90 sentra noise in tranny need opinions

[ahardb0dy]

I thought i asked this before but just went thru all my topics and don't see it so I'm asking now:

 

90 Nissan Sentra, originally a 4 speed manual, swapped in a brand new surplus 5 speed a few years ago, have new clutch kit and clutch cable. Car runs fine and shifts perfectly. Problem is lately when engine is running and transmission is in neutral, clutch out I hear a sort of knocking sound, sound goes away when clutch is depressed. My mechanic first said it was the input bushing but now says the noise is caused by the first bearing inside of the transmission that supports the input shaft. I took the old 4 speed transmission apart and I see the bearing he is talking about. Just wanted to ask for a second opinion. Noise is definetly coming from tranny and not the engine.

 

last weekend I e-mailed a local shop that does a radio talk show that is about auto repair, the shop has been in business about 30 years this is there reply:

 

"Don't want to argue with your mechanic but that wouldn't make any sense being theirs no more of a load placed on the main shaft end bearing with or with out the clutch being depressed! I would expect an irregular area or high spot on the pressure plate fingers hitting the release bearing then when you apply clutch pressure it levels out the fingers removing the high spot. This can be caused by a warped flywheel or something didn't line up correctly when it was installed. Most likely the unit will need to be removed and the pressure plate and flywheel inspected.

Larry "

 

What do you guys/gals think??

 

Thanks

[nismothunder]

Second shop sounds correct, since there is no more load on the bearing when the clutch is in or out, unless its make noise when its in gear and the car is moving there cant be any noise coming from a bearing.

 

I would double check your transmission mounts too make sure there good though, that will make all kinds of whierd noises.

[sewebster]

I'm not really arguing, but if your car is stopped and you are in neutral with the clutch pedal depressed, then your transmission won't even be spinning at all right, hence no noise? Once you release the clutch pedal, everything except the output shaft will be turning, hence noise is more possible, even, presumably from a bearing. But the pressure plate thing might be more likely.

 

?

Edited April 26, 2011 by sewebster

[nismothunder]

I'm not really arguing, but if your car is stopped and you are in neutral with the clutch pedal depressed, then your transmission won't even be spinning at all right, hence no noise?

 

Once you release the clutch pedal, everything except the output shaft will be turning, hence noise is more possible, even, presumably from a bearing. But the pressure plate thing might be more likely.

 

?

1. yes,

 

 

Conserning the ops topic again, pulling out my trusty haynes red top for my old ford, it says for transmission noise while in neutral the following.

 

1. Input shaft bearing worn

 

2. Damaged main drivegear bearing

 

3. Worn countergear bearings

 

4. Worn or damaged counter gear anti-lash shims.

 

Not sure if this helps since it kinda disagrees with what my first post said but thought you may find it help full.