Broken Lower Rear Shock Bolt
That's a stock 10mm lower rear shock bolt. Cannondale realized the stress on this part and had Ohlins & Fox make all their shocks with 12mm lower bolts. I tried making these in SS but they are too soft and I have had a report of a bent one (not broke though!). My advice is to find a 12mm bolt that is not too soft or too hard. Too soft and it will bend (grade 5 or SS), too hard and it will be too brittle when you jump and will likely break. Metric bolts have a diferent hardness scale, I was thinking something along the line of the what ever is equal to a grade 8 bolt in metric. I have been using SS hardware for a long time, and I will not use SS on the lower rear shock bolt. My thoughts are the same on the upper one as well. The front shock bolts & a-arm bolts do not seem to have as much of a load on them though. Please be careful if you are a big jumper, as I have seen this bolt fail many times in person.
QUOTE (kdeal @ Aug 26 2006, 07:05 PM) <{POST_SNAPBACK}>
That's a stock 10mm lower rear shock bolt. Cannondale realized the stress on this part and had Ohlins & Fox make all their shocks with 12mm lower bolts. I tried making these in SS but they are too soft and I have had a report of a bent one (not broke though!). My advice is to find a 12mm bolt that is not too soft or too hard. Too soft and it will bend (grade 5 or SS), too hard and it will be too brittle when you jump and will likely break. Metric bolts have a diferent hardness scale, I was thinking something along the line of the what ever is equal to a grade 8 bolt in metric. I have been using SS hardware for a long time, and I will not use SS on the lower rear shock bolt. My thoughts are the same on the upper one as well. The front shock bolts & a-arm bolts do not seem to have as much of a load on them though. Please be careful if you are a big jumper, as I have seen this bolt fail many times in person.
Wasnt there a thread recently on titanium components being made.. I think it was the ten pounds less on the front end thread maybe he could make this bolt in ti Im sure the strength would be there for the application
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Canniboomer
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Custom Ti bolts would be cool!
But that bolt pictured above does not look anything like our stock of Cannondale 10mm shock bolts, part 5000424. The OEM's are 12.9 metric grade, and harder than a Grade 8 (= 10.9 metric). The 10mm OEM bolts are the best 10mms available, but can still break. But they have a longer shank, and a short thread length, so there is no grinding of threads against the bushings or frame -- Those features are often ignored if guys just replace them with local hardwares.
The 12mm stockers are also grade 12.9, and the same long-shank design, but with a finer pitch.
But that bolt pictured above does not look anything like our stock of Cannondale 10mm shock bolts, part 5000424. The OEM's are 12.9 metric grade, and harder than a Grade 8 (= 10.9 metric). The 10mm OEM bolts are the best 10mms available, but can still break. But they have a longer shank, and a short thread length, so there is no grinding of threads against the bushings or frame -- Those features are often ignored if guys just replace them with local hardwares.
The 12mm stockers are also grade 12.9, and the same long-shank design, but with a finer pitch.
QUOTE (Canniboomer @ Aug 27 2006, 01:06 AM) <{POST_SNAPBACK}>
Custom Ti bolts would be cool!
But that bolt pictured above does not look anything like our stock of Cannondale 10mm shock bolts, part 5000424. The OEM's are 12.9 metric grade, and harder than a Grade 8 (= 10.9 metric). The 10mm OEM bolts are the best available, but can still break under radical riders (mostly from THIS site!). Also, they have a longer shank and short thread length, so there is no grinding of threads against the bushings or frame -- That's a feature that is often ignored by guys just replacing them with local hardwares.
The 12mm stockers are also grade 12.9, and the same design.
But that bolt pictured above does not look anything like our stock of Cannondale 10mm shock bolts, part 5000424. The OEM's are 12.9 metric grade, and harder than a Grade 8 (= 10.9 metric). The 10mm OEM bolts are the best available, but can still break under radical riders (mostly from THIS site!). Also, they have a longer shank and short thread length, so there is no grinding of threads against the bushings or frame -- That's a feature that is often ignored by guys just replacing them with local hardwares.
The 12mm stockers are also grade 12.9, and the same design.
I thought that 10.9 = grade 8 but I wasn't quite sure, so I didn't say for sure. 12.9 grade scares me a little, because it maybe too brittle for the application. I have seen the stock 10mm bolt fail more than once in person. I have seen someone run up and down the road, and while sitting on the bike moments later with the motor off, watch the nut & part of the thread just pop off! If I wouldn't have seen it with my own eyes I would not believe it! There is definitly an issue with either fatigue or stress cracks or something with that bolt. As I said above Cannondale even knew of the problem as they updated all their quad shocks with the 12mm bolt near the end. I have been advised that the strongest sheer strength (grade) may not be the best for this application. The bolt is required to flex some due to the load, but still retain it's shape (no bending or breaking). The bolt Speed2424 showed above came off a Walsh swingarm, so it's anybodys guess where it came from or the grade stamping.
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Canniboomer
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I also wonder if there has be a common problem with over-torqueing of that bolt? -- Torque will change the flex vs. breakage point of any fastener. If some are too tight from the factory, they could be on the verge of breakage at any time.
Or, a looseness will allow up/down racking of the shock. I'll think I'll start adding a cam-lock to each, and tighten enough for a firm pinch of the bushing, but not over-doing it.
I've never paid attention to a torque spec back there, but maybe we all should. It's good to at least jiggle the grab-bar up/down to detect shimmy.
Does that washer pictured above also looks suspiciously soft?... like an SAE grade 2 bin washer from Ace Hardware? If the frame holes are oblonged larger, then the bolt had been loose for a while, and caused the smooshed flat threads. If the frame holes are perfect like new, then the bolt was too tight and brittle, or just too weak.
Or, a looseness will allow up/down racking of the shock. I'll think I'll start adding a cam-lock to each, and tighten enough for a firm pinch of the bushing, but not over-doing it.
I've never paid attention to a torque spec back there, but maybe we all should. It's good to at least jiggle the grab-bar up/down to detect shimmy.
Does that washer pictured above also looks suspiciously soft?... like an SAE grade 2 bin washer from Ace Hardware? If the frame holes are oblonged larger, then the bolt had been loose for a while, and caused the smooshed flat threads. If the frame holes are perfect like new, then the bolt was too tight and brittle, or just too weak.
Guys let me tell you first hand I was on the bike when it happened and then rode a full lap on a mottocross track without the bolt in there 
check it and replace it I almost had a heart atack when speeed2424 pointed it out!!!!! Buy the way this is the first time being fat and out of shape helped me because i was going to do another lap but I got tired, lol MAY HAVE SAVED MY LIFE, now where is my cheeseburger at.
check it and replace it I almost had a heart atack when speeed2424 pointed it out!!!!! Buy the way this is the first time being fat and out of shape helped me because i was going to do another lap but I got tired, lol MAY HAVE SAVED MY LIFE, now where is my cheeseburger at.Boomer may be on to something here with the varying tightness from the factory theory. Since this was in an aftermarket swingarm it didn't come from the factory like that. So maybe we should go with a 12.9 hardness bolt. I also heard that the threading on the 10mm bolts may have been a contributing factor as well. I think I heard that the threaded area needed to be longer due to the nut bottoming out on the last thread????