Helicoil 5521-4 1/4-20 Inch Coarse Thread Repair Kit

Worked great to replace the stripped threads on my Harley primary for the derby cover. Recommend buying an actual tap handle to go with it. Tap cut the threads cleanly and the helicoils went in well. Set comes with enough coils to replace all the threads for the derby cover. May as well drill them all out and replace them.

Great tool, works like a charm. One thing you should know is that the kit does not come with the tap handle. The image above does not match what you get. This is more like what you get Helicoil 5546-6 M6 x 1...

Five starts for ease and result I had stripped threads for a bracket inside the stern of a small boat, hard to tell what it was until doing some "surgery." I determined that it was about 3/8" thick, probably steel, and worth tapping, so I bit the bullet. Tried JB weld first to make threads: *bzzzt* FAIL Next stop, Helicoil. SO easy, it seemed to good to be true. Drill out, quick. Tapping was a bit dicey; I have NEVER tapped threads before, and it was hard to turn at first, then real easy, like it had stripped (it had not). Still, easy. Helicoil screwed right in; being inside it was a little hard to see when to stop turning it in, but no big deal. With such a thin bracket there was a narrow "sweet spot." Bolt went right in, not to loose, not too snug. Done. Pros quick and easy enough inserts for many more fixes saved me LOTS of time and money Cons enough inserts for many more fixes = $$ (cheaper kit with fewer inserts would be nice) need your own 17/64 drill, which is in most bigger drill sets

This kit has plenty of extra thread inserts for a noob like me that messed up the first (or 3rd time). You'll need a 17/64 drill bit to widen your opening for the tap. You'll probably also want a tap wrench so the tap cuts your threads evenly. All in all, did the job I needed.

I didn’t see any reviews specifically about a primary but I went ahead and did all 11 holes for my primary cover for my Harley. The kit doesn’t come with the 17/64 drill bit but it was like $5 for a dewalt. You’ll also need a tap wrench. Easy peasy. I did everything in under 2 hours.

I teach Precision Workmanship class for a major Semiconductor Equipment manufacturer and teach a Precision Workmanship class for new hire employees. Students have varying degrees of experience with hand tools, so tools are frequently damaged or broken. Bought this set to replace a broken handle. The installation handle is better then the other sets I've acquired from major tool supply companies. Quality tool, especially at the price point. I have paid more for less quality.

This is a great and easy-to-use tool kit. However, it didn't really stand the test of time as the driving nub on the post broke after only 5 uses, making it essentially useless. I did manage to grind a new nub, but it wasn't the same. Worth the purchase as a quick use tool, but I wouldn't recommend it for reliable, consistent use.

For the uninitiated this is a thread repair insert and I used it to replace the threads on the base of a telephoto lens. You drill out the existing threads carefully with progressively larger bits until you get to the recommended size: 17/64 for the 1/4 #20 helicoil, then tap the hole with the provided tap: one full turn in, then a quarter turn out to loosen the shavings. It's important to lubricate the tap with WD-40 &/or bacon grease. Just take your time and it should all go in quite easily. Remember to sink the helicoil into the drill hole a quarter turn and use a flat bottomed punch to break off the insert tap when you're done. As mentioned this kit works best for through holes, it might not work as well in blind bottom holes.