronounced, and much easier to detect. I can detect two specific binds, possibly coming from two adjacent ring teeth.

When I pulled this thing apart last time I spent a good bit of time inspecting the ring gear, with nothing obvious looking out of sorts. Now that I’ve marked the problem area I’ll know specifically where to look.

 

[NashvilleTJ]

OK - Pulled everything apart, and despite knowing where to look I still don't see anything. Here is the ring gear in the area of the bind:

The only strange thing I see is the wear on the inside edge of the teeth. Is that normal?

Here is the pinion:

Again, no vision damage. You can see than the wear pattern goes right to the top of the tooth. My guess is that the non-worn area at the bottom of the teeth is a consequence of the shave on the ring gear. Seems to me that the pattern should be more centered, but this is with only 15 thou total on the pinion support shim stack. Can't go much deeper. I wonder if I should be looking at adding shims between the pinion gear and the bearing? Anyone familiar enough with the 14 bolt setup to know? I'll have to do some 14 bolt research there.

Based on the wear pattern, here is how the pinion engages the ring:

So I'm still at a bit of a loss. All I know at this point is that the noise was definitely from the ring gear.

 

[hosejockey61]

OK - Pulled everything apart, and despite knowing where to look I still don't see anything. Here is the ring gear in the area of the bind:

View attachment 669341

The only strange thing I see is the wear on the inside edge of the teeth. Is that normal?

Here is the pinion:

View attachment 669342

Again, no vision damage. You can see than the wear pattern goes right to the top of the tooth. My guess is that the non-worn area at the bottom of the teeth is a consequence of the shave on the ring gear. Seems to me that the pattern should be more centered, but this is with only 15 thou total on the pinion support shim stack. Can't go much deeper. I wonder if I should be looking at adding shims between the pinion gear and the bearing? Anyone familiar enough with the 14 bolt setup to know? I'll have to do some 14 bolt research there.

Based on the wear pattern, here is how the pinion engages the ring:

View attachment 669343

So I'm still at a bit of a loss. All I know at this point is that the noise was definitely from the ring gear.

My money is on the fact that they are another crappy set of Yukon gears. I'm at the point with Yukon that I just have no interest in installing them anymore, they're just that frustrating. Even in the great forum people hate them.

I'm no 14 bolt expert, but I would suggest posting up to this FB page as there are a lot of experts on various axles. At the very least, it will provide different input to consider.
https://www.facebook.com/groups/732975063811349/?ref=share&mibextid=NSMWBT