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K5 tapered front caliper bolts

  1. #1
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    K5 tapered front caliper bolts


    I'd like to shoot the person that thought putting tapered head bolts on K5 front brake calipers was a great idea. I'm sure each PO of this bike flinched every time they removed them. I'm just that last in line and the socket for the hex tool is toast. Even with a new hex socket tool has no chance of getting these out. The inside corners in the head are already rounded. With the tapered bolt head I can't grab it with anything. Drilling it or slotting it is a no go.

    To add insult to injury I had removed the 1st 3 bolts when the last one finally gave up and rounded off. Had a 5/8" bolt tig welded to the socket head of the stuck bolt to get it out. Didn't think to the others were in bad shape so...reinstalled them. Dumb move. Should have replaced them all. I can feel each of them giving a bit at the modest 20lbs of torque as I started installing them again. What a shit design.

    Thought to use the flange bolts from my GSXR1000. They were about 3/4" too long. Bikebandit and other sites typically list the OEM bolt with the same tapered head. The only sites that I see carrying flange head bolts for of the same length seem to be made from titanium, and are likely from questionable ebay sources over seas.

    While I get this latest bolt welded and removed I'd appreciate any suggestions for suitable replacements.K5 tapered front caliper bolts-05-front-caliper-bolt-jpg

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  2. #2
    Lifer jasnmar's Avatar
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    Re: K5 tapered front caliper bolts


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  3. #3
    Lifer golden chicken's Avatar
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    Re: K5 tapered front caliper bolts

    A dab of valve lapping compound on the end of the bit before it strips the bolt has saved me some head/heartache in the past.

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    What's the difference between a bolt and a screw?
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  4. #4
    Unsafe At Any Speeds Jim's Avatar
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    Re: K5 tapered front caliper bolts

    Pro-Bolt USA.
    can even get the stainless pre-drilled ones

    https://www.probolt-usa.com/stainles...c-ssfbmon190r/

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    Last edited by Jim; 04-06-21 at 12:04 PM.
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  5. #5
    Lifer
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    Re: K5 tapered front caliper bolts

    Quote Originally Posted by Jim View Post
    Pro-Bolt USA.
    can even get the stainless pre-drilled ones


    https://www.probolt-usa.com/stainles...c-ssfbmon190r/
    Stainless is terrible for those bolts. You only get a few uses out of them before they begin to get suspect.

    A word of caution on those bolts, dont use allen keys with the rounded head. Only use ones that are flat and sit straight in.

    I use titanium for those bolts now. Its a pretty common type of bolt in ti.

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  6. #6
    Resident Turkey Tricky Mike's Avatar
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    Re: K5 tapered front caliper bolts

    Yeah, stainless, despite being pretty is often a poor choice for high-stress bolts. Cruising McMaster shows a regular M8 bolt in 316 stainless has a typical tensile strength of 70,000PSI compared to an alloy steel equivalent at 170,000PSI.

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  7. #7
    Member PurplePackage's Avatar
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    Re: K5 tapered front caliper bolts

    So why can't you buy a 10.9 grade bolt that fits?

    1. Measure bolt length.
    2. Determine threading. They're always metric. Probably M8 1.25 but maybe not, so measure twice.
    3. Buy 2 replacement bolts (Amazon, Home Depot, etc.) that meet above, if you are paranoid use grade 12.9. Flanged bolts are nice but you can just use washers.

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  8. #8
    Unsafe At Any Speeds Jim's Avatar
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    Re: K5 tapered front caliper bolts

    Quote Originally Posted by Tricky Mike View Post
    Yeah, stainless, despite being pretty is often a poor choice for high-stress bolts. Cruising McMaster shows a regular M8 bolt in 316 stainless has a typical tensile strength of 70,000PSI compared to an alloy steel equivalent at 170,000PSI.
    interesting. i have the stainless caliper, pad, and fork pinch bolts. never an issue. plus the torque spec is fairly low (16.5 ft/lbs) for pinch bolts

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  9. #9
    Super Adventurer SRTie4k's Avatar
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    Re: K5 tapered front caliper bolts

    They're not guaranteed to round off just because they are stainless. It just becomes more likely vs non-stainless if they are torqued improperly, galled, rusted, etc.

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  10. #10
    Resident Turkey Tricky Mike's Avatar
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    Re: K5 tapered front caliper bolts

    Quote Originally Posted by Jim View Post
    interesting. i have the stainless caliper, pad, and fork pinch bolts. never an issue. plus the torque spec is fairly low (16.5 ft/lbs) for pinch bolts
    My skydiving rig has a reserve parachute I've never used.

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