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Old 08-23-2009, 07:54 PM   #91
Lion BR
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That's a lot of damage.

Quote:
Originally Posted by itsatdm
That is the left mounting flange, the right flange is welded on the right side of the frame visible in the pic. The tube the left flange is welded to is a frame crossmember. The silver cylinder object to the left of the left flange is threaded and serves a nut for the bolt that holds it together.
A bent bolt is fixable, but in this case, it appears that after it bent, the left flange took more force that it was designed for and bent the crossmember. From the pictures it looks like the way the flange is cantilevered rearward, it acted as a lever twisting and bending the crossmount.
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Old 08-23-2009, 08:07 PM   #92
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Sorry for the hack job, but this is what Gary is describing. As the tab bends (in red) the cross tube arches (in yellow).


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Old 08-23-2009, 08:49 PM   #93
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I take it that a lot of force was pushed through the system to bend the bolt, the sleeve, the tab, and the cross tube. Wow.


Quote:
Originally Posted by johngil
Sorry for the hack job, but this is what Gary is describing. As the tab bends (in red) the cross tube arches (in yellow).

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Old 08-23-2009, 08:52 PM   #94
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Either that or the materials/design in question need to be revised.

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Originally Posted by Lion BR
I take it that a lot of force was pushed through the system to bend the bolt, the sleeve, the tab, and the cross tube. Wow.
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Old 08-24-2009, 08:00 AM   #95
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Quote:
Originally Posted by DockingPilot

John this from a suspension guy when asked about this situation:

"Frank,
I have seen bent top and bottom bolts (mainly on GS’s) with Wilbers shocks. It happens when the bike comes crushing down after a lift off and the shock bottoms out.
Agreed.

The question here is how much force will cause the above to happen on a GS 800. It may be unacceptably low. We have no way to know and compare with other motorcycles' designs.

Quote:
Originally Posted by DockingPilot

John this from a suspension guy when asked about this situation:

"This should not happen with a Hyperpro shock/spring.The progressive spring is so stiff at the very end, that it is almost impossible to fully compress it under these conditions."
Wouldn't that impart nearly the same force on the bolt, ears and cross tube ?
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Old 08-24-2009, 12:54 PM   #96
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Yeah it would. Compressed is compressed. Just be cause it doesn't bottom like a pancake doesn't mean its not transferring forces.

I bet bad bolt that bent frame parts. Any others have this issue?
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Old 08-24-2009, 01:21 PM   #97
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So hitting with same force, a rubber mallet and a regular hammer with same mass, would effect same indentation on a given surface?

Quote:
Originally Posted by Gangplank
Yeah it would. Compressed is compressed. Just be cause it doesn't bottom like a pancake doesn't mean its not transferring forces.

I bet bad bolt that bent frame parts. Any others have this issue?
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Old 08-24-2009, 01:41 PM   #98
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Huh? Not a great example. More like comparing two different rubber mallets. If you hit hard enough to fully compress the rubber mallet... Then theoretically one that is more absorbant would transfer less force than one that is less. If you put on a different shock with a stiffer spring it will transfer mire force. If it stiffer and very progressive... It will absorb, sure but it will also transfer more forces than less stiff and less progressive up to the point of bottoming out. At bottoming the one that is fully compressed transfers more.
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Old 08-24-2009, 03:01 PM   #99
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Quote:
Originally Posted by Gangplank
Huh? Not a great example. More like comparing two different rubber mallets. If you hit hard enough to fully compress the rubber mallet... Then theoretically one that is more absorbant would transfer less force than one that is less. If you put on a different shock with a stiffer spring it will transfer mire force. If it stiffer and very progressive... It will absorb, sure but it will also transfer more forces than less stiff and less progressive up to the point of bottoming out. At bottoming the one that is fully compressed transfers more.
If it's not fully compressed, it's not bottoming.

that's the point of stiffer springs, after all.
There is a big difference between running out of force to continue to compress a spring, and running out of compression. In the first instance, deformation of hard parts will not occur at the same point as it will on a softer spring that bottoms.
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Old 08-24-2009, 07:01 PM   #100
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Well, I went to the extreme example to dig for the rational for why different shocks would be more likely to transfer more or less force to the bolt and cross member. It seems like you are saying that different shocks may absorb differently and hence may transfer forces differently. If that is the case, we are in agreement.
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Quote:
Originally Posted by Gangplank
Huh? Not a great example. More like comparing two different rubber mallets. If you hit hard enough to fully compress the rubber mallet... Then theoretically one that is more absorbant would transfer less force than one that is less. If you put on a different shock with a stiffer spring it will transfer mire force. If it stiffer and very progressive... It will absorb, sure but it will also transfer more forces than less stiff and less progressive up to the point of bottoming out. At bottoming the one that is fully compressed transfers more.
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Old 08-24-2009, 07:04 PM   #101
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In other words, would a bolt and cross member bend without a full compression of the shock if even if the compression is non linear?

Quote:
Originally Posted by ]I)Money
If it's not fully compressed, it's not bottoming.

that's the point of stiffer springs, after all.
There is a big difference between running out of force to continue to compress a spring, and running out of compression. In the first instance, deformation of hard parts will not occur at the same point as it will on a softer spring that bottoms.
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Old 08-24-2009, 07:14 PM   #102
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And since I got your attention, another variable in this equation is the distance a shock can travel before full compression. The longer it is, the more gradual this compression can be, the higher rate of possibilities for absorption. Perhaps a contributor for the flaw (if it is proven to be a flaw) is on the length available for the shock to compress for the weight of this bike.
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Old 08-24-2009, 09:16 PM   #103
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Joel, I really appreciate your input and it would stand up as truth in a court of law. I'm sure the engineering works out to a gnat's ass and combines function and economics that will serve 99.6% of the riders out there in the real world.

My personal uneducated opinion is that the design sucks. For the intended (advertised and otherwise) use of the bike it is a stretch. This bike is aimed at a market that includes or even targets the 950/990 KTM's.
If you are a dealer, which is what I gather, then it would not benefit you in any way to say anything other than this is a great design.
I have come to the adventure bike/riding world straight from racing desert in southern California and doing so on KTM's. I have never in over 100 desert races bent or mutilated a structural member of my race bikes, ever.
I'm not looking for BMW to wipe my ass. I do think they went out on a limb w/ this design. I have not hidden a thing from my dealer or BMW. We will see how this plays out.

I have never crashed this bike or even bent a rim.
I am not the guy who wins raffles or could score some $$$ on a lottery ticket. What ever happens is what it is.

Most owners of these bikes would never know there was a bent bolt or frame to begin with. That isn't a knock, just the truth.

Whether my frame is replaced by BMW or I run it through my insurance, I don't trust this design. I will check the bolt after every off road ride.
If I have to fabricate a fix on my own, I will check it once or twice and forget about it.

Something is not right here.

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Old 08-24-2009, 09:51 PM   #104
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All parts replaced and torqued to spec. Covered under warranty.
Ride 175 miles the next day and bend bolt.

How many times do I have to do this?

By Wednesday BMWNA should be in contact w/ me. Patience is a virtue, but is hard to come by when a few thousand dollars are at stake.
Joel, you and I would be sitting down shooting the breeze if we lived nearby. Thanks again for your input.
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Old 08-24-2009, 09:58 PM   #105
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A question for Joel; In this design is the hardness of the bolt or the torque more important?
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