100% drive unit failure rate??

[deonb]

If this can't be accommodated with a more appropriate bearing, the fix should be to use a hearingbone gear. I can imagine with the repair costs continuing to ramp, that Tesla is looking real hard at this to determine when a major design change needs to be implemented.

Explain how a herringbone gear is a substitute for a bearing? I've used both, many times. I can't imagine substituting one for the other.

 

[wdolson]

My current car is a 23 1/2 year old Buick I bought new in 1992. I did have to replace the catalytic converter a while back, but it still has the original radiator and transmission, as well as the original starter, water pump, and air conditioner unit. I did have to replace the alternator at 6 1/2 years, it went before the original battery.

I've read about the milling noise complaints, but finding a recording of it wasn't easy. I did finally find this: https://www.youtube.com/watch?v=FrOixtfh4H8&app=desktop

I've had to debug some very strange problems encountered in the field. I'm chasing one right now that only happens on one system in South Korea. Sometimes it can be tough to run a problem to ground and sometimes there are actually multiple things going on that can have the same symptoms.

Micropitting in the bearings from stray currents could be a problem. Stray ground currents is one of those topics that can get so complex people write doctorate dissertations about them. I had a colleague try to introduce me to the topic once and I delved into it deep enough to know it was one of those things you either base your entire career on as an expert in the field, or you find an expert in the field to troubleshoot anything beyond the basic ground problems. With the levels of currents going through the motor, especially at high acceleration, keeping the current going where you want it to go is tricky. If you try to isolate currents with insulators without doing it right, you could end up creating capacitors within the motor, which is a whole other problem. High currents could also eat through insulators over time.

It would be interesting to know the characteristics of the cars and drivers who are seeing the problems. Do they tend to be performance drivers who tend to drive with more aggressive throttle, or some other identifiable characteristic, or does it happen more randomly? It obviously isn't one batch of drive units. If the problem isn't the bearings, but is something in the electronics, what are the batches on the electronic parts that are in bad drive units compared to the batches in other units?

Counterfeit parts is a serious problem in the electronics business. Even big companies have been bitten. A few years back several LCD monitor makers got bitten with counterfeit capacitors and had a lot of failures in the field. I had a high end Viewsonic that I resurrected by replacing the capacitors. Even non-counterfeit parts can have problems. I ran into one problem years ago where one batch of parts in a box going on aircraft was bad and only failed under certain conditions.

 

[vortexz]

what does a MS DU consist of ?

 

[HVM]

If reason for noise is the bearings, whole UT is not destroyed and only those bearings needs to be change. If it's lose stator windings then it practically is.


Stator:

Bearings:

Inverter:

 

[brantse]

This, I was going to add information along these lines to this thread if nobody else had..

I was told similar. The milling sound has to do with micro-pitting of metal bearings as caused by high frequency high power transmission through them. Induced eddy currents of the massively powerful motor generating a lot of magnetic flux creates current in parts that don't need to have current in them. Like bearings. That chatter under load with power applied.

This makes a lot of sense, and based on all the theories I've read about, I'd put my money on this. I know that most stationary motors that get retrofitted with VFD's should always be fitted with a motor shaft grounding ring, for this exact reason. http://www.est-aegis.com/ASHRAE_Paper-Shaft%20Grounding-A_Solution_To_Motor_Bearing_Currents.pdf

 

[brantse]

Explain how a herringbone gear is a substitute for a bearing? I've used both, many times. I can't imagine substituting one for the other.

Sorry, not a replacement of the bearing with a gear...a swap from a standard single cut helical - axially loaded gear to a herringbone gear. The herringbone (double helical) gear is intentionally designed and used to eliminate resulting axial forces.

 

[mknox]

The cars with high mileage that dont make the milling sound have drivers with VHF hearing loss and/or always drive with the windows up

Well, mine is loud enough to hear easily with the windows up. Passengers ask me what the noise is. Pedestrians on the street turn around to see what's coming as I drive through my neighborhood.

 

[ecarfan]

Because that is exactly how Tesla described it to me and they even wrote it like that directly in the service repair report that the milling noise is caused by a bearing problem.

I would like to publicly apologize to @yobigd20 for my snarky tone and for missing his post and @scottm's post saying they were told by Tesla that the "milling" sound was a bearing issue.
I read the explanations posted but have a difficult time truly understanding them, no doubt because I am a neurophysiologist, not an electrical engineer. I understand how the motor can produce currents in associated parts but not being a metallurgist do not understand how those currents can physically alter the surface of a bearing. That amazes me!
I hope those Tesla personnel who provided the explanations had accurate information. I am quite surprised that Tesla was willing to provide a fairly detailed explanation of a design problem. We don't usually get that.

 

[deonb]

Sorry, not a replacement of the bearing with a gear...a swap from a standard single cut helical - axially loaded gear to a herringbone gear. The herringbone (double helical) gear is intentionally designed and used to eliminate resulting axial forces.

I take it you mean the gear design change for the klunk problem and not the wirr problem?

 

[Joeviocoe]

Statistics

I am sure nobody bothered to go through all 369 survey results, to count.I wrote some javascript to do it for me:369 vehicles reported so far.Batteries:24 swapped from23 vehiclesChargers:23 swapped from19 vehiclesDrive Units:109 swapped from80 vehicles(many of the DU swapped were 3 or 4 times on the same car, I imagine its the same two units)https://openuserjs.org/scripts/Joeviocoe/Plugin_America

 

[brantse]

I take it you mean the gear design change for the klunk problem and not the wirr problem?

I meant for the wirr problem. If this is the failure mechanism (which I do not think it is), it would be as a result of the shaft's axial load causing the bearing to fail over time. In other words, the shaft is trying to push the inner race out of the bearing's outer race. Many bearings are not really designed to withstand significant axial loads.

 

[deonb]

I meant for the wirr problem. If this is the failure mechanism (which I do not think it is), it would be as a result of the shaft's axial load causing the bearing to fail over time. In other words, the shaft is trying to push the inner race out of the bearing's outer race. Many bearings are not really designed to withstand significant axial loads.

But the bearing wear is caused by EMF that is micro-pitting them. Not axial load. No?

 

[Joeviocoe]

Statistics

I am sure nobody bothered to go through all 369 survey results, to count.
I wrote some javascript to do it for me:


369 vehicles reported so far.
Batteries:
24 swapped from
23 vehicles


Chargers:
23 swapped from
19 vehicles


Drive Units:
109 swapped from
80 vehicles
(many of the DU swapped were 3 or 4 times on the same car, I imagine its the same two units)


And as it has been mentioned, the majority of the Drive Unit problems are on cars that well exceed 20,000 - 30,000 miles per year.

Plug In America
https://openuserjs.org/scripts/Joeviocoe/Plugin_America

 

[brantse]

But the bearing wear is caused by EMF that is micro-pitting them. Not axial load. No?

I don't know if anyone on here knows for certain, but the micro-pitting would be my choice theory. Not sure if the mechanism itself is EMF, however, but we're beginning to get into semantics. I think, similarly to much of the development with battery chemistries....many would agree that we really don't fully understand a lot of the minutia. Many of these things are being developed and tweaked somewhat on the fly, as results of design changes are monitored.

 

[Electricfan]

Well, mine is loud enough to hear easily with the windows up. Passengers ask me what the noise is. Pedestrians on the street turn around to see what's coming as I drive through my neighborhood.

Have you posted a recording of yours? Just curious if its like mine was. Don't understand why they haven't swapped yours out.

- - - Updated - - -

March 2015 build, drive unit started milling sound at 10,000 miles. Replaced at 12,000 or so miles. My previous S was a 2013 with no drive unit problem at 40,000 miles.

My case:

May 2015 build, drive unit started milling sound at 8,000 miles. Replaced at 12,000 or so miles. My previous S was a 2013 with no drive unit problem at 18,000 miles.

 

[mknox]

Have you posted a recording of yours? Just curious if its like mine was. Don't understand why they haven't swapped yours out.

They told me they would once they had the parts. That was over a year ago. At the time, they said they were working through a significant backlog of DU replacements and that most of the problems were with "P" cars. Mine is just a plain old 85.

 

[electracity]

They told me they would once they had the parts. That was over a year ago. At the time, they said they were working through a significant backlog of DU replacements and that most of the problems were with "P" cars. Mine is just a plain old 85.

If you tolerate the noise, obviously Tesla would rather wait and install the final solution (for lack of a better term). It seems to me they may have multiple problems, considering the higher mileage cars with multiple replacements. Obviously the DU on an EV should be nearly perfect. Talking about a million mile motor turns me off a bit considering they haven't taken care of all existing customers yet.

 

[Tslynk67]

Just to mention, as this is the relevant thread, that I got a new DU on Tuesday - this is my second replacement and I was told it a V2 redesign, totally new DU, not a revision:

Description du problème: Loud humming noise coming from front of vehicle while driving at
cruising speeds and above. Recording and toolbox session done.
Mode de paiement: Garantie
Corrections: Rear Drive Unit - Remove and Replace
Pièce Quantité Prix unitaire
ASY,P-TRAIN,SPORT,MECH,COMPLETE (1002633-01-P) 1.00 0.00 0.00
AUTOMATIC TRANSMISSION FLUID - DEXRON VI - SYNTHETIC
212B (1031106-00-A)
1.00 0.00 0.00
BOLT, M8-1.25x30MM, MATPOINT (1008722-00-A) 1.00 0.00 0.00
BOLT, M8-1.25x50MM, MATPOINT (1008724-00-B) 2.00 0.00 0.00
NUT HFPT M12x1.75 [10]-G720 (2007063-00-B) 2.00 0.00 0.00
LOCK WASHER ASSEMBLY M24x39 (1020296-00-A) 2.00 0.00 0.00
NUT, HEX FLANGE M24x1.5 (1020297-00-A) 2.00 0.00 0.00
HIGH VOLTAGE INVERTER ENCLOSURE COVER O-RING
(1003784-00-A)
2.00 0.00 0.00
SIDE MOTOR MOUNT ASSEMBLY (1028034-00-B) 1.00 0.00 0.00
CONN, CLIP.LCK, MNLC, 001, 023P, CBM,HSG (1017075-00-A) 1.00 0.00 0.00

 

[mknox]

If you tolerate the noise, obviously Tesla would rather wait and install the final solution (for lack of a better term).

And I'm kinda of the same mind. They told me it's just a "cosmetic" problem so I'm not worried about an imminent total failure, and it would be nice to have the "final solution". I just wonder if there will actually be a final solution. I keep reading/hearing about revisions to DUs, new service techniques and such, but the problems seem to persist.

 

[electracity]

Just to mention, as this is the relevant thread, that I got a new DU on Tuesday - this is my second replacement and I was told it a V2 redesign, totally new DU, not a revision:

Nice. Having V2 DU may become meaningful for resale value.