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A lesson learned about Torque Wrenches

Discussion in 'Maintenance and Servicing' at netrider.net.au started by mick89, Aug 11, 2015.

  1. Just thought I'd share a learning I had today in regards to the use of torque wrenches, particularly for those similar to myself who are quite new to workshop DIY.

    Got some time (first track time ever) at Eastern Creek in October, and I'm about to head off for work for a month or so, so I thought I'd drop the oil in my KTM Duke 390 and replace the oil & filter, as well as a chain clean and such whilst I still have time. Being a diligent and padantic (inexperienced) DIY mechanic I decide to check out all the torque specifications for the sump plugs etc. from the service manual (I have a PDF for any D390 owners, inbox me if you want me to send you a copy).

    15nm for the side sump plug, too easy.



    Gee this feels a lot more then 15nm... SNAP.

    Head sheared off of the threaded section.

    image_4.

    The last time I used my torque wrench was probably around 18 months ago. After double checking the specs in the manual, double checking the settings on the wrench I know something isn't right. In the booklet in my torque wrench case there was a caution note to always make sure you can get the wrench clicking on something else at least 8-10 times after the wrench has sat for long periods of time before using, especially on items requiring lower torque specs.

    Threaded section was easy enough to remove from the casing, just with a hammer and screw driver to back it out (no tension in the threads due to the head broken off), however its a beautiful day here in Newcastle, and of course its always nice to go for a ride after doing these things, which I can't until my new plug comes to the shop (which I won't be around to collect for a month). Stoked I didn't leave it until the day before, otherwise I'd be cancelling my Superbike School seat and losing my money.
     
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  2. Unfortunately that's Murphys Law - when something's going to go wrong, it will.
     
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  3. sump plugs are notorious for shearing, along with oil cover bolts. I don't bother with the torque spec, just do it up "tight enough", pretty easy to see if it's too loose visually
     
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  4. Hah that's what you get for not using a deflecting beam wrench.
     
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  5. A real mechanic would use a shifter, also known as a 'nut f**ker'.
     
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  7. nice fracture surface :)
     
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  8. #8 Al_Cam, Aug 11, 2015
    Last edited: Aug 11, 2015
    I think I used this recentley but it's topical: Harley Davidson torque wrench - tighten till it strips then back off half a turn.

    I'm with loseph, anything that low in torque makes me nervous, it's usually Al alloy. Just do it firm. If I'm worried about it coming undone I use some loctite, RTV etc...
     
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  9. This x1000
     
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  10. QuarterWitQuarterWit knows what he's talking about. Torque wrenches shear sump bolts. FACT!





    And they're for homos.
     
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  11. So true, a deflecting beam wrench might be slower and harder to use but they're so simple it's hard for the tool to fcuk up, only the nut at the end of the wrench.
     
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  12. That made me laugh.
    Don't worry, I felt bad afterwards.
     
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  13. Sheared the 8Nm OFC bolt off my 390 Duke just the other day, from now on its hand tight.
     
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  14. Mate who is an aircraft maintenence guy (engineer) puts a couple of rounds of thread tape on the sump plug each time he changes the oil. When i asked why answer was simple first it stops any seeping second you don't have to tighten so hard (jokes about how his elbow clicks at a certain torque rating) which is basically every setting known to man and according to him for this application acts like a weak but effective loctite.
     
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  15. I tighten mine up like a sparkplug.
    Hand tight then 1/8 turn with a socket so its firm, check for drips and your done.
     
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  16. Doh (head slap). I use that on brake caliper nipples so you can open them good and wide for systems that are hard to bleed. Stops the fluid leaking out past the thread. Why haven't I thought of that for sump plugs?

    VISE-GRIPS: Generally used after pliers to completely round off bolt heads. If nothing else is available, they can also be used to transfer intense welding heat to the palm of your hand.
     
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  17. Check out a YouTube channel by "AvE", it's a Canuck and he's hilarious with this sort of stuff. Especially his '2 minute man skills"
     
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  18. Yup tight.....is "just" tight.
    Done.
     
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  19. This is why ring spanners come in different lengths. You already know what too much feels like. You said so in the OP

    Save your torque wrench for head bolts.
     
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  20. Been out of service for a few days, cheers for the replies. I've since read about the use of torque wrenches at such low settings, I use to just wing it on my old 68 Beetle and never had issues, so I'll go back to that.

    Anyway, intention of the post was for other amateurs to read and learn from my mistake.
     
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