Kona, Niro, (original) Ioniq and Soul will benefit from a gear oil change

[KiwiME]

Thanks for the interest in my post. I popped by today because there have been some developments.

The latest news is that an Ioniq owner in Poland had to rebuild his gearbox due to noises and found bearing degradation. He also posted internal photos of the gearbox. As clear as day there is a ceramic magnet captured in the casing halves at the bottom of the sump. So, at least I know the designers aren't complete idiots.

But here's the kicker - it was reported by the owner that the magnet was clear of ferrous debris but the oil was black. The failed bearings were said to be "sticky", specifically those on the intermediate shaft.

And this is why I'm looking to hear some Leaf expertise: The Leaf gearbox has one item that the Hyundai/Kia doesn't - a grounding brush on the intermediate shaft. The Hyundai/Kia motor has a carbon brush on the motor shaft as it exits the drive-end bearing, nothing else.

So, here's the question: why is the Leaf ground brush on the intermediate shaft instead of the input shaft?

[shark]

Looking at the drains over in the leaf oil changes. The fluid looks about the same. Maybe a change early for the leaf would not hurt. I have seen ptus with dark oil like that with low miles also. Usually heat related. I don't think the leaf gets that hot though.

[SageBrush]

Oil color is not a good indicator of wear particles. An oil analysis tells the tale. Swapping out oil once early in the life of the car is easy enough in a LEAF, and hopefully so for Kia// owners that I would say anybody who bothers to ask the question should just do it.

As for the work involved in identifying and finding compatible extra magnets, I'd personally want an oil analysis to point me in that direction.

[goldbrick]

I'm all for the efficiency gains of using the lower viscosity fluid but I don't think I've ever heard of a single EV that failed due to a worn out transmission.

[nlspace]

...
So, here's the question: why is the Leaf ground brush on the intermediate shaft instead of the input shaft?

i would guess that it is easier to access the end of the i/m shaft versus right at the motor shaft, and as long as they are grounded to the same potential it doesn't matter

Plus it might be that more components are in the ground path to bleed off any stray charge or induced fields or eddy currents. Not sure how effective it is with bearings and oil films in the path.

[KiwiME]

I would expect the intermediate shaft to be the most insulated part of the gear train during operation, due to oil films. But I'd also expect stray currents to be handled first close to the source to reduce risk to the input shaft bearings. As I mentioned the Hyundai/Kia motor has a circular conductive brush on the output shaft but none at any other location as best as I can make out. Does anyone know if the Leaf motor has one?

Our three Kona UOA indicate:
kms / Fe / Al / Si / Ca / Zn / ISO
3700 / 95 / 46 / 50 / 2293 / 1760 / ISO: 24-21-14 /
15,600 / 195 / 145 / 65 / 2554 / 1488 / ISO:23-23-20 / 4u = 49892, 6u = 42956, 14u = 9204, 21u = 380, 38u = 22, 50u = 16
28,000 / 205 / 283 / 64 / 2635 / 1371

Essential data from two Leafs posted elsewhere on the forum, for comparison:
kms / Fe / Al / Si
20,090 / 91 / 130 / 63
107,870 / 120 / 36 / 34

[voltamps]

Well, the good news is, here in N. America at least (don't know about New Zealand, kiwiME...), Kia & Hyundai have a long 10 year / 100,000 mile (160,000 km) in case the gearbox starts making strange noises.

@KIwiME , Could it be possible Kia-Hyundai did not harden the gear wear surfaces and/or bearings in there enough? Lack of proper carbonitriding has caused a Ford Focus EV gearbox recall in my own experience, and I've heard of that problem popping up on some (VW?) cam surfaces in valvetrains.

Its easy to change the fluid on a Leaf, so I can do it just for fun at home really.
I will sort of copy what Hyundai-Kia specs with their GL-4 70W/75W at about 6 cSt (Mine will be Redline MT-LV all-POA at a similar 6.5 cSt kv100). GL-4 has more phosphorus for anti-wear than ATF (Matic S, Dex VI, etc) fluid does.

[KiwiME]

As I mentioned above I'm leaning towards shaft eddy currents being the root cause because if the single grounding brushed ring fails to work effectively the gearbox will deteriorate without leaving debris. A gear wear problem would result in metal debris.

In most countries, 96% of the global population, Hyundai/Kia only offer a 3 or 5 year warranty like many other brands. We did not suffer the Excel so they don't have to beg. My Kona EV warranty expired Oct 2021 with the exception of the battery which runs for another 5 years. It's in my best interest that the gearbox doesn't fail.

https://youtu.be/aAsG6SEQ8Qs

[voltamps]

As I mentioned above I'm leaning towards shaft eddy currents being the root cause

Earlier Teslas had that problem, I think it's similar(??). Somebody else on this forum told me about it, and I googled it a bit to get the story. Anyway, if you're interested, google terms: tesla bearing failure ceramic milling noises

Ceramic bearings are not conductive, allowing current to bypass the wear surfaces, if I understand that right.