Do you guys ever have this? When your car is in neutral and your not pressing in the clutch peddal your car sounds way louder like somthing is grinding very sofly? but once the clutch peddal is engaged its gone? Is my clutch going out? I ve never heard that before? loud when just idleing from beneath the car but quiet when peddal is pressed in?? HELP!!!!

 

I assure you that has to do with your transmission.
Sometimes I get that as well. Only thing confusing me is that my Z sounds like ****, but drives like a champ.

[awaiting more experienced driver to chime in]

 

so you only hear the sound when its in neutral? Is it sort of like a rattle (maybe slightly sounds like a light grind)/rocks in a can kind of sound?

If so its normal.

 

Thanks bro!!!!!!!!!!!!!!! what is that noise though????

 

oman, go here

https://my350z.com/forum/maintenance-and-repair/239714-rattling-sound-when-you-turn-off-ignition.html

it discusses the reason: something to do with the nissan throwout bearing i believe. it's also the same reason the car makes that rock in a can noise after you turn the car off with out the clutch depressed.

i have an '07 with less than 2000 miles on it and it did the same thing the other night. you can hear well with the door open, but when the door is closed, it's pretty faint.

 

^ and read my posts.... nevermind the noobs....

it's not the throwout bearing... it's the transmission.

 

In a synchromesh transmission the gears are connected all of the time. When the transmission is in neutral, and the clutch is engaged (clutch pedal released) the transmission must spin with the engine, even though the output from the transmission is null and void. When you have that many gears constantly meshed and constantly spinning, they are going to make noise.... that noise that always gets described as rocks rolling around in a can....and it's because of the multiple gears clashing...

This is why when you lighten your flywheel, the noise becomes more pronounced. There is less mass in the flywheel to absorb the imperfect power delivery from the engine, which sends more of those power surges through to the transmission, thus making more noise.

If a throwout bearing is going to make much noise, it's going to be when it's in use ie: the clutch disengaged (when the clutch pedal is pushed in).

Here is some documentation

http://www.uucmotorwerks.com/flywheel/gear_rattle.htm
http://www.mn12performance.com/mn12h...Diag-noise.pdf
http://www.carcomplaints.com/Ford/Ex...992/tsbs.shtml (search rollover)
"POWER TRAIN:MANUAL TRANSMISSION

* TSB #7366 -- SOME VEHICLES EQUIPPED WITH MANUAL TRANSMISSION MAY EXHIBIT NEUTRAL GEAR ROLLOVER NOISE (A LIGHT METALLIC RATTLING SOUND FROM THE TRANSMISSION) WHICH OCCURS AT IDLE WITH TRANSMISSION IN NEUTRAL CLUTCH ENGAGED (CLUTCH PEDAL UP). *TT (NHTSA ID #610793, NOVEMBER 01 1999)"

"
TRANMISSION GEAR ROLL-OVER NOISE
Applicable Models
Model Starting S/N Ending S/N
2004 RX8 00000000 ZZZZZZZZ

Some customers may complain of a whirring noise from the transmission while at idle N in neutral. The noise may also be described as a light rattling when the AC compressor cycles on. This noise is normal N no repairs should be made. Confirm the gear rollover noise by depressing the clutch pedal, the noise should be eliminated. Compare noise to another vehicle to verify this is a normal characteristic. 1. No repairs should be attempted on vehicles with gear rollover noise."

And the list could goes on and on...... but I've proven the point.

 

If its the same noise i hear .. more like a smooth grinding... its normal. I asked the dealer about that. Other than that everything roast has been posting is some great info. Thanks for the info!!

 

Excellent info, I always wondered if that was normal on my 03 Z. The 07's have it too, so that only confirms that it is the norm, and not the exception. From what I remember, its not that bad of a sound. But does it get worse with more mileage on the car, or is it at a constant level?

 

Dang I only wish my Z was like my Scion tC then. I have a Lightweight fly with a 6-puck clutch in my tC and it's as if it was stock sounding (no griding). Only at take off when I get that initial bite do I ever get a slight clutch chatter. And that can be prevented by reving out a little more. But nothing can stop the Z's noise while at idle, except holding your foot down on the clutch.