Stripped shaft threading In a honda clone

[AAIM]

I have a coleman ct200u and a couple of weeks ago I accidentally stripped the threads inside of the shaft. The engine is basically the same as a predator 212. Anyways what should I do to fix this? I would go out and just buy a predator 212 but I'm too short on money for that. I've read on another forum someone suggested to drill new threads for it, which is what I want to do, but don't know where to start. If someone could tell me what kind of thread size I should drill out for this, or anything else It would really help out a noob!

(Thanks for reading/replying to this thread!)

 

[mckutzy]

Off hand I think it's 5/16 but I know it's fine..
If its totally screwed(edit:sorry my bad)... Might be able to work it up to a coarse pitch or the next size up...

 

[wardog]

The only issue I see is unless you have the proper drill bit and tap already, buying them will likely cost half of a new engine.

 

[Nosandwich]

Off hand I think it's 5/16 but I know it's fine..
If its totally screwed(edit:sorry my bad)... Might be able to work it up to a coarse pitch or the next size up...

I think what he's saying is you can drill out the stripped threads with a 5/16" bit.

Well, it's a 5/16-24 thread IIRC, but, that doesn't completely match everything up.

I would get a little larger bit (11/32") or bigger and drill just far enough to hit good threads and try again. (To thread the bolt without crossthreading.)

 

[landuse]

You might find a machine shop willing to do it for you for free? Ask around

 

[TT540]

You could step it up to 3/8" x 16 threads.

https://www.amazon.com/Kodiak-Cutti...d=1515170660&sr=1-7&keywords=3/8+tap+straight

The bolts are plentify and can find the right length at a hardware store. taping might be hard. Have to find a way to stop the crank from spinning. Piston stop or something like that. Depending on how hard the crank is you may have a workout ahead of you.

Another option, thinking outside of the box is to weld a nut to the end. Then when you put a bolt on to it, you also put washers or a sleeve to get the contact you want with the pulley on the crank.

Before you throw the engine in the trash, heck, you could even weld a thick washer onto the crank AFTER the pulley is installed. the pully will remain there until you grind away the welds that hold the washer in place. Not a big deal in work, maybe 1 hour of work to weld it up and 3 hours of work to grind those welds away in the future. It's not a load bearing weld, but rather just a retainer. That versus a $100+ new engine That's pennies.

 

[Nosandwich]

You could step it up to 3/8" x 16 threads.

https://www.amazon.com/Kodiak-Cutti...d=1515170660&sr=1-7&keywords=3/8+tap+straight

The bolts are plentify and can find the right length at a hardware store. taping might be hard. Have to find a way to stop the crank from spinning. Piston stop or something like that. Depending on how hard the crank is you may have a workout ahead of you.

Another option, thinking outside of the box is to weld a nut to the end. Then when you put a bolt on to it, you also put washers or a sleeve to get the contact you want with the pulley on the crank.

Before you throw the engine in the trash, heck, you could even weld a thick washer onto the crank AFTER the pulley is installed. the pully will remain there until you grind away the welds that hold the washer in place. Not a big deal in work, maybe 1 hour of work to weld it up and 3 hours of work to grind those welds away in the future. It's not a load bearing weld, but rather just a retainer. That versus a $100+ new engine That's pennies.

And....exactly what do you think will happen to the crankshaft seal while all this welding is going on?

Let me step out on a limb here....you haven't done this, have you?

 

[AAIM]

And....exactly what do you think will happen to the crankshaft seal while all this welding is going on?

Let me step out on a limb here....you haven't done this, have you?

No, I haven't done exactly what he said, however, I have done something similar and it's worked! What I ended up doing was cutting the top off of a bolt and then welding it to the end of the shaft, with the threads sticking out and a nut to hold on the driver pulley. Now as stupid as this may sound, it works quite well. I was close to going through with drilling new threads inside of the shaft but saw that it was pretty expensive to buy a tool and a drill tap at Lowes. As wardog said up above a little kit with a drill tap and the tool costs half of a new engine. I saw cheaper ones online but decided to go with welding a bolt onto the shaft for free instead of spending some money. I also was thinking of how to hold the shaft from moving when drilling so this route probably saved me a lot of problems! Only problems I see is that I can't put a centrifugal clutch on it anymore. (Although I never plan to do so) And I find that this works better than a bolt inside of the shaft. I have tested this out and it works just like new. Unless if I run into any problems in the future I believe this was probably the cheapest way to fix this problem, maybe not the best but definitely the cheapest!

Also the belt wasn't too hard to put on either since its added around another 3 inches to the shaft!

 

[TT540]

I like it. So you put the bolt into the shaft to make sure it was straight. A better approach I think.

Regarding not melting the crank seal. Just take breaks and have some water handy.

 

[Whitetrashrocker]

As wardog said up above a little kit with a drill tap and the tool costs half of a new engine.

Always good to have tools.

 

[mindymogul]

When in doubt Cobalt. Just about any hardware store has them an they don't break the bank. Irwin or Dewalt has them. 11/32nds bit should easily handle it if you spray it with some sort of oil to keep it cool. If one can drill through 1.25" thick steel and last after 30 goes I'd say it can handle that shaft. If I remember right you want a 3/8x28 tap.