Alright bad news about the rattling sound within my tranny

[The Wizard Of Z]

so if anyone remembers, about month back i posted a thread about a possible throw out bearing problem, im having this really loud knocking/hitting type sound from somewhere between the transmission and the engine, transmission is perfect, nothing wrong with it, sounds like theres something loose or something broke off and its rattling around inside the engine or trqanny, thought i had a bad throw out bearing because when i pushed the clutch in, it would be alot more silent, almost bearly making a noise, but soon as i let off the clutch, bam!! rattles like my trannys not on right or something, i dropped the tranny and looked at the throw out bearing, its practically brand new, so i wasted money a new one =/, my clutch other then just alittle worn, looks prefectly fine, so it has to be maybe behind the clutch or ever possible the fly wheel, its not inside the engine, its just some where from the clutch and the engine and i dont know whart the heck it is, hopefully someone has and idea cause i need to get this fixed fast before i really damage my engine, it hasnt even hit 15k miles yet, and i cant afford another 6k engine >.<

[TBK1]

only thing I can thnk of at this point is the main Shaft Bearing in the tranny!

You could start the engine with tranny removed and if sound gone it eliminates the engine and bearings!

[er34gtt2000jp]

only thing I can thnk of at this point is the main Shaft Bearing in the tranny!

You could start the engine with tranny removed and if sound gone it eliminates the engine and bearings!

Sorry but how is he supposed to do that when the starter bolts into the trans?:stupid:

[TBK1]

My Bad you are correct !!!!!

[240ZMan]

Given that the sound goes away when you disengage the clutch, it sure does sound like the main shaft bearing. Perhaps if you wiggle the shaft with your hand you can feel excessive play? Maybe turning it by hand will give you a clue?

Or maybe since you have it out already, you should change it now. I say this without knowing how easy/hard it is to do that. The transmission is one of the few things I didn't rebuild myself.

[Arne]

Ahh, but I HAVE rebuilt transmissions before.

First, I'm sorry I missed the earlier thread, might have been able to save you from buying the throwout bearing. A bad throwout bearing makes noise when it is in contact with the fingers of the pressure plate - i.e. it makes noise when the pedal is DEPRESSED, but is quiet when released. Just backwards from your description.

Now. If the noise is quiet while in neutral, suspect the mainshaft. But if the noise is present at all times the clutch pedal is released (even in neutral), your problem is more likely in the input shaft. The mainshaft doesn't move while the car is stopped and in neutral, but the input shaft does (assuming the clutch pedal is released).

[The Wizard Of Z]

well no the rattling sound only happens when the clutch isnt in, and it just sits in nuetral, if i have the clutch pushed in and put the transmission into gear or just sit there with the clutch pressed in, the sound is alot quieter, i still hear it though and i can feel the rattling sound on the clutch and the stick shift, like something is actually hitting against the clutch and the stick shift, im pretty much out of ideas, but im gonna pull the tranny again next week, this time just to be 100% sure im gonna thow on the new throw out bearing, and im also gonna pull and check the clutch plate and the fly wheel,

[sblake01]

Sorry but how is he supposed to do that when the starter bolts into the trans?:stupid:

Not :stupid: at all. This can be done by bolting the starter to the mount plate. I've done it. And the further we get into this, based on the info so far, I'd have to lean towards the input shaft also. I've also rebuilt a tranny or two in my time.

[Arne]

well no the rattling sound only happens when the clutch isnt in, and it just sits in nuetral, if i have the clutch pushed in and put the transmission into gear or just sit there with the clutch pressed in, the sound is alot quieter, i still hear it though and i can feel the rattling sound on the clutch and the stick shift, like something is actually hitting against the clutch and the stick shift, im pretty much out of ideas, but im gonna pull the tranny again next week, this time just to be 100% sure im gonna thow on the new throw out bearing, and im also gonna pull and check the clutch plate and the fly wheel,

OK, with that description I'm at least 90% certain that your problem is in the input shaft area. The input shaft has one large roller bearing just behind the front seal, and is supported at the front of the mainshaft on needle bearings. From your description, I'd lean toward the needle bearings as the source, but that's just a wild guess at this point.

The other 10% possibility would be bad bearings on the countershaft (or layshaft, in a british car), as it also spins in neutral. In a Z, the countershaft is supported by a single roller bearing on each end of the shaft.

Doesn't matter much either way though, as any of those will require a complete transmission tear-down.

[Victor Laury]

Agreed - input Shaft -

Your description matches the death song of my FS5C71A roadster tranny. It may have needed just the input shaft bearings replaced, But I went for the complete rebuild - Just In Case!