Bolt Extraction

Mudeblue

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The alternator bolt to the block has broken at the block, again. It is a #8, plated. I am attempting to extract it and have been "trying" to drill a hole in the middle of it so I can screw the extractor into it. I am using a recommended titanium drill bits which came with the extractor kit I purchased at O'Reilly's starting with 1/8". It is like trying to drill steel with an aluminum bit. Does anyone have a suggestion as to how to drill it out or a different type of bit?
 
The alternator bolt to the block has broken at the block, again. It is a #8, plated. I am attempting to extract it and have been "trying" to drill a hole in the middle of it so I can screw the extractor into it. I am using a recommended titanium drill bits which came with the extractor kit I purchased at O'Reilly's starting with 1/8". It is like trying to drill steel with an aluminum bit. Does anyone have a suggestion as to how to drill it out or a different type of bit?

Cobalt bit. (HSCO) Be sure to use a grade 5 bolt as a replacement. Grade 8s are too brittle for that application. It usually works the best to take a hardened center punch to center the hole to be drilled. Be sure to buy quality bits at Ace hardware or similar first line store as many of the cheap imported bits are only titanium or cobalt coated. The correct HSCO bits will have a relief trench on the cutting surface.

Dave
 
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The alternator bolt to the block has broken at the block, again. It is a #8, plated. I am attempting to extract it and have been "trying" to drill a hole in the middle of it so I can screw the extractor into it. I am using a recommended titanium drill bits which came with the extractor kit I purchased at O'Reilly's starting with 1/8". It is like trying to drill steel with an aluminum bit. Does anyone have a suggestion as to how to drill it out or a different type of bit?
The drills with the extractor kit might be left hand. That is they have to be spun in reverse to cut. The left hand drills are nice because they tend to back the broken bolt out.

These are left hand drills in this kit.

s-l1600.jpg


I'm not a fan of extractors... I've seen too many snap off and then it's a ***** to drill the broken extractor out.
 
John is right about the extractors, what usually works the best is keep drilling larger holes until nothing but the threads of the bolt are left, those can be chased out with a tap. Drill at low speed with some good cutting oil.

Dave
 
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If it is close to flush with block I would weld a larger nut onto its end. I have even used a washer first to aid ease of first weld and then weld nut to washer. Also really dislike extractors but have had good luck with left hand bits
 
I'm not a fan of extractors... I've seen too many snap off and then it's a ***** to drill the broken extractor out.
i'll never use an extractor. i use a snap-on torx bit. with the hole drilled, drive the appropriate size bit in. the flutes of the bit cut channels in the hole without expanding the broken bolt. also the post above (#5) works great with experience. seen it done over and over with broken exhaust manifold studs in aluminum heads.
 
The drills with the extractor kit might be left hand. That is they have to be spun in reverse to cut. The left hand drills are nice because they tend to back the broken bolt out.

These are left hand drills in this kit.

View attachment 347626

I'm not a fan of extractors... I've seen too many snap off and then it's a ***** to drill the broken extractor out.


That is the exact set I bought and they are left handed bits and extactors!
 
If it is close to flush with block I would weld a larger nut onto its end. I have even used a washer first to aid ease of first weld and then weld nut to washer. Also really dislike extractors but have had good luck with left hand bits

I agree but 1) not enough of the bolt to get a nut on and 2) I don't have a welder but thanks anyway.
 
i'll never use an extractor. i use a snap-on torx bit. with the hole drilled, drive the appropriate size bit in. the flutes of the bit cut channels in the hole without expanding the broken bolt. also the post above (#5) works great with experience. seen it done over and over with broken exhaust manifold studs in aluminum heads.

Getting the hole drill is my problem but, thanks.
 
A quality sharp bit will drill the grade 8 bolt, go slow though. I do a lot of exhaust manifolds on trucks with broken bolts, GM, Ford and Ram. They all break bolts and some are worse then others to get out. Good luck.
 
The drills with the extractor kit might be left hand. That is they have to be spun in reverse to cut. The left hand drills are nice because they tend to back the broken bolt out.

These are left hand drills in this kit.

View attachment 347626

I'm not a fan of extractors... I've seen too many snap off and then it's a ***** to drill the broken extractor out.
So... Were you running the drill in reverse?

Problem solved. As I said previously stated, I had already purchased the Bolt Extractor kit you suggested with the left handed titanium bits (yes I did reverse the drill). That didn't work at all on the grade 8 bolt. Visited my local Ace Hardware store and visited with a clerk who was a retired machinist (who stated he had removed hundreds during his career). I purchased a right handed hardened "steel bit", used a little motor oil as a lubricate as he suggested (he said any lubricate would work including vegetable oil), I let the bit do it's work at low speed and mild pressure and it cut through the grade 8 bolt extremely well, but took some time; used extractor and bolt has been extracted. The clerk/machinist said "do not use a grade 8 bolt which is to brittle and will not allow for vibration and any movement. use a grade 5." The grade 8 bolt was originally used, and several times thereafter when it broke, when I had the engine overhauled and I had the original alternator bolt and checking that, it was a grade 5. Have everything put back together with the original bolt. Thanks for the comments and help and as Paul Harvey use to say; "now you have the rest of the story.' Now to move on to several other issues. One thing about owning an old classic cars, there is always more to do; kinda like owning a Harley Davidson motorcycle - easy you Harley Davidson owners - running a 77 Gold Wing!
 
Why is that alternator bolt so prone to breakage? Had one let go on my 69 Charger back in the day & the same thing happened awhile back on my 67 Fury 383 (knew exactly what it was by the sound this time!). Pisser is you almost always lose the spacer in the process!
 
Why is that alternator bolt so prone to breakage? Had one let go on my 69 Charger back in the day & the same thing happened awhile back on my 67 Fury 383 (knew exactly what it was by the sound this time!). Pisser is you almost always lose the spacer in the process!

The alternator flexes the bolt while it is under load, and the A/C, when operating tends to do the same thing. Eventually the bolt cold works and breaks off. Bolt probably should have been a larger size. Sine the bolt is in a cold working application it should never be replaced with anything but another grade 5 bolt.

Dave
 
The alternator flexes the bolt while it is under load, and the A/C, when operating tends to do the same thing. Eventually the bolt cold works and breaks off. Bolt probably should have been a larger size. Sine the bolt is in a cold working application it should never be replaced with anything but another grade 5 bolt.

Dave
Thanks Dave, great explanation!
 
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