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madman
01-20-2009, 12:41 PM
I am curious what material are crankshaft pins made from? Nitrided 4340 ?? I may have to make some. Lucky my friend is a Guru of Centerless Grinding. Thanx Mike

shawnspeed
01-20-2009, 01:05 PM
I assume we are talking 2-cycle cranks...snowmobile maybee??? I don't know exactly, but they are weldable, I don't think 4340 would weld without heat treatment after without cracking . The ones I was welding were 800 thundercat cranks that the guy had put some 1200 Pierce cylinders on with a 3-stage nitrous set-up.....would throw the crank out of whack without tigging the pins in the cheeks...He said it ran a best of 156mph@9.56 before loosing the motor at a 1000'...not to shabby for coasting the last 300'....It just had a short fuse that's all..also the pins are usuallya little tapered and knurled / splined depending on who mad the motor(yamaha had some with X-hatch some straight ,and some not at all) Good luck , Shawn

John Stevenson
01-20-2009, 05:35 PM
God knows what the US spec is but we used to make them out of EN39B.

motorworks
01-20-2009, 06:09 PM
Depnding on what you need you can buy crank pins from various manufactures:

Just need the od and the length
(you can order longer and cut )

see wiseco as an example:
http://www.wiseco.com/Catalogs/Powersports/Comp-CrankPinsBearingsWashers.pdf

franco
01-20-2009, 09:39 PM
Some discussion on crankin material here:

http://www.practicalmachinist.com/vb/showthread.php?t=158446&highlight=franco

franco