I lived with the buzz for 10k+ mi, then got DU replacement. I would never say I had a DU "failure." The vehicle always ran fine. Never failed me. Never a stall, like an ICE vehicle did. Never would it not start up and go. It just buzzed, that is, it made noise.
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Drive Unit Replacement Poll
- Thread starter nleggatt
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- Driving Dynamics Model S
I lived with the buzz for 10k+ mi, then got DU replacement. I would never say I had a DU "failure." The vehicle always ran fine. Never failed me. Never a stall, like an ICE vehicle did. Never would it not start up and go. It just buzzed, that is, it made noise.
rxlawdude
Active Member
Re-whatevered* drive unit installed yesterday. Nice and quiet! Excellent service as usual from Chicago service center, including timely updates on progress during the day. For the doomsday crowd, I suspect mine was "cosmetic" rather than any threat of on-the-road failure... noise on load that grew over the last year.
FWIW part 1025598-00-P marked RMN, so I assume re-whatevered*. Who knows, maybe the donor is reading this!
* Refurbish and remanufacture are synonyms, but not worth fighting over...
FWIW part 1025598-00-P marked RMN, so I assume re-whatevered*. Who knows, maybe the donor is reading this!
* Refurbish and remanufacture are synonyms, but not worth fighting over...
mknox
Well-Known Member
I'm still waiting for mine... my noise is also getting louder, but my SC has assured me it is just a "cosmetic" problem and I'm certainly not worried about any impending failure. Would be interesting to understand the root cause of these problems, however. Doubt Tesla will ever say.
Forty Creek
Member
I'm waiting for the results of the sound check. The sound is growing louder as well.
Question from a non-EE
You EEs plz forgive me if this is silly question. I just had drive unit replaced. WH/mi seems up over equivalent trips. As I recall, when I first got car, it was difficult to crack 290 in summer for my typical mix. Before new drive unit, I was doing 270 easy. Now with new unit it's back above 290. I know tires, alignment, firmware, inflation weather, wind all have impact. But is there any plausible reason a drive unit could get more efficient with use???
PS, not complainin, car sounds and runs like new!
You EEs plz forgive me if this is silly question. I just had drive unit replaced. WH/mi seems up over equivalent trips. As I recall, when I first got car, it was difficult to crack 290 in summer for my typical mix. Before new drive unit, I was doing 270 easy. Now with new unit it's back above 290. I know tires, alignment, firmware, inflation weather, wind all have impact. But is there any plausible reason a drive unit could get more efficient with use???
PS, not complainin, car sounds and runs like new!
After my recent replacement, I noticed a significant drop in energy consumption on similar routes. However, I also noticed a huge increase in consumption at higher speeds. I know that when they do a DU replacement, they do a realignment. It appears that in my case, the front wasn't properly aligned. Still pending, as I just returned from a road trip, but my front tires that were fine before the trip are now flaking terribly at the edges, and will likely need replacement. Rears are the same as before the trip, with plenty of tread.
I believe the alignment has a much greater impact than any variation in DU, but that's just a guess.
There is no way this is "merely cosmetic". The mere fact that the noise is developing over time indicates that some part is *wearing* which isn't supposed to be wearing.
It looks like it's the sort of thing which slowly gets worse and which *eventually* causes drivetrain failure, but only after a *really long time*.
Best hypothesis I've seen for the "milling" or "cicada" sound is from kennybobby, who looked at the video of the drivetrain construction and has a very likely hypothesis.
Drive unit problems explanation by Elon - Page 16
I think it's going to require a redesign to make the drivetrain last more miles. I think this is totally affordable for Tesla and that it should be straightforward to swap new units in; it'll just be an unwelcome one-time cost. The drivetrain is actually a pretty small fraction of the cost of the car, it's not like the engine on an ICE car, so it's not going to sink the company or anything.
It's worth noting that a previous noise was diagnosed as the main pack contactor bouncing, arcing and melting, that this *eventually* caused drivetrain failures (after a lot of driving), and that Tesla has redesigned the contactor (at minimal added manufacturing cost). It's not appropriate to downplay these issues, they are important, but once they're diagnosed, they're also not likely to be huge financial hits to the company. The whole idea of Tesla's business model is to work out and solve bugs like this (which show up after 20,000 miles) with the Roadster or Model S, in small release quantities on a high margin car, so that they're completely solved before Model 3 is designed.
It looks like it's the sort of thing which slowly gets worse and which *eventually* causes drivetrain failure, but only after a *really long time*.
Best hypothesis I've seen for the "milling" or "cicada" sound is from kennybobby, who looked at the video of the drivetrain construction and has a very likely hypothesis.
Drive unit problems explanation by Elon - Page 16
I think it's going to require a redesign to make the drivetrain last more miles. I think this is totally affordable for Tesla and that it should be straightforward to swap new units in; it'll just be an unwelcome one-time cost. The drivetrain is actually a pretty small fraction of the cost of the car, it's not like the engine on an ICE car, so it's not going to sink the company or anything.
It's worth noting that a previous noise was diagnosed as the main pack contactor bouncing, arcing and melting, that this *eventually* caused drivetrain failures (after a lot of driving), and that Tesla has redesigned the contactor (at minimal added manufacturing cost). It's not appropriate to downplay these issues, they are important, but once they're diagnosed, they're also not likely to be huge financial hits to the company. The whole idea of Tesla's business model is to work out and solve bugs like this (which show up after 20,000 miles) with the Roadster or Model S, in small release quantities on a high margin car, so that they're completely solved before Model 3 is designed.
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mknox
Well-Known Member
I have no way of knowing for sure, but that is what I've been told. To me, it sounds "electrical" and not "mechanical". Mine is now "buzzing" quite loudly... I can hear it with the windows open reflecting off surfaces like curbs and such outside of the car. It is only there under power and not when "coasting" near zero or under re-gen. It could simply be a loose winding in the inverter or motor vibrating to the ac current.
Seems kind of extreme to say "no way" as if that were fact! Who knows? Regardless, there's 8 year warranty, so not a big worry for owners.
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Update on the above - must have been an aberration. After a week, consumption seems pretty close to prior.
Gizmotoy
Active Member
I had my drive unit replaced back in February because it was clunking very badly in low speed transitions between consumption and regen. This weekend I noticed the clunking has returned. It sounds about as loud as it was when my car was first delivered in 2013, but not as bad as it was when it was replaced earlier this year. I was really hoping they'd fixed this. :crying:
I did get about 6 months of perfect, silent, driving, though.
I did get about 6 months of perfect, silent, driving, though.
Could be electrical, in which case it's probably even cheaper to fix/redesign. It's still a case of something wearing when it shouldn't, which isn't "cosmetic". I'm not saying it's serious, I'm just saying it has long-term functional implications.
Electricfan
Active Member
Your description sounds like a perfect fit for mine. It started a couple weeks ago. Took it in to get it checked today and now I have a replacement scheduled 10/21. He said it was caused by electricity shorting through the bearings. I didn't mind the sound at all and only took it in to make sure it wasn't serious, but I guess it is serious or they wouldn't want to replace the drive unit. I drove it while it was making this noise on a 2400 mile trip last week. My car was delivered 4 months ago and I estimate the noise started at about 8000 miles.
ArtInCT
Always Learning
Why is the ZERO drive replacements choice missing from this poll? Can someone explain this critical poll design oversight?
Because the OP had his replaced and was only interested in " who else has had theirs replaced? how many times?", so zero wouldn't make any sense.
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Author is not understanding a) that Tesla has elected to exchange drivetrains (and re-manufacture centrally) rather than have Service Centers fix them. The work done to repair is probably more equivalent to a new head gasket than an engine/transmission replacement but appears to be more because unit is shipped back to factory, and b) that Tesla remanufactures and re-uses the drivetrains, so the hit on their bottom line is not the total cost of each drive unit needing repair.
While drive unit repair is something to stay attentive to, I believe it is incorrect to equate it to engine/transmission replacement, and also incorrect to extrapolate its impact on post-warranty costs or Tesla earnings AT THIS TIME. If Tesla does not either provide service-free drive units, or begin less-expensive SC-based repairs within 2 years (5 years into S rollout), then I think we should start to get concerned.
PS: Author is also distorting by quoting trudelta, which only has 150 cars in its database, and is therefore not a statistical sample. As we all know, on-line ratings skew towards too-high (planted) or too-low (only the gripers) when the sample size is small.
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Also fails to mention that the majority of drive unit replacements are not due to failure. Both of my drive units were replaced due to noise, not failure to operate, which to me at least, is a big difference. True Delta proponents seem to only show up in threads like this, where people are discussing problems (I believe a similar thread is where I heard about it), so I assume it tends to attract those who have issues.
I noticed the very small sample size on truedelta as well, not to mention the selection bias and non-reporting biases it has. Funny that someone on an investing website (seekingalpha) would have such poor statistical skills. Maybe that's why they're blogging instead of trading.
jrickard
Member
I might suggest a possible cause for these geardrive bearing issues.
AC induction motors are a bit peculiar. The field in the rotor is the result of currents "induced" by the field in the stator windings. But this obviously causes a bit of voltage differential between the rotor and frame ground.
As a result, most AC motors suffer from some currents through the bearings of the motor from the rotor shaft to the case. This can cause wear on the bearings.
I have it on pretty good authority that Tesla cunningly used ceramic bearings on their motor. This prevents the flow of current from the shaft to the motor case and so the bearings do not develop pits and spawling from the currents.
Pretty nice fix. But it may well have simply moved the problem. The rotor shaft is of course terminated with a gear into the gear box. And so that same voltage potential would be transfered. Unfortunately, the bearings in the GEARBOX are not ceramic. And so the current flow is simply moved to THAT path between drivetrain and case instead of at the motor. These currents eat away at the gearbox bearings.
Again, I cannot provide attribution for this, on pain of a horrible death. But it would appear that Tesla is looking at some other options, including a rather expensive brush solution. In this scenario, a largely silver composite "brush" rides on the shaft and is connected to the case - providing a path for these currents and of course the wear is then on the brush. Again, this is being tested, not currently implemented.
This is all the ravings of a delusional mind of course. A bit of info gleaned here and a bit there combined with a too active imagination. But it rather neatly summarizes and accounts for what is known about the problem.
Jack Rickard
EVTV Motor Verks - Custom Electric Car Conversion Instructional Videos
AC induction motors are a bit peculiar. The field in the rotor is the result of currents "induced" by the field in the stator windings. But this obviously causes a bit of voltage differential between the rotor and frame ground.
As a result, most AC motors suffer from some currents through the bearings of the motor from the rotor shaft to the case. This can cause wear on the bearings.
I have it on pretty good authority that Tesla cunningly used ceramic bearings on their motor. This prevents the flow of current from the shaft to the motor case and so the bearings do not develop pits and spawling from the currents.
Pretty nice fix. But it may well have simply moved the problem. The rotor shaft is of course terminated with a gear into the gear box. And so that same voltage potential would be transfered. Unfortunately, the bearings in the GEARBOX are not ceramic. And so the current flow is simply moved to THAT path between drivetrain and case instead of at the motor. These currents eat away at the gearbox bearings.
Again, I cannot provide attribution for this, on pain of a horrible death. But it would appear that Tesla is looking at some other options, including a rather expensive brush solution. In this scenario, a largely silver composite "brush" rides on the shaft and is connected to the case - providing a path for these currents and of course the wear is then on the brush. Again, this is being tested, not currently implemented.
This is all the ravings of a delusional mind of course. A bit of info gleaned here and a bit there combined with a too active imagination. But it rather neatly summarizes and accounts for what is known about the problem.
Jack Rickard
EVTV Motor Verks - Custom Electric Car Conversion Instructional Videos
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