Possible reduction gear failure noise

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estomax

Well-known member
Joined
Jan 20, 2017
Messages
326
Location
Seattle
EDIT 2022/05/15 - After neglecting this issue for a year, i finally replaced the transmission, and the noise did not change. :? The next morning i went and got a new wheel bearing and replaced the driver side wheel bearing. all quiet now. About to write a howto for transmission replacement at least :) The fact that the wheel bearing failed while i was messing about with the gearbox fluids was a coincidence.

Hey Everyone,

My leaf has started making a noise that is audible on fresher pavement where the tire noise does not overcome it.

The noise is a hum/gear clicking that is speed dependent and doesn't really change with throttle.
https://imgur.com/PR0Pu65

the noise up close with the tires off the ground and me spinning the wheel by hand in neutral
https://imgur.com/q98tfio

and with tires spinning in drive off the ground
https://imgur.com/3EmYjZs

I just changed out the gear oil for a fresh variety (i had tried some slightly lighter weight for the last 1000 miles) but i am willing to bet that something must have been on the way out already, the car was tboned in the front a few years back and that could have exerted some forces on the transmission through the passenger side corner that took most of the damage, and the car now decided that was enough.

searching the forums i can find cases of people with reduction gear failures but they seem exceedingly rare still, so i am going to start keeping my eyes open on a part out leaf in my area to snag the reduction gear out of. I will probably try some thicker fluid in the reduction gear to document how that affects the noise or makes it quieter so i can limp it along farther.

if anyone has thoughts about this noise being something other than the reduction gear, i'd love to hear it. is the 2011-2012 reduction gear the same as 2013? that is the other thing to figure out, there is a 2011 part out near me.

cheers
Marko
 
Def doesn't sound right.

In case you are gonna replace the reduction gear assembly, here are the specs;
1-speed fixed gear ratio (7.937:1 for 2011-2012 and 8.193:1 for 2013-2017)
If you opt for the older reduction gear you won't have as quick acceleration (3% difference)
 
It sounds more like a clicking or knocking sound than "grinding" to me.

In the second clip while manually turning by hand it sounds like a loose ball knocking in the CV joint, or something loose in the differential spyder, or gear knocking due to backlash when the direction was reversed.

Since you said it was in a front end collision this may be residual un-detected damage from the incident, such as a broken gear tooth. It might be worth getting a cheap boroscope to take a look inside thru any fill, drain or vent openings if the noise is internal and not in the CV joint.
 
If you haven't already, try an automotive stethoscope or even a 3' long dowel to localize the noise. Press one end to a housing, and the other to your ear, and when your are on the noisy part, you will hear a much stronger and more detailed sound.

Agree with NL, in the second video at the end that knocking when the rotation was going back and forth sounds like something rattling. Localize it. Good luck.
 
That was smart to stop one wheel while letting the other wheel turn.
----- No sound when both are turning, sound heard when only one wheel turning, means the spider gears are turning & rattling (differential).
Still, hard to tell what's happening exactly.

Does exact diagnosis matter yet?
A technician or you would have to take the unit apart anyway and search for the issue to be sure enough to know which parts to order.
For example, diff shafts (bearings) or the gears meshing, can't tell without taking it all apart.

Might as well try thicker oil in there. Cheap to do that first, and for a long time people have been trying thick goo to keep them on the road with much success. Delaying thousands of $$ for who knows how long is great.

The only direct experience I've had with an EV differential was when Ford recalled the Focus EV's diff due to factory defects on the surface of the pinion shaft (spider gears ride on those). Never failed on mine in particular, but others reported differential rattling around & some got complete failure.
 
i'll see what concoction of higher weight diff oils i have at home tonight to mix up and test in here. The noise, i agree sounds likely from the differential spyder and taking it apart to replace a single bearing is probably not worth my time/risk if i can get a good condition used box for about 500 bucks and throw in there instead. Thanks Dala for the gear info, the older and newer boxes bolt to the motor the same right? I know the inverter mounting/motor parts changed between 11-12 and 13 and up.

i do have an automotive stethoscope and i have localized the noise to the gearbox, but i havent gone and compared top and bottom for example to see where in the gearbox it's coming from, ill try that tonight.

either way i am likely to ride this noise until it gets louder than the radio :)
 
well, i put 75w90 synthetic gear oil, a mix of redline and oreilly brand that i had at home in there, this is much thicker than the ATF. Did not make a big difference with the bearing noise, on the drive to work did not make a huge difference to efficiency either though, but that is only 20 miles, my drive to work ended at a 3.7 mi/kwh. more data :)

did not mess around with localizing the noise, i suspect it is an output bearing from the transmission, if i had to bet then the passenger side which may have taken extra impact in the collision that happened a few years back. will try to localize that tonight or tomorrow.

Marko
 
Worse than we thought if something 3 times more viscous than Matic S didn't quiet it down. A "big" chunk is missing in there.
Still, you could just see how long it goes. Do nothing, Spend no bucks.
Even with the noise, you've now got a high-phosphor anti-wear GL-5 level lube doing it's best to protect it.

...........Unless you're into DIY. If you can take those half shafts off & the rest, take it apart & see if something small inside (could be a $50 part & easy to replace once you have the thing off the car) can be ordered from Nissan. I'm assuming Nissan will sell you new internal bearings or pinion shafts, etc., the smaller stuff inside.

If not feasible, then go for the junkyard whole-gearbox replacement method. I mean, once you have the thing off the vehicle, it could be easy to check to see if the part can be replaced. You have a Service Manual, which is a great start.
 
Given the rarity of these things failing, or even getting noisy, I'd go the salvage replacement unit route. You can always tear the noisy one down at your leisure. I can just picture you spending months trying to fix it but not finding the exact failed part, or replacing one part only to have another one fail six month later. Occam's Razor suggests that something in that lube is very inadequate for this particular job, unless you made a serious mistake of some sort...
 
LeftieBiker said:
Occam's Razor suggests that something in that lube is very inadequate for this particular job, unless you made a serious mistake of some sort...
Given estomax's Leaf had a collision near up front a while back, from what he reported, maybe it was just a weakened part finally giving way. The other possibility is the usual fear one might have if using thinner visc fluids than what Nissan recommends, although the stuff (Valvoline ULV kv100 4.5) he put in recently appears to be very close to Nissan Matic S's kv100 5.5 physical properties, and of course it's got the typical ATF fluid additive package to work in gears. 4.5 vs. 5.5, or around 20% difference for most relevant temperatures, doesn't seem that different.
Certainly the kv100 16 GL-5 oil in there now won't sacrifice protection.
 
I've got over +4k miles on my gear oil change, no issues (well at least nothing I can hear) yet. I plan on changing it next month since I've already put it through plenty of abuse with my lead foot driving and several +600 mile trips now on the vehicle. :)
I am curious to see if the next oil analysis shows anything to worry about, but I won't hijack this topic, I have my own to post in. :mrgreen:
 
estomax said:
i put 75w90 synthetic gear oil, a mix of redline and oreilly brand that i had at home in there, this is much thicker than the ATF.
Nubo said:
Might fragments big enough to represent a problem stand a better chance of being captured by the lower plug?
I was wondering about that lower plug too. Catch anything? The upper one was very clean anyway, as you already showed.
 
the lower plug was clean just like the top one, did not get any bits coming out with the gearoil, though i did notice a few flat dark color, about 1/16"x1/8", slightly magnetic slivers in the bottom of the drain pan that came out with the oil, so something is eating itself based on that. i didnt grab a pic though.
 
Sounds the same as the gearbox in my 2016 Leaf which has just failed, although mine is louder/worse than yours I suspect. Check the videos I linked here:

https://www.speakev.com/threads/leaf-30-driveshaft-failure-update-no-its-the-gearbox.160142/page-2#post-3037918

In my case it is noisy - a regular ratchet noise when there is reverse torque but quiet when there is forwards torque.

You can rule out a problem with the driveshafts quite easily - here is how I did it:

Jack up and support the front of the car with axle stands so the front wheels are a able to turn in the air. Disable traction control, keep the foot operated handbrake on (which is attached to the rear wheels) and put the car in drive without pressing the accelerator.

The front wheels will both spin at about 5mph road speed. This should be smooth and quiet. Mine is quiet forwards and noisy in reverse. If you hear a regular "clack clack clack" like in my second video hold one front wheel still so the differential causes only the other wheel to turn - you'll hear a new noise from the differential spider but ignore that - if the original clacking noise continues when you hold both wheels still one at a time you've just ruled out the driveshafts as a source of noise.

Although I don't have any proof, one of the tapered roller bearings supporting the large differential gear seems the most likely as the helical gear will push on one bearing with torque in one direction and the other bearing with torque in the other direction.

I'm trying to work out what to do with mine - 35k miles and 4 1/2 years old so low mileage but out of warranty. I haven't had a response from Nissan yet but I assume paying dealer money to fit a new box would cost many thousands for a new gearbox.

At the moment I'm exploring the options of having the gearbox rebuilt or replacing with second hand, but that still leaves getting it out of the car first, and whether I can tackle this myself or whether I'll need to get someone to do it for me.

Does anyone know if it's possible to separate and remove the onboard charger and drive inverter from the drive-train stack in-situ ? I don't really had the equipment to lift the entire stack out as one (and I'm not even sure if the Nissan method is to lift it out the top or lower it through the bottom) but if I can strip it down to just the motor and gearbox at the bottom it looks feasible to then be able to lift out the motor/gearbox pair leaving the engine mounts behind.

Also does anyone know if it's possible to disconnect the heat pump from the side of the stack leaving it connected to the A/C piping, or is a gearbox removal going to require a system re-gas ?
 
Just a quick update.

I have repaired my Leaf (a couple of months ago now) by swapping the gearbox for a low mileage second hand one, and this has definitely cured the noise.

While it took me a few days, I was able to do the job by myself on my driveway with some careful planning and purchasing a few extra tools.

For more details see the following thread starting at post #261:

https://www.speakev.com/threads/leaf-30-driveshaft-failure-update-no-its-the-gearbox.160142/page-14#post-3055300

I have not yet had time to open the old gearbox to see what was wrong with it, but my guess is one of the bolts on the large differential gear came undone until it started hitting the intermediate gear.
 
Howdy Simon, didn't know that you had bought a laef and were on this forum, but good work to swap out the gear box. i'm definitely interested in the root cause of the noise since i've been driving a 2012 during the pandemic. It is so comfortable that kiev just sits and waits until needed...
 
nlspace said:
Howdy Simon, didn't know that you had bought a laef and were on this forum, but good work to swap out the gear box. i'm definitely interested in the root cause of the noise since i've been driving a 2012 during the pandemic. It is so comfortable that kiev just sits and waits until needed...
Yes, I traded the Ion in for the Leaf in July 2020 during the pandemic. The Leaf is a far better car but it hasn't been smooth sailing.

I was pretty gutted to have the gearbox fail at 35k miles however thankfully that is now fixed. All up it has ended up costing me about £1300 to repair - £850 for a second hand 10k mile gearbox (new is £3500!) and the rest in tools/materials etc to do the work myself. (Had to buy some better equipment like a bigger floor jack, scissor lift for the gearbox etc)

I'm now about to replace the 12v battery which seems to be very sick to the point that it is causing weird issues with the climate/charge timers and loss of remote connectivity when the car is parked, due to the battery voltage dipping too low. It looks like the original 5 year old 12v battery and it also suffered a very deep discharge while the car was off the road so that probably finished it off.
 
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