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Discussion Starter #1
Thought I would share the carnage from my last ride.

Got 30 miles east of Amarillo TX when I noticed "crunchy" noises coming from the rear end.

My brother "The Saint" drove from Phoenix the same day to pick me and the bike up.

Dropped it off the next day so I could fly back east for vacation and meet up with the wife who was already there..

Here is what the dealership found when the opened the drive.

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They found the cracked bolt after the test ride so they replaced it for free..

All better now...

I guess my big question is "Why?"

What would cause the cage in the bearing to fail like this?

Ideas?
 

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Thought I would share the carnage from my last ride.

Got 30 miles east of Amarillo TX when I noticed "crunchy" noises coming from the rear end.

My brother "The Saint" drove from Phoenix the same day to pick me and the bike up.

Dropped it off the next day so I could fly back east for vacation and meet up with the wife who was already there..

Here is what the dealership found when the opened the drive.

[URL="[/URL]

They found the cracked bolt after the test ride so they replaced it for free..

All better now...

I guess my big question is "Why?"

What would cause the cage in the bearing to fail like this?

Ideas?
That is the classic crown bearing failure that happens to the LT final drive. It is caused by over shimming of the bearing in the housing.

Welcome to the 4% club.
 

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...I noticed "crunchy" noises coming from the rear end...
What would cause the cage in the bearing to fail like this?
Ideas?
Dozen's of threads going back years on the subject.
Here's one place to start reading, Grasshopper. ;)

http://www.bmwlt.com/forums/k1200lt/63109-indications-impending-fd-failure.html

What year bike, how many miles?
Are you first owner, or is there bike history unknown to you?

(Now that you have it fixed, you may not want to read about the track record many dealership service departments. They have been know to do a "summary" crown gear replacement without correcting the problem that caused the failure in the first place.)

(The 4% statistic is pretty old and I'm not sure how valid it was at the time is was first put out.)
 

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Discussion Starter #4
What year bike, how many miles?
Are you first owner, or is there bike history unknown to you?

Charlie,

The bike is an "09" and it has just over 57k on the odometer.

I am the original owner and it has been serviced my this dealer since new.

It had 25 miles on it when I bought it...
 

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What year bike, how many miles?
Are you first owner, or is there bike history unknown to you?

Charlie,

The bike is an "09" and it has just over 57k on the odometer.

I am the original owner and it has been serviced my this dealer since new.

It had 25 miles on it when I bought it...
That mileage is consistent with many I have read about reporting the failure. Some went earlier and some later with others not reporting any issue at all.

Charlie is one of the early onset rebuilders and the current master is Dave ( Saddleman)

The part that Charlie is referring to is the shimming process. Some dealers have been known to simply pull the bearing and replace it with the same shim that was likely the cause of the failure. It saves them shop time but the likelihood of it failing again is high. The following clip is and I think it is Charlie, showing one method of doing the measurement tht some shops have been known to bypass. He will tell you this was early on and there are several other issues to look for while you are examining the FD that his videos did not cover. If you don't do the measurement then you don't know if the shim you are installing is the right thickness to provide the preload on the taper bearing. Too thick ind it puts too much side load on the crown bearing and is what the collective has determined causes the early failure. I used this method on my FD and found that it was .15mm over shimmed.

If you were billed for shims, then the chance is higher that they did the measurement.

 

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I think it is a rare failure for a 2009.
57K miles is more miles than the average mileage of failures for the earlier model bikes. Early bikes often failed in the 20-30K miles range.
You would probably get around another 57K miles is they had done a "summary" bearing replacement.
However, that they sourced a new shim is very suggestive that they took the time to measure for preload.
(That was a really good suggestion by Gordon).
No reason not to have full confidence in your final drive now.

BWM has had plenty of time to educated dealerships about what I termed the "classic" crownwheel bearing failure.
I chose that term to distinquish it from other final drive failure modes known.

That video was made around 2007-8 and was shown at the Midway Utah CCR in 2008.
There are some errors in the method but none of real consequence and the method remains a good one.
Credits to DMAN for first proposing this method on this site.
Opinions expressed by me in the video regarding the reasons for the bearing failure are outdated. Subsequent to making the video, data gleaned from rebuilding final drives and the input from experts in their field (mostly mechanical engineers on this site), we concluded that excess preload on the crown gear assembly was the culprit.

PS I've seen dozens of bearing retainers chewed up like that, but this is the first time it occured to me that someone was trying to turn the retainer into a Gordian Accordian. ;)
For those mystified by "Gordian Accordain", google it...
 
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