first gear whine- manual trans

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What do you guys think about this whine?

This is your average 5 speed, front-wheel drive tranny in a car.


The noise:

* 1st gear only
* higher pitch than reverse and quieter
* only present under load in 1st, silent when coasting in gear and on overrun(engine braking)



A lot of folks would say the bearings closest to 1st gear. But wouldn't that make noise under load in both directions? As in accelerating and overrun?

I think wear on the tooth face, but not the back of the teeth, for the 1st gearset makes sense. That would explain the noise only when loaded in one direction. What do you think? And how could this condition develop in an otherwise healthy trans?

I have already changed out the fluid and filled with MT90, which made no difference. The old fluid was clear and showed no metal debris. The car is at 102k miles and has been well maintained.
 
Drive it; if the noise starts to worsen quickly or suddenly then have it looked at. Over the years I have had several manuals that had some noise in one gear or another (usually first or o/d) and none failed or had an issue.
 
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What car is this?
Yep.


I would first make sure it is not the clutch's throw-out bearing since I have seen throw-out bearings make more noise in one gear than another because of different mechanical/coupling oscillations.

Most likely it is gear cut as others have stated.

Since a heavier grade of oil did not quench the noise, I doubt the bearings are at fault.
 
Thank you guys for the input.

The car is a 4th gen Maxima.

I was concerned because folks on the Maxima forums seem to agree that 1st gear shouldn't make any noise, although nothing I have found says definitively that it's helical cut.

Glad to hear it's probably not the bearings.


I thought about the throw-out bearing too but it's dead silent when I push in the clutch pedal and the car just had a clutch job done before I bought it so I would hope the T/O bearing is new/good.
 
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I agree. Most likely straight cut gears (which don't have the gentle hand off from gear to gear you would get with helical cut gears).

So drive it and see if it gets any worse.

Meanwhile you can tell passengers, "Straight cut gears, they whine a bit, but they're very strong."
 
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