HELP! Broken threads, can they be saved?

[snowjim]

Since you bought the bike from a company, consumer purchase law applies. Read up a bit on it and you will see that the gym cannot pass the problem onto you as a consumer.

Well, this is probably what they knew so the owner sold it as a private person to me via blocket. Probably not much to go on there unfortunately.

 

[Paxman]

Aha, no then it's more difficult.

 

[cpalm]

Yes, I have tried this, but when it seems to be straight and I start tightening, it unfortunately jumps off. I can of course tilt it again, but in the long run, it probably won't hold, I guess.

Yes, it's much easier said than done. Locate the entry of the thread on both the hole and the screw and mark it with a marker so you know where to start. Try to clean at least the first turn - file it, remove burrs with something pointed. Thread the screw in a bit and hit it with a hammer. If the thread looks better a bit in, you can sand off the first part of the thread. Yes, use your imagination, the tools you have access to, patience, and a little bit of force.

P.s. is it possible that the seller has more in stock, so maybe you can exchange it for a fresher one?

 

[richardtenggren]

But isn't that the height adjustment for the handlebar? Who doesn't adjust the height of the handlebar and saddle at a gym?

If you're going to have the bike at home for personal use, you could just use a through-bolt a bit lower if you don't master a thread tap/thread file. Should you try the file/tap, you'll still need to determine the thread type before purchasing either, as the outer diameter is just one of several parameters describing a thread.

Do you have a BOM list for the exploded view? Maybe it reveals something?

Since you have the screw, you could visit a store with a good selection of nuts and test to find out what thread and pitch you need.

Edit: The brass part probably acts as some kind of bushing, and the screw you removed acts as a lock for the bushing and a holder for the handle that, in turn, affects the bushing and locks the handlebar stem. So perhaps you can weld the screw or use some thread lock if you manage to fit the threads reasonably, as the likelihood of needing a bushing replacement for personal use is probably small.

 

[snowjim]

After all, it's quite a large hole (32mm), so I think it would be better if I remove the brass plug (which is supposed to press and hold the handlebar) and simply clean it with a sponge and something effective against grease (maybe YES). When I felt with my finger yesterday, there were quite a few shavings.

Sanding drainage grooves in the screw sounds like a good idea for smaller holes, but in this case, the hole is quite large, so you can fit in a sponge or something similar.

When the hole is completely clean, hopefully, it's easier to see its condition. I'll take a photo of it and post it here.

The next step is not obvious, though. There is a thread file, but it seems a special thread file is required, and the question is where I can get it? As you say, many other parameters need to match, like pitch and so on. Maybe it would be better to try to get the screw in as well as possible even if it goes in crooked, and then live with it being faulty. Can you really hammer on the screw? Isn't there a risk of causing even more damage then?

 

[snowjim]

But isn't that the handlebar height adjustment? Who doesn't adjust the handlebar and seat height at a gym?

In this case, it works like this: the handlebar is held in place by a brass spacer (7040000) which is completely solid and is pushed in by the handle (10300010) that is screwed in through the defective screw (70400100).

Therefore, you only need to unscrew the defective screw if you are going to replace the top cover on the bike. One might think of drilling up the hole and welding the defective screw in place, but I would preferably like to avoid this if possible.

 

[Paxman]

In the exploded diagram, it looks like the threaded part sits on the outside of the frame and that everything is then covered by a plastic cap. It should be a fairly simple task to cut away the entire part with threads and weld on a new one. If it's a standard M32 thread, it's just a matter of welding on a nut. Once the plastic covers are on, no one will see the modification.

Contact a metal workshop or smith and they'll fix that part fairly quickly.

The above is what I believe is the best solution. It seems to be a very short thread on the screw itself, and if there's a bit of cross-threading, it's very unlikely that the threads can be refurbished sufficiently well. Since it's only about the handlebar height adjustment, you can probably get away with quite significant modifications to the locking function without it affecting the actual adjustment.

 

[snowjim]

P.s. it's not like the seller has more copies in stock, so maybe you can switch to a fresher one?

Yes, the seller has 10 more bikes but getting it exchanged for one of them seems very difficult to me. If he himself can't get the screw in, then the bike is likely unusable for him. My first thought was to offer him 500 kr to swap for another bike, but as I said, I think it will be difficult to manage that.

 

[snowjim]

In the exploded view, it looks like the threaded part sits outside the frame and everything is then covered by a plastic cap. It should be a fairly simple thing to cut away the entire part with threads and weld on a new one. If it's a standard M32 thread, you can just weld on a nut. Once the plastic caps are in place, no one will see the modification.

Contact a metal workshop or blacksmith and they should be able to fix that part quite quickly.

When I saw the exploded view, it was indeed a thought that crossed my mind, but as you say, it's nothing I can do myself, so it was placed lower on the list of possible solutions. I'll see if I can find a metal workshop around where I live, and we'll see if that can lead to anything.

 

[snowjim]

Is there a tool I can use to file the threads with that is reasonably easy to acquire (e.g., biltema/jula/Harald)?

 

[snowjim]

Washed the threads clean last night and had to work quite a while before I got the screw back on. Once I got it in straight, of course, it met some resistance, but I screwed it in as far as it would go, and I suspect it's the beginning of the threads that made it a bit sluggish. If it had gone crooked in all the threads, it would probably have been much harder.

So now the screw is in place and the bike can be used again. However, if you're going to change the top cover, it won't be fun; then you have to remove the screw, but under normal use, it should work.

However, I wouldn't say this is mint condition; if I had known about the screw problem, I wouldn't even have bought it for 1000 SEK.

Here is a video of how the threads look, not so easy to capture in a photo unfortunately.

[video=youtube;bdC9qZIFIgo]https://www.youtube.com/watch?v=bdC9qZIFIgo[/video]

The screw that goes into the hole is in good condition, although you can clearly see tool marks where a previous owner (or whoever it might be) worked on it.