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Old 10-19-2009, 09:43 PM   #1 (permalink)
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Cut off 1inch crankshaft and modifying to a 3/4....

I cut off the 1 inch shaft, left room to drill hole and tap with a 3/4 tap.
I have a grade 8 3/4 bolt I mounted into it but when I turn the crankshaft, it is very, slightly crooked when i turn it.

Any suggestions on how to get it straght after I already drilled and tapped?

What about set screws to use to keep new shaft bolt from loosenig, would it work?
Is there any reason this set up might not work? I drilled a 1/4 into the crankshaft that goes into the engine but not past where it rests on the bushing, should I be conserned with a balance problem?
Thanks
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Old 10-19-2009, 09:48 PM   #2 (permalink)
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sounds like you need a new crank.
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Old 10-19-2009, 10:10 PM   #3 (permalink)
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Quote:
Originally Posted by Hent View Post
sounds like you need a new crank.
agreed....
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Old 10-19-2009, 10:58 PM   #4 (permalink)
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Could you explain further why you did this before you posted it as a HOW TO question?

We are here to help you... We cannot help if you do not ask first and await instructions. Find new crankshaft and move ahead with your adjenda...

Best of luck!

TT
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Old 10-19-2009, 11:16 PM   #5 (permalink)
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Tell us please???

Why not turn the shaft down to 3/4 ???
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Old 10-19-2009, 11:25 PM   #6 (permalink)
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Quote:
Originally Posted by Hent View Post
sounds like you need a new crank.
Quote:
Originally Posted by milo raptors View Post
agreed....
that. ....
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Old 10-20-2009, 04:03 AM   #7 (permalink)
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Quote:
Originally Posted by machinebike View Post
I cut off the 1 inch shaft, left room to drill hole and tap with a 3/4 tap.
I have a grade 8 3/4 bolt I mounted into it but when I turn the crankshaft, it is very, slightly crooked when i turn it.

Any suggestions on how to get it straght after I already drilled and tapped?

What about set screws to use to keep new shaft bolt from loosenig, would it work?
Is there any reason this set up might not work? I drilled a 1/4 into the crankshaft that goes into the engine but not past where it rests on the bushing, should I be conserned with a balance problem?
Thanks
How much did you cut off? Did you really use a 3/4" tap? If you cut off too much, and now the 3/4" (WOW!) bolt wobbles...you screwed up. LOL.
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Old 10-20-2009, 06:39 AM   #8 (permalink)
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Here are pics. looking closelt at the measure stick, you can see after turning engine, slightly off one part of turn. I did not turn enough to see correctly, its about half of one of those notches.
Attached Images
File Type: jpg crank1.JPG (71.1 KB, 29 views)
File Type: jpg crank2.JPG (136.9 KB, 33 views)
File Type: jpg crank3.JPG (93.5 KB, 29 views)
File Type: jpg crank4.JPG (103.4 KB, 30 views)

Last edited by machinebike; 10-20-2009 at 06:43 AM.
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Old 10-20-2009, 06:50 AM   #9 (permalink)
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What would be your next move, if the bolt was straight? What were you trying to accomplish?
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Old 10-20-2009, 07:52 AM   #10 (permalink)
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I was doing this to use a 3/4 centr. clutch.

Next moves are to cut end of bolt off, drill and tap end and put groove in the bolt to hold clutch on.

Its not crooked by much but enough to make it spin with a slight wobble.
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