Commando Crankshaft Porn

I've had two Norton twins with lighter than stock cranks and both of them left permanent impressions as extra responsive tire smoking dragsters. Famous racers here say they were faster on race tracks with cranks on the heavy side but I found I like the tire break free ON/OFF sense of control the lighter cranks seemed to allow. Both started one kick, both could idle steady below 600 rpm and never stalled on shifting or throttle cuts out of gear. 5 llb off crank should allow quicker spool up but less engine drag if that's your 'bad' habit, reflecting on recent slipper clutch reasons.

Anyone here recognize this crankshaft? The pictures were sent to me by someone in Spain, asking if I knew anything about it, but I don't. Looks like a Norton crankshaft to me, but I've never seen it before, and it could be for a different marque. In any case, it's an interesting construction.







Ken

Hi , it may look like this one, but........no!!

http://www.sr500forum.com/forum/viewtop ... 99&p=65495

That is an interesting one. Another one I've not seen before. I'd post the pictures of the Woods Racing Norton crankshaft, but Photobucket is down for maintenance at the moment.

Ken

That pin for the big end journal doesn't look to be engaged into the outer crank plate very far.

If that was my crank, I'd be a lot happier to see it extend right through.....

lcrken said:

Anyone here recognize this crankshaft?

Click to expand...

This is the Woods Racing crankshaft from Marinatlas' link





Another interesting design.

Ken

lcrken said:

This is the Woods Racing crankshaft from Marinatlas' link



Another interesting design.

Ken

Click to expand...

Nice, It gets the weight out of the center and concentrates it along the outer edge where it will do you some good. Jim

comnoz said:

lcrken said:

This is the Woods Racing crankshaft from Marinatlas' link
......Another interesting design....Ken

Click to expand...

Nice, It gets the weight out of the center and concentrates it along the outer edge where it will do you some good. Jim

Click to expand...

I really like the looks of that center section.....any chance you could turn a couple of those out comnoz ?? :roll: I'd love to get rid of my cast iron and bolt in one of those in it's place

cjandme said:

comnoz said:

lcrken said:

This is the Woods Racing crankshaft from Marinatlas' link
......Another interesting design....Ken

Click to expand...

Nice, It gets the weight out of the center and concentrates it along the outer edge where it will do you some good. Jim

Click to expand...

I really like the looks of that center section.....any chance you could turn a couple of those out comnoz ?? :roll: I'd love to get rid of my cast iron and bolt in one of those in it's place

Click to expand...

cj, you may not be seeing what you think you are seeing...... that additional section is described in the SR500 forum as a 'windage cover' (by someone who may or may not know what he is talking about, I have no idea)

I am not sure that managing air and oil drag is it sole purpose or benefit, but it certainly does seem to be a cover on a more conventional flywheel, unlike the crank from Spain tha Ken posted images.

Both interesting for sure.

Thanks SteveA, you're right about that. Looking at it again, it would need to be the whole assembly. I was thinking that having some of the weight higher up in the 90 and 270 positions (discussed earlier in this thread) as opposed to just 180 out, might be desirable in a street bike.

New item for my billet cases, unfinished , needs the mains and big ends ground, there is plenty of scope for large radii as well
11.2kg(24.0lb)
Regards Mike

Mike,
Very nice. I have considered adding that outer ring to the crank I made. Jim

Jim, thanks, once i get the rest of the hardware, it will go for finishing/balancing etc, see the added weights to fit inside the fly wheel, these can be lightened to suit balance factor, the outer ring can't be drilled to deep for balancing so balancer must use shallow holes.
Holes centrally drilled either side (sludge trap entry/exit)will be filled with a 2 piece cylindrical bung that is tapped to M6 so once they get tight in the hole, screw in a SHCS and drift them tight with Loctite, then to remove, same M6 SHCS and drift out , long bolt to make a simple slide hammer.
Extra weights are also set with SHCS @ 28FTLBs once all is finished.
Journals are very oversize pre finishing , will have to radius the inner race on the bearing on the mains.
P20 all made on a CNC drill mill
You havent got a set of carbided barrels have you?
Regards Mike

Brooking 850 said:

You havent got a set of carbided barrels have you?
Regards Mike

Click to expand...

None ready to go. I have some that could be sleeved and carbided. Jim

Mike,I think that should be "up" for the Turner prize ! Funny how lumps of steel can give me a hard on Now that's engineering porn.
But what the hell am i doing look at this at 3.30am :!:

Hi John, I wonder why?
Not bad for small workshop at the end of an industrial estate on the East Coast of New Zealand!
There a few by the same guy running in the classic scene, including a classic side car with a heavy weight Norton motor,
Will keep up the thread once I get it closer to installation, maybe a few months off yet.
Regards Mike

New billet for a new version of the 500 cc Norton ultra short stroke.

4340 Steel.
Nitrided.

59.6mm stoke
35mm main bearing journals.
1.750" rod journal diameters

Nice. Do you just bore the cases (Maney?) for the larger mains?

Who made the crank?

Ken

No need to bore the cases Ken. I have two options in front of me that fit the standard envelope of the bearing bores in the cases.

1.) Use an NJ2207E but you must machine down the sides of the bearing inner and outer races to fit the full width of the bearing bosses in the cases. This also requires reestablishing the appropriate radii on the bearing, demagnetizing and cleaning after machining. I have used this bearing before in my 750 USS with great success. I could only source pressed steel cages at the time and they proved inadequate so Herb Becker made up a set of brass cages.

2.) Use an NJ207E but you need to shim up a 2mm width deficit. Jim Comstock put me on to this approach. I have some concern that there could be a down side to this with a stressed motor as the narrower width of the bearing 17mm versus 19mm will result in greater stress concentration on the bearing bosses.

The static and dynamic load ratings as well as the speed limitations of these two alternate bearings are comparable if not better than an NJ306E. Of course they are only suitable for a 35mm main journal whereas a stock Norton is 30mm.

The crankshaft was made by Moldex. They made the billet crank for my 750 USS engine as shown in the following link.

http://www.accessnorton.com/commando-crankshaft-porn-t8365-195.html

Early Christmas pressie...

Very challenging for a Lancastrian to be sending money over the Pennines, but needs must.