IMPORTANT - Please read! (pics of crack in frame)
#71
02-11-2012, 09:11 PM
#72
04-15-2012, 12:20 PM
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My '87 was cracked in the same spot with around 40k on it. I also didn't notice the crack until I read this thread, so thank you from me as well! It was an easy fix since we had a nice Miller MIG at work.. only took a few minutes to weld it up.
Now I'm thinking I should change those two engine spacers to a steel material like cwr suggested. That's the only reason I can think of that would cause something like this to happen other than just plain abuse. Those spacers are really soft too, when I was pulling my engine I put a big dent in one by tapping it out w/ a hammer. Didn't realize they were aluminum until that happened haha.
Now I'm thinking I should change those two engine spacers to a steel material like cwr suggested. That's the only reason I can think of that would cause something like this to happen other than just plain abuse. Those spacers are really soft too, when I was pulling my engine I put a big dent in one by tapping it out w/ a hammer. Didn't realize they were aluminum until that happened haha.
#73
06-03-2012, 06:22 AM
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Ok, I have left this for a long, long time.
A few years ago now, Gearloose very kindly removed a section of frame on a CBR and paid 17 NZD to have it delivered to me.
I received the component and over the next few months I sectioned the component and investigated the failure mode.
I then wrote a report to be released and had it peer reviewed to make sure it was ok (we call these white rabbit jobs). In the meantime I had to "go to work" and was abroad for two weeks. When I came back this particular thread was a mess and had to be cleaned up by the admins. Because of the e-mail trail I read what had gone on. Unfortunately the content really knocked my confidence and I could not release the report. This is the one job I haven't been able to deliver on.
Well it has haunted me long enough so here goes. And I don't need a pdf report to back up what I found.
The crack is a fatigue crack - this happens to all metallic structures which undergo cyclic loading ie vibration. All vehicles to which structural integrity is essential (think more airworthiness not roadworthiness in a car - but I think bikes should be regarded with the severity of the former) have a Fatigue Index (FI). This is the lifespan of the vehicle or a component and it has to be replaced after certain amount of cycles/operating hours (these are based on hundreds of millions of cycles) otherwise the vehicle is not serviceable. As it might fail due to fatigue crack propagation - there are plenty of resources on the web to increase knowledge on this stuff and I'm crap at explaining.
Anyway, I opened the crack looked at the surfaces, analysed the material composition and came up with this:
The frame is made from a plain carbon steel nothing fancy, the as you can see from the various pictures on this thread, the crack goes around the Heat Affected Zone of the weld which means Honda's welding capabilities were fantastic in the late '80s.
The crack surfaces were heavily corroded, this is quite common with fatigue cracks because they propagate over a number of years. You can calculate the propagation rate with the correct information but there is no need to here.
I stripped the corrosion product away from the surface but the corrosion had damaged any evidence of striations (see fatigue striations on interweb). So working at the macro level, the crack surface was relatively smooth and had propagated transgranularly (through the material grain structure not around the grains) which is indicative of a fatigue mechanism.
The recent posts regarding the elongation of spacers does sound very plausible as a source of vibration but I would advise caution if you are going to replace the spacers. Use the same material as I bet the aluminium is softer than the surrounding components (I don't have my 600FJ anymore but i'm guessing they are steel). You do not want spacers with a greater hardness than the surrounding components. The softer spaces can be sacrificed. Basic rule - the harder material wears away at the softer material, that is why most washers, etc are softer because it is easier to replace them than a major component.
As to mitigation of the crack, welding seems to be successful regarding other posters on this thread. If you don't have access to a welder, stop-drilling will remove the stress concentration from the tip of the crack (get info from google first). But corrosion will return eventually - which may kick it off again (corrosion fatigue) so keep an eye on it.
If you want to have an experiment with a premature crack, mark the tip with a fine permanent marker and look every month or so and see how far it has progressed its not that accurate but could be interesting. If the crack is over 1/2 of the length of the frame - get it seen to just for peace of mind.
During this investigation I used a Field Emission Gun Scanning Electron Microscope (FEG SEM) with Energy Dispersive X-Ray (EDX) analysis, a Carbon-Sulphur analyser, various binocular microscopes/cutting machines - including an angle grinder.
The basis for my knowledge comes from a BEng in Forensic Engineering, 2 years in aviation testing industry and 3 1/2 years as a Failure Investigator. In addition my unit sponsors my part time Phd.
I may not be able to spell that well, but I have some experience in this field.
I am now getting off my high horse, sorry everyone but I had to get this rid of this ghost haunting me.
Gearloose, I can only apologise for the delay, if you pm me your address, i'll be more than happy to return your 17 NZD.
As for my CBR, she (and me) were written off in May 2010 , in Aug 2010 I bought a Blackbird.
Thanks for you time.
Cuzy
A few years ago now, Gearloose very kindly removed a section of frame on a CBR and paid 17 NZD to have it delivered to me.
I received the component and over the next few months I sectioned the component and investigated the failure mode.
I then wrote a report to be released and had it peer reviewed to make sure it was ok (we call these white rabbit jobs). In the meantime I had to "go to work" and was abroad for two weeks. When I came back this particular thread was a mess and had to be cleaned up by the admins. Because of the e-mail trail I read what had gone on. Unfortunately the content really knocked my confidence and I could not release the report. This is the one job I haven't been able to deliver on.
Well it has haunted me long enough so here goes. And I don't need a pdf report to back up what I found.
The crack is a fatigue crack - this happens to all metallic structures which undergo cyclic loading ie vibration. All vehicles to which structural integrity is essential (think more airworthiness not roadworthiness in a car - but I think bikes should be regarded with the severity of the former) have a Fatigue Index (FI). This is the lifespan of the vehicle or a component and it has to be replaced after certain amount of cycles/operating hours (these are based on hundreds of millions of cycles) otherwise the vehicle is not serviceable. As it might fail due to fatigue crack propagation - there are plenty of resources on the web to increase knowledge on this stuff and I'm crap at explaining.
Anyway, I opened the crack looked at the surfaces, analysed the material composition and came up with this:
The frame is made from a plain carbon steel nothing fancy, the as you can see from the various pictures on this thread, the crack goes around the Heat Affected Zone of the weld which means Honda's welding capabilities were fantastic in the late '80s.
The crack surfaces were heavily corroded, this is quite common with fatigue cracks because they propagate over a number of years. You can calculate the propagation rate with the correct information but there is no need to here.
I stripped the corrosion product away from the surface but the corrosion had damaged any evidence of striations (see fatigue striations on interweb). So working at the macro level, the crack surface was relatively smooth and had propagated transgranularly (through the material grain structure not around the grains) which is indicative of a fatigue mechanism.
The recent posts regarding the elongation of spacers does sound very plausible as a source of vibration but I would advise caution if you are going to replace the spacers. Use the same material as I bet the aluminium is softer than the surrounding components (I don't have my 600FJ anymore but i'm guessing they are steel). You do not want spacers with a greater hardness than the surrounding components. The softer spaces can be sacrificed. Basic rule - the harder material wears away at the softer material, that is why most washers, etc are softer because it is easier to replace them than a major component.
As to mitigation of the crack, welding seems to be successful regarding other posters on this thread. If you don't have access to a welder, stop-drilling will remove the stress concentration from the tip of the crack (get info from google first). But corrosion will return eventually - which may kick it off again (corrosion fatigue) so keep an eye on it.
If you want to have an experiment with a premature crack, mark the tip with a fine permanent marker and look every month or so and see how far it has progressed its not that accurate but could be interesting. If the crack is over 1/2 of the length of the frame - get it seen to just for peace of mind.
During this investigation I used a Field Emission Gun Scanning Electron Microscope (FEG SEM) with Energy Dispersive X-Ray (EDX) analysis, a Carbon-Sulphur analyser, various binocular microscopes/cutting machines - including an angle grinder.
The basis for my knowledge comes from a BEng in Forensic Engineering, 2 years in aviation testing industry and 3 1/2 years as a Failure Investigator. In addition my unit sponsors my part time Phd.
I may not be able to spell that well, but I have some experience in this field.
I am now getting off my high horse, sorry everyone but I had to get this rid of this ghost haunting me.
Gearloose, I can only apologise for the delay, if you pm me your address, i'll be more than happy to return your 17 NZD.
As for my CBR, she (and me) were written off in May 2010 , in Aug 2010 I bought a Blackbird.
Thanks for you time.
Cuzy
#74
06-03-2012, 08:12 AM
#75
08-24-2012, 11:36 AM
#76
08-25-2012, 12:15 PM
#77
08-25-2012, 08:54 PM
June 2013 ROTM
#78
08-26-2012, 02:13 AM
#79
07-07-2013, 05:48 PM
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#80
10-01-2013, 06:03 PM
mine is cracked too 24K on the odometer