So ive just been trying to fit the Chromoplastic front mudguard, prettymuch lost the will to live after 2 hours, finally got it centred, tryed to tighten it up and now the srews just spinning. Carbon fork, with some kind of alumminium insert. Pic of the healthy mount (above the brake).
So help please.
Bike Forum
Cross threaded mudguard mount
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Posted 3 months ago #
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oh. can you make do with a/some cable ties. works for my ratty old gt. i would hazard a guess that a helicoil will not work here because there probably isn't much material left.
has the thread died on the bolt, or the 'nut'?
Posted 3 months ago # -
Looks like it's a rivnut, and it's not been fully tightened. If you can remove the bolt then it can be tightened using either the proper tool, or a combination of nuts and bolts(probably find exact details if you search for loose bottle cage mounts).
Posted 3 months ago # -
aha, i see, so not the material of the 'nut' damaged then?
Posted 3 months ago # -
Just tried a new bolt, and the its the thread on the nut, at least the first half of it is damaged. The pic is showing a healthy mount, before i took a hex key to it.
Posted 3 months ago # -
Just took a photo of the damaged part
Posted 3 months ago # -
And it's actually rotating?
Posted 3 months ago # -
No the rivnut isnt rotating, just the thread inside it isnt grabbing the bolt.
Posted 3 months ago # -
Guess you'll be needing to run a tap into it to clear the thread. Should be an M5x0.8mm, obviously don't run it in too far as it may bottom out on the other side of the leg, and cause damage.EDIT-Read it that only first half is damaged, is there any thread left?
Posted 3 months ago # -
hmm you could possibly drill it out and fit a new one but I would probably try and find another route.
Couple of options:
Helicoil - expensive and maybe not enough meat and risky cutting a new thread (due to the torque)
Bonded in stud - bit of araldite and some M6 threaded rod OR use an M6 bolt with the head cut off and bond in the non-threaded shank if it's a better fit. But you will always have a stud.
Knurled brass insert. I've got some M4 ones and just measured the outside diameter which is about 5.7mm. I would insert it with a bit of glue. I can send you one if you want to try it? M5 might be better as you may be able to get it a tighter fit but would probably need the hole opening out. M4 should be okay for a guard but not for a pannier rack.
Posted 3 months ago # -
hmmm thanks for the ideas, emailed a couple of lbs to see what they think. Its pretty much the same as a bottle cage mount on a carbon frame, and im sure ive read about people having problems with them and getting it sorted. Surley it cant be an expensive job?
Posted 3 months ago # -
It is the same, they can be drilled out and replaced with a new rivnut(not sure how you'd get the remnants out of the fork leg though, usually easy on a frame)if the thread has gone completely. If the thread is only partially damaged then you may be able to reclaim it with a tap if it's only for a mudguard.Catch me in a good mood when it's quiet and i'd run a tap through for nowt, cost you a fiver if it's hectic and i'm P'd off,expect to pay in the region of £20 for replacing the rivnut.
Posted 3 months ago #
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