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Post by masonmart on Feb 8, 2023 11:33:30 GMT 1
I'm looking for new bolts to hold the crankcases together and would like to use polished stainless. A friend has advised against it as the Tensile strength of SS is lower than High tensile bolts which may be standard and they may loosen. I would have thought that the strength of SS is still OK but I could be corrected.
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Dave B
Drag-strip hero
Posts: 240 
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Post by Dave B on Feb 8, 2023 11:59:58 GMT 1
Unless I am very much mistaken, the standard casing screws used on all Japanese motorcycles are far from being high tensile. There are various derogatory names for the steel alloy used, but I would call them "easy machining steel", or "Free cutting steel". My father called it "Lead-loy". I don't know if there is lead in the mix, but the steel is very malleable, and many case screws have rolled threads rather than cut ones. You can tell if the threads are formed by a thread roller rather than a tap if the diameter of the threaded portion is greater than that of the unthreaded shank.
For some people, it's like swearing in church to use anything other than the original case screws, and not only do they have to be the original JIS crosshead pattern, but they must have the correct colour of surface treatment.
Some are bright zinc silver, some are passivated black, and some, the holiest of holies, are "olive drab"- green.
Mine are all hex headed stainless- but nothing else on the bike is factory standard either.
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Post by midlifecrisisrd on Feb 8, 2023 12:00:59 GMT 1
They are low torque so stainless is fine
Steve
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Post by Robbieben on Feb 8, 2023 12:26:54 GMT 1
I'm looking for new bolts to hold the crankcases together and would like to use polished stainless. A friend has advised against it as the Tensile strength of SS is lower than High tensile bolts which may be standard and they may loosen. I would have thought that the strength of SS is still OK but I could be corrected. Stainless crank case bolts will be perfectly adequate as they will be capable of a lot more loading than the actual torque figure. Plenty of builds on here and other forums where stainless have been used in preference to steel, remember to lubricate any steel, stainless or otherwise before fitting into aluminium. I use a white grease with PTFE, its a good lubricant and helps to prevent granular corrosion. |
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Post by masonmart on Feb 8, 2023 13:31:39 GMT 1
Thank you. I have no fundamentalist wish to use whatever was the original, my policy is that if you improve the bike without changing the basic form then that is great. Polished stainless looks just brilliant against a black finish.
Where is it best to find recommended torque values?
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Post by reedx on Feb 8, 2023 16:25:27 GMT 1
Where is it best to find recommended torque values? Workshop manual as first port of call. Colin |
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Post by dusty350 on Feb 8, 2023 19:19:32 GMT 1
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Post by donkeychomp on Feb 8, 2023 22:20:31 GMT 1
Ditto. Stainless steel and yes they look fantastic against the black of the engine.
Alex
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Post by masonmart on Feb 9, 2023 1:41:19 GMT 1
Thanks Dusty. Can you help me with which of these are the M6 and M8 crank case top bolts and underside nuts.
Mind you, just checking and bog standard low grade CS and 316 SS would yield at 18 ft.lb on M8. All of these bolts have to be annealed and cold worked. For example, some stainless bolts on eBay are stamped A2-70 which has an increased yield and UTS. Yielding itself is not a major problem but may mean having to check again after use.
MM
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Post by Robbieben on Feb 9, 2023 13:01:52 GMT 1
Thanks Dusty. Can you help me with which of these are the M6 and M8 crank case top bolts and underside nuts. Mind you, just checking and bog standard low grade CS and 316 SS would yield at 18 ft.lb on M8. All of these bolts have to be annealed and cold worked. For example, some stainless bolts on eBay are stamped A2-70 which has an increased yield and UTS. Yielding itself is not a major problem but may mean having to check again after use. MM You'll be fine with A2-70, I've used them for years. We even use them on road going Chemical tankers, never had a problem if they are lubricated and torqued up correctly. |
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Post by masonmart on Feb 9, 2023 14:48:35 GMT 1
Thanks Robbieben.
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Post by Jona on Feb 13, 2023 21:57:09 GMT 1
Does anyone know of a supplier of a full stainless kit for the whole bike as there are with other makes like my GT380 ?
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Post by Robbieben on Feb 13, 2023 22:14:37 GMT 1
Does anyone know of a supplier of a full stainless kit for the whole bike as there are with other makes like my GT380 ? Have a look in the online shop on here. Norbo has all you'll need. |
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Post by Jona on Feb 13, 2023 23:03:33 GMT 1
Does anyone know of a supplier of a full stainless kit for the whole bike as there are with other makes like my GT380 ? Have a look in the online shop on here. Norbo has all you'll need. Lovely. Thanks |
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