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Old 08-26-2009, 05:52 AM   #136
CCer
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hey john, sorry to hear about the issues with the 800. one of the l.a. riders mentioned it last weekend and i just read through the thread. i know you're pretty far along with this but let me know if you need my bike for anything, pictures of a (hopefully, i haven't checked) non-bent shock bolt/ frame, etc.

dale
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Old 08-26-2009, 06:44 AM   #137
Bruno T .
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Quote:
Originally Posted by itsatdm
I am not an engineer so I will reserve judgement on the strength of the design,
Agreed.

Quote:
Originally Posted by itsatdm
though intuitively I still have trouble with two bushings butted together at 74ft# will adequately prevent the bolt from bending. How much that supported bolt load is spread over both mounts is also open to question. One look at the mounting flanges makes it obvious which one is expected to receive the most load.
That's where my doubts lay as well. From my layman's perspective, i'm inclined to say that the mount isn't very strong. I can't prove that, and i have no factual basis of comparison to go by.

Here's the F8 mount (courtesy of DockingPilot);



Note the black rubber part on the right side of the picture, under that is a metal bushing. The mounting bolt goes through the frame ear (fairly thin) barely visible to the right of the aforementioned rubber bushing, through the shock and its two bushings. It then threads into the aluminum bushing with the 17 mm flats visible on the left of the image. The ear on the left side is pretty thick, about 3/8".

Note the span between the frame ears on the F8 configuration.

In contrast, here is the same shock mount on my 950 Super Enduro;



And one without the paw;



One that depicts the triangulation;



That looks much stronger to me.

It's not just the 950 Super Enduro, here are a couple more;

640 Adventure;



660 Rallye;



520 EXC;



I know those pictures aren't very good (i was too lazy to remove parts . .), but in every case the ears are only as wide as they need to be to span the upper shock mount.

I'm not sure whether the above mounting configurations would have prevented my bolt from bending. I know one thing for sure, i've never bent one of the others. In fact, i haven't ever bent a shock mounting bolt or any of its associated components.
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Old 08-26-2009, 08:48 AM   #138
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Quote:
Originally Posted by Bruno T .
In contrast, here is the same shock mount on my 950 Super Enduro;


Hehe, I was going to post such a pic (the 950 Adventure has the same mount) but feared Id start off another BMW vs KTM hoo-ha...

But, certainly in light of the 950's mount (and the photo only shows some of the story - the longer section of the mount point also has a diagonal brace down to the vertical section of the frame) the F8GS mount looks weak ... you can see why the argument of a design issue has legs.
The 950/990 adventure and the F800GS have very similar intended uses, very similar specs in terms of weight & carrying capacity - yet it doesnt take much of an engineering qualification to see how one is bound to be much stronger than the other ....

Still, if it were a significant design issue, you would think problem reports would be more widespread....
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Old 08-26-2009, 09:16 AM   #139
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The F800 does seem to have a different approach to upper shock mounting. Here's the vstrom upper mount. As a reference.

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Old 08-26-2009, 09:59 AM   #140
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Quote:
Originally Posted by mookymoo
Still, if it were a significant design issue, you would think problem reports would be more widespread....
Only time will tell.

I think that the F800 mount is fine as long as it isn't subjected to loads from a bottomed shock. I think that, because i have ridden my F8 in varying conditions. I have ridden it on dual sport rides (and i'm not talking about dirt road rides . .), jumped it, descended ledges with it, etc., all without incident. The key factor here, in my opinion, is that at no time did i bottom the rear shock.

I also opine that the mount (especially on a motorcycle marketed in this segment) should be engineered to withstand some degree of abuse, ie; a bottomed shock. Maybe it is, just not enough.

I don't know how much force it takes to bend the components in question, but in comparison with other mounts it certainly doesn't inspire confidence.

A better view of the span (courtesy of Johngil);

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Old 08-26-2009, 10:14 AM   #141
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A dollar to a donut you see that changed in 2011 models, umongst other things.
I mean how much would you pay to get a hold of the dope who ok'd this frame design and grab him by the neck tie and say "you flippin arrogant idiot, is this the 1st bike you designed" ?

Hey, where's Griz anyway, these threads don't quite have the entertainment value they once did
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DockingPilot screwed with this post 08-26-2009 at 10:20 AM
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Old 08-26-2009, 02:58 PM   #142
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The engineer in me looks at Bruno's last picture & shudders.
DP, you assume this was actually designed buy an engineer, computer analysis probably said it was OK, but people in the real world often know better, looks to me like the cross tube could do with some bracing as well
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Old 08-26-2009, 03:01 PM   #143
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Quote:
Originally Posted by trustme
The engineer in me looks at Bruno's last picture & shudders.
DP, you assume this was actually designed buy an engineer, computer analysis probably said it was OK, but people in the real world often know better, looks to me like the cross tube could do with some bracing as well
Ya think?



If I have to fix this myself, this is kind of what I was thinking. It may be cryptic, but some of you get the idea. The yellow would be new and welded in.
This wouldn't be a big deal if the cross tube weren't bent. Still, I don't think it is heavy enough to carry the load over time.


johngil screwed with this post 08-26-2009 at 04:48 PM
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Old 08-26-2009, 03:01 PM   #144
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Need to add another ear like the one on the left but closer, then redesign the bushings for what ever they do, attach seat or whatever.

I am assumeing there is some meat to weld another ear to in that area.

I don't like the split bushings in the Ohlins either.
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Old 08-26-2009, 03:04 PM   #145
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Quote:
Originally Posted by llamapacker
BMWNeeds to add another ear like the one on the left but closer, then redesign the bushings for what ever they do, attach seat or whatever.

I am assumeing there is some meat to weld another ear to in that area.

I don't like the split bushings in the Ohlins either.
Fixed it.
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Old 08-26-2009, 04:55 PM   #146
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Quote:
Originally Posted by JoelWisman
As a public service...
Yawn
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Old 08-26-2009, 04:57 PM   #147
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Quote:
Originally Posted by JoelWisman
As a public service, many here should pop over to orange crush and tell everyone how KTM engineers screwed up on the design of that bike since the subframes and frames bend occasionaly.

Same with KLR's.

Heck, my uncle is a proffesional engineer with Boing and would you believe that landing gear struts bend and even break when jumbos land hard, perhaps if I get you guys a picture you can inform him how they should be engineered!

My thought is that it is not just the upper mount that needs beefing up, after all, haven't a few bent the lower mount bolt as well? And to think, that mount only has an 1/8" gap on each side, we better make it less!

Actually I heard someone bent their handlebars, better add 20 lbs to them.

Ohh ohh the wheels, many bend rims all the time, better add at least 50 lbs of meat a rim.

Actually, let's just make the bike so heavy that it sinks if someone tries to ride it off road, that should fix any bending problems :)
Joel, as you have stated, my problem is not going to go away. If BMW doesn't step in, or I don't file a claim w/ my insurance company the bolts will continue to bend due to the previous damage. I don't have the $2000 + to just buy a frame. I do own a few tools, have a few friends, and a TIG machine. That and some beer should provide a fix for the time being.

I'll take my chances w/ orange.
I started racing them in 2001 and have been pleased.

johngil screwed with this post 08-26-2009 at 05:08 PM
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Old 08-26-2009, 05:08 PM   #148
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Quote:
Originally Posted by JoelWisman
As a public service,
Now now ... dont send this thread off on a tangent...

If it makes you feel any better, here is what happens when you treat 1st year model KTM 950's like a motocross bike. (this occured during a day of jumping the 950 off dunes - one day of many apparently)

http://www.advrider.com/forums/showthread.php?t=470371

After reports of a number of cracked swingarms on the 03 bikes, KTM had to up-rate the part.

If there are enough reports of shock mount bending, BMW will have to do the same.

(BTW, the shock mount wasnt bent on the 950 )
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Old 08-26-2009, 07:07 PM   #149
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I thought the rims were made out of old beer cans already
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Old 08-27-2009, 12:29 AM   #150
trustme
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Quote:
Originally Posted by JoelWisman
As a public service, many here should pop over to orange crush and tell everyone how KTM engineers screwed up on the design of that bike since the subframes and frames bend occasionaly.

Same with KLR's.

Heck, my uncle is a proffesional engineer with Boing and would you believe that landing gear struts bend and even break when jumbos land hard, perhaps if I get you guys a picture you can inform him how they should be engineered!

My thought is that it is not just the upper mount that needs beefing up, after all, haven't a few bent the lower mount bolt as well? And to think, that mount only has an 1/8" gap on each side, we better make it less!

Actually I heard someone bent their handlebars, better add 20 lbs to them.

Ohh ohh the wheels, many bend rims all the time, better add at least 50 lbs of meat a rim.

Actually, let's just make the bike so heavy that it sinks if someone tries to ride it off road, that should fix any bending problems :)
As a public service please note that all motorcycle manufacturers are infallible & we mere mortals have no right to query them. Ralph Nader is a total toss pot who had no idea of what he was talking about, after all how could the car manufacturers possibly get it wrong & how could he possibly know better . I seem to remember that even aviation engineers have on occasion got it wrong,Of course we have absolutely no right to criticise because we are just the dummy end user, what the hell would we know.
I apologise for my temerity in questioning motorcycle designers . no doubt I will burn in hell for this outburst.

trustme screwed with this post 08-27-2009 at 01:03 AM
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