worn hole on main frame from rear suspension bolt. advice needed urgently!!!!- Mtbr.com
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  1. #1
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    New question here. worn hole on main frame from rear suspension bolt. advice needed urgently!!!!

    worn hole on main frame from rear suspension bolt. advice needed urgently!!!!-untitled4.jpgworn hole on main frame from rear suspension bolt. advice needed urgently!!!!-untitled5.jpgworn hole on main frame from rear suspension bolt. advice needed urgently!!!!-untitled6.jpghi folks I've got a problem.. the equallink bolt has worn through the hole on the main frame. The bearings have not stopped it from eating away at the frame and now there is about 1mm-2mm play and it makes a slight clicking noise when i peddle from the gap! has anyone had this problem before? can it be fixed by a specialist cmc engineer or something along those lines? your help would be greatly appreciated worn hole on main frame from rear suspension bolt. advice needed urgently!!!!-untitled1.jpgworn hole on main frame from rear suspension bolt. advice needed urgently!!!!-untitled2.jpgworn hole on main frame from rear suspension bolt. advice needed urgently!!!!-untitled3.jpg
    Last edited by mtbuk; 05-10-2015 at 03:19 AM.

  2. #2
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    What's a "worm hole"?

    Several people have looked at your description and photos, but still are not clear on what you are describing or trying to say.
    A bad day of cycling is better than a good day at work

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  3. #3
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    From your description, I'd assume both ends of the hole have been ovalized, see if you can find a stainless bolt of the correct diameter that is not turned down in the middle, this would spread the load across all of the hole instead of just the ends.

  4. #4
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    it doesn't look oval just evenly worn around the bolt. the problem is the bolt fits perfect through the centre of the bearing so the hole in the frame has to match to operate properly

  5. #5
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    Are your bearings Turing freely? Make a couple of washers to stick in there that take up the slack or warranty the frame?

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    Reading the topic title at first I thought I read "worm hole". Then I tried to read it the second time, there it is "worn hole". It's a worn-out hole you mean. If the hole is worn out evenly, how about putting a shim? We put shims on seatpost and stems which have mis-match diameters.

  7. #7
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    Warranty the frame.

    putting a shim in the hole would be difficult, but could be done. A complete pain though because the shim would be super thin, probably bend when trying to install it, plus difficult to find. I truly doubt it's an approved manufacturer component. A solid bolt (non-tapered at the center) may work, but since the ends are already damaged, may just be a short term fix for the problem. As the OP said, a larger diameter bolt wouldn't work because he needs to get it through the bearing. With this in mind, maybe new bearings with a larger diameter center, drill out the frame hole a slight bit and use the next size larger bolt.

  8. #8
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    Quote Originally Posted by bgkz25 View Post
    Reading the topic title at first I thought I read worm hole.
    Funny, that's what I saw too.
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  9. #9
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    Thanks for the help guys! The bike is 2nd hand I've only had it a few weeks picked it up very cheap. The wear is on the inside of the worm hole lol. Its got some fat washers inbetween the bearing and the frame. The bearings are very bumpy when I spin them with some rust coming out so I have purchased new ones to fit and a tool to remove them because they are all stuck. The frames not under warranty.
    I have found a CNC engineer who can drill out the hole and fix in a alloy sleave so it will be as good as new and he has done it before with no come backs so i might go with him?

  10. #10
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    don't do an alloy sleeve, go with a much harder metal. cromoly is strong and cheap

  11. #11
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    cromoly? what about stainless steal? wouldn't the harder metal damage the frame?

  12. #12
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    Going with a Cromoly or stainless sleeve will spread the load over all of the hole. An alloy sleeve and your existing bolt will just replicate what looks like a faulty design. You'd see the same issue farther down the line.

  13. #13
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    Once it's in the frame, it's solid. An aluminum sleeve would be best if one can be inserted. That might be where the challenge is because it will be softer. Maybe small inserts right at the ends. If aluminum won't work, I like the idea of chromoly because it's closer to aluminum from a corrosion aspect. Considering it's location, I'd want to minimize the corrosion as much as possible.

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    its a hard choice. if a harder material was put in then wouldn't it damage the frame so it would have to be drilled out even bigger the next time and then the frame would have to be thrown away. and also it would change the friction

  15. #15
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    Quote Originally Posted by mtbuk View Post
    its a hard choice. if a harder material was put in then wouldn't it damage the frame so it would have to be drilled out even bigger the next time and then the frame would have to be thrown away. and also it would change the friction
    I encountered an almost identical problem on a friends bike (in the UK) about a year ago in respect of the hinged bottom end of a strut where it was connected to the frame. The design was a stationary cross spindle with a ball bearing at each end, fitted into the forked end of the strut.

    The cross hole for the (stationary) spindle had worn oval towards the strut suggesting repeated upwards impact through the wheel. There was no rotational friction issue. I drilled and reamed the cross hole to a sufficiently larger size to drive in a turned sleeve - moderate interference fit. I made a steel sleeve but changed my mind and inserted an aluminium one (unknown alloy) for exactly the reason postulated by mtbuk that if the problem continued, the frame hole might keep getting larger. Over a year later, the user says the hole in my sleeve has started to wear on one side.

    Having no other option that I can think of, I intend to remove the alloy sleeve, fit the steel sleeve and hope for the best. Or maybe I will fit a new alloy one and face up to replacing it regularly. Unfortunately none of the cycle repair shops would touch it and I can see why!

    By the way, the bearings in the strut were turning OK, but I fitted new ones anyway as he had them.

    This seems to me to be a design fault that is difficult to fix retrospectively. Probably the makers should have fitted a hard rubber sleeve in the first place, to take the shock - not something I can easily do. (I believe one can turn rubber if frozen with liquid nitrogen - if I still worked where that was available I might have a go.)

    Anyone else found a better solution?

  16. #16
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    Thats so frustrating, because the engineers knew damn well that the inner section should also be supported by bearings. But they declined to remove a few dollars of cost. The bolts specd are not sufficient quality to withstand the load in that manner. Bolt bends a little, then the frame gets an egg shaped hole and permanent play in the pivot. Specialized and giant were also guilty of a few design flaws like this a while back.

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