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So about that baby's arm holding an apple. Weird reference. Is the last line in this song what you meant?
Yup, that is the reference. Always liked that song.
 

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Are you saying swallows have nothing to do whether or not your KLR is going to fall apart into two or more pieces if you don't tighten your bolts?...
Certainly not! I simply forgot to mention the swallows and Monty.!
 

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Just once, I would like to have someone explain why and how the drill-through mod is better than having a pair of screws on either side, perhaps upgraded in diameter and grade as in the Gen 2. How is it that drilling completely through a necked-down section of frame member, especially with the possibility of drill wandering, a good idea?

The website provides no justification beyond "Eliminates the weaker 2 bolt setup in favor of one bolt all the way through for the upper subframe attach point. No more worry about keeping the bolts tight, or the original bolts breaking." How is the two-bolt setup weaker?

I'm known to carry some heavy loads on my subframe, as well as being a big fella in my own right. I run a filled Chase Alaska bag or my home-made Super SE540 top case, plus panniers. Frankly, I'm way over the weight limit that KHI specifies quite often. Hell, my pannier racks and the Seahorse stuff exceeds the weight before I have even loaded the stuff up! My Gen 2 subframe screws are installed with blue LoctTite and properly torqued. I have never lost a subframe bolt nor have I found one to be loose on a pre-ride inspection.

I am serious; I'd really like to see an engineering justification for drilling through the frame and installing a single bolt in the place of two screws.
Hey Tom, not sure if someone sufficiently answered this already, but I am mechanical engineer at SpaceX, so I thought I’d give you my 2 cents. The single bolt is better because it takes the threads out of the shear plane - it keeps the threads from being directly at the interface of the 2 mating parts that are trying to slide past each other. The shank of a bolt is stronger for taking shear loads than the threads. This is because the sharp corners of the threads create stress concentrations. How much weaker is up for some debate, but typical stress concentration factors used for threads in shear is 2-3X. Automotive industry puts threads in shear from time to time, but I can say with some confidence there’s not a single highly loaded structural bolt on falcon 9 with threads in shear - at least on purpose :) That said, with out knowing the loads your subframe takes im not sure I could say it’s totally worth drilling thru.
 

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Thanks for that and welcome to the forum. Sometimes I like to stir the pot. Just a little bit.
 

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SOMETHING We AGREE on TOM !!! write today down !! lol

Just once, I would like to have someone explain why and how the drill-through mod is better than having a pair of screws on either side, perhaps upgraded in diameter and grade as in the Gen 2. How is it that drilling completely through a necked-down section of frame member, especially with the possibility of drill wandering, a good idea?

The website provides no justification beyond "Eliminates the weaker 2 bolt setup in favor of one bolt all the way through for the upper subframe attach point. No more worry about keeping the bolts tight, or the original bolts breaking." How is the two-bolt setup weaker?

I'm known to carry some heavy loads on my subframe, as well as being a big fella in my own right. I run a filled Chase Alaska bag or my home-made Super SE540 top case, plus panniers. Frankly, I'm way over the weight limit that KHI specifies quite often. Hell, my pannier racks and the Seahorse stuff exceeds the weight before I have even loaded the stuff up! My Gen 2 subframe screws are installed with blue LoctTite and properly torqued. I have never lost a subframe bolt nor have I found one to be loose on a pre-ride inspection.

I am serious; I'd really like to see an engineering justification for drilling through the frame and installing a single bolt in the place of two screws.
 

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The shank of a bolt is stronger for taking shear loads than the threads. This is because the sharp corners of the threads create stress concentrations.
The shank of the bolt has a larger cross-sectional area than the thread root, hence there will be a lower shear stress across the shank for a given force.

Jason
 

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But the 10mm individual bolts used on the Gen2 bikes with Proper Torque pretty much ended Upper sub-frame bolt failures, even with luggage. To the best of my reading/knowledge.
 

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Just to stir the pot, as I am wont to do - I would like to see a report of a properly torqued set of 8mm subframe bolts where one bolt's head was sheared clean off like as if Dirty Harry got to it.

I'm waiting for the same report on properly torqued footpeg bolts...
 
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Just to stir the pot, as I am wont to do - I would like to see a report of a properly torqued set of 8mm subframe bolts where one bolt's head was sheared clean off like as if Dirty Harry got to it.

I'm waiting for the same report on properly torqued footpeg bolts...
I don't think you can shear those 8mm bolts without destroying the motorcycle.

Jason
 
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