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Bike problems (pics added)

11BravoCrunchie
There are 2 bolts that anchor the seat of my motorcycle to the frame. They're both supposed to be 12mm, but one of the previous jackasses owners didn't know any better and replaced one of them with an SAE threaded bolt--1/2 inch, I think. Now, the threads in the frame (it's a nut welded to a hole in the frame) are stripped out to the point that a 12mm doesn't work anymore. What can I do to fix this situation?

Seat mount, right side:
seatissues001.jpg
Seat mount, right side w/o seat:
seatissues002.jpg
Seat mount, left side w/ bolt:
seatissues003.jpg
Seat mount, right side w/ bolt (note angle of bolt):
seatissues004.jpg
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Comments

32 comments

Date Votes
  • David Nunn
    helicoil
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  • LOKO383
    run a smaller dia. bolt thru and put on a flat washer and lock washer,them a nylon lined nut, problem solved, Loko
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  • 11BravoCrunchie
    quote:Originally posted by LOKO383
    run a smaller dia. bolt thru and put on a lock washer and flat washer,them a nylon lined nut, problem solved, Loko




    Thought about that, can't do it. The hole doesn't go all the way through the frame.
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  • sig232
    quote:Originally posted by LOKO383
    run a smaller dia. bolt thru and put on a lock washer and flat washer,them a nylon lined nut, problem solved, Loko




    +1 or try chasing the threads with a 12mm tap to clean them up and try a new 12mm bolt.

    You can drill it out to the next size and retap it to 13mm or 14mm. Another thought is drill it out and have a new 12 mm nut welded to the bottom of the existing nut.

    Good Luck![:)]
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  • 11BravoCrunchie
    Could I fill the existing nut in with a welder, and drill and tap a 12mm hole into the new metal? I'd need to get Dad-o's help with that....
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  • LOKO383
    quote:Originally posted by sig232
    quote:Originally posted by LOKO383
    run a smaller dia. bolt thru and put on a lock washer and flat washer,them a nylon lined nut, problem solved, Loko




    +1 or try chasing the threads with a 12mm tap to clean them up and try a new 12mm bolt.

    You can drill it out to the next size and retap it to 13mm or 14mm. Another thought is drill it out and have a new 12 mm nut welded to the bottom of the existing nut.

    Good Luck![:)]
    my next suggestion, thanks sig,saved me some typing[:D] Loko
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  • LOKO383
    quote:Originally posted by Zulu7
    Could I fill the existing nut in with a welder, and drill and tap a 12mm hole into the new metal? I'd need to get Dad-o's help with that....
    you could...but it will burn away the frame paint and maybe soften the frame ie too hot... you talkin about mig. or stick? [weld]
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  • hawkeye6020
    quote:Originally posted by nunn
    helicoil


    Right there is your quickest, easiest, and least expensive option. If you weld it it may wind up to hard to drill and tap. it also will burn away your paint and could weaken your frame.
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  • likemhot
    Not sure if it would work in this instance, but how about j/b weld, then drill and tap.
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  • Grunt2
    Grind that nut off and weld another one on! Looks like that's just a nut welded to the frame now? MIG or TIG would be easy!
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  • sig232
    quote:Originally posted by Grunt2
    Grind that nut off and weld another one on! Looks like that's just a nut welded to the frame now? MIG or TIG would be easy!


    Yes, after seeing the pictures I too think that is an easy solution. Use a small grinder and take it off and Mig on a new one. Heat can be controlled just fine, by an experienced welder!
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  • LOKO383
    quote:Originally posted by Grunt2
    Grind that nut off and weld another one on! Looks like that's just a nut welded to the frame now? MIG or TIG would be easy!
    agree, looks like the easiest solution, use a cut off wheel[thin] just to shave the nut off then clean the area good with a wire wheel or brush weld a new nut on and repaint the area..btw is that a brake line or air shock line in the pic? looks like its getting cut or rubbed by the seat?, Loko
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  • jwb267
    i think you would be better off to remove the old nut and have someone tig weld it for you
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  • buschmaster
    krazy glue
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  • HandgunHTR52
    You could just cut the nut off and then JB Weld a new one on. That way you don't need to worry about heat.
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  • MVP
    I would ream it out to the next bolt diameter and tap it for what ever is handy. 9/16 or whatever.
    I could have those threads like new and bolts in them in 15 minutes or less if you ride it over to my shop[8D]
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  • guns-n-painthorses
    quote:Originally posted by MVP
    I would ream it out to the next bolt diameter and tap it for what ever is handy. 9/16 or whatever.
    I could have those threads like new and bolts in them in 15 minutes or less if you ride it over to my shop[8D]


    That's what we would do.

    Got Guns?
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  • 1911a1-fan
    what ever you choose to do replace those bolts with hardened steel bolts only
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  • iceracerx
    Cut off exsisting Nuts and reweld new Nuts inplace. Brazing is a lower temp the welding and works just fine on bicycle frames and older British motorcycles. Something else to think about.

    + 101 on welding on new nuts.
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  • Johnnylikesguns
    Buy a Harley it's got SAE threads
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  • catpealer111
    Cut it off and weld on a new one. Make sure when you weld the new one on you thread a bolt in with antiseize on it to keep the nut from warping. And since it's behind the shock mount, I personally wouldn't worry too much about heat because the only real stress on that point is your ass. But of course, weld only as hot as you need to to get proper penetration.
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  • Da-Tank
    Get a 13mm bolt that is the right lenght. Cut a V slot with a file about 1/4 of the way up the threads. This will become a self taping bolt. After running that in 2 or 3 times(carefully) your ready to install a 13mm bolt to a 13mm hole.
    Old shop cure even on american bikes.
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  • Colt Super
    I mostly don't care for millimeters.

    D.
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  • catpealer111
    Look in the top of my roller tool box and you should find the metric tap you need. It's in the white plastic tray.
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  • fugawe
    The bolt is 8mm, not 12mm. 12mm is the head size. As much as I hate mixing metric and SAE sizes, you can drill it out to just under 3/8 and tap it out, then use a 3/8 bolt. Fine thread. You could go 11/32 but the one hole looks pretty wallowed out.
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  • axlerfan
    Zulu...you got a couple good answers there. Helicoil is a fast, inexpensive answer that should work well. they are easy to use and make a strong set of threads to screw into. make sure to drill the hole out for the correct size coil you need to use. 2nd choice would be to grind the old nut off and weld another in its place. this will certainly burn some of the paint off the frame. it may weaken the freame in this area a bit, but since the only stress here is to hold the seat and probably fender brackets it shouldnt be an issue. you would need to either disassemble the bike further to do this or use welding blankets to protect parts of the bike you dont want slag getting onto. If you go this route, use a mig. much easier to use. ive had to make similar repairs on other bikes ive owned with no adverse effects.

    dan
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  • select-fire
    Duct Tape [:)][:o)][:o)]
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  • SXSMAN
    quote:Originally posted by buschmaster
    I've been huffin krazy glue
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  • Oren Rudder
    yep ream and tap.
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  • MVP
    quote:Originally posted by Oren Rudder
    yep ream and tap.

    Exactly.
    There is nothing wrong with the weld or the nut, the problem is the threads inside the nut.
    Why would anyone go to the trouble of cutting the old nut off and welding a new one on and repainting when the threads can be fixed in 15 minutes to like new condition with the original nut and welds in place?
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