So following this thread - https://www.nortonownersclub.org/forum/fitting-alternator-crank-dynamo-cases
I'm searching for an 88 crank with a crank pin bore less than the crank I have which has a 1" bore. Referring to the text from the dominator service notes (see attached pics) Im led to believe that I have one the early weaker cranks and should replace it with a stronger one. Realising that it's unrealistic to ask vendors to strip cranks and measure the pin bore I've asked them to do a depth measurement from the journal face to the opposite inside face of the pin so that I can compare it to mine. Mine measures 31.5mm.
Norvil have a reconditioned crank that measures the same and Eldon at Owens has been through about 20 500 cranks (dynamo and alternator) and says they're all the same.
Can anyone confirm that the three bore sizes mentioned in the service notes existed??? Norvil seemed to think there were only two and only the SS had the thicker pins.
im rebuilding this bike to ride it so don't want to ride in fear of it blowing up every time I wind it up.
Please advise.
cheers,
pete
The 88 SS crank is a very…
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So I'm not necessarily…
So I'm not necessarily looking for an 88SS crank according to the service notes which suggest the ss crank took the bore down to 5/8 from 7/8 and that only the very early cranks had the 1" bore that mine has. The service notes make me believe that the majority of standard 88 cranks have a bore of 7/8 (stronger than mine) yet the ones vendors have measured seem to be the same as mine. Either the service notes are wrong or the vendors are lying to me but judging by how exasperated they are getting I don't think that's the case!
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I'm probably waffling a bit…
I'm probably waffling a bit and confusing the issue so to clear it up -
has anyone measured the crank pin bore of a standard 88 crank (dynamo or alternator) and if so, can you remember what it was?
thanks,
Pete
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I have heard that std cranks…
I have heard that std cranks are made more vulnerable because of the stress raiser change in section that occurs internally. It may be possible to have that "eased" /
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Thanks Robert, I'll have…
Thanks Robert, I'll have another look in mine tonight. I'm beginning to think the 7/8" version is a myth
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N = N+1
Hi Pete,
For what it's worth, I have what I believe to be a standard 1959 88 crankshaft, which appears to be similar to your own, and to all the others that you mention above... it's pin bore is 1", it's OD 1.5", and the "depth" measurement you ask for is 1.25". It's definitely an alternator crank, so doesn't really fit in with the "really early" ones mentioned in the service notes. Probably not what you're wanting to hear, sorry! But fingers crossed, maybe someone else can chip in and give you some better news just in time for Christmas.
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Thank you Nigel! that is…
Thank you Nigel!
that is super helpful! It seems Ive been sent on a bit of a wild goose chase by the service notes. If my crank is as strong as it's going to get rather than the weakest type there is then things get a bit easier!
anyone know the process for flagging up potential errors in the service notes?
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The 88 SS crank is a very rare item , thats why you are likely to be wasting your time looking for one. Not many were sold when you could have a 650.