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Heli-coil Alternatives
#1
I recall a thread on the old forum on other alternatives to the heli-coil and forgotten the name(s).
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#2
Hi Scott,
I have been using Helicoil brand "Save-a-Thread inserts. They are a full steel insert that fits into a hole tapped by the installation tool, then swedged into place with another tool. These installation kits an inserts are available on eBay and probably other places. I get my inserts and the kit on eBay.

They have worked very well for me but are a bit tricky to install straight, it takes some careful re-threading with the tool but I think they are the best option.

To back that up...I just received an engine for service that had a standard helicoil insert. A piece of the helicoil broke off at the bottom and was smashed between the piston and head. Mare a mess. This could never happen with the Save-a-thread inserts.
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#3
I've also used Keenserts. There are others. https://www.acmeindustrial.com//insert_comparison.html
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#4
I always just cut an aluminum slug that got threaded to replace old thread inserts after they pulled out. It worked especially well on the two exhaust side studs on Yamaha KT100 cylinders. Out of the hunderds I had repaired only two ever failed.
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#5
I agree with Paul F on the Keenserts (brand name for key-locking inserts).  I've purchased them from McMaster-Carr.

Unlike a Helicoil, they do NOT require a special tap.  To keep them from unscrewing, they have two or more (depending on the size) longitudinal "keys" that are tapped into place as the last step.

My success rate using Helicoils for field repairs has not been as good.  I'm guessing that hole has to be drilled perfectly straight, which obviously doesn't always happen in the field.


BTW, for spark plug thread repair on modern cars, I hear only good things about TIMESERTS.  Like a Helicoil, they require a special drill, special tap and installation tool.  In addition, they require a special counterboring tool to prepare the hole.  In exchange, they have much thinner walls than Keensert.  This is a pretty good video as long as you speed it up: https://www.youtube.com/watch?v=A4sS3T6g...tion=share
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#6
I'm thinking that the Timesert may be the same things as the "Save-a-Thread inserts" Scott K mentioned.

Either way, I'm sure that Scott has installed more inserts than I have!

I just read one of the comments on that monotone video I posted (can't vouch for its accuracy):
These time serts are so much better than a heli-coil it isn't even close. you can use a heli-coil tap to cut threads for a time sert and buy a counterbore tool for the flange. Use a grade 8 bolt as the installer. Just toss the heli-coils and use the drill & tap that comes with the helicoil set if you already have the helicoil kit..
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#7
Ok, it turns out that Sav-A-Thread products are similar but different than Time-Serts and Keen-Serts.  Made by Emhart (owner of Heli-Coil trademark, which is now owned by Stanley-Black & Decker).

See attachments.

Sav-A-Thread inserts appear to come in three flavors.
1.  Regular ol' wound-wire heli-coils (they say to NOT use them on taper-seat plugs).

2.  For taper-seat spark plugs, the insert is solid (not wound wire like a heli-coil) but uses knurled threads at the top, along with some sort of peening tool to lock it in.  Um, other than avoiding a Time-Sert patent(?), I have no idea why they'd go that way.

3.  For general thread repair, the other type of Sav-A-Thread inserts seem to be VERY similar to Keen-Serts, except with only one locking key (they call it a peg) and the top of the key breaks off once the peg is hammered into position.  Hmmm....


Attached Files
.pdf   Sav-A-Thread_non-spark-plug.pdf (Size: 123.03 KB / Downloads: 14)
.pdf   Sav-A-Thread_for_SparkPlugs.pdf (Size: 100.28 KB / Downloads: 8)
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#8
Thank you for the GREAT contributions. The old forum discussed the repair options and is no longer readily retrievable.  It nice to know this information is now available here.

I'm sure inquries by future visitors will find this information a godsend.
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#9
I've had pretty good luck with the original Heli-Coil thread repair kits, though nearly all my use of them has been for automotive repair.  I've used SAE (fine) thread, NC (coarse), Metric, BSP (British Straight Pipe) & a recent first was the installation of a 3/8 x 24 LEFTHAND insert to repair a "clutch retaining, 3rd bearing support combination starter nut" (no data yet on its longevity of repair...).

Re-Coil is another brand that's the same as Heli-Coil, and seem to be supplied more often than not when sourcing the (individual thread size) kits from either McMaster- Carr or MSC.  While the packaging is different, the products and supplied tools (drill bit, tap, insertion tool and tang break-off tool when included) appear and function the same.

On an unrelated matter, Scott Kneisel, I'd like to ask you about some (McCulloch R200/F100) frame dimensions you may have.  At a recent playdate in Bushnell, Florida, it was recommended that I contact you.  I can go through any of the forum or Facebook PMs, or preferably, via email (mine is e randy forbes @ aol . com with NO SPACES).  Thanks!
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#10
I just bumped into another kit. https://www.sparkplugs.com/product.aspx?zpid=46648 The price is rather good but I have to wonder if they are meant for taper seat applications.
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