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Broken crank bolt extraction

Discussion in 'SN95 Cobras' started by captthunderpnts, Nov 15, 2013.

  1. captthunderpnts

    captthunderpnts Member Established Member

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    Well, I seemed to have screwed the pooch on my 98 vert, all because I wanted to install a fluid damper.

    Backstory: Picked up a March 1158 to replace an unknown set of UD pulleys that were on the car when I purchased. I've been eating through belts every 10k, so natural instincts told me to go ahead and refresh the entire pulley system under the hood.

    The first issue arose when I went to break loose the crank pulley to remove the existing balancer. I assumed it should have been torqued to over 60 ft-lbs at the very least. She came out with nothing more than the flick of my wrist. Of course, I didn't really think anything of it because I was so excited for my new fluid damper.

    After some light reading, I threw the 1158 into the oven for a half hour to expand it (I was unable to get it to slide on the crank out of the box). To my dismay, this did not help the situation, and I could barely get the pulley onto the snout, much less pressed into the front oil seal. In my haste, I decided to put the old balancer back on and make sure that it was torqued to spec. Here's where the fun starts.

    Everything was going well, the balancer was snugly back on the crank, and I finger-tightened the OEM bolt until it was snug. I then proceeded to unbox and use my brand new Craftsman torque wrench, in the 1/2in drive flavor. I set it to 60 ft-lbs and started torquing. Turn after turn, it just kept spinning...getting more resistant along the way, but never setting off the refreshing click of the torque wrench. One more turn, and the bolt snapped off into the snout, about 3/4in recessed.

    I decided to try my luck at drilling out the hardened steel bolt from the crank, only to end up with this:

    Q49PZP4l.jpg

    Now, on a scale from 1 to 10, how screwed am I? I don't have the means the yank the motor out of the car to remove the crank, and I also don't know of any shops in my area that would successfully do the job without charging me the cost of a new motor. Any suggestions or even blunt realities are warmly welcomed.
     
    Last edited: Nov 15, 2013
  2. DVJ38

    DVJ38 One mod at a time Established Member

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    OUCH! Sorry to hear OP, that's terrible.

    Have you tried the easy outs? This is a big bolt, but hopefully it isn't torqued very much. How exactly did you try to drill it out, what did you use? Maybe something like the following links would help. I'd wait to hear what somebody who has done this before says though.

    Sears.com

    Sears.com
     
  3. bumsoil

    bumsoil Active Member Established Member

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    Easy outs And a lot of PB blaster. That's my best suggestion.

    This scares me. I have pulled my balancer 4 times. And I'm about to install march pulleys and now I'm nervous. I'm going to get a new bolt.
     
  4. encasedmetal

    encasedmetal WHINO! Established Member

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    once you get it out, you may need to retap and get a larger custom bolt.
     
  5. CJK440

    CJK440 Active Member Established Member

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  6. captthunderpnts

    captthunderpnts Member Established Member

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    I first tried to use an EZ out. Started off with a small bits and moving progressively larger to fit the extractor. Snapped it off inside the bolt. I was able to punch and drill it out, but the aftermath left me with a grossly off-center hole.

    Also attempted to use a left handed drill bit, but she wouldn't even bite into the bolt.

    That said, my current arsenal is just a right angle hand drill and a box of cobalt drill bit. If I go any larger, I have to remove my radiator to even fit the drill in there. :nonono: I mean, that's not really that big of a deal, I know...but I'm at that mileage now where once I start jacking around with the natural order of things, I will have opened Pandora's box, so to speak.
     
  7. Blown_By_You

    Blown_By_You Richard Head Established Member

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    Damn dude.. this really really sucks... It's kind of a little late, but it was very important that the first hole that you drilled thru the bolt was CENTERED. If it's not centered, the EZ outs aren't going to work because you'll be trying to unscrew something that is wobbling..

    I just had to drill two bolts out of my OEM heads. It sucked, and I was able to do it on the bench as well.

    I would keep drilling.. Do your best to keep off of the threads and make sure to stay in the bolt.. be patient.. very patient.. Any hurry now can really **** you.

    Take your time.. walk away..

    Drill little by little. Having an offset hole to begin with is going to make this more challenging.. If you get the end of the bolt drilled out, you can always drill the crank larger, retap, and use a bigger diameter bolt.. BUT.. since it rotates at up to 6500 rpm, keeping that bolt and hole parallel to the centerline of the crank is going to be critical. I would definitely pull the radiator to give you a better shot at keeping the drill parallel.. Also, I wouldn't be afraid to spend some money, talk to a mechanic/machinist, tow it, whatever..

    Because if this gets messed up beyond repair.... well, I think you know.
     
  8. captthunderpnts

    captthunderpnts Member Established Member

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    I flirt with 7k when I'm having a good time, so that makes it just a little worse, lol.

    That's the battle plan, as you've mapped it...I've put a couple hours into it each evening for the last few days before regrouping. At this point though, I need to find a best friend with a shop to pull the motor for the low, low cost of $free.fiddy. I have no reservations on replacing the crank altogether, but the labor cost is going to give me an aneurysm.

    Does anyone have any tips on re-centering my pilot without a friggin drill press? I'm having a hell of a time keeping the drill straight because the break wasn't clean across. Of course, why would it be? That would be too easy.
     
  9. Blown_By_You

    Blown_By_You Richard Head Established Member

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    See if you can rent a tool called a MAG Drill.. It is a miniature drill press with a magnetic base.. VERY strong magnetic base. We use them at work alot to drill precision holes in the field where normally you would have to use a drill by hand.
     
  10. CJK440

    CJK440 Active Member Established Member

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    The problem is with an all alum motor, not many magnetic things to attach to.

    If you want to center that hole get a carbide burr and an angle die grinder.
     
  11. Blown_By_You

    Blown_By_You Richard Head Established Member

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    I understand everything is aluminum.. BUT.. I don't think there is any other way to drill a precision hole in the crank while it's installed.. It would be very easy to attach a steel plate to something, especially a pulley which should already be aligned.

    Personally, I think I would talk to some local mechanics and see what they say. If the crank isn't drilled perfectly, it's gonna cost alot of money to fix..
     
  12. na svt

    na svt say no to power adders Established Member

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    I used a reverse rotation drill bit and extractors to remove a broken ARP cam bolt. The stock bolts are hard but not so hard that they can't be drilled.
     
  13. Wawful

    Wawful Member Established Member

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    If you have a lot of patience and the concentration of a monk I have a serious suggestion for you. Drill the thing out.... literally drill it out using smaller or larger drill bits to take away what ever metal is stuck in there, once you take enough material out, see what you can do with a large diameter bit lined perfectly with the crank and hog out the material left then clean up the threads with a tap. pray to the snake gods and pucker your bunghole like never before and you could save your self....
     
  14. ESVEETEE

    ESVEETEE Active Member Established Member

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    Damn if I still lived in Aiken, I'd make the trip up there to at least give it a look.

    Best of luck man.
     
  15. Metal Head

    Metal Head Member Established Member

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    That recess is going to be the only thing that may save you. Your only shot at getting that hole back on center is using a drill bushing and trying to drill with an endmill. A drill bit is going to try to follow whatever hole is already there and will just end up breaking even if using the drill bushing. An endmill will cut straight regardless and you need the bushing to keep you centered since you are forced to do it by hand.

    Buy a couple high speed steel "HSS" endmills. Carbide is too brittle and will chip since your setup will not be rigid so don't bother with it. You'll need a drill capable of low speeds, you won't want anything over 500rpm or so. Stop and blow the chips out often. Endmills do not pull the chips out as well as a drill bit. Use some sulfuized "dark thread cutting oil." You can get it at Home depot in the plumbing section for threading steel pipe.

    Once your endmill drilled hole is deeper than your ****ed up hole you can start drilling with a drill bit again to speed up the process. Do not do anything else until you get a bushing to keep you on center. That first hole you tried to drill is beyond saving by hand, grinding, or straightening with a drift.

    You probably need to tow it to a machine shop so they can turn up some drill bushings as needed. I wouldn't bother with an auto repair shop, 99% of mechanics will end up ****ing it up worse.

    I am a machinist by trade.
     
    Last edited: Nov 17, 2013
  16. 95PGTTech

    95PGTTech Active Member Established Member

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    Stop fooling around and replace the crank.
     
  17. Blown_By_You

    Blown_By_You Richard Head Established Member

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    Yeah..... cause that's no big deal
     
  18. 95PGTTech

    95PGTTech Active Member Established Member

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    Depends on your perspective. This is how I put food on my table, so no, it's no big deal to me. Suck it up and crank it out in half a day's work and be done with it not dicking around not trying to drill it out and fubaring the threads.
     
  19. captthunderpnts

    captthunderpnts Member Established Member

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    Would be my luck, lol. I appreciate the sentiment.

    I've been having a hell of a time finding a place around here that even sells end mills. Would they fit in a typical 3/8in power drill? Also, I've called every machine shop within 30 minutes of me, and none of them want anything to do with this issue, so I'm SOL on that front.

    Unfortunately, my livelihood is NOT in a garage. I don't have the tools or space to take on this project to your suggestion.

    That said, I am at a standstill, as I managed to break my right angle drill (idk, lol) and am waiting on a replacement Makita piece. I have had some luck, believe it or not, with a carbide grinding bit for my Dremel. It's been putting a bigger hurting on the broken extractor than any drill bit combo I could come up with.
     
  20. caveeagle

    caveeagle Currently Decompressing Established Member

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    I could not get your pic to open, but I think I get the gist of it....

    If you can get a decent size hole drilled in the bolt... I would try a reverse thread tap and then screw the reverse bolt into it. If its not in there to tight, you should be able to back it out.

    .....Of course a 'pro' is always going to recommend the "heart transplant" option. No doubt, this is probably your "best" option, but a lot of work without a lift, tools, and experience tearing into mod motors.

    For starters.... Pull that darn radiator!! 10m of work will at least get you a better perspective on things!! Its gonna come out anyway, if your cant extract that darn bolt!!
     

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