Heli-coils

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dj

Heli-coils

#1

Post by dj » Fri Mar 04, 2005 8:22 pm

A while back I bought a set of 5/16" 24 helicoils (38 bucks!) to repair a triple tree side hole for mounting tins and spotlight brackets.....and had good success. The remaining 11 inserts will undoubted be of good use in the future with HD's insistance on using the 24 thread at nearly every opportunity.
A couple of weeks ago I discovered a stripped stud that holds the axle cap under the right side lower leg. The nut thread is 5/16" 24. So I ordered a new stud set just knowing that the other end would, of course, not be 5/16" 24, (just my luck) so I'll have to buy another set of 5/16" 20 helicoils. I have not yet removed the stud and that is going to have problems of its own because the ol' nylock nut is really holding and I can't seem to turn the stud out of the hole because it's turning but not coming out, even while pulling and turning with vise grips. The cap is also still on, "swinging" on the stud. I don't want to take a chance on breaking the cast aluminum cap so I'm thinking of cutting the nut off so that I can work more vigorously at it. I'll get the stud out! I'm not really too worried about that.....but.....
Any tips, ideas, or warnings on using helicoils in aluminum or should it work just as well as in steel?

Handy damn things, those helicoils. Expensive, but handy. I've heard of other repair inserts that are solid, anybody know anything about them?



Red55FL
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Re: Heli-coils

#2

Post by Red55FL » Fri Mar 04, 2005 11:05 pm

DJ
I personally prefer Keenserts to Helicoils because they are more permanent. Helicoils sometimes back out with the bolt, but Keeserts are locked in. They work very well in aluminum. Keenserts are readily available from many sources, but they are more expensive than Helicoils. The tools to install them are also more expensive.
I have used both for many years and have had a lot better results with Keenserts.
Image
This sight shows how to install Keenserts

http://www.newmantools.com/kee.htm" onclick="window.open(this.href);return false;

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Re: Heli-coils

#3

Post by Cotten » Sat Mar 05, 2005 9:21 am

I have never seen a properly installed Heli-coil back out with a bolt.
(The only possible instance that comes to mind is chubble exhaust studs that can gall themselves to the insert from overheating. Keenserts would remain in the head, but the stud would snap! A Heli-coil is easily replaced, but the plugged Keenserts are a b*tch to drill out in the chassis.
There are many fine brands and designs of inserts.
Heli-coils have the advantage of minimum intrusion into the metal. (and you do not even need a special tap for 1/4"-24!)
I almost daily helicoil aluminum, potmetal, and bronze. And in odd circumstances, I have used them for sturdy threads in plastics and wood!

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Re: Heli-coils

#4

Post by BigMike » Sat Mar 05, 2005 11:54 pm

I don't know if it makes a difference, but I've never had problems with Heli-coils. After prepping the hole, I clean it thoroughly with lacquer thinner, then put a dot of red locktite on the insert before I install it. After knocking off the drive tit, I let it sit for 24 hrs before running a bolt in. A quick spritz of WD40 on the bolt to get a nice smooth tightening of the bolt helps too. I have not noticed any difference in durability in AL or FE. Both seem to hold well.

dj

Re: Heli-coils

#5

Post by dj » Sun Mar 06, 2005 6:11 pm

RED

Thanks for the info on the Keenserts. You're right. They do look like more of an expensive yet robust solution. Aerospace and nuclear power plant stuff. My first complaint about the helicoil tool is... it's plastic, but it seems like it'll last for at least 12 uses; then you buy another kit. The Keensert tool looks metal which is cool. Excellent site on fasteners in general, btw. I learned from the chart that 5/16" 18 is the size I'll need..not 5/16" 20 as I originally assumed.

Cotten

Speaking of busted studs, I just learned about the EDM (Electical Discharge Machine) process of removing broken studs and drills or other tooling. (Broken easy outs trying to remove a stud..etc.). Apparently the process disintegrates the stud and leaves the original threads intact. Probly expensive as all get-out and suitable for aerospace and nuclear power plant stuff as well. The EDM machines look like they cost 200k or more. It got my attention when I came across it however. Here's a guy in California who specializes in repairs using this process:

http://www.brokentap.com/services.html" onclick="window.open(this.href);return false;

BigMIke

24 hours? You've got a lot more patience than I do. Locktite sounds good to me. I ground my drive tit off with a Dremel tool.
Great...eh, thread!

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Re: Heli-coils

#6

Post by BigMike » Sun Mar 06, 2005 11:01 pm

DJ: 24 hours? You've got a lot more patience than I do. Locktite sounds good to me. I ground my drive tit off with a Dremel tool.
I always try to take my time, the newest real Pan out there is 40 yrs old. gotta be careful not to spoil ANYTHING

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Re: Heli-coils

#7

Post by Red55FL » Mon Mar 07, 2005 12:42 pm

I have been through some real nightmares with Heli-coils. Usually 100 miles offshore, way back in the bowels of a piece of equipment working on something that you can just barely reach with a multi million dollar job coming up with in hours.
As for whether or not they were properly installed, installing Heli-coils ain’t rocket science. It only requires a little bit on care and patience, the same as properly doing any type of mechanic work.
I would not want to be on the side of the road trying to fix something that should be a simple thing & have a Heli-coil back out. Yes, they are easily replaced, if you have one and the tool with you.
I prefer a repair that is permanent. In my business, I consider Heli-coils a quick patch. Heli-coils have their place, but not on anything that has to be taken apart on a regular basis.
On any bolt or stud used in an exhaust or other high heat application, I use high heat Never Seize. Stops the thread-galling problem.

Just my humble opinion
Red

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Re: Heli-coils

#8

Post by PanPal » Mon Mar 07, 2005 10:01 pm

Heli coils have always worked well for me, but I have had them back out like the others when I was in a hurry.
As Cotton says, the heli coils use minimul intrusion.
You will end up with a strong longer wearing thread in aluminum parts and even thin walled threads can be repaired with Heli coils.
I recently used E-Z Lok inserts. They have a coating on the threads that lock after they mash into the threads when installing them. Also you use standard taps to oversize the holes. The problem I have had with these is getting them screwed into the hole before they stop and the driving tool screws up the slots used to screw them in. They have worked well for me once installed.
I like Keenserts, Funny mine never look like the picture of the insert installed. And don't even try them without buying the tool to set the pins.
I have had great luck removing studs that have snapped off flush with the surface by tig welding a nut to the broken stud. The nut allows you a good surface to turn with, and the heat helps relieve the pressure locking the stud into the threads.

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