• This topic has 16 replies, 11 voices, and was last updated 14 years ago by DezB.
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  • Full suspension linkage pin replacement- options and advice! Photos inside!
  • rockthreegozy
    Free Member

    For my mates Mongoose Teocali. One of the pins has bent, and is only available as part of a £80 kit.

    Needless to say, looking at cheaper options!

    Current thinking is to replace the two pin halfs with one M8 pin, with a m6 internal diameter and then run a bolt nut through it, secured with a washer and nut.

    However, if I do that, any issues with;

    a. Running a M6 bolt thats threaded along the whole length
    b. Running a M6 bolt thats threaded along part of the length

    Ideally a M6 bolt with a 63mm unthreaded section would be used, but its not going to be readily available/easy to find!

    Photos

    bbb
    Free Member
    mildred
    Full Member

    Orange use a similar idea to mount their shocks, though it is a central blank piece with internal threads and the bolts are threaded (if you know what i mean). I cannot for the life of me recall the size as I no longer own either bikes, but they are cheap at £3.95 each. I think there are different sizes available.

    Looking at your photos, you may need some kind of spacer/washer to get them to fit properly. Look here:

    http://www.orangebikes.co.uk/components/components.php

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    compositepro
    Free Member

    dont use a bolt that is threaded along its entire length for this
    take the good pin to your local machinist with a crate of beer for the gaffer and speak nicely to him

    squattingmouse
    Free Member

    Bolt supplier? It’s quite likely Mongoose used a standard part that can be got from somewhere. You just may end up with about ten of them…..

    rockthreegozy
    Free Member

    dont use a bolt that is threaded along its entire length for this

    Why not? Would like some sort of justification..

    Don’t think its a standard part, but the original setup seems overly complicated anyway (and Mongoose are notorious for having poor linkages on the earlier bikes)

    charlierevell
    Free Member

    why not use a hollow threaded rod, 2 washers with a larger internal Diameter than the rods ext. dia. then nip it up with some bolts (M6)
    Washers will spread the load onto the bearings but you wont have to worry about this threaded bar mallarky!
    Will need to be a tough bar tho…. dont want that going ping

    compositepro
    Free Member

    you said the pin had bent in your post that shank or non threaded section adds a lot of strength to a bolt in this type of design

    it would take a long time to go into the science behind fasteners but bolts aren’t just bolts and are designed to do different things despite just being a bit of threded bar with a head on it

    rockthreegozy
    Free Member

    why not use a hollow threaded rod

    Thats an option, but availabilty is an issue (but can maybe get it made up)

    Compositepro, the pin that bent was a different setup (shown in the photos) but I know what you mean.

    uplink
    Free Member

    Find a little engineering shop & take the damaged part along
    IME the guys at these places like to help out & don’t usually quote silly prices

    compositepro
    Free Member

    im sure 65 mm grip length bolts are available ill dig out me book tommorrow and hopefully i will be able to find this thread again

    rockthreegozy
    Free Member

    Any luck compositepro?

    DezB
    Free Member

    I might have something – have to have a look when I get home.

    Offroading
    Free Member

    A threaded bolt is slighty weaker than a partially threaded bolt because the thread cuts into the grain of the metal thus weakening it.

    This can be solved by rolling the thread rather than cutting it but im not sure they do that with steel bolts – certainly do on good Titanium bolts but a M6/M8 Ti bolt is going to cost a fair whack at that lenght.

    coffeeking
    Free Member

    It’ll cost you £20 and an hour for any half-decent engineer/machinist to knock up something suitable. Find a local eng workshop. Granted they may choose to make it hex-head by turning the thread an existing bolt rather than socket head but it’s a small price to pay if the alternative is £80.

    thepodge
    Free Member

    A threaded bolt is slighty weaker than a partially threaded bolt because the thread cuts into the grain of the metal thus weakening it.

    This can be solved by rolling the thread rather than cutting it but im not sure they do that with steel bolts – certainly do on good Titanium bolts but a M6/M8 Ti bolt is going to cost a fair whack at that lenght.
    you have it slightly out there… although its possible the thread is cutting into the grain of the steelwork a bigger issue is that by cutting you are reducing the cross section. by rolling a thread you should keep the cross section and as such you don’t require as thick material as the cut thread.

    I used to have to explain this weekly to my customers who insisted on cutting threads into rolled threaded bar because re-rolling M120 costs a bomb but hiring a machine to cut a thread is fairly cheap

    DezB
    Free Member

    This any good?

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