Simple fix for stripped threads?
11-21-20, 03:30 PM
#1
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Simple fix for stripped threads?
Just got a used dropper. It's a USE gravity dropper turbo from a few years ago.
It's external routed. There are two small bolts that hold the cable into the seatpost. One is fine, the other is stripped.
As it sits, it works fine but I'd like to fix it.
I'm sure a sheet metal screw of approximately the same size would fit in there and tighten up. Kinda permanent but I bet it would never give me trouble.
My other thought is that a longer bolt should fit in the hole just fine and the hole is probably threaded all the way back. Might work, might not.
I don't have a tiny tap and die set. If I did, I think the hole could be widened and the next size up used. Sounds expensive for little to gain.
On stripped wood holes, it works to cram some pieces of wood into the hole before the screw. Maybe I could do this with thin wire or JB weld or something.
It's external routed. There are two small bolts that hold the cable into the seatpost. One is fine, the other is stripped.
As it sits, it works fine but I'd like to fix it.
I'm sure a sheet metal screw of approximately the same size would fit in there and tighten up. Kinda permanent but I bet it would never give me trouble.
My other thought is that a longer bolt should fit in the hole just fine and the hole is probably threaded all the way back. Might work, might not.
I don't have a tiny tap and die set. If I did, I think the hole could be widened and the next size up used. Sounds expensive for little to gain.
On stripped wood holes, it works to cram some pieces of wood into the hole before the screw. Maybe I could do this with thin wire or JB weld or something.
11-21-20, 03:53 PM
#2
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If duct tape don't work on something JB Weld it!
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11-21-20, 05:08 PM
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Epoxy something on it?
I would avoid drilling holes in my seatposts, but maybe that's just me.
If you do, however, remember to round the edges with a file to avoid stress risers.
Edit: I now see there is already a couple of holes. Yeah, clean the thing up, clean a machine screw, and put some epoxy/JB weld in there and set the screw. Or use a rivet if you have access to that.
I would avoid drilling holes in my seatposts, but maybe that's just me.
If you do, however, remember to round the edges with a file to avoid stress risers.
Edit: I now see there is already a couple of holes. Yeah, clean the thing up, clean a machine screw, and put some epoxy/JB weld in there and set the screw. Or use a rivet if you have access to that.
11-21-20, 05:13 PM
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A small drill bit and a tap aren't expensive. I'd use the next size screw if possible.
11-21-20, 05:18 PM
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Nope on the sheet metal screw. It's just not a good idea for reasons I'd rather not explain. Suffice to say they operate on different fundamentals.
For obvious reasons matching the same thread pitch & diameter between bolt & hole is the best way to go. A hand tap is only a few dollars.
You probably want a chaser tap & or a bottom tap to clean up what you have, (if you have any) & to cut clean threads all the way to the bottom of the hole, assuming the hole has a bottom. Then you can use a slightly longer bolt to reach all the way down to good threads. You'd not want to bottom out, so a washer or 2 under the bolt head to fine tune the protrusion into the hole would be the way to do it. A bit of blue Loctite 242 & due care wouldn't hurt, either.
Failing that, & please excuse my ignorance about your seat post in particular, but maybe another option is to go through the part completely with a much longer bolt & use a nut on the back side to transfer the load from the defunct parts threads to the nut threads & mating nut face. If the nut doesn't sit flat & square due to surface contour, an aluminum bushing is availavle at your local hardware store & the propper angle can be installed easily with a belt sander & some time. You'd want everything flush & square with the bolt axis.
From there, assuming there is no good threads left to clean up or bolt-through-part options available, you can make contingincies about oversizing the hole or component replacement. Surely the post has a component list/repair manual somewhere...
If it's just the toggle bolts that adjust the saddle angle, you can just get new ones. Something like this: Saint Johns Cycles or: Another random internet search result.
For obvious reasons matching the same thread pitch & diameter between bolt & hole is the best way to go. A hand tap is only a few dollars.
You probably want a chaser tap & or a bottom tap to clean up what you have, (if you have any) & to cut clean threads all the way to the bottom of the hole, assuming the hole has a bottom. Then you can use a slightly longer bolt to reach all the way down to good threads. You'd not want to bottom out, so a washer or 2 under the bolt head to fine tune the protrusion into the hole would be the way to do it. A bit of blue Loctite 242 & due care wouldn't hurt, either.
Failing that, & please excuse my ignorance about your seat post in particular, but maybe another option is to go through the part completely with a much longer bolt & use a nut on the back side to transfer the load from the defunct parts threads to the nut threads & mating nut face. If the nut doesn't sit flat & square due to surface contour, an aluminum bushing is availavle at your local hardware store & the propper angle can be installed easily with a belt sander & some time. You'd want everything flush & square with the bolt axis.
From there, assuming there is no good threads left to clean up or bolt-through-part options available, you can make contingincies about oversizing the hole or component replacement. Surely the post has a component list/repair manual somewhere...
If it's just the toggle bolts that adjust the saddle angle, you can just get new ones. Something like this: Saint Johns Cycles or: Another random internet search result.
Last edited by base2; 11-21-20 at 05:34 PM.
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11-21-20, 06:08 PM
#7
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Without running to the garage to take pics, it's where the cable goes into the seatpost at a 90 degree angle. It's held in by two very narrow bolts.
Not something that can be replaced.
I'll try to figure out the thread pitch, metric and skinny, and look at the price of a tap.
Feeling a little burned on the deal, except the price was right.
Not something that can be replaced.
I'll try to figure out the thread pitch, metric and skinny, and look at the price of a tap.
Feeling a little burned on the deal, except the price was right.
11-21-20, 06:12 PM
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Borrow a riveting tool, get some reasonable rivets, and do that. It is not something where strength really matters much. Rivet both sides so it looks like it was built like that.
11-22-20, 03:15 PM
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For those suggesting rivets, I don't think you understand where I'm talking about. This is the part of the seatpost that the cable from the remote goes into. If I riveted it together, it would mean drilling it out to replace the cable.
I grabbed my n95 and went to the hardware store. Turns out it's an M3 bolt. I found one about 1/4" longer. It threads in great without bottoming out. I replaced both bolts. It's much more secure than before.
I wonder if the kpo (knucklehead previous owner) had lost the original bolts and replaced them with short ones.
I grabbed my n95 and went to the hardware store. Turns out it's an M3 bolt. I found one about 1/4" longer. It threads in great without bottoming out. I replaced both bolts. It's much more secure than before.
I wonder if the kpo (knucklehead previous owner) had lost the original bolts and replaced them with short ones.
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11-22-20, 04:17 PM
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Originally Posted by rosefarts
For those suggesting rivets, I don't think you understand where I'm talking about. This is the part of the seatpost that the cable from the remote goes into. If I riveted it together, it would mean drilling it out to replace the cable.
I grabbed my n95 and went to the hardware store. Turns out it's an M3 bolt. I found one about 1/4" longer. It threads in great without bottoming out. I replaced both bolts. It's much more secure than before.
I wonder if the kpo (knucklehead previous owner) had lost the original bolts and replaced them with short ones.
I grabbed my n95 and went to the hardware store. Turns out it's an M3 bolt. I found one about 1/4" longer. It threads in great without bottoming out. I replaced both bolts. It's much more secure than before.
I wonder if the kpo (knucklehead previous owner) had lost the original bolts and replaced them with short ones.
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11-23-20, 06:22 AM
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Originally Posted by rosefarts
On stripped wood holes, it works to cram some pieces of wood into the hole before the screw. Maybe I could do this with thin wire or JB weld or something.
For future reference an M4 tap is only $6 at most home stores. Some come with a matching drill bit.
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11-23-20, 10:49 AM
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Not sure if this has been mentioned:
https://www.mcmaster.com/stripped-thread-repair-kits
Maybe not adequate for structural fasteners but should work for a small screw holding a cable in place. I used to use a Loctite product we called Form-a-thread but I don't know if this is the correct name for it. It may very well be the product listed at McMaster Carr but they strip most brand names off their catalogue listings.
https://www.mcmaster.com/stripped-thread-repair-kits
Maybe not adequate for structural fasteners but should work for a small screw holding a cable in place. I used to use a Loctite product we called Form-a-thread but I don't know if this is the correct name for it. It may very well be the product listed at McMaster Carr but they strip most brand names off their catalogue listings.
