Has anyone replaced or needed to replace the Transfer Case chain?

[JeepOfTheseus]

There is a clicking noise that seems to be getting progressively worse, typically when slowing/idling to a stop and especially when going downhill, which I have not been able to pinpoint yet. The closest thing I've been able to find in terms of similar descriptions is a sloppy transfer case chain.

But at only 28k miles, and no truly extreme wheeling, I'm not sure how this could have happened. Either way, I'm wondering if it's worth attempting to replace, and what it entails (i.e. any speciality tools).

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[MoxiesDad]

More likely to be the driveshaft, especially if it's lifted.

 

[JeepOfTheseus]

Driveshafts have been upgraded to 1350 Adam’s Driveshafts. I was hoping it was those, too, but I guess not. The rear diff and both t-case yokes were swapped as part of that.

 

[Renegade]

T-case chain should last the lifetime of the Jeep. At only 26k miles, I would look elsewhere first.

 

[JeepOfTheseus]

T-case chain should last the lifetime of the Jeep. At only 26k miles, I would look elsewhere first.

Kinda what I was thinking...just completely dumbfounded at the moment. There was nothing visible/obvious during any of the installs/swaps I did. I've pretty much removed and reinstalled all rotating parts during these upgrades:

Front wheels and calipers were removed to install axle shafts
FAD module had to be uncovered to remove plastic bushing on intermediate shaft (for new passenger shaft to fit)
Rear wheels and calipers were removed to install axle shafts
Rear axle shafts got new studs pressed in since they did not come with any
Rear diff, and both t-case yokes were swapped (as mentioned)

I was expecting to find something stupid like a piece of plastic or loose wire/hose/cable hitting one of the wheels, but nothing. It literally sounds like a playing card flapping on bicycle wheel spokes, but it doesn't seem to happen under actual power/load...only once I let off the gas.

 

[jac04]

FAD module had to be uncovered to remove plastic bushing on intermediate shaft (for new passenger shaft to fit)

Can you elaborate on this? Are you saying that you kept the stock intermediate shaft and only replaced the outer RH front axle shaft?

 

[JeepOfTheseus]

Can you elaborate on this? Are you saying that you kept the stock intermediate shaft and only replaced the outer RH front axle shaft?

Yea, admittedly I didn't realize/do the full research before swapping this. I'm not aware of any chromoly intermediate shafts to pair with the axle shafts...if there are, I'd be happy to take a look.

I was bummed when that became apparent to me, but it was already too late to return and I couldn't keep throwing money at it (i.e. switch to RCVs).

 

[jac04]

Yea, admittedly I didn't realize/do the full research before swapping this. I'm not aware of any chromoly intermediate shafts to pair with the axle shafts...if there are, I'd be happy to take a look.

I was bummed when that became apparent to me, but it was already too late to return and I couldn't keep throwing money at it (i.e. switch to RCVs).

So, why did you need to remove the plastic bushing? It would seem strange that the replacement outer axle shaft would not use the plastic bushing. If the pilot fit of the new outer shaft is a loose fit with the intermediate shaft (either due to removal of the bushing or wear due to metal-to-metal contact), then that could cause noise.

 

[JeepOfTheseus]

So, why did you need to remove the plastic bushing? It would seem strange that the replacement outer axle shaft would not use the plastic bushing. If the pilot fit of the new outer shaft is a loose fit with the intermediate shaft (either due to removal of the bushing or wear due to metal-to-metal contact), then that could cause noise.

The pilot on the new outer shaft is larger than the original; it is effectively the same size as the original pilot with the bushing over top. The new one fits snuggly into the intermediate shaft as-is. Oddly, Dana Spicer says the bushing is only discarded if doing the FAD removal, but @Northridge4x4 confirmed it applies if you're retaining as well.

Can see pics here

 

[Uparms]

I once had a 2005, TJ Unlimited with 14K miles on it and it felt like the chain was binding on the NP231. Bound up and would not pull in the sand trying to pull off. Dealer replaced it.

 

[jac04]

The pilot on the new outer shaft is larger than the original; it is effectively the same size as the original pilot with the bushing over top. The new one fits snuggly into the intermediate shaft as-is. Oddly, Dana Spicer says the bushing is only discarded if doing the FAD removal, but @Northridge4x4 confirmed it applies if you're retaining as well.

Can see pics here

Hmmm, interesting. Did you ever get confirmation directly from Dana on running that setup with the FAD? I have a lot of experience with gearbox design for critical power plant equipment, and I would never use that metal-to-metal pilot fit with the relative motion required by the FAD.

Does engaging 4HI change the sound that you are trying to fix?

 

[pcrawfordpt]

Looks like it’s been suggested, but take a look at the FAD. There is a TSB on replacing the bushing, intermediate and passenger axle shafts. Here’s an excellent video of the sound it makes when it goes bad. Fixed under TSB/warranty. Drove me nuts for months trying to figure it out. I only had 20k miles on her. True solution is FAD delete axles or RCV FAD which uses a bronze bushing instead of plastic.

 

[JeepOfTheseus]

Hmmm, interesting. Did you ever get confirmation directly from Dana on running that setup with the FAD? I have a lot of experience with gearbox design for critical power plant equipment, and I would never use that metal-to-metal pilot fit with the relative motion required by the FAD.

Does engaging 4HI change the sound that you are trying to fix?

I could never personally get through to Dana. My understanding of this came through Northridge. Regarding metal-on-metal, is that still a concern given there is gear oil in there and the pilot is not moving side-to-side or up and down? The only motion it should have is rotational when not engaged, as best as I could tell.

I will try 4H again, but iirc it did not make a difference, for better or worse.

Looks like it’s been suggested, but take a look at the FAD. There is a TSB on replacing the bushing, intermediate and passenger axle shafts. Here’s an excellent video of the sound it makes when it goes bad. Fixed under TSB/warranty. Drove me nuts for months trying to figure it out. I only had 20k miles on her. True solution is FAD delete axles or RCV FAD which uses a bronze bushing instead of plastic.

If I'm hearing the sound properly, that seemed to be a lower pitch thrumming/warbling type sound? I'll try to get a recording of mine, but it is very much a clicking/ticking that is linear with wheel speed.

I can take a look at the FAD again, but it did start before the axle shaft swap and bushing removal, so all that's left really is the intermediate shaft. So now the question is: what path can I even take?

1.) The "FAD delete" from Dana, from my understanding, is just a different/permanent coupler and a block-off plate. It still doesn't eliminate the "weaker" intermediate shaft.

2.) Assuming RCV sells just the intermediate shaft, which I don't believe they do, if it uses a (bronze) bushing then I'm guessing it's almost certainly not compatible with my shafts. I don't really have the option of getting the full RCV kit, so I'm trying to work with what I have.

Lastly, can someone help me understand the implications of doing a FAD delete and how it relates (or doesn't) to driveshaft engagement and/or 4H Auto? I know the FAD basically breaks the passenger shaft in half, resulting in a free spinning passenger wheel and therefore no resistance on the passenger side sun gear in the open diff. I assume this is what allows the planetary gears to rotate in opposite direction, and therefore the ring gear (and thus driveshaft) don't have to rotate. With the FAD engaged (or deleted), does that mean the driveshaft will always rotate even if the transfer case is not engaged? Is it basically like driving in 4H Auto all the time?

 

[jac04]

I could never personally get through to Dana. My understanding of this came through Northridge. Regarding metal-on-metal, is that still a concern given there is gear oil in there and the pilot is not moving side-to-side or up and down? The only motion it should have is rotational when not engaged, as best as I could tell.

I will try 4H again, but iirc it did not make a difference, for better or worse.

The issue, IMO, is that the pilot fit between the shafts is not continuously bathed in oil. It may get some 'splash' lubrication from the oil, but it is definitely not continuously oiled. With the FAD in operation, the inner shaft is spinning backwards at the same rpm that the outer shaft is spinning forward. With nominal 33" tires, that means the relative speed at the pilot fit is over 1000rpm at 50mph. With metal-to-metal contact of 2 similar steels, this is concerning IMO. That is why the plastic bushing was there from the factory - it offers a much lower coefficient of friction both with & without lubrication.

 

[Gee Man]

More likely to be the driveshaft, especially if it's lifted.

My Tcase was replaced for leaks total miles 3200.

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