SOHC.co.uk Forums > Project Board
1967 CB450K0 Black Bomber Rebuild - By Royhall
AshimotoK0:
--- Quote from: royhall on December 01, 2019, 12:52:08 PM ---
--- Quote from: mick on December 01, 2019, 12:02:34 PM ---Hi Roy Arch Stanton & Sean are the same person :-), cheers Mick.
--- End quote ---
Ha. Well I never.
Sent from my Pixel 3a XL using Tapatalk
--- End quote ---
Sorry Roy .. I should have been more specific...just like to call members by their proper names when I can ... a seeming impossibility with Hairygit though ... I reckon he's called Rumpelstiltskin ;D ;D
Any news on the hubs from Sean? ... You are still welcome to a free slightly cracked one ... I reckon yours is far worse than the 3 I have. Feedback from Facebook group is that unless crack goes through hub it will be OK and there are lots out there being used that have slight cracking ... not that I am happy with that or agree but just reporting back from another group.
royhall:
Sean is popping round on Saturday morning with some bits so I shall know better then. He says there is one very small crack in his hub so will probably go with that. The one I have is going in the scrap bin it's so badly cracked, I wouldn't use it nor do I want anyone else using it. Not bad really, out of the entire back wheel I have a brake plate, axle, and spacers left. That's what you get with a 53 year old bike I guess.
K2-K6:
--- Quote from: AshimotoK0 on December 02, 2019, 08:45:54 AM ---
--- Quote from: royhall on December 01, 2019, 12:52:08 PM ---
--- Quote from: mick on December 01, 2019, 12:02:34 PM ---Hi Roy Arch Stanton & Sean are the same person :-), cheers Mick.
--- End quote ---
Ha. Well I never.
Sent from my Pixel 3a XL using Tapatalk
--- End quote ---
Sorry Roy .. I should have been more specific...just like to call members by their proper names when I can ... a seeming impossibility with Hairygit though ... I reckon he's called Rumpelstiltskin ;D ;D
Any news on the hubs from Sean? ... You are still welcome to a free slightly cracked one ... I reckon yours is far worse than the 3 I have. Feedback from Facebook group is that unless crack goes through hub it will be OK and there are lots out there being used that have slight cracking ... not that I am happy with that or agree but just reporting back from another group.
--- End quote ---
You're probably right about usage there Ash. Given that so many observed here display it then it's likely that most of them are in similar state from usage.
They look like they survive as the loads are separated for different functions and preventing the cracks from propagating further than exhibited. The sprocket and chain load is going directly in through the bearing housing from it's spigot ultimately directly to be supported by the wheel spindle, so avoiding the cracks. The brake liner also misses the load path as torque is enacted outside of the cracked site and directly into the spokes.
Leaving just the drive to go through the cush drive sites, even that is "self supporting" to reasonable level as all the bolts flanges to the sprocket keep the load into the cush drive rubbers effectively in the same plane rather than the rubbers having to accommodate anything outside perpendicular to the sprocket face.
Cracks are never going to look competent, but as most of the wheels haven't broken it seems the design does ultimately cope with what it's doing.
royhall:
I don't have a picture unfortunately as it just wouldn't show it. I cleaned the outside of the hub for a look and one of the cracks has gone right through to the outer face. If that propagates suddenly it would literally split the hub in two as there is also a serious crack to the boss opposite. That hub is going to the scrap bin.
K2-K6:
I can see your point Roy, don't think anyone would volunteer to be involved in a wheel collapse during use.
From an integrity point of view, it would seem that many examples could be heading for "exhibition use" only given what you and Ash are finding.
If they modded the CB500 production to better protect against initiation and propogation of those cracks, could you machine the brake plate outer by the dimension of the additional sprocket offset, and so move the hub over to align the sprocket correctly? Then make a bespoke spacer for sprocket side to reinstate overall dimensions, finally lace the rim up offset to correct chassis alignment.
I worked at a place that ran an aircraft with a cracked main wingspar, this was in the section that passed through the fuselage centre. They had applied strain guages to monitor if the crack was getting worse as part of pre-flight inspections :D
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Think it was this one from memory, a Vickers Varsity.
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