Helicoil for transmission bolt

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Dino soar, Oct 21, 2019.

  1. Dino soar

    Dino soar Road Train Member

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    Well I'm finishing up under my transmission and there was a hanger there that the battery cables bolt up to.

    That's the same spot where they had a PTO hooked up on there and it supports the pump. I removed the PTO for now.

    I tightened it up with a 3/8 ratchet and the bolt stripped. I think those guys that put the PTO on must have used an airgun or maybe they had another Helicoil in it before because when the bolt came out there was just a little tiny piece of thread on it. There's no way I stripped that with a 3/8 ratchet.

    At any rate I have to repair that or it's going to leak.

    Is there any issue using a helicoil for a transmission case Bolt?
     
  2. Tx Countryboy

    Tx Countryboy Road Train Member

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    Any threads left ? Try a longer bolt
     
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  3. Goodysnap

    Goodysnap Road Train Member

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    Helicoil should work just fine.

    My only other thought is to go up a bolt size to 1/2" and tap it over size. Drill open the one hole in the cover. I hate making things different for future issues, but it would work plus you dont have to buy a helicoil kit if you dont have one.
     
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  4. Collie

    Collie Guest

    I agree helicoil.
    Each helicoil usually requires an odd drill bit. It tells you on the package which drilll bit to use. I get the bits off Amazon. The helicoil works as good if not better than original hole
    I keep helicoil kits for most common bolts on the truck and have had to use them once on trans.
     
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  5. Mototom

    Mototom Medium Load Member

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    Tap is the way to go. I only use helicoils on things that can’t be tapped larger (looking at you ford)
     
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  6. Hulld

    Hulld Road Train Member

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    I second the use of a helicoil.
    The threads will better than new and all the bolts will remain stock.
    We use helicoils weekly and sometimes almost daily in our transmission shop.
    Of the literally hundreds and hundreds used over the last thirty years we have had zero issues.
     
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  7. pup

    pup Light Load Member

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    If you've got threads left maybe you can bottom a stud in the hole.
     
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  8. Collie

    Collie Guest

    Yeah and then try torquing to spec at 50 foot pounds. That’s what the pto bolt torque spec is. You won’t even make it to 20 foot pounds. That’s half assed type of fix shops do without the owner of the truck knowing about it
     
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  9. Tx Countryboy

    Tx Countryboy Road Train Member

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    Some shops put too short bolts in & that's why pulled
     
  10. Dino soar

    Dino soar Road Train Member

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    That's probably what they did, LOL.

    I suppose that's possible but that bolt looks pretty dang long.

    That's an interesting idea.

    Now that I'm thinking about it, that mount that holds the battery cables has a built-in spacer. I'll have to check tomorrow to see if any threads are left.

    If I have to do anything to it, as long as a larger bolt won't interfere with that mount, I would probably tap it One size larger.

    I probably have the right drill and tap and then it would just be the cost of one bolt and a washer.

    I gotta do something. The mighty big cam is ready to Roar! :)
     
    Last edited: Oct 21, 2019
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