Quality Billet crank
- Thread starter jseng1
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will it flex?
ashman
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A good friend of mine (Don) that got me into Nortons so long ago (40 years ago) has been making solid build Norton cranks for years, he runs them in his very hot Triumphs (drag bikes and road racers) he also makes his own Triumph crank cases with his name machined on them (Donny cases) the solid Norton cranks are the only cranks he doesn't break.
Ashley
Ashley
SteveA
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jseng1 said:Check out this photo of a 4340 Nitrided solid one piece billet steel crank with .090" radiused stubs. 23 lbs. It would be nice if these were OEM in all our Nortons. Dream on.
If Norton had been using cranks like that 40 to 50 years ago you would not even have a Norton, the original owner would not have boughtt it on a price basis!
The production costs would have put the bikes out of the price range of most buyers.....and clearly most users didn't actually need them!
Sometimes we forget that Norton was a business trying to sell in volume....so they were also trying hard to keep costs down...OK, sometimes trying too hard and in the wrong areas....
Now what would have been good would have been an aftermarket race product like that.....Oh I forgot, Dave Nourish was making them...and I couldn't afford that either...then again...I raced and didn't break a standard (ish) MkIII one....
The stuff available to a lucky few today is fantastic....I still doubt I could afford that crank and will have to make do with my Steve Maney 3 piece, at least for a while ;-)
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stockie2 said:
Its really just for show. Its a very good crank and I would like to offer them. But availability is very limited. I only have one of them at the moment. When you tap one of these cranks with a piece of metal it makes a nice ringing sound that lasts about 10 seconds - its the Nitrided surface hardening that makes it "ring" and the surface hardening helps prevent fatigue - as well as extending journal life.
Its 23 lbs and that's the same weight as stock - you don't find other one piece cranks that light.
And yes Matchless - the fabrication may be a bit tricky, but those details are not available - at least not for awhile.
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As above ..it looks like a casting , very hard to machine this shape, the angled tooling would have to via the slots, plus the internal faces show no tool marks? Like the external faces do...
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I doubt it is a casting. Where the radius is on the flywheel, looks like a run of weld which has been cleaned up very well. Casting an alloy steel like that gives a problem due to composition. To get max strength the sulphur and phosphorus contents need to be extremely low, I don't know how you would cast it without getting inclusions. Even making one out of barstock is a problem. You really need to machine well away from the centre of the bar. If you do a sulphur print of the end of the bar, you will often see almost a pipe down the middle. This crank might have been made in three parts and welded together ?
If its been welded, it can hardly be described as 'one piece' or 'machined from billet' ....
Nortons would loved to have been able to machine that.
The original crank that Bert Hopwood designed for the early dommies circa 1949
were drawn as a one piece design.
But the machine shop said they couldn't do it.
So it was redesigned as a bolt up 3 piece item.
Not by Bert the story goes, he hated the idea.
It did allow an internal sludge trap though.
Not required for racing, but prudent for a road bike....
Nortons would loved to have been able to machine that.
The original crank that Bert Hopwood designed for the early dommies circa 1949
were drawn as a one piece design.
But the machine shop said they couldn't do it.
So it was redesigned as a bolt up 3 piece item.
Not by Bert the story goes, he hated the idea.
It did allow an internal sludge trap though.
Not required for racing, but prudent for a road bike....
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It might have been built from three parts, the outside two being press fitted into the flywheel, centred up and welded then the outside of the bob weights and flywheel machined and the half shafts ground on the same centres. If the thick bits where the outer components fit into the flywheel are strong, the whole assembly would be strong .
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Years ago I worked in an Ordnance factory. A friend made a long stroke bottom end for a Vincent out of gun barrel material. The crank was pressed up and he then had it electron beam welded to get the paper thin weld. It pulled in several directions so then he took it to another machine shop and had a cut taken off all over it. These things are never simple. I like the look of that crankshaft. An easier way to do it would be similar to an early Triumph unit construction 650 crank, and use that flywheel.
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With a non - filtered system , o.k. ,
but these went out with the ark . A modern oiling system would ( does ) not require a centrifugal partical capture receptical .
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