Teralow 4:1 231HD Transfer Case

[TJustin]

Okay, here's my rig: TJ with the NV3550, NP231 w/ Teralow 4:1 T-case, Teralow 2-low shift selector, and AA SYE.

The Jeep has 83,000ish miles on it. The Teralow gearset has been installed for ~5 years, with maybe 10,000 miles on it since the install. The last few years, the Jeep is lucky to see 1,000+ annually. It is almost strictly trail driven, and is trailered to and from the trail. I occasionally take my better half to dinner, or for a Sunday drive.

While at EJS last weekend, I noticed while out wheeling that there seems to be a noise coming from the t-case that I hadn't noticed before. I do not consider it a grinding noise, or a noise that imploding is imminent. With the Teralow, there is a very noticeable amount of "gear whining" which I expect to be typical for the unit. The noise I noticed was more of a rhythmic gear meshing sound, or a sound similar to a chain and sprocket noise. It is prevalent in low-range, in 2nd gear or higher but can be heard in high range as well.

I intend on tearing it down further to be safe, but am reaching out here to see if anyone else has experienced similar sounds, or can give any indication if I am making it up in my head, if it's normal to hear other noises beyond the gear whining etc.

Can anyone provide input on whether this is a normal noise, or something to be concerned with?

Below is a video of the noise.

Thanks,

Teralow 231 HD Noise Video

 

[Agility Customs]

I would be willing to bet the chain is stretched and needs replaced, Every teralow T case I have ever seen after a few years of wheeling stretches the chain. They just arent designed to to deal with the extra gear reduction.

 

[Bart]

I had a couple of them and I distinctly remember that they made more noise in 4 low than I expected.

 

[I Lean]

Um...is there any fluid in there? The front output has been leaking, and it sounds dry...I hope it's like @Agility Customs said and the chain is just rubbing the case though.

 

[jedi]

Best bet is to give it to me and buy an atlas, we both win. I will figure out the problem

 

[TJustin]

Tore it down and took some pics. I would imagine if the chain were rubbing the case there would be marks on the case. I didn't see any, but did take pictures for the more experienced. I ran my finger along the wall of the housing and below it shows what I picked up. I also took a picture of the pump pickup filter, as well as the planetary gears Any conclusions? Any other pictures/information I could provide to help diagnose?

In response to Carl's comment about the fluid being low, I had wondered the same thing, so before pulling the drain plug, I did check the fill plug and fluid was running out the fill plug, so it was full.

 

[N8RB8R]

Looks like you have some fine copper color thrust washer debris. You need to remove and inspect the planetary gears for wear/play. I have been into many of these for similar noise and that is typically where the issue is found. I believe I am local to you if you need a hand inspecting it.

 

[Agility Customs]

Looks like you have some fine copper color thrust washer debris. You need to remove and inspect the planetary gears for wear/play. I have been into many of these for similar noise and that is typically where the issue is found. I believe I am local to you if you need a hand inspecting it.

In your experience does the planetary need replaced or just the thrust washer?

 

[N8RB8R]

Back in the day we were swapping them out for new assemblies. They have a welded pin and not sure if there is a bushing internal to the gear. Typically if the planetary gears have been loose the outer gear in the case may have damage as well. It may be possible to repair, see the pictures attached.

 

[TJustin]

Looks like you have some fine copper color thrust washer debris. You need to remove and inspect the planetary gears for wear/play. I have been into many of these for similar noise and that is typically where the issue is found. I believe I am local to you if you need a hand inspecting it.

PM'ed you.

 

[crimsonride]

Are you hearing the noise in both 2H and 4H? I think I may have a similar issue with mine.

Keep us posted.

 

[TJustin]

Are you hearing the noise in both 2H and 4H? I think I may have a similar issue with mine.

Keep us posted.

I do, but it is not as prominent.

 

[TJustin]

Special thanks to @N8RB8R. I finally made time to pull the planetary assembly out, and had Nate look at them. He confirmed that it is ruined. I ordered an Atlas earlier this week in anticipation of it being bad, knowing the odds were against me. AA is about 5-6 weeks out currently, so I'll have plenty of time to fix the leaks from my transmission. 4.3 here we come.

 

[TJustin]

Well, brown santa delivered yesterday. It took about 7 weeks to get it. Not too bad compared to other friends who have waited over 3 months to get their t-cases. Hope was to install it same weekend it got here, but will be down in Manti with a youth group this weekend. I've taken off Monday next week to install it. I hope to have it all buttoned up other than getting the driveshafts re-lengthened.

Any suggestions for the ease of installation?

 

[Bart]

Congrats. You will love it.

 

[Jinx]

Congrats. You will love it.

x2

Some of the best money I have spent on my rig...

 

[Herzog]

My atlas is now 14 years old and technically in its 3rd rig. Consider that! Definitely worth the $. You will be happy.

 

[TJustin]

Good call. If the day comes where I sell the TJ for another rig, I'll keep in mind to pull it out before selling.

 

[mesha]

Awesome!

 

[Toad]

How does the Atlas compare to a 231 in physical size?