Commando Crankshaft Porn

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dennisgb said:
comnoz said:
Great, I love porn. As long as it's dirty motorcycle parts.





I had not seen this thread before but I just want to comment on that 24.5 lbs crank. The mass looks very large when you look at how small the shaft ends appear....they look tiny :shock:

Yes, They are small -they are also known to break when used hard. Jim
 
4340VAR steel
35mm pto shafts
1.985 rod journals
91mm stroke
Jim what rods are you going to use with the 1.985 rod journals?
 
Ditto :

Wondrin if theres a superblend with a bigger hole in the middle , 7 same load rateing .

So as to have larger output shaft , on the Custom Crank . As it wouldnt be a bad idea .

could mastch fillet radiuses to bearing corner radiuses also , if theyre larger .
 
There is: NJ2207E but you need to shave a mm off each side and reestablish filet radius on the inner piece. You can bump the main journals up from 30mm dia. to 35mm dia. It also allows one to use a larger filet radius on the crank.

I've only been able to source the NJ2207E with steel cages; we opted to make our own bronze cages.

In the end, increasing the main journal diameters is probably overkill considering billet material is superior to the factory cast steel.
 
fredful said:
4340VAR steel
35mm pto shafts
1.985 rod journals
91mm stroke
Jim what rods are you going to use with the 1.985 rod journals?

I will be using rods designed for a Honda K24 turbo car. Jim
 
Matt Spencer said:
Ditto :

Wondrin if theres a superblend with a bigger hole in the middle , 7 same load rateing .

So as to have larger output shaft , on the Custom Crank . As it wouldnt be a bad idea .

could mastch fillet radiuses to bearing corner radiuses also , if theyre larger .

I will be using an nj307 on the drive side which requires enlarging the hole in the case. It has a 35mm center hole.

I will fit an nj 207 on the timing side. It has a 35mm center hole with the original OD so I will not need bore the timing side hole which brings it too close to the timing spindle hole. I have seen a crack there with the larger bearing installed. Jim
 
A few more pounds off. It's starting to look more like a crank.

Commando Crankshaft Porn


Commando Crankshaft Porn
 
Looks really great ! How do you calculate what shape to make the shaft so it ends up somewhere near the correct balance factor ?
 
acotrel said:
Looks really great ! How do you calculate what shape to make the shaft so it ends up somewhere near the correct balance factor ?

Actually I don't. It's just cut and try. It's setting pretty close right now. Jim
 
Nice doorstop,Jim!
I have followed this great forum for a while, getting an awfully lots of inspiration, this is my first post here.
I am doing a crankshaft myself, it`s just roughly machined at the moment. No CNC machine.
Rod journal will be 47,8(vw) for increased stiffness and stroke will be 84 mm.
I saw that you are going to use bigger roller mains, it seems to be a good idea. Question: I have heard that some high grade oil can destroy brass cage in the roller bearing but brass cage seems to be preferred, anything wrong with steel cage?
Out of curiosity, will you supercharge the new engine? (The cranshaft rod journal and mains being so big?)

I will send some pictures when i have learnt how to do it (i`m not the smartest data user)

Sten
 
Sten,
Some sort of forced induction is in the eventual plan. I have both a blower and a turbo but I have not decided which one I want to use. I am working on an engine that will take it but I still need to do something with a transmission -I know what happens when you try to put more than 80 horse through a Norton box.

I would like to see what you have going. I have built up a few cranks before but this is the first time I have tried to cut one from billet. It has been a challenge and my CNC machine has only been of limited help. My machine is so small that it would have been working at it for a week to cut the throws and I would have spent a big pile of money on carbide bits. That 4340 is some tough stuff.

I have used crank bearings with brass cages and plastic cages successfully but I have not tried the steel cages. I really can't make any recommendations there.
I just scored a pair of NOS FAG 307's on e-bay for $45.00 each. Brass cages with c3 clearance. Jim :D
 
Sten,

With the particular main bearings I was using (NJ2207E) they were available with pressed steel cage only. The application is an ultra short stroke 750 Norton with 35mm main journals. The cages broke up on me. I had custom bronze cages made and the bearings work fine.

I am staying away from the pressed steel cages based on my previous experience.
 
Dances with Shrapnel said:
Sten,

With the particular main bearings I was using (NJ2207E) they were available with pressed steel cage only. The application is an ultra short stroke 750 Norton with 35mm main journals. The cages broke up on me. I had custom bronze cages made and the bearings work fine.

I am staying away from the pressed steel cages based on my previous experience.


Thanks for that info.

I just bought a pair of 207's on e-bay also. NOS with brass cages. Jim
 
Jim,

With the 207's, do you shim the cases or the crank cheek.

Making your own billet might allow you to add 2mm to where each of the bearings shoulder up against providing further crankshaft stiffness.
 
Thank you all for your replies and advices.
I will stay out of steel cages, the sucessful use of plastic cage was interesting news and brass cage is obviously ok because it is commonly used.
I`ts just that i heard about a catasrophic result of a friends renovated HD with brass cage and using top class expensive Red Line oil.
Having thougt of how to make a crank for a very long time and not finding any useful info i had to figure it out myself.
I would be happy to see some other examples and trying to exlain how i did myself, english is not my native language but i will do my best.
I asked for help sending photos of my project, nobody succeeded, can anyone please tell me how to do it?

Sten
 
Dances with Shrapnel said:
Jim,

With the 207's, do you shim the cases or the crank cheek.

Making your own billet might allow you to add 2mm to where each of the bearings shoulder up against providing further crankshaft stiffness.

I never install a shim on the crankshaft. They come loose and cause damage. I would install the shim in the case. Jim
 
Well it's not exactly a Van Norman but, I am impressed. My improvised crank grinder does a really sweet job. Anybody got an extra Arnold gauge laying around? Jim

Commando Crankshaft Porn


Commando Crankshaft Porn


Commando Crankshaft Porn
 
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