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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%

Bearing Failure vs Driving in L

27K views 33 replies 15 participants last post by  mark ohm 
#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)
 
#2 ·
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.
 
#4 ·
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 Many of these folks are no longer active forum participants.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
 
#5 · (Edited)
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.
 
#6 · (Edited)
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.
 
#7 ·
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?
 
#8 ·
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.
 
#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.
 
#12 ·
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?
 
#16 ·
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"
 
#17 ·
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.
 
#21 ·
I voted, but, as others have said, I don't see the point. Without accounting for other variables, such as time in service, how is any correlation between 'L' and bearing failure going to mean anything.

Don't you get the same gear lash issue when hitting the brakes? The car is still in regen mode even if not in 'L'.
 
#25 · (Edited)
This is a good question, in this poll the only controlled variable is the ratio of people driving in l vs d. It is making an assumption that all other variables like time in service and miles are on average the same for people driving in L vs D. I think this should be close, but there could be some dependencies like people that drive in L have more miles or time in service on average than people that drive in D. If this is the case the data will be screwed.
There is a test for this, but it would have to be done after this study is complete. It would require another poll though, and based on the fun this one has created, I'll think I'll pass.

As far as the second question, I have no idea. But so far the data is looking like the answer is no effect of driving in L. Need much more data though.
 
#23 ·
Why the continued focus on D vs. L? Everyone knows it's the daytime running lights that causes this issue. Virtually all those reporting a bad bearing use their DTRL's all or most of the time.

Even though WOT reported GM found the cause to be an assembly error, I can prove it's the DTRL's, perhaps in conjunction with the radio being on :)
 
#24 ·
I love the trash talk! In forums you can speak like an Design Engineer without having any data at all! :)

There is no where near enough data yet (except in the control group), but if the entrees continue in the same ratios, then we will actually have data showing that driving in L has no correlation to Bearing failure.

I know people with opinions will say they knew that all along, but at least technically oriented people will have some data to back it.
 
#26 ·
I had the bearing failure about 2 weeks after I bought my Volt. I took it back to the dealership, they gave me a rental, it took three days until they got the part and I had my Volt back. Was it a pain to pay for gas on the rental, yes, but they did a great job on the maintenance and I haven't had any problems since:)

Kenya
Go Blue Volt!
 
#28 ·
statistical status as of 89 respondents.

Because of the shift in population between the test group and the control group, even with the small number of test group respondents (9), some preliminary data can be analyzed.

This poll is reporting that with a 70 percent confidence level driving in L has no negative effects on bearing failure. Meaning that there is now only a 30 percent chance that the continuation of this data collection will result in other conclusions. Now a true Actuary would say I probably just skewed the rest of the study, but for me 70 percent confidence is enough for me to start driving in L.

What the poll can't say with any confidence is wether or not driving in D has adverse effects on bearing failure, but I just wanted to make sure that driving in L does not.

If anyone is interested in the math you can E-mail me, but it's pretty boring stuff. If more people vote over time I will update the confidence levels.
 
#30 ·
statistical status as of 89 respondents.

Because of the shift in population between the test group and the control group, even with the small number of test group respondents (9), some preliminary data can be analyzed.

This poll is reporting that with a 70 percent confidence level driving in L has no negative effects on bearing failure.
Did you move the one confirmed incorrect vote from "Have had" to "Have NOT had" (http://gm-volt.com/forum/showthread.php?66482-Bearing-Failure-vs-Driving-in-L&p=862498#post862498)? That change may make the case even stronger.
 
#29 ·
GM's explanation was that the cause were a few parts damaged during assembly, resulting in the eventual bearing failure. Slapshot's info appeared to support this, finding no correlation between MY, L, D, miles and the bearing failure. IOW, it appeared to be random and rare.

I hope this finally puts your poll analysis finally puts this Low/Bearing Failure conjecture to rest. Unfortunately, history says otherwise and that 6 months from now we will be dragged through this yet again by someone who feels L is the cause. :)
 
#33 ·
People with a Volt problem tend to post, those who don't are rarely heard from. So the validity of any poll on this forum is always suspect. The results are of those who are 1) members 2) who see the poll and 3) actually choose to participate. In addition, most of the reported problems happened in the first few model years and very few with later years. So I doubt it's representative of all model years.
 
#34 ·
I agree with your comment about polls.
Was checking out our forum and ended up here because of bearing MGB failure on our 2012 with 72,000+ miles on it. GM is taking care of the repair, but would hope to understand what caused this condition.
 
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