1. Mudeblue

    Mudeblue Member

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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?
     
  2. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    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
     
    Last edited: Jan 24, 2020
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  3. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    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 bitch to drill the broken extractor out.
     
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  4. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    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
     
    Last edited: Jan 24, 2020
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  5. James Richardson

    James Richardson Active Member

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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
     
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  6. rags

    rags Well-Known Member

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    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.
     
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  7. Mudeblue

    Mudeblue Member

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    That is the exact set I bought and they are left handed bits and extactors!
     
  8. Mudeblue

    Mudeblue Member

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    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.
     
  9. Mudeblue

    Mudeblue Member

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    Getting the hole drill is my problem but, thanks.
     
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  10. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    So... Were you running the drill in reverse?
     
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  11. 65sporty

    65sporty Old Man with a Hat

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    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.
     
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  12. rags

    rags Well-Known Member

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    that's been the key to my success. learning how to sharpen my own drill bits and going very slow. people get impatient and run the drill faster. only makes a dull bit worse.
     
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  13. James Richardson

    James Richardson Active Member

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    No welder makes it difficult but for clarity this works on flush to surface broken bolts really well.
     
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  14. Mudeblue

    Mudeblue Member

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    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!
     
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  15. ALRUI

    ALRUI New Member

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    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!
     
  16. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    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
     
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  17. ALRUI

    ALRUI New Member

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    Thanks Dave, great explanation!