Hi All,

My car sounds like it's "knocking" when at idle. However, when I put it in first gear, the noise stops. Does anyone have any idea what could be causing this?

I'd like to have a better idea before I dump tons of $$ to drop my tranny.

Thanks!

Does the noise go away when you just press the clutch in and leave in neutral?

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Adam Perry
Datsun 260Z

Yes, it does. Should have said that. As soon as I release the clutch, the noise comes back.

Yep...sounds like a throwout bearing.

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Adam Perry
Datsun 260Z

*&)(*(&(&(&(*&


The clutch was replaced not too long ago!

Did you replace the clutch? Or did the PO do it/have it done? If it is failing that quickly then I am guessing it is a defective bearing.

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Adam Perry
Datsun 260Z

I did the same thing. About 2,000 miles ago I pulled the engine to repaint the engine bay. I stared at the 'perfectly good' throwout bearing for 2 weeks while the bay was being cleaned and RhinoLiner'd. The bearing had never made a noise, so I saved a few bucks by leaving it alone. I figured, 'if it aint broke, don't fix it'. 300 miles later the bearing started to sing.
Moral ~ change your T/O bearing any chance you get.

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1970 240Z

Previous owner had it replaced.

Sounds like I'm going to have to send this one out to a shop.

The throwout bearing is something that can last 20 minutes or 20 years. Beware the generic "white box" parts, saving a few bucks now will cost big later. Use quality parts! The bearing is inexpensive, getting to it is not.

Might want to check the pressure plate and clutch disc while you're in there, might be money well spent for new parts as long as you are there.

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John Taddonio
1970 240Z
1977 530Z
1984 300ZXT
zcarnut@hotmail.com
FB: Zccr zcarclubofrochester

It's strange John, and I fear that's what happened with the previous owner. The clutch is only 5k/5yrs old!!

Driving technique can have a lot to do with T/O bearing lifespan, also. If you 'ride' the clutch a lot your bearing uses lots of useful years in a short time.

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1970 240Z

It is not likely to be your throwout bearing as the noise would just the opposite of what you described: noise is worst when clutch is depressed. The noise you are experiencing is more likely to be your input shaft bearing which is a common (and annoying) issue on Z31's.

Good news: no imminent damage will occur. Car can literally be driven several more years like this with the same noise. might not even get any worse...

Bad news: a fluid change may help it quiet down a little but unless you are willing to install a rebuilt tranny it is something that you'll have to learn to deal with.

This noise is common in the 90A (T5) trannies as well as the 71c trannies. The only ones not known for this are the 30a's.

Did this noise exist before the clutch was installed? The input shaft turns when in neutral, when you depress the clutch, now the throw out bearing is spinning, and the input shaft has stopped. You said Knocking, that does not sound good. If it was just a whining noise, then not so bad. I had a ZX tranni like that, long story short, and many bearing falling out, I removed the input shaft without dismantling the tranni.......that's how bad it was. The input shaft bearing was wasted, and so was the countershaft bearing. That input shaft sits on my bench now, and it is now my official clutch alignment tool.......you can't get any better than that. I suspected that the pilot bushing being so worn out it put a strain on that bearing. O, Yea, always replace the bushing as well. I also do the rear main seal while I'm there as well. I have a handful of these bushings laying around somewheres. It was one of the few mistakes I got from rock auto.....they were suppose to be roller bearing bushing. I knew the deal was to good to be true.

Thanks Greg, he's due for a tranny fluid change anyway. There's a leak coming from the speedo cable pinion gear.




[quote="Paul"]Did this noise exist before the clutch was installed? /quote]

Paul, not sure. The clutch was changed before I got the car. It's definitely not a wine. The knock isn't really audible when the car is cold, but becomes more audible after it has warmed up a bit. The knock stops when I press the clutch pedal down.

Is it a knock, or is more of a growling noise. (not like a bear)