Female Thread Fix Help

boostin53

boostin53

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Long story short, I ended up with a stripped female thread and need advise. I'm in the middle or reassembling an atv motor. While putting the wet clutch housing back on, I stripped a single female thread in the right crankcase. It is not a bolt that holds the left and right cases together, but simply holds a wet clutch housing cover.

The bolt was to be torqued to 7 ft lbs. I began torquing procedure by going around all the bolts on the cover in a criss cross pattern and incrementally tightening to avoid warping and what not. Well it stripped before the torque wrench would click on the last pass. The others torqued just fine.

My question comes to a few options, I just don't know which one I should do. I can helicoil or time-sert, drill and retap for the next size bolt up, or do my own threaded insert (which would invlove using my lathe, hence why I post this in this forum). If I were to make and press in my own threaded insert, how would I go about it? The stripped threads are in aluminum and I'm limited to how much bigger I can make the hole. What does the hive say?
 
I have a complete helicoil kit for 10-32 up to 1/2-13 for that very reason. A lot easier to just drill and tap for the helicoil. My father gave me the kit many years ago and I have used it many many times..
 
It somewhat depends on how much "meat" you have to work with. Personally, I would likely use a stainless steel Helicoil as
I have done it before with good success and have the taps and tooling. From what I gather in your post, you don't have a lot
of metal to work with, thus the Helicoil or similar would be a good choice for the repair. Also one might consider reducing the
torquing a pound or two if that is possible.
 
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I sure like the thread sert with the little pins on the side, I used those on a Yamaha break caliper that was stripped,
 
Yeah there isn't much extra meat around the threads. Reason behind this post is that I haven't had a problem like this in my young life so far. If I stripped a hole in the past, I had plenty of meat around it to go up to whatever bolt size I want. And I have never used a helicoil before. It's a metric bolt pattern, can't remember the size off the top of my head. I want to say m6 1.25, but not sure.

Can one buy just the helicoil? Or does it have to be in a kit? I have a rather large assortment of taps and dies in metric and standard.
 
as long as the hole does not go through to the inside...if it does you should blow air into the case to blow drill/tap chunks out as you go
 
you can buy a small helicoil kit that has the tap, helicoil & plastic insertion tool. would have to check where but would need the proper size.
I have seen some at automotive parts places though.
 
Hard to say without seeing the part but the JB weld type option might be the only one. If memory serves Heli coil inserts require an oversize hole so if there is not enough meat to go up to the next largest thread then maybe you can't Heli coil either.

Rather than JB weld I would use a thread restorer kit from Loctite that molds news threads in the hole using the original fastener coated with a release agent. No need for subsequent drilling and tapping.

https://www.napaonline.com/napa/en/p/NCB28654/
 
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Well I went ahead and did the JB Weld method that was mentioned earlier. I cleaned out the hole real well then mixed up some JB. Made sure to fill the hole without any air pockets. Tomorrow I will drill and tap the new threads.

Although this isn't a mechanics forum, you guys are pretty handy to have around! I'm only 28, but I could spend 28 more years just learning from you kind folks. Thank you guys for the help, suggestions and advise.
 
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