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View Full Version : O/T Helicoils and stainless steel



Fasttrack
03-06-2006, 09:03 PM
Any advice about helicoils? I broke a bolt off, despite everything i could think of to prevent this from hapening, in my transmission. Its one of the 5/16 inch bolts that hold the pan on. I see mcmaster has helicoils made of stainless steel but how compatible is that with the aluminum case, also do you guys have any advice about installation, tools to buy etc? Helicoils are new to me...i know they arent really the prefferd method of repairing something, but i don't really see any alternative. It is a through hole, but no room for a nut on top, besides that seems kinda hoaky. Thanks

wierdscience
03-06-2006, 09:11 PM
It won't matter one bit the stainless helicoil in aluminum.

Helicoils are okay,but I like King serts and Threadlock inserts better since both are soild and not a coil spring.The one drawback they have is they require more metal around the hole.

As for Helicoil instalation,it's pretty straight forward,just buy the kit and follow the instructions.

The old nut on the backside trick was fine,it's the way things used to be made before "cheaper" took over for "better".

JCD
03-06-2006, 09:18 PM
Stainless helicolis work fine in aluminum. You should plan on buying the special tap and the installation tool. Sometimes if a person is just as well off to just go to the next size bolt, in your case 3/8 Dia. It may be more economical.

coles-webb
03-06-2006, 09:27 PM
I have put hundreds of Heli-coils in aluminum aircraft parts and some do corrode due to dissimular metal. With all the oil around the engine it souldn't be a problem. Heli-coils are not very good for items that you are removing and installing a bolt. Every time you remove a heli-coil you risk it coming out. You can also get locking heli-coils that have the two center rings crimped to lock (like a lock nut) the bolt in. Regular heli-coils can be cut with end cutters if they are too long. When installed a heli-coil should be at least 1 thread below the surface. Heli-coils use their own special taps and pay attention to the tap drill size. There are two basic tools, one is a rod with a slot in it that is used to turn it in. The other tool pre-compresses the heli-coil by putting it in a tube that has the same threads as the heli-coil. If you have the tap and acces to Lathe you can make a compression tool. The pre-compression tool is better and has a better sucsess rate. I reccommend that you make a jig block first as you will only get one chance to drill and tap it. I use a 1 by 1 inch block of aluminum about 3 inches long. I will drill 2 holes in it about 3/4 inch from the end (the tap drill size) on a drill press or milling machine (you wand the holes 90 degrees to the surface). One of the holes I will thread using the heli-coil tap, again in a drill press or milling machine. Using this block as a jig when drilling and tapping the part will ensure it is straight. With out it you rink being off at an angle. If you have the wall thickness, Keenserts are better for items that you will be removing and installing the bolt as they are a solid insert. If you have any more questions, ask. Do some searching on the net for more info also.

Mike

doug931
03-06-2006, 09:53 PM
A thing to remember! I believe Helicoil recommends using Red locktite to secure the inset.
I have never had an insert back out in hundreds of applications in motorcycle cases. Doug

John Garner
03-06-2006, 11:32 PM
Fasttrack --

I'll suggest EZ-Lok inserts. The thin-wall EZ-Lok doesn't need much, if any, more meat around the hole than a Heli-Coil-type wound-wire insert.

The EZ-Lok insert uses a standard external thread, so no special tap is necessary to tap the to-be-repaired hole. Just be sure to use the tap drill size EZ-Lok specifies, which is larger than the regular tap drill chart will tell you to use.

Neither are special tools needed to install an EZ-Lok insert in "onesey-twosey" repair work, a bolt and nut matching the internal thread on the insert works just fine.

Take a look at EZ-Lok's website . . . www.ezlok.com (http://www.ezlok.com)

John

chief
03-07-2006, 01:06 AM
John is right I also prefer ez-loks.

WJHartson
03-07-2006, 01:09 AM
Since you broke the bolt off and it is a through hole have you tried drilling it with a left hand drill to see if it will come out. Even if it doesn't come out you will have a hole in it an you could try an EZout. Don't like them but it might work in this case. If all else fails then go to the helicoil.

Joe

dsergison
03-07-2006, 12:03 PM
dang it isn't rocket science. buy the kit, it comes with tap, drill and install tool (and instructions).

the inserts alone are of no use without the special tap the kit includes.

any fool can use it.

madman
03-07-2006, 12:20 PM
Used to use epoxy primer in the helicoil drilled hole prior to inserting the helicoil itself. This was on aircraft parts. Prevents corrosion electrogalvanic rot whatever. Some of the guys actually inserted the helicoil with a very thin coating of epoxy applied lightly to the outside of the insert when they screwed it into place.

Fasttrack
03-07-2006, 04:42 PM
"A thing to remember! I believe Helicoil recommends using Red locktite to secure the inset."

I was already planning on that, thanks!

"Used to use epoxy primer in the helicoil drilled hole prior to inserting the helicoil itself. This was on aircraft parts. Prevents corrosion electrogalvanic rot whatever. Some of the guys actually inserted the helicoil with a very thin coating of epoxy applied lightly to the outside of the insert when they screwed it into place. " Thats something to consier, thank you!

"dang it isn't rocket science" lol also duly noted! Just don't want to screw up a several hundred dollar part! http://bbs.homeshopmachinist.net//smile.gif

Thanky you John, sounds like that might be the way to go!

Joe- tried everything i could think of to get it out. Drilled w/ left hand drill and nothing. Tried e-z out, nothing. Tried a rigid brand broken bolt remover, twisted the tool but still couldnt get the threaded part out. I don't know if the guy put some epoxy on it or what. I heated it to soften any locktite, even locktite's high heat stuff was only good for 700 seems to me. I dunno what the deal was with that bolt but sure as heck wasnt coming out so through i drilled http://bbs.homeshopmachinist.net//smile.gif

lynnl
03-07-2006, 04:58 PM
If this is a steel bolt in aluminum case, can you position it so that you can keep the broken bolt immersed in a solution of alum?

That's been reported as very effective in dissolving steel within aluminum.

[This message has been edited by lynnl (edited 03-07-2006).]

Fasttrack
03-07-2006, 05:02 PM
Wow! You can even request a free sample from E-Z lock! Thank you very much for that website! I think i'll get a kit - working on this truck i am bound to break off more bolts and screw up plenty of threads http://bbs.homeshopmachinist.net//smile.gif

Fasttrack
03-07-2006, 05:12 PM
Well i've already got the bolt drilled out, but i did considering talking w/ my chem teacher to see if she could hook me up with a sol'n i had in mind to dissolve it, but the trouble is the bolt is going up from the underside and i can't really get at the top of the hole. I could if i took the tranny out, but thats not really feasible in my case for several reasons (not least of which is the homeowners association) Thanks for the suggestion though!