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Author Topic: Best idea to repair this in place?  (Read 109 times)

Offline gentner8

Best idea to repair this in place?
« on: June 19, 2022, 06:29:33 PM »
I decided today was the day to put the CR ignition in.  There was some crunchy whitish stuff on the outside of the nut, and just figured it was dried thread locker of some sort.  This is what I found, after cleaning it with my wire wheel.  Half a thread an JB weld may have been holding it in place before.  Can this be retreaded enough to hold?  The red neck in me says rethread it,  snug it,  and tack the tip with my welder.  My die set does 1.5 and 1.75, so I will have to order that size.  What is the best type to use if Im buying one?  I see they have split types, carbon steel etc. 

Offline croat1

Re: Best idea to repair this in place?
« Reply #1 on: June 22, 2022, 12:01:27 AM »
Man that’s bad.   I cut threads at work everyday (single point , thread mills and rolled threads).  I can get long winded on thread form… the importance of thread: major OD, thread flanks, pitch diameter, thread root….
If I needed to save a week/weekend of riding especially far away from home I’d to what I needed to do to save the trip.  But then again I’d park it and fix it the right way by getting a new crankshaft.

Is this your only engine?  Back up?

Thread file won’t work.  I’ve used honing stones to “deburr” thread imperfections but what you have is beyond that.
From the looks of it you have to re cut the threads.  I’m thinking the thread blank diameter is going to undersize thus causing a sloppy fit with the nut.  A thread chaser won’t work.

Joe

Offline The norm

Re: Best idea to repair this in place?
« Reply #2 on: June 22, 2022, 12:10:45 PM »
I would absolutely not weld a nut on a crankshaft! Those threads also look beyond repair. Even if you can run a die nut over them they will never be the same. I recommend a new crankshaft. Sorry.....
Loren
1986 Trx250r-- Hybrid Engineering 391(Good bye super 310)
1986 Trx250r-- Hybrid Engineering  ported stock 86 cylinder
1986 Trx250r-- craigslist engine with unknown ported 89 cylinder.
1985 Atc250r-- Needs a lot of work (Super 310's new home)

Offline gentner8

Re: Best idea to repair this in place?
« Reply #3 on: June 22, 2022, 07:07:26 PM »
I know I need a new crank, but can't do it right now.  I also have an old Jeep YJ that has taken a good chunk of my toy money this year.  Knowing the crank is done, is why I thought about the tack weld until I needed to do the bottom end again.  How a crank gets stripped when it only needs around 40 ft lbs is beyond me.  If it was done when the last topend was done, it was likely a ticking timebomb the way it was Im guessing. 

Offline The norm

Re: Best idea to repair this in place?
« Reply #4 on: June 22, 2022, 07:29:15 PM »
I do not believe that you can apply enough torque to the nut to seat the flywheel on the taper. The flywheel could wobble which will make your situation worse. Cases are not cheap neither is case repair.
Loren
1986 Trx250r-- Hybrid Engineering 391(Good bye super 310)
1986 Trx250r-- Hybrid Engineering  ported stock 86 cylinder
1986 Trx250r-- craigslist engine with unknown ported 89 cylinder.
1985 Atc250r-- Needs a lot of work (Super 310's new home)

 

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