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Old 09-07-2012, 01:00 PM   #676
twinjet
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Originally Posted by reenmachine View Post
Noooooooooooooooooo! This thread was nice and quiet for a while.

It's amazing how some people will let one questionable example put them off the bike while ignoring the multitudes of people posting pics of big jumps, routine off-road abuse and crashes, and already relatively high mileage (~11,000 mi here) with perfect reliability. It defies logic to give more weight to one than the other!
What you say is true and for most parts of a bike I would agree with your logic 100%. Forks on the other hand are for me a different matter. I want my bike to be designed so that the front wheel never detaches from the forks even if I slam into a wall and bend the forks, I want the wheel to stay on the forks.
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Old 09-07-2012, 11:22 PM   #677
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If you had any idea how close to the design limits of engineering most car parts are designed/built, you'd curl up in a ball and never leave the house.

Can this die please? If you don't want to buy and F650/G650, don't buy one!
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Old 09-07-2012, 11:43 PM   #678
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Originally Posted by atomicalex View Post
If you had any idea how close to the design limits of engineering most car parts are designed/built, you'd curl up in a ball and never leave the house.

Can this die please? If you don't want to buy and F650/G650, don't buy one!

"design limits of engineering" What do you mean by that?

You seem to be suggesting auto parts are built to some engineering spec that is barely above the extreme danger point.
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Old 09-08-2012, 09:10 AM   #679
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Originally Posted by reenmachine View Post
..
I've flown on airplanes other examples of which suffered failures and crashed, killing all aboard, yet I continue to go visit grandma. Am I stupid or crazy?
I'd say you're uninformed.
Tell me of a design flaw that caused an airplane crash, that when discovered, didn't cause the fleet of the affected airplanes to be grounded until the flaw was fixed.
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Old 09-09-2012, 12:04 AM   #680
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Originally Posted by Center-stand View Post
You seem to be suggesting auto parts are built to some engineering spec that is barely above the extreme danger point.
You don't realize that most of them are? Weight savings, cost savings, etc take their toll on all parts of all goods. Toyota truck frames cracking, VW engines coking (not sludging - coking!), manifold gaskets on 3800s melting, you name it, somewhere out there, a part is within an inch of its life. 99% of the time, there is enough room for extended duty cycle. But if the spec calls for a duty cycle and load limit, no Teir in their right mind is going to eat the cost of going beyond it. And if there is no clear DFMEA or FMEA or (worse) the failure mode was not anticipated, then all bets are off when it comes to failure analysis.

Toyota Tundra tailgate... 1.5mm frame stock instead of 2mm stock. But it saved about 1kg.
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Old 09-09-2012, 02:56 AM   #681
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You continue to mystify me with your terminology. A VW motor "Coking". I have a very limited understanding of coke used in the iron ore/steel making process, I know it has been used in the space program, and many years ago as a home fuel under certain conditions. Coking, the process of making coke happening in a auto engine, how does that happen? If you are speaking of petroleum coke, wouldn't that be a fuel issue?

Still wondering about "design limits of engineering".

Thin/soft tailgates on pickups have been around for several years, I recall bending at least two on an '86 model Nissan, but I wouldn't condsider them to be dangerous, and certaily not in the same way as a fork failure on a motorcycle, regardless of the cause/reason for the fork failure.

I have a family member in the towing business. He has shown me pictures of badly damaged vehicles that drivers and passengers walk away from, modern vehicles with severly damaged front and back ends, and the passenger compartment is still intact with operating doors. Many parts of a vehicle are built to surrender to a specific load in order to protect the occupants.

Without being very specific there is little to no correlation between parts on an auto that bend vs.forks on a motocycle. If you are aware of A frames or other critical suspension components breaking on a specific model auto with low milage and no severe corrosion, then maybe they would be relevant in this discussion.
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Old 09-09-2012, 08:39 AM   #682
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All the examples given by this atomic fellow are irrelevant to the central issue, IMO. If a few Toys have soft tailgates or a very few VW's have crystals in the oil due to overheating aren't issues nearly of the magnitude of the front end of a motorcycle coming apart at speed and killing or gravely injuring the rider.

The first two are issues of longevity while the fork issue is one of safety. They are utterly different classes of issues.

As to we driving or riding in / on vehicles one mm from catastrophic failure as this atomic fellow claims - well we are NOT because they fail so rarely and not within patterns.
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Old 09-09-2012, 08:46 AM   #683
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Originally Posted by slide View Post
As to we driving or riding in / on vehicles one mm from catastrophic failure as this atomic fellow claims - well we are NOT because they fail so rarely and not within patterns.
If you happen to be riding behind a truck with a thin tailgate that has a long, undetected fatigue crack and it finally falls off in front of you, it couild be bad news for you.

BTW, she's female, not a fellow.
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Old 09-09-2012, 08:56 AM   #684
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Except they do NOT fall off and if they started to, then Toy would ack the issue and fix it.

You and the atomic fellow are claiming that there are many almost failures just waiting to happen but I look at it since they are NOT occurring, I'm not concerned about these theoretical failure vectors.

Here, I"m concerned about the fork failures because they did occur for sure on the older F bikes but BMW never ack'd that. Had BMW said, yes, this was a problem and the problem was due to (whatever), and we addressed it (this way) then I'd feel better about the newer style forks.

As it is, for all I know the new style bosses are only newly styled for the heck of it.
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Old 09-09-2012, 11:04 AM   #685
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Originally Posted by Benesesso View Post
.

BTW, she's female, not a fellow.

Perhaps you need to take a look at your Funk & Wagnalls.

I suppose there could be many reasons why a female might not be considered a "fellow", but being female is not one of them.

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Old 09-10-2012, 12:14 AM   #686
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I'll be blunt on this: either you understand engineering parts design or you don't. It's fine if you don't, but please do not pretend that you do. Some of us do this for a living, and we are being honest about what goes on in our world: compromises are made everywhere. They have to be, or the bike would cost $120K.

If BMW wanted to make the forks indestructible, the forks would be made of forged titanium and cost about 40x what they do. BMW made weight, cost, and design compromises based on the expected use of the forks. Those compromises put the original design very close to the real world load and duty cycle limits in the case of certain casting conditions. Changes were made to mitigate those design issues, and failure rate went down. WTF more could they do? If they used a different material, the cost would go up. If they added too much metal, the weight would go crazy (and cost would go up). If they told you not to ride dirt, you'd bitch about the bike not being good enough.

There is no win in this for them.
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Old 09-10-2012, 02:00 AM   #687
Center-stand
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Originally Posted by atomicalex View Post
I'll be blunt on this: either you understand engineering parts design or you don't. It's fine if you don't, but please do not pretend that you do.
I have no problem with blunt. I'm not pretending anything, thus my question about "design limits of engineering". It could be my ignorance, but the smarter some folks act like they are the more foolish their remarks sound to my ears.

Personally, I think that the suggestion that BMW would deliberately design and build a fork tube within "an inch of its life" is ridiculous, and doesn't reflect an accurate knowledge of the design, engineer, build, process. I think the number of failures vs. numbers in use that haven't failed supports the assumption that failure is an anomoly. While that may not be consolation to those who experienced failure, or those riding on forks that haven't failed, it does not mean it was a bad design or a compromise taken too far.

I think the failures are a result of a breakdown somewhere between the design, engineering stage and the consumer use. Certainly BMW should discover the cause and implement policy changes to insure it doesn't happen again. I hope they have done that.

Just so you know, I looked before I asked. I've learned a lot more in my life by acting dumb than I have by pretending to be smart. Below you will find the results of a google search for "design limits of engineering". I couldn't find anything that I thought fit in the context that you used the phrase. If you can explain I would appreciate it.

http://www.google.com/#hl=en&output=...w=1440&bih=795

http://www.google.com/#hl=en&output=...w=1440&bih=795

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Old 09-10-2012, 06:15 AM   #688
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Originally Posted by atomicalex View Post
I'll be blunt on this: either you understand engineering parts design or you don't.
And I'll be blunt with you, parts are engineered. They are not engineering, because they do not do any of the strength and serviceability calculations. They are inanimate objects.
It's also slightly pompous of yourself to assume people cannot understand a concept. If you merely made an effort to explain yourself properly it would be helpful.
Even a ball joint failure is less dangerous than a fork failure. I'd say they would've been engineered to be as far as foreseeable safe, but the problem is likely a defect in casting. Crack propagation then probably ensued.
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Old 09-10-2012, 07:03 AM   #689
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Originally Posted by atomicalex View Post
I'll be blunt on this: either you understand engineering parts design or you don't.
I am not a PE, but I do know about business practice. If you have a product which fails, causes grave injuries or maybe even deaths, you take remedial action or you don't. In this case, I see no reason to believe that the so called new design addressed the failure cause(s) in the old style because BMW have never said there is a problem so obviously they also haven't said they've addressed it..

Do I really need to be a P.E. to grasp that?
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Old 09-10-2012, 07:44 AM   #690
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Originally Posted by slide View Post
I am not a PE, but I do know about business practice. If you have a product which fails, causes grave injuries or maybe even deaths, you take remedial action or you don't. In this case, I see no reason to believe that the so called new design addressed the failure cause(s) in the old style because BMW have never said there is a problem so obviously they also haven't said they've addressed it..

Do I really need to be a P.E. to grasp that?
This is an interesting discussion.

I am not a P.E. but am a EE and do some product design on the electrical side and work with a couple of MEs. There are a lot of tradeoffs.

I want to go back in time. IF the axle (bolt) was bent during shipping or installation, which appears to be very possible, and the assembly monkey did not notice it, or bother to say something if [s]he did, I can certainly see that the boss would have been placed under possible large rotational forces that it is not designed for (not correct wording, sorry). There is no way I would expect BMW can design for that, of course, if it is possible the method of shipping could cause damage to the axle bolt, then a new one should be used when attaching the front wheel, but I digress.

On the flip side, I have never heard of a DRZ's or KLR's front wheel falling off in a similar fashion, and they are cheaper made bikes (I owned a KLR, and will contest to it being well engineered cheap bike, except for the oil consumption thing ), but again, I digress.

Personally for me, there is far to much anecdotal evidence that BMW has lost there way in manufacturing reliable products. Weather it is the miss alignment of the input shaft to the 1150's transmission, 1200GS rear drive failing, or the supposed fracturing of the engine cases of the 800GS around the counter shaft. BWM seems to suffer from the most epic trip ending failures.

The designers at BMW produce some spectacular looking designs that frankly have amazing specs, but I just can't get all of the stories about failures out of my head.

I will admit, I am really hoping it was just a bent axle that cause this failure, but sadly I doubt we will ever know. I am an engineer, so if the same thing happened to me, the only way I would not be in this discussion is if I got paid (settlement) to not be. But for many I know, they would not want to re-live the incident over and over again. So I can readily see that AntiqueWidow has long unsubscribed to this thread, and is living her life

It is only us engineers, and wannabe product engineers that keep this going

ride safe y'all! personally I got a kitchen pass and put 670 miles on my Tiger 800XC yesterday

tom
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