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crank stroking

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Posted by: endurohero

What material is used to fill the existing crank pin bore when relocating the hole further away from the crank center.4130 4143 moly , high carbon steel , stainless , an old crank pin?


Posted by: Ol'89r

4130 will work.


Posted by: SFO

I like to bush the bore before reboring. I have used old crank pins and d2 tool steel for this bush. Depends how earnest you are about cutting that material back out. I always error on the less heat the better. Tack in a spud and thats it, besides the machine work.
I make a custom 5c collet to hold each crank half on the brg journal.
I prefer hartinge emergency collets, they have the best steel, IMHO.
It is easier to cut a d2 spud than a bunch of weld goober, albiet, it is not that hard to cut weld if you have the killer set up.
Don't mean to step on anyones dick here, including my own...


Posted by: endurohero

Thank you! Do you center drill the spud so as to find the center of the old bore and off set your new bore according to that center. Are most shops using a cnc mill to machine the bore or a manual machine with a boring bar set up.


Posted by: Ol'89r

Quote:
Originally Posted by SFO
Depends how earnest you are about cutting that material back out. it is not that hard to cut weld if you have the killer set up.
Don't mean to step on anyones dick here, including my own...


No worries Bill. It's all good info.

I use 4130 because it is easier to machine on my antiquated machinery.

endurohero.

I use a standard mill since I don't have a lathe large enough to swing a crank half. I index from both the center of the spud and the center of the main crank shaft to align the flywheel. Then, index from the center of the spud for the new pin hole. Also, I use a boring bar for the final cut.

Good luck.


Posted by: endurohero

thanx muchly



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