Sound from NV3550 transmission when not under load

Ppd7207

Ppd7207

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Joined
Apr 28, 2019
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Location
Phoenix, AZ
2003 rubicon, 4.0 with a 5 speed NV3550 transmission.

So there is an odd noise when the vehicle is moving but not powering the transmission. It’s almost a grinding or maybe a bad bearing sound. What happens is when you are at speed and you depress the clutch, the noise begins. However the sound continues when you put it in neutral and release the clutch. The sound goes away if you put it back in gear. Anyone have any ideas?
 
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I did the throwout bearing yesterday, replacing it with a National bearing because that’s what I thought it was too. Sadly, the same noise as before is present.
 
Ppd7207 said:
2003 rubicon, 4.0 with a 5 speed NV3550 transmission.

So there is an odd noise when the vehicle is moving but not powering the transmission. It’s almost a grinding or maybe a bad bearing sound. What happens is when you are at speed and you depress the clutch, the noise begins. However the sound continues when you put it in neutral and release the clutch. The sound goes away if you put it back in gear. Anyone have any ideas?
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Same issue here. When coming to slow rolling stop I here the grinding noise too. Same transmission. I’ve also noticed lately that occasionally when I shift from 2nd to 3rd, I’ll hear/feel a loud clunk when pushing the clutch in as I’m shifting to 3rd, and a loud clunk when letting the clutch out after getting into 3rd. Time for a new advanced adapters AX15 I suppose.
 
When the clutch is "in" or when the trans is in neutral there is no torque from the engine powering the drivetrain.(says Captain Obvious!) But the road is now applying a torque load through all the way to the transmission. Could there be a bearing or thrust plate that is protesting the reversed load? This is just a spit ball. Or could the noise always be there and you just dont hear it when you are on the gas?
 
Definitely not there when on the gas. If while at speed you put it back in gear the noise goes away. It’s also fairly loud, so there is not missing it. I’m starting to think it may be a bearing in the transmission.
 
I agree with transmission. Input bearing? In gear changes the route the torque moves through. Have you tried the Redline trans oil yet? Many claim success with noise issues by changing fluid. Cheaper than a rebuild of it works for you.
 
Did the transmission fluid about 2 months ago with redline MTL. Got frustrated and it has an apt on Tuesday at a Jeep shop. While on the phone and describing the symptoms, the guy thought it could be the transmission cover wasn’t on right or was bent or something. Not sure about that, but I’m going to let him check. Hopefully that’s it and it’s a quick and inexpensive fix. I’ll keep you posted.
 
I'm currently replacing my NV3550. I had a rumble when engine braking in 3rd and 4th and a clicking at all times. Transmission shop had tranny apart and there were no signs of what the issue could truly be, just possibly gear wear.
 
So here is an odd twist, took out the rear drive shaft, drove it in 4 high, and there is no sound. Opened up the rear differential and all looks good. We shall see once the RTV is dry and new oil is back in. Thinking I will do the U-joints too for good measure.
 
Every trans I tried a heavier oil in either showed synchro issues or problems getting oil up to the top rail in the transmission. Others may have better luck.
 
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