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Clutch Rattle


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I have a 77 280z, I recently had the clutch replaced. I also had what I believed to be a bad throw out bearing, had a rattle when the clutch was not pushed in and the car is at idle. I had the clutch and throw out bearing replaced and I still have the rattle, just as bad, maybe worse. Any thoughts?

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That's very common.  It's one of the bearings in the transmission.  Can't remember which one.  Seems to be inherent to the design and the bearing that Nissan chose.  Most make that noise.  If it's really bad though it could be a sign of impending failure.

 

If it just sounds like a rough rumbly bearing it's probably fine.  If it's crunchy and poppy, maybe not.

Edited by NewZed
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  • 2 weeks later...

Nobody said that Redline would help the noise  BUSZED just made a point about thick oil damping the noise a little bit.

 

You're not being very clear on what the noise IS,beyond a "rattle".  A video might help your cause.  To be more clear on this end, the bearing noise is more of a dull internal rumble than a rattle, that goes away when you press the clutch pedal.  If you have a real, "bare metal shaking around" kind of noise, it could be something completely different.  And Redline fluid isn't going to fix the bearing noise anyway.

 

Edit - just saw your post on another forum where you call it a "chatter".  Words are all we have out here, you have to pick the right ones and use them the right way, to create an image.

 

Edit 2 - it also looks like you're getting your various suggestions confounded, like talking about Redline in this thread that never mentioned Redline.  You're going to create a mass of confusion.

Edited by NewZed
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The ones I've heard sounded like a marble rolling around in the bellhousing. Again, these were due to light flywheels. My friend had her transmission rebuilt twice trying to stop this noise. Didn't help.

If you're using a standard weight flywheel, then you could rebuild the transmission and see if that helps. Probably try some heavier gear oil first, as that's a heck of a lot less hassle.

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The ones I've heard sounded like a marble rolling around in the bellhousing. Again, these were due to light flywheels. My friend had her transmission rebuilt twice trying to stop this noise. Didn't help.

If you're using a standard weight flywheel, then you could rebuild the transmission and see if that helps. Probably try some heavier gear oil first, as that's a heck of a lot less hassle.

It's nothing that significant, it's unfortunately something that wouldn't show up on video. I have a friend that has a second transmission, we were considering a swap. Unfortunately I don't know the history of that Trans so it's a bit of a shot in the dark.

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If you know some people with Z's or the same transmission you could take a ride and compare.  I've had four in my car that all make the same noise, they all sound like they need work..

 

Did you find anything on the magnet when you drained the fluid?

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If you know some people with Z's or the same transmission you could take a ride and compare.  I've had four in my car that all make the same noise, they all sound like they need work..

 

Did you find anything on the magnet when you drained the fluid?

Yea, I know someone with the same Trans, doesn't make a noise like this at all. The magnet had some very tiny shavings.

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There's a nut on one of the shafts that's known to come loose.  It affects shifting also though.  Did you have the pilot bushing replaced when you had the TOB done?

 

Also noticed in the other forum post that you said it makes the noise in the lower gears, but not 3rd and 4th.  Might be meaningful.

 

Good luck.

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There's a nut on one of the shafts that's known to come loose.  It affects shifting also though.  Did you have the pilot bushing replaced when you had the TOB done?

 

Also noticed in the other forum post that you said it makes the noise in the lower gears, but not 3rd and 4th.  Might be meaningful.

 

Good luck.

No, I did not know at the time that this was something commonly replaced when the clutch work is done. I used a shop to do the work, my guess is they didn't know either. My thought is that once the car is into the higher gears, road noise and other sounds are simply drowning the sound out, just a guess.

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The pilot bushing, while small and simple (dull) and cheap, is very important.  It supports the end of the input shaft.  A loose pilot bushing can let the shaft rattle around.  You might ask the shop.  Any decent shop would know, it's a normal part of clutch replacement.

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I also have some noise from my 5 speed out of a 81 280zx. In my case I only hear it when the transmission is up to temperature and the car is idling in neutral. Noise goes completely away when the clutch pedal is pressed. I have changed oil viscosity to slightly thicker and this has made some difference but slight. 

 

My engine has a slightly lumpy cam so it doesn't idle super smooth so maybe a contributing factor. My best guess is the gears rattling around slightly while the input shaft is turning in neutral ? Nothing turns inside the tranny while the clutch is pressed in. I have read that these trannies are noisy.

 

I'm not worried about it and will run it until there is issues. Then it will be easy to see what it was. :D My opinion is to try to put it out of your mind and just enjoy the ride. You could have it rebuilt and it may be the same afterward.

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  • 2 months later...

I ended up purchasing an almost complete set of bearings from zcar depot for the 5spd.  We tore down the trans and found one bearing had the slightest of bad spots.  A rough spot that only showed up about every other spin.  We reassembled and used Redline trans fluid.  The noise has gone away completely.  I cant help but wonder if it would have disappeared with addition of the Redline only. 

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No, it was the rough spot. If you can feel a " rough "  spot through your fingers, the bearing is bad enough to make noise. I remember seeing a demonstration by Ford back in the early 80's. They had a new Ultrasonic testing machine that automatically spun and listened to every bearing as it came down the production line.  

 

In the Demo, they had a test bench setup with this machine. They tested a new, but faulty bearing, on the Ultrasonic machine. Oscilliscope showed all the harmonic peaks etc indicating that this bearing was starting to fail, even though it passed the old production line inspection. They then took a BNIB bearing out, randomly of the Ford inventory to apparently show what a " good " bearing should look like. The new bearing was even worse than the  than the faulty one!! The instructor was on his toes though. He quickly stated, "Errr... I guess this was old stock ".... LOL.

 

Point being, a bearing can make noise, and you may not even be able to feel the defect with your fingers. If you can feel it... you know the bearing is bad. 

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