rods

Seems like bushing would at least let you replace the bushing without pulling the crank apart. 


Ok lets test out this new (to me) camera.   This one is an Olympus C-4040 and its about 8 years old.   It's a huge step up over my last used Olympus.  Battery life is greatly improved, lens is better and it can shoot some video.  These pictures were taken with just the standard camera, no added lens.   Pictures were then compressed to upload to this site.  


On to the cast or forged question....

Nothing new for the GS guys in these pictures.   Hope they are good enough that you can tell how the cranks are processed.  After pulling one back out I realized I should have looked more close before posting.  The parting line looks different depending on the throw.


This is a virgin 1982 GS1100 crank.  Calipers are set at 0.1" for a reference. 




This is the same 1982 crank on a different throw.  There looks to be two different parting lines for the various throws.





This is a 1983 GS1100 crank that was reworked by Falicon maybe 9-10 years ago.   



Same 1983 crank



Same 1983 crank.  In this picture you can see the two different parting lines.



Falicon crank. 



Same Falicon crank










Edited by geek - 18 January 2009 at 9:04am

Originally posted by Roland Tamaccio On the "virgin" crank with calipers, it looks like a steel forging that has laid in a creek bed for thirty years and was taken out once a year for a HARD sand-blast (lol); however it seems to be an exception in appearance.

Yea, you blow these things up a few sizes and hit them with a flash, all the details come out.   Just like HDTV, the female actors don't look so perfect anymore. 

Sounds like both the 83 and 82 throws that have the much finer lines are still a forged part?    In the picture of the 83, on the top throw you see that same fine line.  It's faint but its there.    It also looks like the starter throw on both the 82 and 83 have that same faint line.   So do some of the others.   This is what I first noticed as I did not unpack the whole crank when I looked the first time.  I was thinking that the fine line would point to it being a cast part.  

Look like forgings to me.

This is the 82 crank that has laid in a creek bed for thirty years and was taken out once a year for a HARD sand-blast.   I was trying to get a side shot that would show you what that shadow looks like so you could see how much of a step it has.   

Is that whole part that is sticking out the line?  That would make a lot of sense and it would be about the same width as the other parts. 

Zoomed out, you can see where it is machined how much of a step there is in the part.  Its more than a shadow for sure.



Same but zoomed in as far as I could go.   The FBI could lift my print off the bearing so don't spread this around too much.   





Edited by geek - 18 January 2009 at 2:51pm

... Mark, looking at these narrow line/marks, two things come to mind. The surface is generally rougher than cast and it might be possible that a fresh set of dies and just the right amount of steel left these narrow forging parting lines. Also, looking at the crank in sections, are there both types of parting lines, in any individual section.

Edited by Roland Tamaccio - 18 January 2009 at 6:22pm

HD's pressed twincam cranks are junk from stock ,, didnt watch the video due to phoneline speed ,,,, they use way too little force in the first place

cast tends toward brittle ,, enough force for a proper fit could result in fracture ,, as to a "cast crank",, eliminate sudden shock or poor balance and they should survive fine ,, here on a drag race site , they dont add up , this is what I've been led to understand

... Mark, it might be possible that the forging plant used pre-shaped blanks in an effort to get as close to "near net shape"  thusly generating less scrap. This is the driving force behind the whole powdered metal industry, these rods need very little machining. So, maybe they used a blank that was very close to the final counter-weight shape. Made possible by the short sections used in roller bearing cranks, and only had to forge / extrude short journal areas. I don't know if the ME's agree with me but I call an extrusion a linear forging.

This is all fascinating stuff guys. I've always wondered why they copper plate (or at least that's what it appears to be) rods. I expect it's something to do with sealing the surface to prevent the propagation of cracks, but what do you think. 

Every motorcycle engine I have ever had from my youth till now had copper on the rods.   I tried a little search for you and saw a lot of different ideas but no real hard core proof of why.   Everything from rods being defective to corrsion resistance to making them stronger.  It's the net, so who knows.....  Then saw this note from a Taiwan motorcycle connecting rod factory:

"Process the design without copper plating decreases the Hardness of the mast, increases the bend resistance, MAST can be bended over 90 degrees angle with breakage!"

 

Other than the english is worse than mine, I'm not sure what to take from it.

 

This was a video I found on connecting rods 101.  He talks about the copper but not thinking this was the reason the Jap. bikes were using it.

 

Connecting Rods 101