Disappointed (gearbox replacements)

[R P]

I can assure you I am not an aggressive driver. I rarely tromp it, and almost all my driving is in ECO mode.

 

[KiwiME]

Yes, the Kona's advertised motor torque of 40.3 kg-m exceeds the rating of all those offerings. I can only assume that the published ratings are for continuous duty based on heat dissipation while the allowable maximum intermittent torque is higher, based on structural strength. That would typically be how a gearbox is rated.

I'll just note that the advertised eNiro gear ratio matches the G1F30 model but photos I've seen of a replacement eNiro gearbox look the same as what's in the Kona. There's certainly no reason why a different ratio couldn't be fitted, or it's simply an error in the Niro specifications.

It seems to me that this failure is due solely to a defective bearing rather than a fundamental gearbox design flaw. But, bearings normally have very tightly controlled quality and this sort of failure mode is puzzling and not mentioned in any forensic analysis guide I've seen.

I tend to agree that the more common clicking issue is a separate defect as the connection with motor replacements is convincing evidence.

 

[ericy]

Yep, tapered rollers on the final drive seen out of place in this design, especially since helical spur gears are used rather than hypoid which require tight axial retention. Certainly the axial loading due to the helical-cut gears is at a maximum on this particular shaft where the torque is highest but larger ball bearings would be the correct choice as they don't require a precise preload, not easy to set prior to the cases being closed up. Plus the aluminium cases are not very rigid axially and a suitable preload of perhaps several 10s of kg might not be maintained over the entire life. Tapered rollers must run with enough axial preload to keep the rollers geometrically in place when under maximum radial load. Mentioning the Chevy Bolt, they also got the primary shaft bearing arrangement correct as well, all following good design practices.

After sleeping on it, I have one further thought. One missing roller shouldn't have caused as much slop as we were seeing when he was pushing on the thing with a wrench. The adjacent rollers still ought to have been able to prevent any side-to-side movement.

In fact, I am wondering if with the amount of slop seen in the video, that the thing simply fell out after the gearbox had been assembled (no idea when or where it ended up). Any preload that may have been present at one time seems like it is long gone.

 

[KiwiME]

The epic amount of radial play must have come from the inner raceway wearing down, as he seems to be showing us. That would also explain why the volume of metallic debris seemed to be far more than one roller's worth.

 

[ericy]

The epic amount of radial play must have come from the inner raceway wearing down, as he seems to be showing us. That would also explain why the volume of metallic debris seemed to be far more than one roller's worth.

Could it just be that the seal between the half-shaft and the gearbox failed to keep some amount of dirt from getting into the gearbox?

 

[KiwiME]

Well, rolling element bearings are fairly resistant to debris, even if dirt could get in. As you can see the ball bearings appear to have survived all that (presumed hardened) steel running around in the oil. Hydrodynamic ('plain') bearings on the other hand (used in ICE engines as I'm sure you're aware) die very quickly when particles are present.

 

[Igor]

Доброго времени суток друзья, хочу внести некоторую ясность в видео с ремонтом КПП. Мастер в поисках причины снял с конического подшипника один ролик и обнаружил износ внутренней обоймы, сделав вывод, что это результат некачественного металла. Я нашел координаты этого мастера и пытаюсь установить с ним связь и позаимствовать ремонтные процессы.

 

[Genevamech]

Доброго времени суток друзья, хочу внести некоторую ясность в видео с ремонтом КПП. Мастер в поисках причины снял с конического подшипника один ролик и обнаружил износ внутренней обоймы, сделав вывод, что это результат некачественного металла. Я нашел координаты этого мастера и пытаюсь установить с ним связь и позаимствовать ремонтные процессы.

Good day friends, I want to bring some clarity to the video with the checkpoint repair. The foreman, in search of the cause, removed one roller from the tapered bearing and found wear on the inner race, concluding that this was the result of poor-quality metal. I have found the coordinates of this master and am trying to communicate with him and borrow repair processes.

Mystery solved; Thank you! (Спасибо большое)

 

[Jamas]

Доброго времени суток друзья, хочу внести некоторую ясность в видео с ремонтом КПП. Мастер в поисках причины снял с конического подшипника один ролик и обнаружил износ внутренней обоймы, сделав вывод, что это результат некачественного металла. Я нашел координаты этого мастера и пытаюсь установить с ним связь и позаимствовать ремонтные процессы.

From Google Translate:

Good day friends, I want to bring some clarity to the video with the checkpoint repair. The foreman, in search of the cause, removed one roller from the tapered bearing and found wear on the inner race, concluding that this was the result of poor-quality metal. I have found the coordinates of this master and am trying to communicate with him and borrow repair processes.

 

[evchina]

Hi guys, this is Sandrae’s hubby.
I noticed a transmission noise about three weeks ago, once it was warmed up and on acceleration. No biggy but it was beginning to bug me!! Last week, coming back into town, I noticed a clicking sound at low speed (pulling away from traffic lights). The faster I went it then changed to a low rumble, then at 50km/h became the transmission whine I’d noticed before.
I immediately took it in to the local dealership, a mechanic accompanied me while I demonstrated the issue. When they hooked up the diagnostic equipment everything checked out, so they contacted tech support ‘hytech’, who told them to replace the ‘gear reducer’, which my dealership said was the Gear Reduction Assembly. I’m now waiting for the assy to arrive.
Hope this has answered some of your questions.

I'm a KONA EV owner from China.I think my car has the same problem with you.I can hear the noise,a sound not the motor,not the tires.I have gone to the dealership,but there is no fault code。Kona EV in China named Encino,options have some difference

 

[electriceddy]

I'm a KONA EV owner from China.I think my car has the same problem with you.I can hear the noise,a sound not the motor,not the tires.I have gone to the dealership,but there is no fault code。Kona EV in China named Encino,options have some difference

Obviously the major difference between Kona EV in China and other parts of the world is the battery pack manufacturers - CATL for China ~ 180 wh/kg where the LG is around 150 wh/kg, note these values are from 2018/19
https://electricrevs.com/2018/03/09/jaguar-and-chevy-have-lg-in-common/
and
https://www.greencarreports.com/news/1125058_catl-considers-us-plant-targets-45-percent-energy-density-boost-in-5-years#:~:text=It can now accomplish more,45 percent improvement—by 2024.
Note; current info brings those values higher (2020)
with CATL leading the pack (pardon the pun) @ 279 wh/kg, SK Innovation @ 269 wh/kg, and LG @ 257 wh/kg:
https://insideevs.com/news/428511/china-battery-energy-density-280-wh-kg/#:~:text=SK Innovation cells: 269.44 Wh,kg in Tesla Model 3