Just was watching a video comparing HeliCoils, TimeSerts, Big Sert, and a couple of others. The BigSerts appeared to win the death match. Still thinking about the low temp aluminum welding with propane or even tapping a slightly larger hole. Thanks for all the replies, this place is like the Hall of Wisdom.
i always considered a heli-coil an upgrade to any thread in just the aluminum. they really work well for a repair.
A properly installed heli coil in a soft material is a stronger thread than original as they are stainless, heli-coil says they are a temporary repairs but we all know there are lots running around that work just fine forever!! Time serts are considered permanent and I feel are a step up! Sent from my iPhone using The H.A.M.B. mobile app
I buy extra inserts at work when I have a repair to do... so if 1 or 2 follow me home that works for me. I have lots of taps and a plethora of drills. Drill bushings and holders galore too if I have to locate something precisely.
If the damaged area is a blind hole (not a thru hole) getting heat to the bottom is near imposable and the flame/heat will flow back out and blow out the torch
$.02: I've installed lots of Keenserts, it's very easy to mangle the keys when driving them in. You absolutely need their key setting tool, if the part is portable an arbour press is a better way than hammering them in. They're tougher to remove than their instructions suggest. Many auto parts don't have enough meat around the hole for a Keensert install. I've installed lots of helicoils too, they work well if installed properly. Use their tap, they're not that expensive. Wherever possible, use a drill press to drill the hole, it's tougher to do well with a hand drill. The finished job will be much better if the hole is straight and not oversized or tapered. Don't be afraid to use a dab of red Loctite on the helicoil, chase the finished threads with a tap to remove excess Loctite. Wherever possible, I prefer to use a stud in a repaired hole. Long set screws work well. You get full thread engagement with a stud, and you don't run the risk of removing the helicoil when removing the bolt installed in one.
I feel bad for the guy who bought my 51 triumph. The fine threads/helicoil in the primary cover must be really effed up.
Do helicoils,"open up" when inserting the bolt? I have some M6 coils but the bolt is 1/4 which is just a hair bigger. When I test fitted the 1/4 " bolt into the helicoil it opened up a whisker so what would happen if I tried that after inserting the helicoil? Strip it out? Should I try it or get the correct 1/4" size?
Get the correct size. For one thing the thread form is not the same between metric and US. Also, I would not put a tap into a Heli-coil. My experience was that the tang end warped into the flutes in the tap, and the tap was stuck forever. I have done this myself and know of another guy doing the same thing. There are oversize Heli-coils if you need them. But then you need the correct tap and all. Also Twin serts which is a Heli-coil inside a Heli-coil to make up for way oversize holes. Again, you need the correct instalation tools. I put lots of Heli-coils in lots of airplane parts. They work fine when properly installed.
I test fitted with the 1/4 bolt not the tap. Will try to find the correct size. I hope I don't need the Twinserts as there may not be enough meat to drill into. Thanks for the tips.
I wouldn't play around with sizes as Rich suggested this is stuff our lives and others depend on. Play invites failure. Metric wrenches fit SAE stuff better sometimes however when it comes to this stuff slop = trouble. Not worth it. Your weakest link is the corner you cut. It may even haunt you next time you work on that connection. I've had heli coils come out on spark plugs before. dont know why it happened but it could have been an inferior install. Have fun with your project
No, helicoils are actually a little bigger before installed. You can get a "prewinder" for most sizes I believe, but are more necessary for sizes under 1/4/6mm. Once installed, helicoils have constant tension outwards into the tapped hole.
I used to make an insert for Stromberg inlets. I drilled the housing an tapping 9/16 I think. I made an insert by drilling and tapping the correct Stromberg threads in the bolt. The housing was not threaded all the way so the insert bottomed out. Worked just fine.
One benefit of the helicoil may be putting the stainless steel helicoil into the aluminum as SS seems to be more compatible with aluminum so placing the SS coil between the bolt & aluminum may be a healthier situation. The helicoil will grab a larger surface that gives more more reinforcing strength to the put an original bolt back. Drilling the hole out & retapping still leaves a larger bolt in the weaker material. It depends how critical the bolt is.
The coil inserts are flexible when loose, they don't "lock into correct shape" until they're screwed into the slightly smaller hole. I'm sure a 1/4" screw fits into a loose coil insert, but once that insert is installed the screw will fit just as badly as in a standard M6 hole.
I've made up special bushings before, big OD thread and the ID of what the hardware to be installed. Quicker than waiting for an oversize insert to show up if it has to be ordered.
I agree, this could be perilous. If the hole is deep and the tap goes past the tapered point all the way through the helicoil it could be trouble. I've never jammed a tap but I've had one back the helicoil out. I guess usually it shouldn't be necessary to chase Loctite out, and if the bolt won't go into the helicoil it's the wrong bolt or helicoil tap.
Usually if you try to remove a Heli-coli winding it from the bottom, it expands, naturally and tightens against the tapped hole. That's why Heli-coil removal tools are like easy outs and catch the top of the coil which pules it away from the tapped hole. They do sell locking Heli-coils. They are red in color, but I thing the thread locking part is the deformed coils in the center. Rather than some Lock Tight kind of stuff.
When I remove them I use a pick to pry the top coil out, grab it with a needle nose vise grip and screw it out. If installed correctly they don't back out. You're supposed to install them one thread below the surface and stake the thread at the top end of the coil. Some don't remove the installation tang and jam the bolt. The instructions are easy to follow but so many don't.
If I have the Heli-coil removal tool (read if I'm at work) I try it. If that doesn't work, it's the pry and needle nose deal. What ever it takes.
Time Serts were mentioned. Best product out there for repairing stripped ID threads. The man that invented them had his shop a couple blocks from ours. One sharp SOB. Everything in a Time Sert kit is made 100% in house, even the Taps. Over the years we acquired kits in most popular American and Metric sizes. They work so much better than a Heli Coil it's not even funny. I was a machinist for 50 years, and have used everything out there for thread repair. Would not consider anything but a Time Sert.
I didn't know of Time Serts before reading this thread. I just looked at their website, certainly looks like the best way to repair a thread if there's enough meat around the hole. Swaging the thread at the bottom to retain the insert is brilliant.
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