Quality Billet crank
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SteveA
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hobot said:
Wrong questions Steve:
How long would an engine with this crank last when revved to 9000 regularly, the answer is longer than most....
And the squish clearance could be tighter.....
Where is the 80.4 version?
And the 90 degree version?
In truth the pricing is not far away from Maney (3 piece lightweight), Nourish (billet heavyweight) and others....
pays your money and takes your choice.....
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Yes Sir for a 9-Grand Norton heavy Twin!!! SteveA ya took my bait and hooked ya good on this cast. But as you made my point about what it'd cost to have an engine that made any sense for a brilliant billet crank I release you unharmed. Peel's engine is as expensive as any for rpm tolerance but I will rev limit to 7700 for special events and 7200 other wise. Truly if I'd known anything about cycles or Norton when I had the P!! I'd not run it nearly as routinely to 9000. How it got away with that I do not know so toss me some crumbs Steve what allowed yours to do so and if it had significant show stopper doing so? I'm cocky SteveA but you make me feel like fella that hooked too big a fish so pulled into water and swallowed ok.
Shot peen and micro polish float to mind after reading this brief.
http://www.scientific.net/KEM.245-246.351
Shot peen and micro polish float to mind after reading this brief.
http://www.scientific.net/KEM.245-246.351
lcrken
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jseng1 said:
As Jim said, you can fit the earlier cranks to MKIII cases with bearing spacers, but it is usually for race bikes. I might be pointing out the obvious here, but the MKIII crank has a longer mainshaft, so with the older crankshafts, you can't use the electric start, and the alternator rotor is in the wrong place. You might be able to make the alternator work (we are an inventive bunch), but not the starter.
Ken
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hobot said:
Steve, if there is a decent race class for a Commando and you are serious about your racing, you buy that. It ends up cheaper in the long run. The only reason I ever persevered with my short stroke 500cc Triton was it had the billet crank. The bike was very difficult to ride, and crashed me everywhere - however the fact that it was almost indestructible when revved regularly to 10,000 RPM made it worthwhile.
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The only problem I can see with that crank is justifying the expense of the investment. For what they are Norton Commandos are a very fast bike. The trouble is that they don't usually compete against bikes of the same type - air cooled two valve four stroke twins. If I'd been racing in the UK during my childhood, I would not have hesitated to seriously race a commando. It doesn't matter what race class you race in as long as the machines comprise pretty much 'a level playing field' - then you will have a level of fun which justifies the outlay. Speed is always relative.
Brooking 850
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Thanks Jim & ken, I am after a billet crank for my billet NZ made cases, they are designed around a Mk3 crank, crank I need is for a race motor & I dont need the e start or alternator
Regards Mike
Regards Mike
Fast Eddie
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SteveA said:jseng1 said:
Probably not as long as it will take for me to save up the money
Order now Steve and you will have it in readiness for the winter 'refresh' and ready for action next season...
SteveA
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Fast Eddie said:SteveA said:jseng1 said:
Probably not as long as it will take for me to save up the money
Order now Steve and you will have it in readiness for the winter 'refresh' and ready for action next season...
Current rate of progress due to my availability means the first 'winter refresh' will be winter 2015/2016, but I always was an optimist! :?
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auldblue said:
We don't make decent alloy steel in Australia, most of it is too dirty i.e the sulphur and phosphorus are too high - gives inclusions, particularly in the centre of bar stock. Most of our low alloy steel for anything serious is imported these days. Bohler Steel is a good source, however I'd still get the end of a bar ground, and do a sulphur print and at least move the machining well away from the centre of the bar if possible.
By low alloy steel, I mean material which has more than 1% nickel, 1 % Chromium. In Australia Comsteel make a 3%Nickel, 1% chromium steel, however it is rubbish. I doubt you can source this type of steel from China - you might get it from Japan - they often use vacuum degassing in their steel manufacture. Somewhere where there is an aircraft industry making the steel bits would be a good place to look. Good material must be available in America, they still make gun barrels and rocket motors. If you live there, buy some scrap from that source.
lcrken
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A chunk of aerospace grade E4340 VAR steel in 8" diameter by 13" long, with certs, is probably going to cost between $750 and $1000 at today's prices, with the higher end being for 300 M spec, pretty much the best grade available. If you were really lucky, you might find cut-offs for less, but usually without the certs.
Ken
Ken
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This crank appears to have an "excess" of metal on the center that could be trimmed off to reduce the weight of the entire crank and particularly the center that contributes to the maximum deflection. Is there a reason that is not obvious to me why more metal would be desirable on the rod side that would require even more weight opposite?
kentvander said:
Strength ??
It has previously been discussed here that lighter flywheels are none too satisfactory in a Commando, even a racing one -
a lighter crank doesn't suit the engines torque characteristics - riders generally prefer a heavier crank - heavy as in about stock weight anyway.
Having ridden a guzzi (but not a Commando) with a featherweight crank/flywheel, it felt that the engine was just a step away from trying to kill you every time the throttle was opened. Fun for a while, but long term it would be sure to come back and bite you.... ?
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If the weight is on the bob weights instead of the central flywheel there is less bending moment on the crank. If the flywheel has the extra weight on it, the imbalance due to the balance factor tends to throw the centre outwards more. I agree with Rohan about the crankshaft weight making for a better ride. The problem is however when you blip the throttle to do a fast down change with the standard box, you need more revs than with the CR box, so the change is not as easy or as smooth. The heavy crank means the motor is not as responsive as a light one. I love my 850 motor with the CR box behind it, it is extremely easy to ride the bike which is very light, and that helps too. I've ridden a few race bikes however none so anxiety free as my Seeley 850. I never believed in the commando motor, and I'm now amazed at how good it is when near standard. I have a lot of respect for the design.
Brooking 850
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You must be a late bloomer Alan, most of the forum members have had that same respect since the first Commandos were available!!!
Mine started with a pre featherbed , all cast iron barrels and head 500 Dominator, love affair never waned!
Regards Mike
Mine started with a pre featherbed , all cast iron barrels and head 500 Dominator, love affair never waned!
Regards Mike
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kentvander said:
I agree with you and yes the crank can be lighter and so deflect less in the middle. Steps have already been taken to move weight to the cheeks so there is less weight in the center - its already been done. Personally I prefer lighter cranks and I won most of my races with lightened cranks. Also note that 18 lb Maney cranks are winning races all over the world. Heavier cranks work best in dirt track and the extra weight helps absorb vibration - so they feel better but they also slow down your shifts and slide more going into turns when road racing. This crank weighs 23lbs same a stock and thats what most people want. The crank can be made with a thinner flywheel section near the journals to lighten things up. You can get a crank that way no problem except that you have to wait until its finished.
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