Clunking Vibration type sound

[KiwiME]

Thanks for the vote of confidence. Hyundai's engineers must be on track to understanding the issues by now and they have the advantage of seeing all the evidence and statistics, nevermind having the accountants on their backs.

It remains puzzling as to what exactly causes the ticking noise and what role the motor plays. I find it hard to believe that the motor could flex on what appears to be considerably-strong mounts but it also can't be ruled out, and you'll note the scoring appears at the inner edge of the raceway housing, which could indicate some sort of misalignment. Otherwise, it's entirely possible that the motor changes (if any) were due to them thinking that was the problem. Reports of metal slivers in the confined area between the motor and gearbox need to be explained as well, as does the one case in Poland of a catastrophic gearbox failure a few days after the noise appeared.

The black oil might look bad but I don't think it's harmful to hardened steel gears or bearings. It's much like polishing aluminium with a fine abrasive, the rag turns black. But several cases have reported 'metal' particles in the oil, more of a worry and harder to explain.

But, it's not by chance that Tesla and Chevrolet's Bolt both use a different design in that area. They seemed to have better understood the pitfalls.

 

[ericy]

It remains puzzling as to what exactly causes the ticking noise and what role the motor plays. I find it hard to believe that the motor could flex on what appears to be considerably-strong mounts but it also can't be ruled out, and you'll note the scoring appears at the inner edge of the raceway housing, which could indicate some sort of misalignment. Otherwise, it's entirely possible that the motor changes (if any) were due to them thinking that was the problem. Reports of metal slivers in the confined area between the motor and gearbox need to be explained as well, as does the one case in Poland of a catastrophic gearbox failure a few days after the noise appeared.

The black oil might look bad but I don't think it's harmful to hardened steel gears or bearings. It's much like polishing aluminium with a fine abrasive, the rag turns black. But several cases have reported 'metal' particles in the oil, more of a worry and harder to explain.

I can't help but wonder if small metal particles get into the bearings, and this is what causes the ticking noise. If I had a failed unit in front of me, I would turn the bearings in my hand to see if they still turn completely smoothly. But this is just a guess as to a possible explanation.

An ATF usually has a fluid filter of some sort to catch small particles. It is still not ideal to have metal bits floating around in there, but if you can filter them out before they get in somewhere else, it would limit the damange. Do we know if Bolt Tesla have such a filter?

 

[R P]

Yeah, but why is it so temperature dependent? Once my car warms up, no ticking noise. Maybe when the metal warms up, everything gets pulled together more tightly?

 

[electriceddy]

Yeah, but why is it so temperature dependent? Once my car warms up, no ticking noise. Maybe when the metal warms up, everything gets pulled together more tightly?

The thing that blows me away is my Kona EV no longer produces the tapping sound in forward (since the weather change) but consistently (I mean like every morning) does it in reverse when backing out of my driveway.
It will not reproduce later in the day when reversing.
I guess that is some kind of improvement, but for how long is anybody's guess.

 

[R P]

And mine now seems to do it only on decelerating when almost coming to a stop. Before it was during gentle acceleration.

 

[KiwiME]

I can't help but wonder if small metal particles get into the bearings, and this is what causes the ticking noise...
An ATF usually has a fluid filter of some sort to catch small particles. It is still not ideal to have metal bits floating around in there, but if you can filter them out before they get in somewhere else, it would limit the damage. Do we know if Bolt Tesla have such a filter?

Particles in ball bearings tends to make them rumble rather than tick, but severe damage to the ball cage can cause clicking, as can a loose fit in the housing, noting that the tick has been reported to be once per motor revolution.
The Model 3 transmission has an oil filter as seen in Sandy Munro's YouTube teardown videos. Generally, at minimum it's customary to have a magnet in transmissions to accumulate ferrous particles but I didn't see one in the Kona photos.

Yeah, but why is it so temperature dependent? Once my car warms up, no ticking noise. Maybe when the metal warms up, everything gets pulled together more tightly?

Well, aluminium expands more than steel so the housing may may things looser with warmth. My guess is that the cold, more viscous oil causes more drag and that may affect the issue. The bearing in question is spinning at around 6,000 rpm plus at highway speed and even the thin GL70 gear oil can be quite thick when cold. Gearboxes often have features that guide the oil away from the gears to reduce drag and subsequent heating. Bearings sometimes have shields to keep oil from flooding the raceways for the same reason. I'm guessing that the reason the Tesla has a filter is because oil is pumped around to the various items needing oil in a measured way to improve efficiency and it may go through a cooler as well.

 

[hobbit]

Yeah, I noted the motor-shaft area shine too, but the picture quality was such that
there also seems to be some "fatigued" unevenness in that near conical race and a
weird roughened texture on the differential part. One of our Prius training sessions
included something like that, a gen-1 transaxle that had eaten itself. Here, maybe
it's a bunch of stuff if dirt got in there. Would the unrestrained motor bearing race
make that rapid "takatakataka" sound we've heard in peoples' recordings, or something
more like an occasional screech?

Next time I have the front end in the air I'm definitely going to pop the fill plug on
my gearbox and have a look at the fluid... but at still less than 5000 miles, not
sure what I should expect to find.

_H*

 

[Jamas]

I took my car for a long(ish) drive today for the first time in a while. It was quiet at first, but after about five miles of driving, I starting hearing the high pitched sound when accelerating over 25 MPH. I pulled into a parking lot and started accelerating slowly (below 10 MPH) and heard the clicking noise clear as day. Could be my imagination, but it's actually sounding louder. This morning's ambient temp was 64 F.

I love this car. I just wish they could figure this out once and for all so that I can enjoy the car and not keep stressing out every time I go for a drive.

 

[R P]

I bought this car all cash, thinking that I may want to keep it a long time. After all, this is not Hyundai's first EV, so thought they were past the initial new technology bugs. And aren't electric motors/drivetrains supposed to be a lot simpler than ICE ones? Now I wish I would have leased it, and not have to worry about resale value after 5 years. This was my first ever Hyundai, and might be my last...

I have had 4 Subaru's in the past (still own one), and all have gone to very high mileage with no problems, and were still running strong when sold. And not to mention how much better they are with driver assist and other driving technology (best AWD). But they didn't have an EV yet. I also owned a Prius, before the Kona, which was a good car as well. But did own crappy Ford, Chrysler and GM products, and basically swore off those. Was really hoping for better from Hyundai. But this clicking problem and inability to solve it, has really shaken my confidence in this company.

 

[ericy]

I came to the Kona indirectly from a VW TDI (I had a brief interlude in a Volvo V60). I ultimately sold the car back to VW for more than I paid for it after having driven it for 2 years, so that was a win. But VW was pushing the limit in many ways with these cars. The high-pressure fuel pump would "grenade" in some cases, which is almost as bad as it sounds - there would be metal fragments that would get into the fuel system all over the place, and one not only needed to replace the HPFP, but also clean the entire fuel system (fuel tank, fuel lines - everything). It didn't happen to me, but I wasn't keen about waiting to see if it would happen. When the dieselgate exit-ramp appeared for me, I took the opportunity.

Before that, my wife had a "PD" TDI car - that had different issues. VW was trying to boost injection pressure, and they needed to add a 3rd lobe to the camshaft so they could drive the injectors. In order to make room they had to narrow the existing lobes. This increased stresses and the camshafts and lifters tended to wear out. I had a mechanic who could replace the thing for me without having to get the dealer involved.

My wife still has a VW TDI - a 2015, that so far seems to be doing OK.

At the moment I am not too worried about the Kona - I still have warranty for quite a while. Even if Hyundai doesn't come up with something in the next couple of years, I imagine that there would eventually be aftermarket kits with replacement parts to repair these things. The actual reduction gear isn't a horribly complicated thing (nothing at all like an automatic transmission), so getting it repaired without involving the dealer doesn't seem out of the question.

The only concern I have is that Hyundai and Kia aren't selling all that many of these things, so there isn't much incentive for anyone to make aftermarket parts. If you needed to order a reduction gear from Hyundai, you seem to have to not only pay $$$, but wait for 3 months or more for the thing to get there.

 

[electriceddy]

Yeah, I noted the motor-shaft area shine too, but the picture quality was such that
there also seems to be some "fatigued" unevenness in that near conical race and a
weird roughened texture on the differential part. One of our Prius training sessions
included something like that, a gen-1 transaxle that had eaten itself. Here, maybe
it's a bunch of stuff if dirt got in there. Would the unrestrained motor bearing race
make that rapid "takatakataka" sound we've heard in peoples' recordings, or something
more like an occasional screech?

Next time I have the front end in the air I'm definitely going to pop the fill plug on
my gearbox and have a look at the fluid... but at still less than 5000 miles, not
sure what I should expect to find.

_H*

Be sure to include detailed pictures in your blog for us "less mechanically proficient" folks

 

[KiwiME]

...Would the unrestrained motor bearing race
make that rapid "takatakataka" sound we've heard in peoples' recordings, or something
more like an occasional screech?
Next time I have the front end in the air I'm definitely going to pop the fill plug on
my gearbox and have a look at the fluid... but at still less than 5000 miles, not
sure what I should expect to find._H*

Very hard to say, per the noise, most likely it's well-enough lubricated that it would be inaudible.
While you're under the car, if you have a traditional compass you might be able to confirm the presence (or otherwise) of a sump magnet.

 

[electriceddy]

Very hard to say, per the noise, most likely it's well-enough lubricated that it would be inaudible.
While you're under the car, if you have a traditional compass you might be able to confirm the presence (or otherwise) of a sump magnet.

Just thought I would mention when I click on your location under the avatar it takes me to this place:
https://www.google.com/maps/place/S...ad0414ae7e8203!8m2!3d43.9708911!4d-79.2808255
Maybe I should have filed this under the forum issues thread but I thought I would give you the heads up

 

[wizziwig]

I just wish they could figure this out once and for all so that I can enjoy the car and not keep stressing out every time I go for a drive.

Give them some time. They've only been building them since September 2017.

I bought this car all cash, thinking that I may want to keep it a long time. After all, this is not Hyundai's first EV, so thought they were past the initial new technology bugs. And aren't electric motors/drivetrains supposed to be a lot simpler than ICE ones? Now I wish I would have leased it, and not have to worry about resale value after 5 years. This was my first ever Hyundai, and might be my last...

If you do some googling, you'll find that the Ioniq Electric had its own share of gearbox and motor problems. Main difference is it usually took many more miles to start. Maybe because it was a much less powerful motor and virtually zero sales (at last here in USA). With the Kona/Niro, some are getting the problem virtually driving the car off the dealer lot.

I can't help but be reminded by Sandy Munro's repeated comments that legacy car makers are "not serious about EVs". Case in point right here.

 

[Rick2020Kona]

Update on the noise from my 2020Kona EV Ultimate - 6,000K:
Hyundai Canada is replacing the motor with the New 701 series motor and they will be checking the gear reduction drive to see if it require replacement also. I was given a ICE Kona as a loaner.
The dealership & Hyundai have been very good.


Sent from my iPad using Inside EVs

 

[R P]

Where are you located and what dealership?

 

[ericy]

Very hard to say, per the noise, most likely it's well-enough lubricated that it would be inaudible.
While you're under the car, if you have a traditional compass you might be able to confirm the presence (or otherwise) of a sump magnet.

The pictures from Korea say that there is a cover over the engine area that might need to be removed before you could get close enough to really test something with a compass.

I was thinking a bit about the actual noise that people are hearing - specifically the frequency of the "thumping". The frequency would seem to match the speed at which the final drive would rotate (i.e. the rotational speed of the axles and tires), and not the rotational speed of the motor itself and the spline.

My thinking is this. At 60mph, tires would rotate at about 800 RPM - the reduction gear has roughly an 8:1 ratio, so at this speed the motor shaft itself would be rotating at 6400RPM at this speed - to the human ear 6400 RPM would be a deep humming noise (106Hz), whereas something going wrong at 800RPM wouldn't be audible as a tone (13Hz), but would sound more like rapid tapping noise, and this seems closer to what people are reporting.

Don't know what to make of this - just an observation....

 

[KiwiME]

So, the cover being refered to is under the gearbox and the magnet would be typically located at or near the bottom of the aluminium casing. It should be readily detectable with an old-fashioned compass. Not that this will resolve the noise issue ...
I thought I had read a calculation earlier where the ticking frequency was found to be once per motor shaft rotation but haven't looked into it any further. Most drivers know what a stone in the tire tread sounds like so that should be a good reference for someone whose Kona has this noise. Frankly, I'm unsure how a bearing would make a 'ticking' when 'knocking' is more what I would expect, much like a big-end bearing in an engine. There is also the possibility that the noise frequency is more or less than once per revolution of the damaged part. Ball cage problems can be once per 2 revs, raceway damage several times per rev. Gear problems at tooth meshing frequency, etc.

 

[R P]

Could it be something simple like mating bolts need to be retorqued? When it warms up, they tighten up themselves, and thus no ticking. The ticking might be the fretting between the mating surfaces when they loosen up. Just my uneducated speculation...

 

[ericy]

I thought I had read a calculation earlier where the ticking frequency was found to be once per motor shaft rotation but haven't looked into it any further. Most drivers know what a stone in the tire tread sounds like so that should be a good reference for someone whose Kona has this noise. Frankly, I'm unsure how a bearing would make a 'ticking' when 'knocking' is more what I would expect, much like a big-end bearing in an engine. There is also the possibility that the noise frequency is more or less than once per revolution of the damaged part. Ball cage problems can be once per 2 revs, raceway damage several times per rev. Gear problems at tooth meshing frequency, etc.

The basic calculation for how fast a car tire rotates is pretty easy.

http://www.csgnetwork.com/tirerevforcecalc.html

At 60mph, you get about 750 RPM. Depends on the tire, of course - that's another issue, but this is really just a rough back-of-the envelope calculation. Anyways that's about 12.5 rotations per second if you are going 60mph. I don't know how fast people were going when they made the recordings.

The reduction gear has a ratio of something like 7.9, so the motor itself turns that much faster. About 100 rotations per second.