So I guess I never updated my story....here's how it played out....
Not for lack of trying, Nissan did attempt to fix my wife's issue. I think I left off when the first dealer replaced the reduction gear, and we pretty much accepted that was the solution at the time.
Nonetheless, the noise eventually re-occurred, at VERY specific speeds. At first it was in the high 60's mph, but eventually it started making a noise at a very specific 49mph. It would be silent at 48mph and 50mph, but noisy at 49mph. And it was getting louder. So we took it back to dealer A (where we leased from). They couldn't find anything, but in discussing with Nissan suggested that I call the support line and open an incident with them and perhaps get Nissan to send an engineer out to look at it.
So this is what I did. The first thing they wanted me to do was take it to a different dealer to get a second opinion. Which was fine by me since the other dealer was literally 5 minutes from my house. They too were told by Nissan that it was probably the reduction gear, so they replaced it again. This time it made no difference at all. (Keep in mind that each time they do this they have your car for almost 2 weeks by the time they get the part in and do the replacement!) So now that I had my second opinion, and they attempted a repair, and it did not solve the problem, I got Nissan to send an engineer out.
There were two issues with the engineer's visit. I had figured they would send a LEAF expert from the factory, but what we got was a guy from Virginia and ours was only the second LEAF he had ever been in
The other issue is that the day he was here, it was raining pretty heavily and between the rain noise and tire noise from the tires, it masked the sound quite a bit. But not completely. And the engineer did hear it. They did quite a bit more testing with the car on the lift but weren't able to replicate the sound. His Hail Mary attempt was to replace the entire front axle assembly! Which happened. But which also made no difference.
So I cannot fault Nissan for not seriously trying to fix this. They certainly spent a lot of money on parts, labor, and bringing an engineer in to help diagnose this. But at that point I simply suggested to my incident manager that maybe we should just restart our lease with a fresh new vehicle. Well, they did even better than that. Basically they bought out our lease (and even gave us back payments to the point when we first reported the issue). This was far more fair than I expected. Now we were prepared to just get another LEAF lease, but really wanted the 30kWh option so we could make it to Charlotte with the car, but the release of that car was delayed in NC for several more months, and we basically had to surrender our car immediately. So we ended up going with a Volt.
To this day I suspect there was something in the motor itself that was resonating at very specific RPMs. Probably a loose part or something. But definitely in the motor because they replaced the rest of the drivetrain almost completely!
However, the story does not end there. Now we have to shift to MY LEAF (2012 SL). As I was getting close to 60K miles (and focused on my battery degradation--it was down 3 bars and getting close to losing its 4th), my LEAF starts making a noise. But this noise was different in the following ways:
- It happened only when under acceleration or deceleration, not while coasting.
- It was NOT at a specific speed. It was pretty much constant through the whole RPM range as long as it was under accel/decel.
- It was a purring, rather than humming, noise that increased with frequency as the RPMs went up.
- It started out barely audible but gradually got louder and louder over the months.
Finally as I crossed 60K miles it had become quite loud. Despite my earlier experience with false alarms with the reduction gear, listening to this noise and the symptoms, and knowing that Nissan, being quick to diagnose "noises" as a reduction gear issue, I felt pretty certain that that was the issue I was having.
However, given that I was so close to losing my 4th bar before hitting 60K miles, I didn't want to leave my car idle for 2 weeks while they ordered the part. I preferred to "take advantage" of the hot summer weather to cycle my battery through use and hopefully drop that 4th bar. And I hadn't realize that the reduction gear was still under warranty (until 60K miles). Once I crossed 60K miles (without losing the 4th bar--that dropped at 61,250), I took the car to my dealer to investigate the noise (at about 60,100 miles), only to discover at that point that I had just missed the warranty :x
So I had the reduction gear replaced (at my cost--it was about $2600!!!!! don't try to tell me that EVs don't have transmissions!) and opened an incident to get out of warranty relief. Which again, I did right by Nissan and they agreed to cover the full cost since I was just BARELY out of warranty, and I was able to convince them that the sound had started occurring at least several hundred miles prior.
Anyway, that was DEFINITELY the problem with my car. The noise went completely away. So the reduction gear issue IS real (just not with my wife's car).
And, as it turns out, Nissan offered a $10K group buy incentive on new LEAFs and I just couldn't pass that one by, so I now have that 30kWh LEAF and am able to make the trip to Charlotte in the LEAF--only having to use the Volt for our annual 1500 mile trip north.