ADVrider

Go Back   ADVrider > Riding > Face plant
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 09-10-2012, 07:14 AM   #691
slide
A nation in despair
 
Joined: Jul 2003
Location: NM, USA
Oddometer: 21,123
Tom,

EE or PE or whatever, the reason I'm involved is not that AW's fork leg failed but that this is a pattern of failure we saw in previous F models.

Sure, it may be that AW's failure had nothing to do with the previous failures and that BMW addressed the issue of the older failures but we do NOT know because BMW isn't saying anything or even admitting any of the old F failures occurred.
__________________
Why be born again when you can just grow up?
slide is offline   Reply With Quote
Old 09-10-2012, 08:52 AM   #692
reenmachine
Rain or Shine
 
Joined: Jul 2011
Location: Studio City, CA
Oddometer: 438
Quote:
Originally Posted by TxLoneRider View Post
ride safe y'all! personally I got a kitchen pass and put 670 miles on my Tiger 800XC yesterday

tom
Nice! Best thing I've read in this thread for a while...

...and I put another couple hundred hard miles on my fork yesterday. [/troll]

I hope everyone else had a great weekend!
__________________
'14 KTM 1190 Adventure
'11 BMW G650GS
'02 Yamaha FZ1
reenmachine is offline   Reply With Quote
Old 09-10-2012, 01:34 PM   #693
atomicalex
silly aluminum boxes
 
atomicalex's Avatar
 
Joined: May 2012
Location: Detroit & Düsseldorf
Oddometer: 2,336
I think close to 250kms for me! Back and forth to Isettaland, over to the Nederlanden, and then up to Kalkarer Kreis and back.

Best thing to do about parts engineering is read up on PPAP - the Production Part Approval Process. It is a template for parts specification that is used one one form or another at all facilities working under QS (US OEM quality system) or ISO (international quality system) quality management. PPAP is specific to the QS system, and I don't remember the name of the equivalent process in ISO, but the elements are identical (because QS basically copied ISO...). You'll get a good feel for what goes into the front end of it and what comes out the back. Usually, it works.
__________________
Katherine, in words - F650GSa - CBR250R (sold) - Super Sherpa - Nine Days in the Alps - More Alps: Finding GS Land
atomicalex is offline   Reply With Quote
Old 09-10-2012, 02:30 PM   #694
Center-stand
Gnarly Adventurer
 
Joined: Nov 2008
Oddometer: 499
Very Interesting. PPAP as described in the following link, seems to be the opposite of your statement about "the design limits of engineering" and "curl up in a ball"

http://en.wikipedia.org/wiki/Product...proval_process

You really have no answer or explanation for your statement do you?
Center-stand is offline   Reply With Quote
Old 09-11-2012, 02:13 AM   #695
atomicalex
silly aluminum boxes
 
atomicalex's Avatar
 
Joined: May 2012
Location: Detroit & Düsseldorf
Oddometer: 2,336
Let's see, what were we talking about? I ask you to put on your spatial thinking hat for a few minutes here.

The engineering limit of a material is the limit of performance of the material in an application. An aluminium alloy has a certain compressive strength and compressive stress and strain limits. It also has extension strength and stress and strain limits. The material does not function as a structural alloy beyond those limits, so those properties limit uses of the material requiring compression or extension along those axes - the limits of which define the design space. You can look at the design space from the outside (requirements to be fulfilled, environmental view) or from the inside (potential to fulfill requirements, material view).

I think the German tanks in Russia is a good example of screwing up the design space calculations and engineering to the limits. Zee Germans built everything to the tightest tolerances achievable, assuming that closer was better. They ignored the requirement to account for the material properties in the shapes of the parts - the entire area devoted to thermal exposure in particular. When they drove into the cold winter, they ran into tolerance issues because they had not built tolerances into the parts designs to mitigate thermal expansions/contractions. They also had a tendency to use materials with properties right on the border of the assumed requirements (fracture strength, etc), rather than exceeding them generously as their US or Russian counterparts did.

This is actually more common today than ever, as we can do much more accurate failure mode prediction and can get much closer to the real min/max requirements. This takes cost out in a big way. The design spaces are not smaller per se, but they are more highly shaped - instead of a sphere, think of ana ginger root or an oddly shaped potato. This is one of the reasons the failures seem so outlandish - they would have been masked by an overall larger sphere of requirements (environmental design space) in the past. Today, they are laid bare because the space is more accurately bounded.
__________________
Katherine, in words - F650GSa - CBR250R (sold) - Super Sherpa - Nine Days in the Alps - More Alps: Finding GS Land
atomicalex is offline   Reply With Quote
Old 09-11-2012, 03:00 AM   #696
xy500
Loser
 
Joined: Aug 2011
Location: Australia, WA
Oddometer: 72
This failure displays no sign of being a compressive, tensile, shear or buckling failure though (you didn't even mention shear or buckling). It is most likely impact failure.
__________________
Experience is wasted on the old
xy500 is offline   Reply With Quote
Old 09-11-2012, 06:10 AM   #697
Benesesso
Beastly Adventurer
 
Benesesso's Avatar
 
Joined: Jul 2008
Location: West of Phoenix, Arizona
Oddometer: 9,898
Quote:
Originally Posted by xy500 View Post
This failure displays no sign of being a compressive, tensile, shear or buckling failure though (you didn't even mention shear or buckling). It is most likely impact failure.
Then apparently it didn't even break, right? (shaking head).
__________________
US out of the UN, UN out of the US.
Benesesso is offline   Reply With Quote
Old 09-11-2012, 06:58 AM   #698
Center-stand
Gnarly Adventurer
 
Joined: Nov 2008
Oddometer: 499
Quote:
Originally Posted by atomicalex View Post

Let's see, what were we talking about?

.......The engineering limit of a material is the limit of performance of the material in an application. .....

........An aluminium alloy has a certain compressive strength and compressive stress and strain limits. It also has extension strength and stress and strain limits........

........The material does not function as a structural alloy beyond those limits, so those properties limit uses of the material requiring compression or extension along those axes - the limits of which define the design space.

.......This is actually more common today than ever, as we can do much more accurate failure mode prediction and can get much closer to the real min/max requirements. This takes cost out in a big way........

Thank you.

So ...... the limits placed on design or engineering are directly related to the material being used, and are not necessarily design limits or engineering limits.

Can you put on your spatial thinking hat now and see that the absence of "material" in your previous statement leaves very little sensibility to the statement, at least to the laymen (like myself) reading this forum.

I would also point out that the last paragraph is in contrast to your previous statements about parts being made so cheaply that they are on the verge of failure at any time. (please excuse my paraphrasing there)

Originally you made it sound as if cheap was so important that risks were taken to achieve it.

This time around, cheap seems to be the result of a learned ability to better predict the needs, and work safely within tighter tolerances.
Center-stand is offline   Reply With Quote
Old 09-11-2012, 08:31 AM   #699
Dave in Wi
Beastly Adventurer
 
Dave in Wi's Avatar
 
Joined: Feb 2007
Location: Madison WI (40 Square Miles Surrounded By Reality)
Oddometer: 1,948
I think what he means is cheap in terms of using the least material possible. In building construcion the more closely you "engineer" structural members, the less steel (for instance) you may be able to use for a structure. But there is always a safety factor built in. For instance, if the anticipated load on a beam is 2 kips, you desing it to support 4.
__________________
Dave in WI
2002 ZRX1200R
1975 XL100
1988 DT50
"Daddy, it's five o'clock sometime!"
Dave in Wi is offline   Reply With Quote
Old 09-11-2012, 08:41 AM   #700
slide
A nation in despair
 
Joined: Jul 2003
Location: NM, USA
Oddometer: 21,123
Guys - the theory of QA in vehicle design here isn't relevant to anything.

Here is what's relevant:

1. BMW F series bikes, in a past version, had several well publicized fork boss failures resulting, in some cases, in serious injury.

2. BMW never acknowledged there was a defect and instead insisted the failures occurred due to the crashes rather than causing them.

3. BMW changed the design of the fork bosses but has not said why this change occurred or what it was supposed to address.

4. In this thread's OP, a poster (who later disappeared) had a disastrous fork boss failure looking identical to the failures in the old series F bikes with the old style boss design.

The question is not the discipline these forks were designed under, but if the new fork design has the same failure mode and frequency as the old.
__________________
Why be born again when you can just grow up?
slide is offline   Reply With Quote
Old 09-11-2012, 09:40 AM   #701
henrymartin
Mr. Tourguide
 
henrymartin's Avatar
 
Joined: Sep 2010
Location: South of the Great North Woods
Oddometer: 3,373
Quote:
Originally Posted by slide View Post
Guys - the theory of QA in vehicle design here isn't relevant to anything.

Here is what's relevant:

1. BMW F series bikes, in a past version, had several well publicized fork boss failures resulting, in some cases, in serious injury.
Agreed, there were some. The total number of failures vs the total number of bikes produced is not known to me, so calculating a percentage is not possible.
2. BMW never acknowledged there was a defect and instead insisted the failures occurred due to the crashes rather than causing them.
And if they did, what do you think would happen: Complete recall of all F bikes? Lawsuits? Lets assume the failure rate is in the hundreds of a percentage point.
3. BMW changed the design of the fork bosses but has not said why this change occurred or what it was supposed to address.
BMW changed the design for the later years, the design change was obvious. Whatever the reason behind that decision, there are no known failures after the redesign.
4. In this thread's OP, a poster (who later disappeared) had a disastrous fork boss failure looking identical to the failures in the old series F bikes with the old style boss design.
You have to take into account that the 2011 G machines are completely redesigned. After the production ended with 2007 model, there was no single for a year. In 2009, the G650GS was born (such as mine) which was mostly exactly the same bike as the 2007 model, except the motor was no longer Rotax, but assembled by Loncin. Forks and all have been the same. The newer G bikes are different. The forks are black powder coated, have different part number (AFAIK). Perhaps, during the redesign there were new cost saving methods implemented, perhaps the caster was changed, perhaps...we will not know. Or, perhaps someone screwed up and sent the caster the specs for the old, weaker forks instead of the newer reinforced forks. We will never know. Either way, again, there is ONE known failure without any explanation, but a bunch of speculations. How many G bikes were sold worldwide since the G was redesigned? Again, one failure, which appears out of the ordinary, does not say anything about design or whatnot.

Personally, should I have a 2011 or newer model, I would worry more about the cast wheels offroad, then about the forks. My 2009 forks are fine (until they fail)


Lastly, no manufacturer has any desire to build a long-lasting, reliable product. They all take into account that they want to sell a new product down the line. It is just a matter of how long does the product have to last before it fails so the customer does not lose brand confidence, and purchase a replacement product by the same brand. Think planned obsolescence. Not that this has anything to do with the forks in question, but you would be a fool thinking it does not go into the design process. Just throwing it out there since we talked about designing, engineering, manufacturing, et cetera
The question is not the discipline these forks were designed under, but if the new fork design has the same failure mode and frequency as the old.
see above
henrymartin is offline   Reply With Quote
Old 09-11-2012, 05:12 PM   #702
Center-stand
Gnarly Adventurer
 
Joined: Nov 2008
Oddometer: 499
Quote:
Originally Posted by slide View Post

2. BMW never acknowledged there was a defect and instead insisted the failures occurred due to the crashes rather than causing them.

If there are documents available to the public that can be directly attributed to BMW stating the above, I would love to read them. Link???
Center-stand is offline   Reply With Quote
Old 09-11-2012, 08:18 PM   #703
_vortex_
snow snow snow :(
 
_vortex_'s Avatar
 
Joined: Jun 2006
Location: Twin Cities, MN
Oddometer: 1,133
Quote:
Originally Posted by Center-stand View Post
If there are documents available to the public that can be directly attributed to BMW stating the above, I would love to read them. Link???
NHTSA investigation. Find the links yourself in this thread. Or maybe the other thread. Don't remember which anymore.
__________________
-vortex
_vortex_ is offline   Reply With Quote
Old 09-12-2012, 12:29 AM   #704
ferals5
865+652
 
ferals5's Avatar
 
Joined: Jan 2011
Location: Goulburn, Australia
Oddometer: 999
Question

I wonder what Showa thinks?



.
ferals5 is offline   Reply With Quote
Old 09-12-2012, 01:21 AM   #705
Center-stand
Gnarly Adventurer
 
Joined: Nov 2008
Oddometer: 499
Quote:
Originally Posted by _vortex_ View Post
NHTSA investigation. Find the links yourself in this thread. Or maybe the other thread. Don't remember which anymore.
I have read the NHTSA report, I was asking about something on a BMW letterhead or similar, some direct BMW response.

Quite frankly I have no more confidence in what was reported by NHTSA than I do my own conclusions based on internet pictures. It would be very difficult to ever convince me that what I see was caused by a single strike while the forks were locked against the steering stop.

http://nhthqnwws111.odi.nhtsa.dot.go...9026-37260.pdf

The fact that the NHTSA report is a summation, not direct quotes, means it is subject to the same kinds of misinterpretation that we sometimes see on this forum. Somebody puts something in writing and I interpret it one way and you or somebody else might read something totally different.
Center-stand is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 09:03 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014