2/3 drivetrains fail at 60,000 miles

2/3 drivetrains fail at 60,000 miles

I suspect the projection is based on Tesla being careful to investigate all weird noises in the interest of getting the drivetrains 'right' ... but on the surface this won't play well to people who don't know the whole story!

SCCRENDO | 9 décembre 2015

Sounds awful high. Didn't see a source for their info

SomeJoe7777 | 9 décembre 2015

I find this analysis questionable because it makes no differentiation between different motor models. If we're talking 2012-2013, all of these are "large" drive units, which have the same motor and gearing. But even within those, do the "P" models have different electronics/inverter? Do different revisions of the drive unit have different parts like bearings?

Because there is no breakdown like this, it's impossible to use the data to forecast anything. Failure rates on a rev "B" large drive unit have no relationship at all to the failure rate on a rev "C" small drive unit (used in the 2014-2015 all-wheel drive models).

No one could possibly make any kind of decision about purchasing a 2016 Model S or X based on this data -- it's nearly an apples-and-oranges comparison.

SomeJoe7777 | 9 décembre 2015

(Note that my revision letters are arbitrary, and are only used to illustrate the point. I make no representation that these are actual revision labels on any production drive unit).

sule | 9 décembre 2015

I don't know the source of the data but I don't take it as seriously as they do. In no particular order:

1. People with problems are much more likely to report problems than those who do not. This is for any product. Whenever I look at stats for anything I keep that in mind, not for Tesla only. To me this means "less than 2/3". That is still a lot, but there are other points.

2. Tesla needed the data from these failures to investigate modes of failure and seek out better designs. They often replaced too much, such as the entire drive unit, even if only a small part of it was faulty - say a nut, bolt or bearing. Thus the data is further skewed towards the more critical side than it really is.

3. We are talking about early cars. Now, maybe we don't have the data for the rest yet, but Tesla did say that some problems were fixed at some point in time... and we know they are working on fixing remaining issues.

4. Unlike other manufacturers, Tesla tends to replace problem parts with parts that have the design correction, not just a newly manufactured part of the old design.

5. We still have time for Tesla to address remaining issues. Note that this is mostly about huge mechanical stresses caused by the powerful motor(s) on otherwise simple parts. There aren't many of these parts. An electric motor has a single moving part - a solid chunk of metal. Electric motors themselves are reliable. We're just dealing with too much power from them for minor components outside. I am more concerned about any inverter troubles if there are any, also a part of the drive unit, but have had no indications so far of those.

tes-s | 9 décembre 2015

But if they simply replace the drive unit when you are in for annual service, what difference does it make to the owner?

sosmerc | 9 décembre 2015

When "negative" news gets out like this it clearly has potential to damage Tesla. We saw that happen with the Consumer Report "downgrade".
Tesla surely will take this kind of negative news seriously and will respond appropriately when they have a better handle on data. Let's hope their response is timely and effective.

DTsea | 9 décembre 2015

Luckily nobody reads that mag

Tropopause | 9 décembre 2015

I was told the new bearings have been out for a few months now. Any feedback yet on the reliability of the new bearings?

My DU is getting replaced next month due to bearing noise.

12/2014 S85
17,000 miles | 9 décembre 2015

My understanding is the original steel bearings pit over time due to electrical currents that flow through the bearings in AC motors powered by a variable frequency drive (such as used in the Tesla). As the bearings pit, they start to make noise. This may be more prevalent on higher power vehicles (i.e. P85, but could occur over time on any model). If used long enough the bearing may fail. I get the sense this is a very slow process and owners normally get months of warning with louds noise before a bearing failure might occur.

I believe the new bearings are ceramic. These are non-conductors, so they avoid this issue. The original Roadster's motor also used ceramic bearings. These are more costly, but avoids the unusual pitting issue. Many non-Tesla EVs use DC motors, which are not affected by this issue, but they require expensive rare-earth magnets.

For those that want to dig deeper, this article gets into the details:

DonS | 9 décembre 2015

I suspect the 2/3 is skewed because people having trouble are more to report than people who had no trouble. Still, from my direct experience, plus the buzz on the forums, the drive train failures are far more common than they should be.
Maybe I'm naive, but I believe Tesla is making the design and manufacturing changes necessary to get the expected reliability. I've rebuilt and customized cars, so I am understanding of the rework commonly needed to make the whole car reliable.,

Sudre_ | 9 décembre 2015

If it's really the bearing issue then sooner or later it will be all drive-trains without the ceramic bearings. There are also shaft grounding bushings that do the same trick but might not work with the Model S setup.

jordanrichard | 9 décembre 2015

The bearings are in the motor. It is the only 2 wear points in the motor. The whole drive unit doesn't need to be replaced, just the rotor. Why the whole rotor? The bearings are pressed onto the rotor shaft and the service centers don't have the tools to remove and re-press new bearings. So the rotor is the next higher assembly and the service centers are to order it take car of the "hum". It is an actual repair classification called "Hum Repair". So presumably the new rotors will have these improved bearings.

How do I know all of this, my car (37,000 miles S85) has developed a hum and a new rotor has been on backorder for almost a month now. This I attribute to Tesla trying to get those 50,000 cars out the door by year's end and need all of the rotors it can muster to complete those cars.

donaldmeacham1 | 9 décembre 2015

19000 miles no noise yet.

jordanrichard | 9 décembre 2015

I just read the article and actually what bothers me the most is the headline. To say that a faulty bearing, which used require a whole DU replacement, as a Drive train failure is the same as saying the drive train on a Chevy failed due to a leaking valve cover gasket.

But hey, these outfits got to do something to get people's attention via attention grabbing headlines.

Bighorn | 9 décembre 2015

The headline should be more like "Buy a Tesla, get a hum job."

NKYTA | 9 décembre 2015

Wrong thread. ;-)

inverts | 9 décembre 2015

67+K, original drive unit, no noise.

Al1 | 9 décembre 2015

From what it looks like changing Tesla drive train is somewhat like changing oil with ICE cars.

Tropopause | 10 décembre 2015

Anyone know if the motor bearings are lubricated with circulated gear oil? My dad said he saw oil lines running to both motor-ends from the gearbox sump; when we were at the Tesla Showroom looking at a display chassis. Similar to a turbo-charger bearing which receives engine oil for lubrication.

MountainVoyageur | 10 décembre 2015

But if they simply replace the drive unit when you are in for annual service, what difference does it make to the owner?

Makes a lot of difference to those who plan to drive their cars significantly past the warranty period.

2015P90DI | 10 décembre 2015

True or not, who cares!! Mercedes, Jaguar, Volkswagen were all considered to be horrible cars in terms of reliability. Mechanical parts break, it's just the nature of the beast.

At least with Tesla, they do make repairing the car as seamless as humanly possible. Sure, for those that live hundreds of miles from a service center, it can be an inconvenience, but that will change as the company continues to grow. That's just the price paid for jumping on the bandwagon early and experiencing what is still the most amazing car ever built (based on 97% of customers saying they'd buy one again, even with the issues). For those within reasonable proximity to a service center...if the car breaks, who cares. It's under warranty. Take it in, they give you another Tesla to drive while yours is being serviced and most times the loaner Tesla is nicer than the one you own. When your car is ready, drop of the loaner and pick it up.

No cost, no inconvenience of being without a Tesla and you now have a part that's likely an improvement over the part it replaced. If nothing else, it's a new part on an older car. I don't think Tesla can make it any easier to have repairs completed, short of adding more service centers to meet demand. As long as my car is under warranty, I could care less if it breaks down every day.

But just for argument sake, between my car, my dads car and a friends car, this report states two of us should have had failures. My dad's car has never seen a service center. My car has been in only for minor nit-pick adjustments. And my friends car has only been in for annual service.

Tstolz | 10 décembre 2015

I'm happy Tesla has an 8 year unlimited warranty on the drive unit and that they identify parts that have issues and redesign them. I just hate how other manufacturers replace defectively designed parts with the same part. If I keep my car for the 8 year warranty period it will have over 400,000 km ... so I'm certainly not worried!

Tropopause | 10 décembre 2015


I agree Tesla makes warranty repairs as painless as possible (and that's not an easy task as evident from the competitors) but I DO care if my car breaks down everyday and so will the masses when Model 3 comes out.

The way I see it, Roadster, Model S and X are learning platforms for Tesla prior to going mainstream with Model 3. I think the training wheels will come off when Tesla goes into mass-productions of 500,000 units per year.

This is history in the making. Silicon Valley in the new Detroit!

AmpedRealtor | 10 décembre 2015

Anecdotal evidence suggests otherwise. While I've had a few DU swaps, most of the owners in our local group did not.

Steve S | 10 décembre 2015

Yes, bad news is not good news, as the vast majority of people believe everything they read.

ir | 10 décembre 2015

"In the survey, respondents provided a variety of information on their Model S ownership experience, including total miles driven, whether they've had a motor swap (drivetrain replacement), and if so, what the odometer reading was at the time"

The study equates a "drive train replacement" as a catastrophic failure (i.e. stuck on roadside with nowhere to go). Another plausible and less fantastic conclusion is that to make a good first impression, Tesla was aggressive in verifying every drive train noise, hum and squeak.

Haggy | 10 décembre 2015

People who don't know the whole story will want to know what Tesla will do about it. It means that, if true, the earliest cars will likely need a drive train replacement within four years. That should be covered by warranty in most cases. The early 40 and 60s didn't get unlimited mileage on the extended warranty. If the failure rate were truly that high, then Tesla would have to acknowledge that there's a defect. For the most part though, it would be a non-issue.

oildeathspiral | 10 décembre 2015

A good way to look at this from a poster on the Yahoo MB:


This would be a lot more informative if they included a Pareto chart showing the failure modes by frequency and expense. It's possible that 65% of the cars need to have some bolts tightened and 1% strip out the splines or gears in a way that trashes the motor and transmission.

I doubt it's the other way around. We heard about the 1000 motors in Norway fiasco. If there was anything bigger, we'd have heard of that too.

But new product introduction is like this. I'm not surprised. The main thing in these situations is:

1: Climb the learning curve to make new products more reliable. (ramp this *before* production ramps)

2: Do whatever it take to fix the problem and keep the customer happy.

lolachampcar | 10 décembre 2015

Well, I was in the not me camp up until a few months ago. My wife's S85 has had one as have two friends that I convinced to buy the Model S.

Tesla did the exact right thing by aligning the drive unit's warranty with the battery's warranty. It makes it a non-issue for me.

The only down side was that they gave my wife an S85D as a loaner so that drive unit swap is going to end up costing $50K!!!


irsalman | 10 décembre 2015

32K miles on a P85+, No noise.

jordanrichard | 10 décembre 2015

Tropopause, those are coolant lines. The only oil in a MS is the gear oil in the gear reduction box.

The bearings are steel ball bearing cages that are pressed onto the rotor shaft. I imagine these are packed with bearing grease. a bearing like the ones on a crankshaft are called bearings, but really they are metal shims that need a constant supply of oil to keep cool.