Transmission noise (sound like bearing failure)
 

I had my car now for 2 years. I drive about 100 miles round trip a day to and from work. The car now has 44000 miles on it. Mainly all highway. Approximately 20000 miles ago I experienced a noise coming from the underside of the car when i release the clutch and the car is in neutral. I could really hear the noise when going through a drive through as the noise bounces off the wall. I took it to a dealer and they told me the input drive bearing sounds bad. Being under warranty the dealer put in a new transmission instead of rebuilding the old one (cheaper for Nissan). Now I'm experiencing the noise again and it seems as if its getting louder. When i take off in 1st gear very slow it sounds really bad as if a bearing is grinding. All in all though the car drives and shifts fine and the clutch doesn't slip. Also, when i depress the clutch the noise goes away. The car is still under warranty so i am going back to the dealer about this, but before i do i would like to get other peoples input. Thanks :-)

I have a similar noise coming from mine as well, maybe not as loud though. I really hear it when I'm at a stand still in N or 1st and I'm slowly letting out the clutch. Almost like a "chatter" sound. I had the same sound on my old 350z so I just figured these trannys are noisy like that. Still shifts nice and smooth. No problems what so ever.

The noise you hear in neutral is normal. It's a little bit of a knocking/clanking sound.

The clutch chatter is also normal when pulling away from a stop. It's more likely to happen if you give too much throttle while feathering the clutch.

When a bearing is going out on the Input gear (main drive gear) The noise will change or even go away while in that range (normally 4th or 5th gear) and be more pronounced in the lower range. If the Trans makes noise in all ranges it would more likely be the Input gear or counter drive gear due to fatigue and an exchange will be your best option. fatigue is normally diagnosed as lack of lubricant.

The one thing that worries me is when they put a "new" transmission in my car the noise was not noticeable at all. The car sounded fantastic. Then the more and more i drove it, the noise came back and i can even feel a little tapping in the clutch pedal when depressed.

Sounds like a throwout bearing to me. Did they replace it when they did the transmission?

I know this is probably not what you want to hear, but what you're experiencing is normal. I'm not exactly sure to what extent, but the "tapping in the clutch pedal when depressed" and chatter or clanking when in nuetral is quite normal on the Z. Nissan just can't get it right when it comes to the transmission. Although its rough, noisy, and sometimes embarassing it functions well IMO.

I don't believe they replaced the throw out bearing. They said when the clutch is pressed in That's when the throw out bearing is engaged and That's not when the noise is happening. This is what the dealer told me. I kinda figure it may be normal. There is absolutely nothing wrong with the car. It runs great! Just maybe a little embarrassing when at a light and your sitting in a fancy new looking sports car and its chattering away. Lol. Ill invest in a loud exhaust.

^factory nissan oil rids of the chattering.

The clutch chatter is simply the material and friction. I get the dreadful bearing whine too. Is it a throwout and pilot bearing or is it my main shaft? It's really annoying too.

Throwout bearing & Pilot bearing issues - noise will change when you engage and disengage the clutch.

I get a slight howle in 4th gear, sounds like a quiet turbo, but I don't have a turbo. Haven't heard anyone else talk about this so I'm hoping it's OK

Im taking my car to the dealer tomorrow. Will see what they have to say after bringing the car in for the second for the same reason.

B&W, you may have a score in 4th gear if its the only one that you are hearing it in. If the pitch is changing with rev's than its just that gear that has a slight score. Is that a popular driven gear for you (maybe you drive side streats a lot?)

I'm pretty all over the map on the gears. I think 2nd & 3rd are my favorites for the corners I get to open it up in. I use 4th on streets between lights and for some rushour stuff but not too much. Most miles are highway miles and I'm in 6th whenever it's flowing. Need to pay a little more attention, think I heard it in 3rd today.

Pending on where you are consistently driving the car is where you will have the most wear at. I had that problem in my stang where 5th gear at 70mph I started getting a whine. When I broke my z in, I kept changing gears to eliminate the possibility of scoring the gear during break in.