Cut off 1inch crankshaft and modifying to a 3/4....

[machinebike]

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

 

[Hent]

sounds like you need a new crank. :weld:

 

[milo raptors]

sounds like you need a new crank. :weld:

agreed....

 

[TT]

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! :hammer:

TT :sadcrying4:

 

[rocketman]

Tell us please???

Why not turn the shaft down to 3/4 ???:grind:

 

[Strigoi]

sounds like you need a new crank. :weld:

agreed....

that. ....

 

[badtec]

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.

 

[machinebike]

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.

 

[badtec]

What would be your next move, if the bolt was straight? What were you trying to accomplish?

 

[machinebike]

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.

 

[Strigoi]

buy a new crank.

if you wanted it down to 3/4" the only real way to do it is to have the shaft turned down.

that does not look safe at all. there's no way in hell i'd get on a bike with something like that done to it.

 

[minibikedude]

Dude you like living dangerously! I never seen that done to a engine before. I agree with everyone else get a new crank, Next time you get a engine that has a 1" crank, remove the crank and take it to a machine shop and get it turned down to 3/4 inch and have them drill and tap the end of the shaft. This is going to be a expensive lesson learned.

 

[bandit 40]

Even so ,if you would have removed it to turn it down to 3/4 , ( like previously stated) why not just get a 3/4 crank.
And you cannot put a price on safety,with it having a little wobble this thing would vibrate so bad it would possibly break, and cause harm to you and trash the engine. do the right thing.:thumbsup:

 

[rocketman]

To remove all doubt..

Just bolt that engine into a frame or to a stand to do a run in and you will see that any harmonic vib. is going to be very and i stress very unmanageable, I predict it will self destruct in less than an hour of run time.

 

[machinebike]

Thanks for the advice everyone, It was kind of an experiemnet that if didnt work, I was going to order a 3/4

I feel a small accomplishment knowing I drilled/tapped a 3/4 hole, though dont want to do it again.