Maintenance & Technical > KX500 Aluminum Frame Conversion (AFC)
Broken AF frame - Do you know of any?
motopunk:
just found this... looks like wrong heat treated and cracked direct at the welds between rails and y-part...
and this pic from 2009 with the broken honda-frame..there is also a video on youtube, where you could see the bike running and little bit later it was happened... name of the video: 500 2stroke day at apex ..
mxaniac:
Correct, you want DIN 6921 fasteners in 10.9 or 12.9 grade.
--- Quote from: ylwgtr on March 30, 2014, 12:51:06 PM ---I like things looking like the manufacturer built them thats why i like OEM stuff....nothing worse than a dirty unflange hex bolt in my books washer or no washer
--- End quote ---
mxaniac:
I'd like to have some strain gauges and accelerometers on a bike. Pretty hard to analyse when you don't know what the inputs are. Head stay comes up again and again, if that is the case I would assume High Cycle Fatigue is the culprit.
--- Quote from: motopunk on March 30, 2014, 10:20:26 PM ---just found this... looks like wrong heat treated and cracked direct at the welds between rails and y-part...
and this pic from 2009 with the broken honda-frame..there is also a video on youtube, where you could see the bike running and little bit later it was happened... name of the video: 500 2stroke day at apex ..
--- End quote ---
mxaniac:
So a quick disclaimer, anything I state is merely a subjective opinion and should not be relied upon for anything other than entertainment purposes. Use of such opinons for any other purpose could result in serious death or injury. Sorry about the ridiculous disclaimer but the world is what the world is.
I modelled up a crude representation of the KX450f frame with the Y moved up in the configuration I used for my conversion to the KX500 engine.
Based on this model and a very simplistic analysis I've reached the OPINION, which I refer you once again to my disclaimer regarding the appropriate use of, that thin wall square tubing is woefully inadequate even with a very rigid head stay in the region directly below the Y.
I'm unable to submit recommendations due to liabilities so I'll leave you to your own conclusions.
sandblaster:
Excellent work, thanks for posting!
I agree with your analysis...
I would like to ask you a favor.
Along with the back head stay, could you model in a head stay at the front like the pics below?
It may well be that thicker walled tubing is needed, but I would sure like to see the front head stay with the stress analysis ran on it..
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