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Be aware! Missing Control Arm Nut: Potential Safety Issue

MP3Mike

Well-Known Member
Feb 1, 2016
14,978
31,853
Oregon
Did our “friend” from the UK get involved? Very opinionated for a non-owner, although there are others likewise inclined here....

No way to know, but they could have filed the one that points to this thread, since Keef seems to sign all of the ones he files.
 
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mycroftxxx

Member
Jun 14, 2020
100
46
Left Coast
Thank you - this crap is so out of control it’s pathetic at this point.
Edit: seriously, I blame the whole everybody gets a participation trophy mindset for this stuff. Six Sigma or not, with enough samples you’ll find defects. Deal with it or don’t play, period.
So far, we’ve heard about a couple of these improperly installed ball joints out of a universe of, what, maybe a few thousand MY owners on this board? That’s a few orders of magnitude worse than six sigma, assuming a Gaussian distribution...:eek:

To speak to your larger point - Of course there will be defects in any complex manufactured assembly. The concern here is the assembly defect is in such a safety-critical assembly; a ball joint failure at highway speeds could easily be a fatal accident. How did this make it through the quality sign-off of that assembly? There are certain basic safety-critical pieces of a car that any reasonable manufacturer should expect to have zero defects in those pieces delivered to the customer - i.e., they should never happen and/or should always be caught by inspection prior to delivery. Single-point failure suspension components should be one of those.

The up side is that this appears at first blush to be a manufacturing escape, not a design flaw. The likely recall would be a simple inspection.

it certainly doesn’t help to panic or immediately extrapolate to the worst possible case for this kind of thing. It is also not helpful to minimize it. Assembly defects in safety-critical parts should be taken seriously, and IMHO Tesla needs to get to the bottom of this expeditiously.
 

EnrgyNDpndnce

Member
Sep 12, 2016
607
1,002
Charleston, SC
So far, we’ve heard about a couple of these improperly installed ball joints out of a universe of, what, maybe a few thousand MY owners on this board? That’s a few orders of magnitude worse than six sigma, assuming a Gaussian distribution...:eek:

To speak to your larger point - Of course there will be defects in any complex manufactured assembly. The concern here is the assembly defect is in such a safety-critical assembly; a ball joint failure at highway speeds could easily be a fatal accident. How did this make it through the quality sign-off of that assembly? There are certain basic safety-critical pieces of a car that any reasonable manufacturer should expect to have zero defects in those pieces delivered to the customer - i.e., they should never happen and/or should always be caught by inspection prior to delivery. Single-point failure suspension components should be one of those.

The up side is that this appears at first blush to be a manufacturing escape, not a design flaw. The likely recall would be a simple inspection.

it certainly doesn’t help to panic or immediately extrapolate to the worst possible case for this kind of thing. It is also not helpful to minimize it. Assembly defects in safety-critical parts should be taken seriously, and IMHO Tesla needs to get to the bottom of this expeditiously.

Of course this is serious and should be investigated and resolved as quickly as possible. But even your math is flawed because you are making the assumption that this board is a representative sample of the entire Model Y fleet. There could be far more or less examples of this flaw, none of us know. We also have no idea how the two examples listed on this board came to be. This COULD be a manufacturing defect, but it also COULD be something else entirely.

So let’s not jump to conclusions on either side of this issue. Tesla knows about it (because those who reported on this board also reported to Tesla). Hopefully those affected will also report to NHTSA so the regulatory body can do its job. If you own a Model Y you merely need a quick visual inspection to give you peace of mind on this issue. Absent any evidence showing this issue is in fact widespread, the rest of us should sit back and see how the investigations unfold.
 

mycroftxxx

Member
Jun 14, 2020
100
46
Left Coast
But even your math is flawed because you are making the assumption that this board is a representative sample of the entire Model Y fleet.
It’s a reasonable assumption: Tesla doesn’t tailor its manufacturing based on whether or not the buyer is a member of this board; therefore, the population of Model Y’s represented by this board can be assumed to be a representative random sample of the total Model Y population. Even it these are the only incidences of the flaw, that’s something like 2 out of maybe 40,000, which is still way larger than six sigma for a Gaussian distribution. Quite concerning.
This COULD be a manufacturing defect, but it also COULD be something else entirely.
Let’s see: a safety-critical nut is missing off a more-or-less brand new car. The universe of possibilities are: design defect; manufacturing defect; third-party intervention. Sorry, but the latter seems rather far fetched to me.
So let’s not jump to conclusions on either side of this issue.
Where did I jump to any conclusions? I even said in my post, “It certainly doesn’t help to panic or immediately extrapolate to the worst possible case for this kind of thing”.
 
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mark95476

Member
Jun 21, 2020
758
399
Bay Area CA
(Lots of speculation and inane chatter. I guess it gets the clicks and engagement.)

Here are some facts:
- We have at least two MY owners whose lock nut fell off completely. They were driving around like that for days? or weeks? or months?.

The steel bolt held and didn't even appear bent or damaged.
The aluminum arm held (and got reamed out as expected).

- Every single car out there has a suspension system and they're all similar. Things will get loose in any car, including Teslas, so don't believe anyone that tells you otherwise. Things are over-built in just about any car, more-so on Teslas, and stuff does go wrong from time to time.
 

EnrgyNDpndnce

Member
Sep 12, 2016
607
1,002
Charleston, SC
It’s a reasonable assumption: Tesla doesn’t tailor its manufacturing based on whether or not the buyer is a member of this board; therefore, the population of Model Y’s represented by this board can be assumed to be a representative random sample of the total Model Y population. Even it these are the only incidences of the flaw, that’s something like 2 out of maybe 40,000, which is still way larger than six sigma for a Gaussian distribution. Quite concerning.

Let’s see: a safety-critical nut is missing off a more-or-less brand new car. The universe of possibilities are: design defect; manufacturing defect; third-party intervention. Sorry, but the latter seems rather far fetched to me.

Where did I jump to any conclusions? I even said in my post, “It certainly doesn’t help to panic or immediately extrapolate to the worst possible case for this kind of thing”.

You and I can agree to disagree on which assumptions are reasonable. Same for which cause of the issue seems to be far fetched. At this point we have zero evidence pointing to a cause, we simply know two cars are missing bolts. I’m willing to wait for a thorough investigation to determine the cause. Until then, and with only two examples, I’m willing to concede an equal chance for each possibility you listed.

As for my statement about jumping to conclusions, it was directed as much at this entire thread (and many more like it on this board) as at you individually. And sure you said it doesn’t help to panic, but you followed that up with “It is also not helpful to minimize it. Assembly defects in safety-critical parts should be taken seriously, and IMHO Tesla needs to get to the bottom of this expeditiously.” At this point I have no reason to believe Tesla is not taking this seriously and I do believe they will get to the bottom if it.
 

mycroftxxx

Member
Jun 14, 2020
100
46
Left Coast
As for my statement about jumping to conclusions, it was directed as much at this entire thread (and many more like it on this board) as at you individually. And sure you said it doesn’t help to panic, but you followed that up with “It is also not helpful to minimize it. Assembly defects in safety-critical parts should be taken seriously, and IMHO Tesla needs to get to the bottom of this expeditiously.”
Still don’t see how what I said is “jumping to conclusions” in any way, shape, or form...but whatever. Peace.
 

Rg3500

Supporting Member
Jun 14, 2020
20
13
Woodstock, NY
I am going ahead with my Model Y purchase despite the missing nuts on two Model Y's reported here. Thank you to both owners for finding and reporting the problems. I cannot imagine Tesla is not checking every Model Y's suspension since you uncovered it, and see no reason to not feel confident taking delivery of my car (hopefully soon).
 

CyberGus

Not Just a Member
May 5, 2020
718
1,594
Austin, TX
BTW, it's possible that some stray defective Nyloc nuts slipped past the manufacturer's QC, and Tesla didn't catch it, so the properly-torqued nuts backed out on their own. Unfortunately the parts in question are gone.
 

rglore

Member
May 12, 2019
47
98
Louisville
I worked for decades in an auto factory. What probably happened is, a worker hand started the nut but it was missed when it was supposed to be torqued down. It looked ok so didn't get flagged before leaving the factory. Road vibration slowly unscrewed the nut and it fell off. Has happened many many times in every factory.
 

Dennisis

Supporting Member
Feb 11, 2020
441
405
Tucson
I worked for decades in an auto factory. What probably happened is, a worker hand started the nut but it was missed when it was supposed to be torqued down. It looked ok so didn't get flagged before leaving the factory. Road vibration slowly unscrewed the nut and it fell off. Has happened many many times in every factory.
Seems perfectly plausible, thanks for the insight.
 
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Pilot1226

Member
Dec 20, 2019
355
155
USA
For what it’s worth my Subaru had a PCV valve recall about a month after ownership that resulted in grenading the engine and transmission at highway speeds. This resulted in catastrophic power train failure and possible loss of control, which could result in an accident.

These things happen, have to figure out the why and how to fix it next. Let’s remain pragmatic here and make our judgements based of facts rather than theory.
 

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