Need help - repair thread without insert?

[bchee]

I screwed up and cross threaded a fine bolt.
I already tried a thread "restore" tap, which isn't working.
Is there a way to use a real tap to fix the damage, without having to use some kind of insert (like helicoil).

This is for a crossmember bolt. (picture is not mine but representative)

 

[2oolhound]

It the threads are knackered the standard tap won't help. Either helicoil or drill and tap to the next larger size. You may be able to run the proper tap through so the proper bolt goes through ok and then put a nut on top so the bolt has some good threads to grab but you may need a longer bolt to do that if there is room. Even if you had to grind the nut down to say 1/2 thickness to make it fit it will help. It is a common belief that only the 1st couple of threads do most the holding.

 

[williaty]

I'm a little worried about myself since I could actually look at that picture and tell which make, model, and year range that fits

To answer your question, no, there's not.

The Subaru weldnut that you messed up is VERY undersize in OD. There's not enough metal there to drill those out and retap to M14x1.5 (they started as M12x1.25) and have them have a realistic chance of not failing under load. The Heli-Coil brand (preferable to other brands at that size, IMO) M12x1.25 kit isn't too expensive (and they're available via Amazon Prime) and the drill bit needed is under 1/2" so it's easy to find. Repair it properly with a Heli-Coil, making sure you're very careful with your drilling, and it'll serve perfectly for years.

 

[williaty]

Also, while you've got that out, I hope you're doing the TiC MOO-008 Crossmember Bushings and the Group N ****** mount, right?

 

[bchee]

It the threads are knackered the standard tap won't help. Either helicoil or drill and tap to the next larger size. You may be able to run the proper tap through so the proper bolt goes through ok and then put a nut on top so the bolt has some good threads to grab but you may need a longer bolt to do that if there is room. Even if you had to grind the nut down to say 1/2 thickness to make it fit it will help. It is a common belief that only the 1st couple of threads do most the holding.

thanks for the input. This is a weldnut as willy has mentioned below. It is completely shielded on every side. I was actually prepared to cut into the floor board to get access to the top of the nut.

I'm a little worried about myself since I could actually look at that picture and tell which make, model, and year range that fits

To answer your question, no, there's not.

The Subaru weldnut that you messed up is VERY undersize in OD. There's not enough metal there to drill those out and retap to M14x1.5 (they started as M12x1.25) and have them have a realistic chance of not failing under load. The Heli-Coil brand (preferable to other brands at that size, IMO) M12x1.25 kit isn't too expensive (and they're available via Amazon Prime) and the drill bit needed is under 1/2" so it's easy to find. Repair it properly with a Heli-Coil, making sure you're very careful with your drilling, and it'll serve perfectly for years.

This is very impressive. You got the exact thread size.
It's not my picture but you got everything exactly correct.
I have NEVER used any insert, so I was afraid I would screw up the installation, and of how strong it would be.

What I don't understand is what keeps the helicoil from going all the way through the nut. There is no bottom.

 

[senlow]

I have NEVER used any insert, so I was afraid I would screw up the installation, and of how strong it would be.

What I don't understand is what keeps the helicoil from going all the way through the nut. There is no bottom.

Helicoil installation is not rocket science. Since you are mechanically inclined, I'm sure that you can do it. A helicoil repair will be at least as strong as the original threads.

Helicoils are heat treated steel coils, with a slightly larger diameter than the tapped hole. So, when a helicoil is wound into the tapped hole, it is forced into a smaller diameter. The spring like characteristics of the helicoil force it against the walls of the tapped hole, holding it in place.

 

[E.Marquez]

thanks for the input. This is a weldnut as willy has mentioned below. It is completely shielded on every side. I was actually prepared to cut into the floor board to get access to the top of the nut.



This is very impressive. You got the exact thread size.
It's not my picture but you got everything exactly correct.
I have NEVER used any insert, so I was afraid I would screw up the installation, and of how strong it would be.

What I don't understand is what keeps the helicoil from going all the way through the nut. There is no bottom.

Upon inserting the thread repair coil, with a dab of thread lock, the coil tightens up somewhat .. On a application like you have, you just stop turning (installing) the insert when it is the depth you want.

If you can drill a straight hole, you can install a Helicoil (or timesert).
the HeliCoil M12x1.25 insert requires a 12.25mm drill bit

But the full kit to install it is not cheap.. about $130 or so.
PN 5405-12
If this is a one time deal... better to pay a machine shop to do the job,, about the same cost (or less). If your likely to need the kit again, but it..and do the job your self.. More tools on the shelf is always better.

http://www.helicoil.com.sg/HeliCoil-Installation-Instructions.htm

HeliCoil Inserts - Retention Principle
HeliCoil wire thread inserts are larger in diameter before installation than the tapped hole. During installation, the HeliCoil inserting tool reduces the diameter of the leading coil so that the HeliCoil insert can enter the tapped hole. After successful installation, each high tensile stainless steel coil of the HeliCoil insert expands outward against the tapped hole to permanently anchor it inthe hole.

 

[Gregg33]

I just take mine to my local machine shop. Depending on his mood and the complexity of the job, he charges anywhere from free to $30. Not worth the aggravation of doing it yourself imo.

 

[williaty]

It's not that expensive:

HeliCoil M12x1.25 Kit w/ Free Shipping: $54.23
31/64" Drill Bit w/Free Shipping: $6.42

 

[4x4gearhead]

Sometimes with a helicoil to make sure I dont put it in too far I will actually let the bolt take it in the hole so that way you dont put the coil in too deep.

 

[z28snksknr]

I would fill it in with a MIG, drill, and tap the orginal size.

 

[4x4gearhead]

I would fill it in with a MIG, drill, and tap the orginal size.

But weld is harder to drill than steel...that would be a headache.

 

[bchee]

Thanks for all the advice guys.
Thanks to williaty for the pm info.
I got a "Permacoil" kit for $44 which is what was available locally, when I needed it (today).
The packaging is funny - it says "the other name in thread repair."
I finished successfully.

If you can drill a straight hole, you can install a Helicoil (or timesert).

This part was my biggest fear, and turned out to be the hardest part. I had a nice cobalt bit, but the threads were so bad it kept catching on the bit and stopping the drill. Literally every 1/4 turn of the bit I had to grind slivers of metal. I have never used a left-handed bit, but I believe it would have helped in this case.

2 more questions:
1) I didn't use thread lock or anti-seize. Is this ok?
2) Original torque specs are 103 ft lbs. Do I use the same torque or adjust it now that there is an insert in place?

 

[E.Marquez]

Thanks for all the advice guys.
Thanks to williaty for the pm info.
I got a "Permacoil" kit for $44 which is what was available locally, when I needed it (today).
The packaging is funny - it says "the other name in thread repair."
I finished successfully.



This part was my biggest fear, and turned out to be the hardest part. I had a nice cobalt bit, but the threads were so bad it kept catching on the bit and stopping the drill. Literally every 1/4 turn of the bit I had to grind slivers of metal. I have never used a left-handed bit, but I believe it would have helped in this case.

2 more questions:
1) I didn't use thread lock or anti-seize. Is this ok?
2) Original torque specs are 103 ft lbs. Do I use the same torque or adjust it now that there is an insert in place?

I always use thread loc when installing threaded inserts. Others may not. Install instructions in general do not say to use it. Though on some Helicoil supplied kits for OEM products (Harley and Ford come to mind) do call for using thread loc.

If installed properly, the threaded insert is as strong or stronger then original. So yes, use the same TQ.

 

[Gtamazing]

I would fill it in with a MIG, drill, and tap the orginal size.

my answer as well

 

[bchee]

Unfortunately I have zero welding experience but I am eager to learn. GJ is a great resource for me.

 

[E.Marquez]

Unfortunately I have zero welding experience but I am eager to learn. GJ is a great resource for me.

Where in Texas ya at?

 

[garfunkle24]

If there isn't enough meat to drill and re-tap to m14 are you sure that after drilling and helicoiling there will be enough material left?

I understand that the threads themselves would be strong (I've used helicoils lots) but you still had to drill oversize to install, right? IMHO, a one-piece insert would be better for this application.

Also, all the helicoils I have used have a break-off tang on them. You install them to the desired depth and then use the provided punch to break it off. Timeserts and others are different, I know.

 

[williaty]

If there isn't enough meat to drill and re-tap to m14 are you sure that after drilling and helicoiling there will be enough material left?

This can definitely be an issue. However, the helicoil dill out is usually smaller than the next-largest bolt size. For instance, the drill size for tapping M14 is 1/2 while the helicoil drill out is 31/64. It's not much, but it can make the difference in a marginal hole.

 

[senlow]

2 more questions:
1) I didn't use thread lock or anti-seize. Is this ok?
2) Original torque specs are 103 ft lbs. Do I use the same torque or adjust it now that there is an insert in place?

Loctite is not needed. Anti-seize in not necessary for insert installation.

Your threads are at least as strong as original. There is no reason to adjust torque.

 

[williaty]

Confirming what others have said, mostly

1) No need for loctite on the helicoil
2) No need for torque adjustment just because it's a helicoil
3) DO use anti-seize on the bolt you put in
9) DO reduce the torque by 10% to account for the anti-seize unless the manufacturer of the anti-seize suggests more than a 10% reduction

 

[bchee]

I think this guy does an excellent job with video and narration to explain the different insert options:

He has 4 videos helicoil, keensert, timesert, ez-lok

 

[WVBrady]

I think this guy does an excellent job with video and narration to explain the different insert options:

He has 4 videos helicoil, keensert, timesert, ez-lok

I agree; those were great. Is it possible that was a computer generated voice?

 

[RAYJAY]

Upon inserting the thread repair coil, with a dab of thread lock, the coil tightens up somewhat .. On a application like you have, you just stop turning (installing) the insert when it is the depth you want.

If you can drill a straight hole, you can install a Helicoil (or timesert).
the HeliCoil M12x1.25 insert requires a 12.25mm drill bit

But the full kit to install it is not cheap.. about $130 or so.
PN 5405-12
If this is a one time deal... better to pay a machine shop to do the job,, about the same cost (or less). If your likely to need the kit again, but it..and do the job your self.. More tools on the shelf is always better.

http://www.helicoil.com.sg/HeliCoil-Installation-Instructions.htm

how do you figure $130 for the kit???


on amazon .... for 36.49

http://www.amazon.com/dp/B0002KL3ZO/?tag=atomicindus08-20

 

[bchee]

I agree; those were great. Is it possible that was a computer generated voice?

I heard a few pauses and stutters.

 

[E.Marquez]

how do you figure $130 for the kit???


on amazon .... for 36.49

http://www.amazon.com/dp/B0002KL3ZO/?tag=atomicindus08-20

Simple.. My price quote was for a complete kit as I would buy.. Not a reduced limited component kit as a one time user might buy. My mistake... I should have caught that.
http://www.amazon.com/dp/B002KF5RJC/?tag=atomicindus08-20

 

[bchee]

A master set with various sizes is definitely more cost effective, IMHO especially for a DIY type who might be more likely to screw up threads.

 

[williaty]

The only difference between the master set and the basic kit is that the master kit also includes both the short and long inserts in addition to the standard length inserts. The packs of inserts only are REALLY cheap, so it's not a very big savings.

Well, and it comes in a convenient box, which actually is worth something for storage.

 

[E.Marquez]

The only difference between the master set and the basic kit is that the master kit also includes both the short and long inserts in addition to the standard length inserts. The packs of inserts only are REALLY cheap, so it's not a very big savings.

Well, and it comes in a convenient box, which actually is worth something for storage.

Correct it is the master Set What I buy anytime I pick of a new thread HeliCoil.
It was in my bookmarks... I should have looked up the basic, install kit It was a good catch

 

[mrbreezeet1]

Those TIME-SERT Insert's look pretty cool, are they a better choice than a heli coil?
Thanks,
Tony