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Bearing Failure vs. Driving in L

  • Have had bearing failure or symptoms and I drive in L more than half the time

    Votes: 15 6.9%
  • Have had bearing failure or symptoms and I drive in L less than half the time

    Votes: 11 5.1%
  • Have Not had bearing failure or symptoms and I drive in L more than half the time

    Votes: 134 61.8%
  • Have Not had bearing failure or symptoms and I drive in L less than half the time

    Votes: 57 26.3%

  • Total voters
    217
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Discussion Starter #1
Not sure how to make this a poll, but I am very interested in the data:

I have had / or am experiencing symptoms of a motor bearing failure, answer below:

I drive in L more than half the time (check here)

I drive in L less than half the time (check here)

I have had no motor bearing failures or symptoms of, answer below:

I drive in L more than half the time (check here)

I drive in L less than half the time (check here)
 

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I have not really followed the bearing failure that much as I have no symptoms as of 60k miles. Just wondering though has the bearing failures occurred on the motor that provides regen? I use L for regen at stop signs, some steep hills and red lights sometimes.
 

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Is this not a 2011-2012 issue for the most part?
If so, 2013 voters may skew the data.
 

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Is this not a 2011-2012 issue for the most part?
If so, 2013 voters may skew the data.
There are 8 reports here of bearing issues with MY 2013 Volts.

I do agree that it will be difficult to get solid data from this poll as only 39 Volt owners here have reported the issue over the course of two years. Many of these folks are no longer active forum participants. I hope we don't get voting mistakes. (I almost clicked on the wrong button.)

Here are a couple of links to my analyses:

http://gm-volt.com/forum/showthread.php?57985-Bearing-Issues&p=776281#post776281
http://gm-volt.com/forum/showthread.php?57985-Bearing-Issues&p=754513#post754513

And here is an important message from WOT, our resident Volt expert:

http://gm-volt.com/forum/showthread.php?56705-GM-fix-my-Lemon-take-2...&p=770553#post770553
 

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This topic is like Area 51, where some people simply want to believe that the truth is being hidden. :)

Some suspect there is a correlation between driving in Low and this rare bearing failure. Others want to believe the bearing failure is not rare at all but a pandemic, because it happened to them. So we have poll after poll (which are statistically irrelevant and therefore meaningless).

We already have an explanation of what causes the failure for the few who have had it: an assembly error. We also know that some dealers have had a hard time replacing the failed bearings (parts delay, lack of equipment, lack of training).

Initially there was discussion about whether the model year, or mileage, or weather or driving style (Low) might be related. But no correlation was found. And then we learned it was being caused by damage during assembly.

Now that we now that, a poll on using Low and bearing failure is like a poll on tire pressure and bearing failure: irrelevant at best.

With the cause determined, we can expect that the assembly process will have been improved and that this rare problem will become even rarer or completely eliminated.
 

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I question what driving in L has to do with the bearing issue. Since L is nothing but a remapping of the accelerator and the 'transmission' is a constant mesh device, it would seem that driving in L couldn't have any effect on the motor bearing over and above that from driving in D.

Any opinions from our Volt experts?

P.S. Sorry, Steverino's post appeared while I was writing mine.
 

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I should have been clearer...

When talking about bearing failure I am assuming the nylon bearing race failures? I believe early 2013 models did still have them. Anyway if there is another "general" bearing failure issue going on I missed that altogether.

Put better:

Have any 2013s, with the steel race, have a bearing failure?
 

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Have any 2013s, with the steel race, have a bearing failure?
I don't know for certain the answer to your question, but I believe it yes. Only rarely has the failed bearing race-material been identified and reported, or photographed.

We do know for certain that a few replacement (non-plastic?) bearings subsequently failed after not many miles. We also know that many many early (plastic?) bearings have not failed, even with lots of miles of heavy driving, including L. My Volt is a perfect example: 2011 Volt with almost 40,000 hard miles, both electric and gas, 100% driven in L.

Finally, WOT has been clear in stating that it is an issue with the bearing installation.
 

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Discussion Starter #11 (Edited)
For some of the previous posts, I did search for data pertaining to the Bearing vs L but wasn't able to find any. If there is a link please let me know. And I mean data, not a back and forth between opinions.

In the absence of finding any the reason I created this poll:

In my 18 years as a Automotive Design and Manufactucting Engineer, I have never once seen a design change of this magnitude for an assembly problem. I was involved with hundreds of assembly issues, most are corrected by 1) changing operator instruction sheets, 2) making new or modifications to assembly tools, 3) increased inspection frequency (to 100 percent), 4) small design modification (ie chamfer, rounding, width, tool locator, poke yoke (error proofing). Almost never is it something as great as a material change from a polymer to a metal on a loaded member like a bearing cage. This would require an entire new D and PVP&R (design and process validation plan and report). A huge undertaking. It would also open you up for a Service Bulletin or worse yet a Field recall. Now that being said, this could be one of those extremely rare cases. So of course, take this as my opinion.

That's what I love most about this forum and College Football, are the opinions.

Now the reason for this poll. I wanted to see more than opinion.

I plan on doing a statistical significance test on the poll when it is done. That's the reason for the control group. Now it is attribute data and not variable so it's going to take more data points, but the test will tell if its valid or not.

My favorite quote, I have said and heard many times at GM:

In God we trust, all others bring data.
 

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Now the reason for this pole. I wanted to see more than opinion.

I plan on doing a statistical significance test on the poll when it is done. That's the reason for the control group. Now it is attribute data and not variable so it's going to take more data points, but the test will tell if its valid or not.
Okay. I admit to being confused. It sounds like you know about statistics. What hypothesis are you trying to prove (or disprove) with this poll?
 

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In my 18 years as a Automotive Design and Manufactucting Engineer, I have never once seen a design change of this magnitude for an assembly problem.
Does this mean you don't believe the explanation given by WOT? Or you don't believe that GM changed the bearing cage material? Or both? Or...?

With your experience, what do you think is going on?
 

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Discussion Starter #14
Okay. I admit to being confused. It sounds like you know about statistics. What hypothesis are you trying to prove (or disprove) with this poll?
Simply, once and for all does driving in L have any correlation to bearing failure.

I do like driving in L but I have been avoiding it out of fear of undo stress on the bearing and gear set.

The reason I still wonder:
I have done quite a bit of gear design. Lash is very bad for gears and bearings when torque direction is changed. We worked very hard in steering systems to "dampen" the torque reversing impact of changing steering wheel direction from left to right. We literally design in springs to absorb the impact. I see when driving in D, I take my foot off the accel that the software will gradually reduce power right at the torque reversing point then gradually increase ren power levels. This is very similar to what gas engines do on manual transmissions so you don't feel the impact of lash torque reverse. We did it with springs, they are doing this by controlling the power levels.
I do not see this when diving in "L", and I do feel the impact.
 

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Simply, once and for all does driving in L have any correlation to bearing failure.
No. Hence the futility of this poll.

"Very few of these have actually occurred and the issue has been identified as potential damage to the bearing race during final assembly of the drive unit." http://gm-volt.com/forum/showthread.php?56705-GM-fix-my-Lemon-take-2...&p=770553#post770553

Note: "the issue has been identified as potential damage to the bearing race during final assembly of the drive unit."

It has nothing to do with using D or L, the car's color, the state you live in, etc. Instead as noted, "the issue has been identified as potential damage to the bearing race during final assembly of the drive unit."

But, like Area 51, no amount of info will deter some from believing there is something else going on. :)
 

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Polls have been done in the past on this too. The findings seem pretty straightforward: Bearing failures are not correlated with heavy use of "L"
 

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How about some background on this subject.
What bearing are you guys going on about?
I read this thread and I don't have a clue. It's in the transaxle, is easily replaced without pulling the transaxle, correct?
I would like to find some factual information on what is being talked about.

I almost bought a '11 Volt yesterday, but I think I'll cough up a little extra and get a leftover '13.
 

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Simply, once and for all does driving in L have any correlation to bearing failure.
I'll be interested to see the results. Driving in L was one of the my first hypotheses; however, I discarded it after realizing how many problem-free Volts drive exclusively in L (http://gm-volt.com/forum/showthread.php?13846-Driving-in-Low-Poll-and-Compilation-of-Threads).

I do appreciate your effort, but even if this poll shows a high percentage of bearing failures associated with L drivers, doesn't that lead to a potential logic trap (http://en.wikipedia.org/wiki/Misuse_of_statistics#Overgeneralization)?

It's like a poll on baldness under 40.

Poll Result: All bald people under 40 are men.
Logic Trap: Men under 40 are likely to be bald.

Again, I appreciate your effort and I'm not a statistics expert, but I think we will need to be careful drawing strong conclusions, especially with a small data set and the potential (reality now) for some voting mistakes.
 

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Discussion Starter #20
I do love all the information and opinions though! Makes forums fun!

If there is another survey please link. I was not able to find it.
 
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