If I go with the threaded insert, I'd rather have the insert fixed in position permanently.
Bolt extractor and max torque?
- Thread starter vavavroom
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No, in fact the Helicoil may be the stronger of the two in this application. First of all it requires less material removal and secondly it is not in an application that has high pressure and heat expansion of the aluminum or is repeatedly removed which makes it a perfect application for a coil rather than an insert.
The Coil threads are many times than the original aluminum threads and unlike a insert tend to "jam" against the threads making it almost impossible to tear out in normal use. You must use a coil of the correct length of a minimum of 1.5 times the diameter for a strong repair, an M10 fastener for example needs a min of 15mm of thread engagement strength 20mm would be better and full strength, more than that is of no benefit. Be sure to buy coils the correct length Some old info that is still relevant today.
I would get a long T handle tap wrench or tap sockets if space is limited and make sure it starts true.
Thanks for the info and links Trav. Thread engagement on the bolt is ca 16mm. The hole is 30mm deep. So I'll be looking for a Helicoil kit for M10 with a Helicoil length of 20mm. I wasn't aware of socket taps. That would solve the problem of limited access but getting the tap started could be tricky.
That is not a problem, use a piece of 1/2" copper pipe or 1/2" pipe connector that fits the tap with little play, you can build the tap up a bit with clear tape about half an inch from the bottom to take up any "wiggle room" and use it as a guide to start it. Yes 20mm long will be perfect.
I use one one similar to this..
EXTRA LONG TAP WRENCH FOR 1/4 THRU 1/2 TAPS | eBay
EXTRA LONG TAP WRENCH. TAP NOT INCLUDED.
www.ebay.com
But these work okay too..
Is the Helicoil supposed to come to a dead stop when threaded in? I want to know if I need to tap to a depth of exactly 20mm for a 20mm Helicoil.
No it expands as you install it so you don't want it bottoming out, just install it about quarter to half a thread below the surface so it isn't proud.
Once it is in use a small punch to break the tang off inside, a slight hammer blow on the punch is all it takes.
Make sure to buy the correct drill bit or buy a kit that includes one.
You don't need to chamfer the hole of need a drill press but this shows how to install one. There are lots of how to videos on this.
Once it is in use a small punch to break the tang off inside, a slight hammer blow on the punch is all it takes.
Make sure to buy the correct drill bit or buy a kit that includes one.
You don't need to chamfer the hole of need a drill press but this shows how to install one. There are lots of how to videos on this.
Trav, where would you use helicoils and what applications would you use a time-sert? I see you suggested helicoils here. what would be the proper place for a time-sert?
Thanks.
Spark plugs, oil pans, cylinder head bolts in aluminum blocks eg North Stars, main bearing bolts and fasteners that are removed frequently and for sure some others I cant think of right off the top of my head especially in aluminum. Spark plugs in aluminum should use aluminum time serts for proper heat transfer.
Helicoils are very good and have their place, they are not as some wrongly believe inferior. Choosing the correct insert type for the repair is key to successfully repairing the part, I use a few different styles depending on the job, the conditions it operate under and how much "meat"is there.
Coils generally require less removal of the material being threaded, this is critical when a larger diameter insert would leave a thin and weakened wall.
On M6 holes that are stripped I many times will just bump it up to an easily available M7 with no insert if there is not much material to work with. The M7 takes an M6 drill so the material loss isn't very much and usually not an issue.
Other sizes may be a problem as M9 is scarce for M8 so for M8 the next size is normally M10 or for 10 it is M12 which is significantly larger.
Sometimes I wish I was down south where you don't need to know much about this stuff or own a portable edm machine aka Elox drill.
Helicoils are very good and have their place, they are not as some wrongly believe inferior. Choosing the correct insert type for the repair is key to successfully repairing the part, I use a few different styles depending on the job, the conditions it operate under and how much "meat"is there.
Coils generally require less removal of the material being threaded, this is critical when a larger diameter insert would leave a thin and weakened wall.
On M6 holes that are stripped I many times will just bump it up to an easily available M7 with no insert if there is not much material to work with. The M7 takes an M6 drill so the material loss isn't very much and usually not an issue.
Other sizes may be a problem as M9 is scarce for M8 so for M8 the next size is normally M10 or for 10 it is M12 which is significantly larger.
Sometimes I wish I was down south where you don't need to know much about this stuff or own a portable edm machine aka Elox drill.
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Still need that knowledge down here with all the ham fisted diy'ers & "mechanics" around.
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I’ve never had to use a heli coil and hope I never do lol. Sounds like a real pain.
I see that Helicoils come in different alloys. Which kind would be best use in aluminum? Also, isn't galvanic corrosion a concern with steel in aluminum? Not that I live in an overly humid area or anything.
Stainless (usually 304) is fine for this job in aluminum.
That can ruin your day too, as if the rust and rot isn't bad enough.
Thanks for the info. It may take me a week or so until I get around to dealing with this but I will give an update.
While reading up on Helicoils I have come across some information that has lead to a few questions. So they maintain their springiness, Helicoils are supposed to be installed without thread lock but what about using thread lock on the bolt going into the helicoil? Wouldn't the regular liquid/gel type thread lock cause the same problem with the Helicoil? Or would it be better to us a dry type thread lock like the one that comes on many OEM bolts? But what product is that exactly? Or is thread lock on the bolt not needed on a Helicoil? Also, what torque can a Helicoil for M10x20x1.5 tolerate and how does this number decrease with subsequent bolt removal and installation? The bolt in question requires 30 foot pound torques, in case that matters.
M10x70x1.5? 0.5 is very fine, well 3x finer than what I suspect I'm looking at. 1/50th of an inchAs mentioned earlier, when the bolt broke it took more than a 1/4" worth of threads with it. The bolt size is M10x70x0.5. My plan is to drill the hole out to 14mm diameter and to the length of the E-Z Lok insert and tap for an M10 (OD M14x2.0) E-Z Lok insert. McMaster-Carr has M10 E-Z Lok inserts that are 17mm long in 316, 18-8, and in black phosphate coated steel. I think the 316 would be best, or will it be too weak? Other opinions? I'd use red thread lock on the insert. What did I miss?
You can use a little red loctite on the outside of the coil if you want, there is really no need just clean the threads with brake cleaner and blow it out (canned air is fine) to remove any cutting oil and chips. As the coil threads are stainless there is no need for loctite but a little never seize is not a bad idea in the salt belt, just reduce the bolt torque 10-15%. 30 ft.lb is nowhere near stressing the coil on M10 threads (max would be somewhere around 55 ft.lb, they are much stronger than the original aluminum threads.
The locking torque of the coil is what decreases with repeated removals, it takes 15-20 cycles before you may experience unwinding and galling of the aluminum threads the coil is in. This is not so much an issue at lower torque values as in this case.
Thanks Trav.
0.5 was a typo. The pitch is a coarse 1.5.
thought that's what it was 
