O/T Helicoils and stainless steel

[Fasttrack]

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]

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]

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]

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]

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]

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

John

[chief]

John is right I also prefer ez-loks.

[WJHartson]

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]

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]

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.