Helicoiling question
Discussion
I'm looking at helicoiling a couple of bolts on my crankcase, it's my first time using helicoils and it looks straightforward enough. But everything I have found says to put the helicoil just inside the hole. But this is my bolt, with the helicoil next to it:
So surely, if I leave it just inside the hole, there's going to be no thread to grip the helicoil? I Googled but can't find any answers.
So surely, if I leave it just inside the hole, there's going to be no thread to grip the helicoil? I Googled but can't find any answers.
You have to drill the hole and tap it to the size corresponding with that particular helicoil. Then you screw the helicoil into the newly tapped hole, break off the tag and then it's ready to use.
There'll be a chart somewhere with the relevant drill and tap size for each helicoil depending on the size of the insert
You can put the insert at whatever depth you want it at
There'll be a chart somewhere with the relevant drill and tap size for each helicoil depending on the size of the insert
You can put the insert at whatever depth you want it at
Edited by spikey78 on Monday 2nd November 19:22
Ah yes.
OP, buy a pack of helicoils, the drill, tap and the applicator all in a packet - about £20 depending on the size.
Drill out the old thread with the supplied drill. Tap the new thread with the supplied tap. Insert the helicoil with the supplied applicator. Only use one, and remember it won't undo,so be careful, as you can't drill them out either.
Bob's you uncle.
Cheers
OP, buy a pack of helicoils, the drill, tap and the applicator all in a packet - about £20 depending on the size.
Drill out the old thread with the supplied drill. Tap the new thread with the supplied tap. Insert the helicoil with the supplied applicator. Only use one, and remember it won't undo,so be careful, as you can't drill them out either.
Bob's you uncle.
Cheers
bearman68 said:
Forgive me, but I think you have the wrong end of the stick (or I do).
Helicoil goes into the hole. Bolt goes into the helicoil.
Unthreaded part of the bolt remains in the clearance hole in the thing that you are bolting on.
Cheers
This, I think. The plain shank of the bolt wouldn't normally go into the threaded hole you are trying to repair, that would usually be the bit that passes through whatever the bolt is fixing. Just the threaded section of the bolt would be in the threaded hole.Helicoil goes into the hole. Bolt goes into the helicoil.
Unthreaded part of the bolt remains in the clearance hole in the thing that you are bolting on.
Cheers
That helicoil looks a bit short, it only has half the length of the threaded section of the bolt. Is that a problem? Can you get longer ones, or put two into one hole? I don't know.
NO YOU CAN'T PUT 2 IN ONE HOLE!
If you look at the original bolt & count the clean threads there are 9, this is how far the threaded section of the bolt will screw into the threaded section of what it screws into.
If you now count the threads on the helicoil you will see there are...................9!
The helicoil bottoms out when fitted with the insertion tool, the rest is as above.
If you look at the original bolt & count the clean threads there are 9, this is how far the threaded section of the bolt will screw into the threaded section of what it screws into.
If you now count the threads on the helicoil you will see there are...................9!
The helicoil bottoms out when fitted with the insertion tool, the rest is as above.
bearman68 said:
Forgive me, but I think you have the wrong end of the stick (or I do).
Helicoil goes into the hole. Bolt goes into the helicoil.
Unthreaded part of the bolt remains in the clearance hole in the thing that you are bolting on.
Cheers
Just checked, you are correct sir. Helicoil goes into the hole. Bolt goes into the helicoil.
Unthreaded part of the bolt remains in the clearance hole in the thing that you are bolting on.
Cheers
This is why I decided to ask before I started drilling, I've been staring at the damn thing for too long. Now can we stop debating whether you can get 2 in one hole, I have the maturity level of a teenager and the cat is looking at me funny because I keep giggling.
blueST said:
This might open me up to yet more ridicule, but assuming the hole is deep enough, why can't you put two in? They should just butt up together shouldn't they?
You might get away with it if you are lucky but the snag is that the threads in the 2 sections rarely align exactly as you'd like them to. As you put the bolt in the first coil insert is fine but when the threads hit the second one they aren't quite in line so you get resistance. At least that's what happened when I tried it...blueST said:
E-bmw said:
NO YOU CAN'T PUT 2 IN ONE HOLE!
Not even if you glue them together first?
This might open me up to yet more ridicule, but assuming the hole is deep enough, why can't you put two in? They should just butt up together shouldn't they?
Not even if you glue them together first?
This might open me up to yet more ridicule, but assuming the hole is deep enough, why can't you put two in? They should just butt up together shouldn't they?
Remember that a helicoil is just a precisely shaped spring, and like all springs will relax when not under strain, the relaxed position is closer together than the full thread, which is why you need to count the threads not measure the length when checking you have the right one.
E-bmw said:
In the first instance, if you read the rest of my post as opposed to just the headline, you will see that it is not required.
Remember that a helicoil is just a precisely shaped spring, and like all springs will relax when not under strain, the relaxed position is closer together than the full thread, which is why you need to count the threads not measure the length when checking you have the right one.
I wasn't really talking about what is required in this case, the reply was idle musing in relation to the bit I quoted Remember that a helicoil is just a precisely shaped spring, and like all springs will relax when not under strain, the relaxed position is closer together than the full thread, which is why you need to count the threads not measure the length when checking you have the right one.
The helicoil has roughly half the length of the full threaded section of the bolt, by counting the threads, hence the chain of thought, granted not directly related to initial problem. Sorry to have disturbed you 
WhatIsIt said:
Slightly off topic, but is it possible to repair a damaged sump plug hole with one of these? Aluminium sump with thread stripped in the hole.
Thanks.
If you're drilling and re-tapping it for the helicoil, why not just source a bolt with the same thread as the helicoil and use that? The reason people use helicoils is so that they can use the original bolt, as it is specifically sized to another component. On a sump plug, the bolt is just to fill a gap, so the size or thread doesn't matter.Thanks.
PhillipM said:
Finding a bolt with the same thread as the helicoil tap will cost more money than putting a helicoil in it 
Exactly, helicoils are special sized threads. Tapping it out to the next size up standard thread may be possible however, if there's enough material to tap into and space for a potentially larger head.Timeserts are often a better option for stuff that needs to be removed regularly since they lock into place so no danger of them coming out on the fastener.
Well I did it! Many thanks to everyone for their help. For anyone looking at this for some pointers, here's a rundown of what I found.
First of all, and I haven't seen this mentioned elsewhere, mask off everything around the hole. When you drill it's going to produce lots of little metal filings, ready and willing to crawl into your engine. This was especially true in my case, as I was helicoiling 2 crankcase cover bolts, and had to leave the crankcase covers off while I was doing it:
I used this kit, 7 quid from Ebay: http://www.ebay.co.uk/itm/131519513835
The drill bit is supplied with the kit, and I was not prepared for how easily it drilled out the hole. It's an aluminium casing, and it went through it like butter. Go slowly, a bit at a time. I also made a mark on the drillbit in marker to mark how far in I needed to drill, using the intended bolt as a guide:
See what I mean about metal debris? Don't blow it away, collect it up. I use sticky tape here:
A small screwdriver is invaluable for getting debris out of the hole as well:
Next you cut a thread for the helicoil with the tap, also in the kit. I used molegrips as that's what I had, but you can get a tap wrench as well, which I would invest in if I were doing it again. Make sure you go in straight and square, be very careful and take your time to line this up. Again I have marked how far down the bolt will go, doesn't make much difference to this part but I figured better safe than sorry:
You then install the helicoil using the installation tool in the kit, and it should hopefully look like this:
Before you break off the tab, test the bolt to make sure it threads on to the helicoil with no issues. I found on the second one I did that the bolt wouldn't screw in smoothly at all, so I caught the end of the helicoil with some needlenose pliers, used this grip to screw it back out again, and put another one in which was fine.
Take the bolt out, break off the installation tab and remove it from the hole (not easy on a crankcase), and success! All in all I found it straightforward and would have no hesitation in doing it again if I need to.
First of all, and I haven't seen this mentioned elsewhere, mask off everything around the hole. When you drill it's going to produce lots of little metal filings, ready and willing to crawl into your engine. This was especially true in my case, as I was helicoiling 2 crankcase cover bolts, and had to leave the crankcase covers off while I was doing it:
I used this kit, 7 quid from Ebay: http://www.ebay.co.uk/itm/131519513835
The drill bit is supplied with the kit, and I was not prepared for how easily it drilled out the hole. It's an aluminium casing, and it went through it like butter. Go slowly, a bit at a time. I also made a mark on the drillbit in marker to mark how far in I needed to drill, using the intended bolt as a guide:
See what I mean about metal debris? Don't blow it away, collect it up. I use sticky tape here:
A small screwdriver is invaluable for getting debris out of the hole as well:
Next you cut a thread for the helicoil with the tap, also in the kit. I used molegrips as that's what I had, but you can get a tap wrench as well, which I would invest in if I were doing it again. Make sure you go in straight and square, be very careful and take your time to line this up. Again I have marked how far down the bolt will go, doesn't make much difference to this part but I figured better safe than sorry:
You then install the helicoil using the installation tool in the kit, and it should hopefully look like this:
Before you break off the tab, test the bolt to make sure it threads on to the helicoil with no issues. I found on the second one I did that the bolt wouldn't screw in smoothly at all, so I caught the end of the helicoil with some needlenose pliers, used this grip to screw it back out again, and put another one in which was fine.
Take the bolt out, break off the installation tab and remove it from the hole (not easy on a crankcase), and success!
All in all I found it straightforward and would have no hesitation in doing it again if I need to.Edited by D-Angle on Thursday 12th November 14:57
Viperz888 said:
WhatIsIt said:
Slightly off topic, but is it possible to repair a damaged sump plug hole with one of these? Aluminium sump with thread stripped in the hole.
Thanks.
If you're drilling and re-tapping it for the helicoil, why not just source a bolt with the same thread as the helicoil and use that? The reason people use helicoils is so that they can use the original bolt, as it is specifically sized to another component. On a sump plug, the bolt is just to fill a gap, so the size or thread doesn't matter.Thanks.
I'm another one who wonders how the OP manages to get aluminium to stick to a magnet.....
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