clutch noise when disengaged

[madkaw]

I have been doing the search and I am still not sure. I ma working on member Jim Derks car and haven't driven but 1 mile. Hell, it just started for the first time in 10 years. Anyway, there is a whirling clutchtype noise coming when car is idling in neutral and stops as soon as the clutch pedal is depressed. I have read of 2 possibilities. First the throw out bearing, the car has 85k original and probably has original clutch--just replace and be done with it. I have also read it can be the input shaft. Is there a way to check this when I have the tranny out. I know very little about trannies and would like to diagnose this so i know whether to replace his tranny at the same time. I hate to post and leave but i need to go to work, any input would be great.I'm sorry can't tell you more except that the clutch seemed to work fine what little i drove it. Too hard to tell if there was any other noises since the cars suspension is shot and making it's own noises.

By the way, after 10 years of sitting, the motor sounds great and the smoke is slowly disappearing out the back, even with the little i have run the motor. Can't wwait to get some miles on her and do a compression check.

[e_racer1999]

IIRC, the throwout bearing only makes noise if the clutch is disengaged, when it is depressed. i believe it to be the input shaft bearing based on this assumption. my car does the same thing, so if that's NOT the answer.....

[Arne]

Probably not the throw-out bearing, as when the pedal is released, the bearing does nothing, it only spins when the pedal is depressed.

Input shaft bearing on the other hand, is spinning when the pedal is out and the tranny is in neutral, and stops spinning when you press the clutch. It is your prime suspect.

Much lesser possibilities are bearings on the layshaft, or the needle bearings between the input shaft and the mainshaft. Here is a bit of diagnosis help:

Input shaft bearing - makes noise at any time the clutch pedal is out. (Any gear, or neutral.) Goes away when clutch pedal is depressed. Generally varies with engine RPM.

Layshaft bearings - Similar to input shaft, as it is directly driven by the input shaft. Less common to go bad though.

Needle bearing at front of mainshaft - Noisy any time the input and mainshafts are spinning different speeds, so it is quiet only in fourth gear, and noisy any other time. May get quiet when the car is moving if you depress the clutch.

Output bearing - noisy anytime the car is moving, any speed, all gears.

[madkaw]

So if it is the input bearing is there a easy fix or is better to just throw in a different tranny? Is there a way to check this when the tranny is out of the car? So this a common trait for the 4 speeds? Will it eventually get worst or should I not sweat it?

[WarrenZ]

I agree with e_racer1999. I had the exact same problem and once the gearbox was out and I spun the bearing in my hand it was pretty obvious that was my problem.

Goodluck

WarrenZ

[undercat]

It could also be a cracked or unbalanced flywheel. I have an undamped/lightened flywheel in my 350z that rattles in neutral and becomes quite with the clutch depressed. My friend had the same noise on his car and it turned out his flywheel was cracked. He figured this out after he changed the transmission and clutch (he had spares so he didn't have to buy anything) but kept the flywheel and still had the noise. Hope this helps,

-Paul

[albert_ey]

I agree with Arne and e-racer, I had a similar problem and it was the Input shaft bearing, I got it replaced and there, the noise is gone. I would get that checked first.

[hd240z]

So if it is the input bearing is there a easy fix or is better to just throw in a different tranny? Is there a way to check this when the tranny is out of the car? So this a common trait for the 4 speeds? Will it eventually get worst or should I not sweat it?

Its easier to throw in a different tranny, if you know the replacement is in good condition. You have to tear down the tranny in order to change the input shaft bearing or any of the bearings for that matter, so you might as well replace the blocking rings and do a complete overhaul once you have it apart.

As Warren said you can probably tell if the input bearing is bad by rotating the shaft by hand once you pull the tranny.

Good Luck

[e_racer1999]

...ant if you wanna have it done, aamco will charge you ~$500 labor plus ~120 in parts, or les @ classic datsun will charge you 800-900 for a fresh rebuild.

just throwin that out there