Rattling Sound when you turn off ignition
Originally Posted by roast
au contraire...
The throwout bearing is what allows the pressure plate to freewheel when the clutch pedal is depressed. This is why your owners manual states not to leave the clutch depressed for extended periods of time. It puts unnecessary wear on the throwout bearing; they are only designed for intermittent use. Although when one starts to go bad, you really only notice it when the clutch is depressed.
The throwout bearing is not even loaded in that situation. When the clutch is released/engaged the pressure plate is no longer freewheeling thus the bearing is stationary and does not rotate with the pressure plate. The phenomenon you're referring to has to do with the transmission being connected to the idling engine. Even though the tranny is in neutral, since the clutch is engaged, the inner workings of the tranny still have to spin with the engine. Push the clutch in and the noise slows to a halt (the tranny gradually stops spinning). Same concept when you turn the car off in this situation and you get a rattle... it's because the tranny is being brought to a halt with the engine. Push the clutch in to disconnect the tranny from the engine.... no rattle.
Do I clearly not understand the situation?
The throwout bearing is what allows the pressure plate to freewheel when the clutch pedal is depressed. This is why your owners manual states not to leave the clutch depressed for extended periods of time. It puts unnecessary wear on the throwout bearing; they are only designed for intermittent use. Although when one starts to go bad, you really only notice it when the clutch is depressed.
The throwout bearing is not even loaded in that situation. When the clutch is released/engaged the pressure plate is no longer freewheeling thus the bearing is stationary and does not rotate with the pressure plate. The phenomenon you're referring to has to do with the transmission being connected to the idling engine. Even though the tranny is in neutral, since the clutch is engaged, the inner workings of the tranny still have to spin with the engine. Push the clutch in and the noise slows to a halt (the tranny gradually stops spinning). Same concept when you turn the car off in this situation and you get a rattle... it's because the tranny is being brought to a halt with the engine. Push the clutch in to disconnect the tranny from the engine.... no rattle.
Do I clearly not understand the situation?
No roast, your understanding of how the transmission works and how everything connects to conduct the powerflow is correct. However the throwout bearing develops wear, both on the input shaft to the transmission and to pressure plate which it controls.
End of discussion, the noise that you are hearing from your car when the clutch pedal is not depressed is primarily the throwout bearing. Why do you think when you depress the clutch the noise silences?
If you still dont believe me and have about 30minutes of time to spare, find a lift, put your car up in the air and drop your transmission and have a look.
End of discussion, the noise that you are hearing from your car when the clutch pedal is not depressed is primarily the throwout bearing. Why do you think when you depress the clutch the noise silences?
If you still dont believe me and have about 30minutes of time to spare, find a lift, put your car up in the air and drop your transmission and have a look.
Originally Posted by undrgnd
If you think that it's the tranny making the rattling noise when the clutch is released, then no, you clearly do not understand the situation.
my money is on the dual mass flywheel bouncing back and forth right before the motor comes to a stop. it will act as a rubber band of sorts and rock the input shaft back and forth. don't see how it could be the throw out. the hydraulic clutch will take up any slack created by wear and keep a little pressure on the clutch fork.
Originally Posted by bleufiend
However the throwout bearing develops wear, both on the input shaft to the transmission and to pressure plate which it controls.
Even still, a worn throwout bearing only makes noise when the clutch is depressed.
End of discussion, the noise that you are hearing from your car when the clutch pedal is not depressed is primarily the throwout bearing. Why do you think when you depress the clutch the noise silences?
If you still dont believe me and have about 30minutes of time to spare, find a lift, put your car up in the air and drop your transmission and have a look.
Originally Posted by roast
Considering it is perfectly normal for brand new cars to make the noises discussed thus far, what does wear have to do with anything?
Even still, a worn throwout bearing only makes noise when the clutch is depressed.
The noise that you hear when the clutch is not depressed in neutral is gear lash and it has nothing to do with a throwout bearing. The noise stops when you depress the clutch because you are disconnecting many moving parts in the transmission from the engine.
What would be the purpose of dropping my transmission just to look at a throwout bearing that has been used? I don't see the point.
Even still, a worn throwout bearing only makes noise when the clutch is depressed.
The noise that you hear when the clutch is not depressed in neutral is gear lash and it has nothing to do with a throwout bearing. The noise stops when you depress the clutch because you are disconnecting many moving parts in the transmission from the engine.
What would be the purpose of dropping my transmission just to look at a throwout bearing that has been used? I don't see the point.
i can and have passed all of the ase cert. tests and been toying with cars long enough that i got the knowledge out of experience and did not have to go to class for it. most of what roast is saying is true, not trying to take sides, but want to make sure people walk away with the correct knowledge.
that being said, my money is on the dual mass flywheel, hahhaa. it is the only thing that makes sence.
that being said, my money is on the dual mass flywheel, hahhaa. it is the only thing that makes sence.
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Sorry if I sound like a noob or whatever, but I have a slight understanding of what you are all talking about. Im just not sure if this is my problem as well. So I have to ask, sorry. I bought my Z about a month ago and just today when I was coming to a stop I heard a buzzing sound. Later I drove it again to try and hear it better and I heard a knock then the buzzing sound. I noticed that it only happened under about 2500 rpms. Is this the normal sound that everyone is talking about?? Im scared sh**less (I love this car) and would appreciate an answer, I know this may have been answered but I just had to ask. It seems like forums like this is the only place you can go, I really dont want to take it to the dealership and get raped.
Gear lash in the transmission? Are you kidding me? Youve got to be kidding. NO roast, that is completely wrong. And the reason Im saying for you to drop your transmission is because you are deadset on being correct. Its the throwout bearing.
Also what roast is saying as far as the powerflow thru the clutch and into the transmission is correct overzealous. But roasts understanding of what is under load and not dependent on the position of the clutch is incorrect. Ive already explained this in my past posts.
Also what roast is saying as far as the powerflow thru the clutch and into the transmission is correct overzealous. But roasts understanding of what is under load and not dependent on the position of the clutch is incorrect. Ive already explained this in my past posts.
Originally Posted by efx
My money is on the interior air filter rattling.
LOL, should of seen our new hourly guy a couple weeks ago when he went to replace one in a 15k service. The parts guy had put it in there to mess with him. Took him 20min before he came to one of us to ask where it went. He was furious when we told him the 350 doesnt have one and chewed the crap outta the parts guy LoL.
Originally Posted by bleufiend
LOL, should of seen our new hourly guy a couple weeks ago when he went to replace one in a 15k service. The parts guy had put it in there to mess with him. Took him 20min before he came to one of us to ask where it went. He was furious when we told him the 350 doesnt have one and chewed the crap outta the parts guy LoL.
Originally Posted by 350JAR
I have the same noise...I think it is the transmission comeing to a stop because when I hold the clutch in and turn the car off...the noise is gone.....
yup
Originally Posted by bleufiend
Gear lash in the transmission? Are you kidding me? Youve got to be kidding. NO roast, that is completely wrong. And the reason Im saying for you to drop your transmission is because you are deadset on being correct. Its the throwout bearing.
Also what roast is saying as far as the powerflow thru the clutch and into the transmission is correct overzealous. But roasts understanding of what is under load and not dependent on the position of the clutch is incorrect. Ive already explained this in my past posts.
Also what roast is saying as far as the powerflow thru the clutch and into the transmission is correct overzealous. But roasts understanding of what is under load and not dependent on the position of the clutch is incorrect. Ive already explained this in my past posts.
Last edited by roast; Jan 3, 2007 at 06:38 AM.
...all I work on is Nissan Toyota and Honda.