Keep Calm and Crank on? Stripped crank

Francois Labat /
frenchee
Jun 12, 2019 11:23PM

Hey yall.

Been moving along on my build. I bought this crank here.Budget Crank

Got the whole motor put together with CDI etc. I tried using this nut and it didn't work.

Moby Reverse Nut

I was told the crank thread was right hand so bought this nutty .

When I had used the reverse i lightly buggered up the threads. Just by trying to put it on my hand. Then I tried to thread on the new proper nut and decided to start 1-2 threads and clean them up by cranking the nut on with a wrench...

I KNOW. This isn't my first nut. Anyways, it messed up the new nut and threads. I bought a thread file, fixed the thread and today I was able to hand thread the nut onto the threads maybe 1-4 threads. Then it got tight and I decided to use my little impact to get it on. I figure it would "clean up" the nut.

WRONG. It was a gamble I know but it got jammed and DESTROYED my crank shaft. I've stepped off the edge of the bridge, and am now debating if I order a new nut and use what thread is left. Will I have enough thread???

I've dealt with thousands of nuts and bolts. The damn work frustration pushed me to force this and was the wronggggg nut to mess with.

IMG_0842.jpg
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Re: Keep Calm and Crank on? Stripped crank

Stephen Simmons /
stephens
Jun 13, 2019 07:26AM

I'm a gambling man also. I'd cut off the messed up tip, make sure the threads are nice and clean, add a little oil to the crank and put a new nut on it.

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Re: Keep Calm and Crank on? Stripped crank

Brandon Weiss (Detective brandon to you) /
mopedallday
Jun 13, 2019 09:06AM

Nut up and run it

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Re: Keep Calm and Crank on? Stripped crank

Dirty30 Dillon /
hydra
Jun 13, 2019 09:26AM

Buy budget and get budget results I guess.

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Re: Keep Calm and Crank on? Stripped crank

P D /
pdcomm
Jun 13, 2019 09:44AM

> Dirty30 Dillon Wrote:

> -------------------------------------------------------

> Buy budget and get budget results I guess.

Sounds more like miscalculation than budget , to me .

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Re: Keep Calm and Crank on? Stripped crank

Zennon Krebsbach /
zentuckyfriedckn
Jun 13, 2019 10:18AM

Maybe try to cut new threads?

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Re: Keep Calm and Crank on? Stripped crank

P D /
pdcomm
Jun 13, 2019 10:36AM

I'd fix the threads , get the right nut and run it .

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Re: Keep Calm and Crank on? Stripped crank

Ken Roff /
roffman
Jun 13, 2019 11:11AM

> Stephen Simmons Wrote:

> -------------------------------------------------------

> I'm a gambling man also. I'd cut off the messed up tip, make sure the

> threads are nice and clean, add a little oil to the crank and put a new

> nut on it.

You got it right

Cut the bad tip/end off and make it nice

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Re: Keep Calm and Crank on? Stripped crank

Matty Lite /
2strokelyfe
Jun 13, 2019 12:59PM

Would using a tap and die work here? I did something similar when I used a metal hammer to hit the crank to split the cases (after heating them up). Threads are bent inwards and I don't want to buy a new crank and take the whole this apart.

For the OP - either buy a new crank or cut off the part of the crank with the bad threads and clean it up. You should be using this nut on the magneto side, https://www.treatland.tv/mbk-flywheel-reverse-flywheel-nut-11mmx-1mm-p/mbk-flywheel-reverse-nut-11x1.htm.

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Re: Keep Calm and Crank on? Stripped crank

Francois Labat /
frenchee
Jun 13, 2019 01:25PM

Yes, it was not a budget crank problem. It was an emotional and frustration problem lol. Next time I'll punt a cabbage or something, not work on my moped instead.

The thread is beyond repair, that's for sure. I will clean it so that it doesn't interfere with the new nut I'll be ordering.

Thanks y'all. This is like my free counseling when moped pisses me off.

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Re: Keep Calm and Crank on? Stripped crank

pat splat /
ggspeed
Jun 13, 2019 06:51PM

looks fine, use a metal file to taper n a new nut.

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Re: Keep Calm and Crank on? Stripped crank

Don Ohio /
don45640
Jun 13, 2019 09:44PM

Yeah, and keep the impact gun away from yer moped. Less chance of a booboo.

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Re: Keep Calm and Crank on? Stripped crank

Thomas TPRF /
thomashsb
Jun 15, 2019 09:46AM

I've got an engine with a flywheel that's been held on by maybe one thread, crank snout is broken, for the last three or four years.

I had to replace the points over the winter and thought that was it, I'd have to finally replace the crank but I got the flywheel back on solidly.

Lots of thread locker on that nut.

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Re: Keep Calm and Crank on? Stripped crank

Rebel Moby /
rebelmoby
Jun 30, 2019 10:52AM

Get a thread file and straight the lead in to the remaining threads, put a new nut on, fortunately it is a taper shaft so the flywheel does not need a lot of torque to grip.

If you feel it still is not trustable then drill and tap the snout of the crank for a M6 bolt and throw in a goodly machine screw as a safety lock.

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Re: Keep Calm and Crank on? Stripped crank

♣Slew Foot♣ /
thewhitedog
Jul 01, 2019 11:12AM

You get a tool called a thread chaser and it clamps on and it's like a nut basically you could take a die and cut it and then put it back together with a set of screws and then work it off with a huge wrench and a breaker bar

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Re: Keep Calm and Crank on? Stripped crank

-Summerai - Shong /
lees
Jul 02, 2019 05:27AM

I've grinded down all the threads before and re-tapped/cut to the next thread size down on a spindle. You could do the same in this scenario.

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