Transmission / Transfer Case Whine

Tim Redman

TJ Enthusiast
Original poster
Joined
May 25, 2018
Messages
170
Location
Tampa Bay, FL
Happy new year, forum.

I just today started to notice a significant whine coming from my 05 TJ. It's drive train related, since I can't reproduce the sound in neutral and does not happen at any specific speed.

My Wranger has an NP231 (w/Advance Adapters SYE, installed a few years ago) and an NSG370. When passing 2000 or 2500 RPM, a whine starts that changes pitch with the RPM. Pressing the clutch makes the sound wind down with the RPMs, and is not perceptible below about 2000RPM or in neutral (both clutch down and clutch up with stick in neutral) at any RPM. I've observed this in 3rd and 4th gear. I've checked for leaks and found none. However, I am going to get under it tomorrow when I have some daylight and make sure both the transmission and transfer case are full. I'm also going to try and capture audio of the sound afterwards and see if I can get it to reproduce in 1st and 2nd gear as well.

Two notes to go along with this:

1. I'm currently replacing the u-joints in the front drive shaft, so that is not currently installed in the vehicle. We're strictly talking 2WD at the moment.
2. I've noticed that the clutch has been stuttering slightly when starting from a full stop since the temperature has dropped. This behavior goes away after the first or second time. Other than that, I haven't noticed any slippage and it shifts smoothly, but I've owned the vehicle for about 100k miles, so I'm sure it's long probably overdue for a fresh clutch.

I've searched YouTube to find other examples of the noise, but haven't been able to locate one. Everything I've watched has been grinding/banging, or vacuum related. The only video I found that might be related was a guy who noticed that the bearing race in the transfer case cover had been spinning in the housing and making a loud whining/whistling noise, but with the transfer case in 2H (I double checked to make sure) and the front drive shaft removed, I don't even see how that bearing would even be spinning or under any kind of load. At least not the front one.

Anybody have any insights?
 
Happy new year, forum.

I just today started to notice a significant whine coming from my 05 TJ. It's drive train related, since I can't reproduce the sound in neutral and does not happen at any specific speed.

My Wranger has an NP231 (w/Advance Adapters SYE, installed a few years ago) and an NSG370. When passing 2000 or 2500 RPM, a whine starts that changes pitch with the RPM. Pressing the clutch makes the sound wind down with the RPMs, and is not perceptible below about 2000RPM or in neutral (both clutch down and clutch up with stick in neutral) at any RPM. I've observed this in 3rd and 4th gear. I've checked for leaks and found none. However, I am going to get under it tomorrow when I have some daylight and make sure both the transmission and transfer case are full. I'm also going to try and capture audio of the sound afterwards and see if I can get it to reproduce in 1st and 2nd gear as well.

Two notes to go along with this:

1. I'm currently replacing the u-joints in the front drive shaft, so that is not currently installed in the vehicle. We're strictly talking 2WD at the moment.
2. I've noticed that the clutch has been stuttering slightly when starting from a full stop since the temperature has dropped. This behavior goes away after the first or second time. Other than that, I haven't noticed any slippage and it shifts smoothly, but I've owned the vehicle for about 100k miles, so I'm sure it's long probably overdue for a fresh clutch.

I've searched YouTube to find other examples of the noise, but haven't been able to locate one. Everything I've watched has been grinding/banging, or vacuum related. The only video I found that might be related was a guy who noticed that the bearing race in the transfer case cover had been spinning in the housing and making a loud whining/whistling noise, but with the transfer case in 2H (I double checked to make sure) and the front drive shaft removed, I don't even see how that bearing would even be spinning or under any kind of load. At least not the front one.

Anybody have any insights?

A few things to consider:

Transmission Input Bearing: Since the whine changes with RPM and goes away when the clutch is pressed, it might indicate an issue with the input bearing in the transmission. The fact that the noise isn't present in neutral could support this theory.

Transfer Case Output Bearing: Although you mentioned that the front driveshaft is currently out, it's worth checking the output bearing in the transfer case. Even without the driveshaft, if there's wear or damage, it could still be generating a whine under load. Be certain to check fluid levels and look for any metal shavings or discoloration in the fluid, which could indicate wear.

Clutch Issues: Given that you've noticed some stuttering and potential clutch wear, it's also possible that the clutch assembly could be contributing to the noise. A failing throw-out bearing could produce a whining noise which may change with engine speed.

U-Joint and Driveshaft Check: Once your u-joints are replaced, and the front driveshaft is reinstalled, pay attention to any changes in the noise. Sometimes, a failing or worn u-joint can cause vibration and noise that may be more noticeable in 2WD, particularly if there are additional load changes on the drivetrain components.

If it were me, I would start with checking fluid levels in both the transmission and the transfer case, and then looking into replacing the clutch (if you're due for it anyway). It could potentially resolve both the stuttering and the noise. Keep us updated on what you find!

Best of luck!
 
Status update:

I decided, just to cover bases, to change out the fluids in both the transmission and transfer case.

Transmission
Removing the fill plug, the fluid was right up to the plug hole. Upon draining, it still had the light honey color typical to Redline MTL. There was a small amount of fine metallic debris on the magnetic drain plug, but I didn't see anything severe. It will need to be serviced at some point though, I'm sure, for the mileage it's accrued. It was refilled with just a shade under 2 qts of fresh Redline MTL.

Transfer Case
Removing the fill plug, I was not able to feel the fluid with my finger. When draining the transfer case, it certainly seemed like it didn't dump the 1.5-2.0 quarts that it should have. In the end, my catch can had about 2.5 quarts of fluid in it between both the transmission and the transfer case, so the transfer case was definitely dangerously low. I am unable to see any indication of if or where it might be leaking. The fluid was still fresh looking red ATF+4 with no signs of debris, though the plug does not appear to be magnetic. If I remember correctly, there is a magnet at the bottom of the reservoir. It was refilled with just under 2 qts of O'Reilly ATF+4.

I'll get a chance to test drive it later to see if it made any impact, but it wouldn't surprise me if a TC rebuild may be in my future. As long as there's nothing physically wrong with the case, particularly with any of the bearing mating surfaces, I should be able to handle that at home. It also still needs a clutch, so when I get to that point, I can also have them check out the input shaft bearing for wear.
 
The noise in the video isn't nearly as pronounced as what I'm hearing, but that may be due to wind noise hitting my phone. You should still be able to hear it, though. The noise starts at around 0:56.


Impressions: I'm pretty sure I'm smoking a bearing somewhere.