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Tips on removing bolts from loose threaded inserts, and how to repair inserts?
Was just stripping the frame for some cleaning and painting. Four of the threaded inserts on the frame started spinning freely with very little torque. Thankfully they weren't holding anything on, so it's just the bolts stuck in them.
Used some penetrating fluid and pliers, but no luck. Any ideas for removing the bolts besides drilling them out? Any way to repair or replace these inserts? Quick search didn't turn up much, but I have a feeling I'm not using the right terminology. https://cimg6.ibsrv.net/gimg/bikefor...dfa12e9cfd.jpg |
Ah, those aren’t (generally called) inserts, those are rivnuts.(rivet+nut) I’d start with trying to put pressure on the flange below the screw head, see if I can get enough purchase to undo the screw that way. Next attempt would probably be to dribble some cyanoacrylate around the flange, hope it’d hold for removing the screw. Next would be to drill or grind off the screw head, then grind the flange off to remove the whole rivnut before installing a new one. |
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Originally Posted by dabac
(Post 20692557)
Ah, those aren’t (generally called) inserts, those are rivnuts.(rivet+nut) I’d start with trying to put pressure on the flange below the screw head, see if I can get enough purchase to undo the screw that way. Next attempt would probably be to dribble some cyanoacrylate around the flange, hope it’d hold for removing the screw. Next would be to drill or grind off the screw head, then grind the flange off to remove the whole rivnut before installing a new one. |
Well... That was fun. Probably going to drill out the holes a little and replace with M6 aluminum rivet nuts. Pairing that with 12mm long zinc-plated steel hex screws, hot dipped steel/neoprene sealing washer, and aluminum based antiseize - should prevent any future corrosion issues!
https://cimg7.ibsrv.net/gimg/bikefor...9bcf28f4d5.jpg |
Originally Posted by Hatsuwr
(Post 20693138)
Well... That was fun. Probably going to drill out the holes a little and replace with M6 aluminum rivet nuts. Pairing that with 12mm long zinc-plated steel hex screws, hot dipped steel/neoprene sealing washer, and aluminum based antiseize - should prevent any future corrosion issues!
https://cimg7.ibsrv.net/gimg/bikefor...9bcf28f4d5.jpg |
Originally Posted by dsbrantjr
(Post 20693181)
Try Tef-Gel, I use it on all dissimilar metal joints. I would also suggest stainless fasteners over zinc-plated. https://www.tefgel.com/contain.php?param=tefgel_infor
As far as stainless fasteners... Well the above is actually one of the reasons I tend to avoid them. But if that's not a concern... Edit: Here's my reasoning for the choices of metals listed earlier: -Aluminum rivet nuts - last thing I want to see corrosion is the frame. Since this will sit direct against the frame metal and damage any coating I might try to apply, it seemed like a good idea to avoid a dissimilar metal. -Hot dipped washer - very resistant to corrosion from the elements. The large amounts of zinc will act as a sacrificial anode. -Screws - three main options are listed below. The zinc plated steel seemed a good compromise between the two others, and is also the strongest of the three if that matters. -----Stainless steel (extremely corrosion resistant, but will cause galvanic corrosion of aluminum if preventative measures aren't taken) -----Zinc-plated steel (very corrosion resistant and will not induce significant levels of galvanic corrosion of aluminum) -----Aluminum (corrosion resistant, but not to the same degree as above. Practically no risk of galvanic corrosion with other aluminum) |
I originally began using Tef-Gel when I lived in the Northeast where roads were salted for 4+ months/year; it resembled the marine service Tef-Gel was designed for. Its high PTFE content adds lubricity and helps avoid galling of stainless and presumably Ti; works great on pedal and BB threads.
Anti-seizes with nickel and copper excel at high temperature service (think exhaust systems) which is not an advantage for bikes. I also think that introducing one or more additional metals into a galvanic mix may be less than helpful. I think that threaded fasteners made of aluminum (cough, spoke nipples, cough) are a mistake in most instances, especially vs other aluminum parts. |
Originally Posted by Hatsuwr
(Post 20693138)
Well... That was fun. Probably going to drill out the holes a little and replace with M6 aluminum rivet nuts. Pairing that with 12mm long zinc-plated steel hex screws, hot dipped steel/neoprene sealing washer, and aluminum based antiseize - should prevent any future corrosion issues!
https://cimg7.ibsrv.net/gimg/bikefor...9bcf28f4d5.jpg |
Originally Posted by dsbrantjr
(Post 20694328)
I originally began using Tef-Gel when I lived in the Northeast where roads were salted for 4+ months/year; it resembled the marine service Tef-Gel was designed for. Its high PTFE content adds lubricity and helps avoid galling of stainless and presumably Ti; works great on pedal and BB threads.
Anti-seizes with nickel and copper excel at high temperature service (think exhaust systems) which is not an advantage for bikes. I also think that introducing one or more additional metals into a galvanic mix may be less than helpful. I think that threaded fasteners made of aluminum (cough, spoke nipples, cough) are a mistake in most instances, especially vs other aluminum parts.
Originally Posted by wschruba
(Post 20694456)
No point in going up to M6, unless you duffed up a hole removing it. You would be forever drilling out holes in bottle cages/accessories, since they are sized for smaller M5 screws.
There are probably the occasional items that have an integrated screw. Haven't used one yet though, so will figure that out if it ever becomes an issue. |
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