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Originally Posted by SenorFunkyPants
As a few people seem to be some mis-understanding what I am doing here, I'm probably not explaining myself very well.
So...lets say we want to find out the % of over 21s who smoke in NYC.
Ask a sample of 1000 over 21s NYers at random and the number who say yes will give a fair idea of the % (not perfect but close enough).
What wouldn't be included is anyone who says "no" but knows 5 people who do - as that distorts the statistic.
Here we have a fixed number of M3post E9x M3 owners and a declared number of failures. From these two number we can produce a statistic.
As M3post is a USA centric forum I focus on USA owners plus we have accurate production numbers for NA.
Problems: The number of M3post E9x M3 owners is somewhat "elastic" - "Swamp" was given membership data by the sites admin from which he made a fair estimate of how many of the 220,000 M3post members are actual E9x M3 owners.
The number of failures is also not exact - against my better judgement I have included a significant number of failures that have been third party reported which tends to inflate the statistic. Also a few posters joined M3post specifically to report a failure which also has the tendency to inflate the fail rate. On the other hand some regular M3post members may not have reported their failure at all - so hopefully it sort of balances out.
Without redoing the numbers (which I will try to do soon) I suspect the failure rate currently works out at between 1 to 1.5%...thats total failures to date.
"///Mpower-Belgium" posted that he knows someone who knows someone at BMW who stated that BMW AG were manufacturing replacement S65 engines at the rate of one a day.
Assuming this rate to be true for all of 2014 it means that of the ~65,000 engines in use worldwide, 365 failed in 2014. That equates to a 0.56% failure rate for 2014 which considering that early cars are now 7 years old and mileages are getting ever higher doesn't seem that bad.
It also fits reasonable well with the 1 to 1.5% total failure rate to date that the numbers here predict.
Note: not all failures are rod bearing related, there have been several other causes and many are simply unknown but assumed to be bearings.
Finally I did try to look at how the failures are distributed geographically in the USA. Using the poll where members noted their location I was able to get a fairly decent idea (from around 300 responders) how sales are spread out by state (the bigger a states population the more accurate the result). Against expectation failure rates are noticeable higher in warmer states.
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Listen, I get it, making everyone aware of the known issue is important, and I don't want to stop the discussion, hell I'm trying to formulate my plan for long term care as I track and deciding on how to make engine stronger. But can we avoid so many assumptions. Things like "I know someone who knows someone".
I know someone who knows a guy who can get you a 100% return on your money, so send me 10k and I will make you rich in 10 years
The only stats are VERIFIABLE facts such as "proof in writing that the bearing failed, how many fails, and then do basic math to figure % of fails".
Cheers,
e46e92