husoi Posted December 20, 2021 Share Posted December 20, 2021 As mentioned elsewhere after my shadow decided to fall on her side by herself when I was getting ready for a ride the result was a bent clutch lever and the left mirror coming out leaving the thread stripped. The clutch was reasonably easy to fix, removing both clutch and brake levers and using the brake one as template I managed to straighten it with a blowtorch and the a tube and the adjustable spanner to do the job. Not really worth mentioning or documenting. The second task, fixing the mirror, I think it is worth documenting and maybe you can take some useful info. First the problem. 1 - Dropping the bike Don't ask how it happened because one second I was getting the gear on while the engine was warming up, next second the bike was on the side I do that all the time, on the same spot with both bikes. 2 - once the handlebar hit the ground the mirror arm just went off. doing this to the thread. Here you can see the thread missing on the top. This is the naughty mirror With a 1.25mm pitch and M10 size stainless steel arm. Locking nut Inside the locking nut. One thing I don't understand is why the thread in the locking nut is 8mm long when the strength required is fairly small as it only prevents the arm to become loose. This results in the usable thread of 5mm which means only 3 turns are available to fix the mirror. Before fixing it I'll be doing some re-engineering the arm and turn the end of the arm (the edge just before the thread) into a tapered shape. This will increase the friction area by over 30% and at same time allowing the increase of the thread. Next we have the problem of fixing the thread in the casing. I've come across several solutions, all of them with pros and cons. Solution 1: Helicoil system. (£40 Set for M5 to M12. £12 for M10X1.25) A spring like thread that is inserted on a size above thread Pros: Price, easily installed Cons: thread can become undone and come out as it relies on the bolt being tighten to hold it in place. Solution 2: Solid thread insert (£45) A threaded tube inserted in the faulty thread (after widened) to receive the original bolt. Pros: more durable and can be used with thread lock liquid to keep it in place. Cons: More expensive than helicoil Option 3 (or 2.1) Wurth time-sert (+£100) Similar to solid insert with the difference of the colar on the top and the insert method being different. Pros: Durable and permanent insert Cons: stupidly expensive, the most time consuming for the insert options. Option 4 (£20 set of 10) Low temperature aluminium (not aluminum) alloy This allow to fill the original hole with a allegedly strong than original alloy then drill and taper to fit. Pros: best price, according to Delboy's garage YT channel takes an extra 15% torque to break it when compared with normal cast aluminium. Cons: Will need to dismantle the entire clutch reservoir and remove all parts before doing the job as the part needs to be heated to 700C to melt the alloy, doubts about bonding new material to existing. In price option 4 is the cheapest although it will take far longer to fix. Will be a more permanent solution although requires to drill a brand new hole and complete taper thread Options 2 and 3 are the most expensive but more durable and looks solid when compared with helicoil. All first 3 options require similar amount of work. Quote Link to comment Share on other sites More sharing options...
Discomfort Posted December 20, 2021 Share Posted December 20, 2021 You can get thread repair kits much cheaper on Amazon and they do a good job. I would be tempted to use a helicoil as its not a vital load bearing item and will only take 15 mins to fix if the res doesn't need removing from the bike. Quote Link to comment Share on other sites More sharing options...
Mr Fro Posted December 20, 2021 Share Posted December 20, 2021 It would be unusual to have a metric tapered thread- are you sure they're not parallel? I've used the lumiweld type rods with varying success - with aluminium stock they're fine but castings I've found that often the casting melts to a blob before the rod starts to melt. You can get the Wurth type inserts for a couple of quid each. All you'd need then is the appropriate drill bit & tap. Also, can you reduce the thread depth on the locking nut to give you more engagement on the mirror thread? 5 mm is naff all on an M10! 1 Quote Link to comment Share on other sites More sharing options...
husoi Posted December 20, 2021 Author Share Posted December 20, 2021 I've measured the thread as 1.25 metric. and 10mm diam. It is a Japanese bike so I have no doubt is metric. I agree with the solid inserts. Even outsourcing the taper and drill bit I could make it slightly cheaper. The only issue would be the colar and get the opening properly aligned which would be a problem thinking that there is already a 10mm hole. 25 minutes ago, Mr Fro said: Also, can you reduce the thread depth on the locking nut to give you more engagement on the mirror thread? 5 mm is naff all on an M10! Yes, hence tapering the arm just above the thread to match the taper on the top side of the nut. Probably worth looking at grinding 1 or 2 mm from the bottom of the locking nut. Quote Link to comment Share on other sites More sharing options...
Mr Fro Posted December 20, 2021 Share Posted December 20, 2021 I think we're talking at cross purposes a bit! I thought you meant a tapered thread rather than a parallel thread: I understand what you mean now though! I see what you mean about the collar. Have you seen the Sealey version? They're straight so you wouldn't have to worry about a seat. 1 Quote Link to comment Share on other sites More sharing options...
iangaryprice Posted December 20, 2021 Share Posted December 20, 2021 I would go for the Helicoil option. Used them lots of times and nealy always been sucessful. I think I havea M10x1,25 helicoil kitid you are anywhere near North Wales (CH5 postcode). Increasing the legth of thread engagement is a good idea. It looks to be that the hole in the top of the nut is too small, it should go over the thicker part of the stem not stop when it gets there. Quote Link to comment Share on other sites More sharing options...
Mississippi Bullfrog Posted December 20, 2021 Share Posted December 20, 2021 2 hours ago, iangaryprice said: It looks to be that the hole in the top of the nut is too small, it should go over the thicker part of the stem not stop when it gets there. I think it does go over the bottom of the stem but not by very much. I'd look for someone who could machine out the inner ridge on the locking nut so that it went further up the stem. It could even be ground out with a Dremel. 1 Quote Link to comment Share on other sites More sharing options...
runningman Posted December 20, 2021 Share Posted December 20, 2021 Bar end mirrors? Quote Link to comment Share on other sites More sharing options...
Bianco2564 Posted December 20, 2021 Share Posted December 20, 2021 We have used helicoil, keensert and timeserts all to good effect depending on the application. Downside of keensert and timesert is space, you have to go up a size, maybe M12 and there physically may not be enough meat on the casting to cope. I'd helicoil it and look at making the locking nut thinner or using a thin half nut to lock it if you don't mind the aesthetics. Try and get 1d of thread engagement, i.e. 10mm 1 Quote Link to comment Share on other sites More sharing options...
billy sugger Posted December 21, 2021 Share Posted December 21, 2021 I have a couple of spare locknuts for mirrors if you want to try them PM me and I'll post them on Quote Link to comment Share on other sites More sharing options...
Bianco2564 Posted December 21, 2021 Share Posted December 21, 2021 Couple of other thoughts. Never seen a helicoil wind itself out as the con would suggest, they can pull out if the parent thread isn't great and the fastener is overtightened. The coil is quite a snug fit and under tension when it's fitted. Whichever method you use be super accurate with your drilling and tapping to keep the thread square to the nut clamping face otherwise the lock nut will be on the wonk and not tightenup so well. If you can get more thread engagement with a different lock nut, have you thought about just cleaning up what thread is there and screwing the mirror arm in deeper? As above with the accuracy, you will have one shot at doing it, sorry if im doubting your skills with a drill and tap wrench. Quote Link to comment Share on other sites More sharing options...
husoi Posted December 21, 2021 Author Share Posted December 21, 2021 5 hours ago, Bianco2564 said: Couple of other thoughts. Never seen a helicoil wind itself out as the con would suggest, they can pull out if the parent thread isn't great and the fastener is overtightened. The coil is quite a snug fit and under tension when it's fitted. Whichever method you use be super accurate with your drilling and tapping to keep the thread square to the nut clamping face otherwise the lock nut will be on the wonk and not tightenup so well. If you can get more thread engagement with a different lock nut, have you thought about just cleaning up what thread is there and screwing the mirror arm in deeper? As above with the accuracy, you will have one shot at doing it, sorry if im doubting your skills with a drill and tap wrench. Not to worry. I always doubt about my skills Quote Link to comment Share on other sites More sharing options...
Mississippi Bullfrog Posted December 21, 2021 Share Posted December 21, 2021 To be honest if you can't remove it and work on a bench I'd be wary of getting the drilling right as well. I think you said it's integral with the master cylinder. In which case my first choice would be to look at adapting the locking nut to give more threads to engage and use locking compound. Quote Link to comment Share on other sites More sharing options...
husoi Posted December 21, 2021 Author Share Posted December 21, 2021 Thank you all for the great advice One thing I just check is the lack of space. I read somewhere that the minimum size hole would be 10mm for a helicoil and 12mm for the solid insert. This will leave a wall of around 3.5mm which in aluminium is not great. Not too sure at chemical fix with resin without making a non circular bedding. Think I will go down the route of low temp alloy. Plus increasing the length of the available thread in the arm by shortening the nut to get more threads in. And yes @Mississippi Bullfrog I'll be working on the bench Quote Link to comment Share on other sites More sharing options...
Mississippi Bullfrog Posted December 21, 2021 Share Posted December 21, 2021 I once glued a cylinder head together with metal repair resin. It lasted fine until some numpty nicked the bike and crashed it into a tree. 1 Quote Link to comment Share on other sites More sharing options...
Mr Fro Posted December 21, 2021 Share Posted December 21, 2021 Another (possibly stupid) idea would be to chop off all but 5 - 10 mm of the thread of the arm, weld on a stub to make it maybe 10 - 20 mm longer than it was to start with and then thread it. It's a sod that it's got a bend in it as it would be difficult to fixture & machine. The more I think about it, the more I think remanufacturing the arm would be the best option. 1 Quote Link to comment Share on other sites More sharing options...
husoi Posted December 21, 2021 Author Share Posted December 21, 2021 (edited) 29 minutes ago, Mr Fro said: Another (possibly stupid) idea would be to chop off all but 5 - 10 mm of the thread of the arm, weld on a stub to make it maybe 10 - 20 mm longer than it was to start with and then thread it. It's a sod that it's got a bend in it as it would be difficult to fixture & machine. The more I think about it, the more I think remanufacturing the arm would be the best option. It cross my mind to do that. So many downsides to it that I gave up. Mainly because I don't have the machinery to do it. Having said that is nothing more than a SS rod with threads at both ends and 1 bend... DAMN YOU!!! Now you made me think about making it... Could even improve the deign greatly by extending below the bottom and have 2 nuts to hold it in place Edited December 21, 2021 by husoi Quote Link to comment Share on other sites More sharing options...
Mr Fro Posted December 21, 2021 Share Posted December 21, 2021 19 minutes ago, husoi said: It cross my mind to do that. So many downsides to it that I gave up. Mainly because I don't have the machinery to do it. Having said that is nothing more than a SS rod with threads at both ends and 1 bend... DAMN YOU!!! Now you made me think about making it... Could even improve the deign greatly by extending below the bottom and have 2 nuts to hold it in place You mean this kind of stuff? What's the diameter of the arm? 14 mm ish? You'd probably need a press or a good bit of heat to get the bend right. Just out of interest - have you unscrewed the mirror end and had a look at the thread on that? 1 1 Quote Link to comment Share on other sites More sharing options...
husoi Posted December 21, 2021 Author Share Posted December 21, 2021 Not yet. will do it later after pretending to be working from home Quote Link to comment Share on other sites More sharing options...
husoi Posted December 21, 2021 Author Share Posted December 21, 2021 Is even more ridiculous that I first thought... The idiotic moron that fitted the mirror didn't screw the locking nut all the way up. I bet was done by hand and once it stopped was just fitted without checking the nut could go further up. Both threads are the same size and the nuts are slightly different, 2mm longer nut on base. This is how it was supposed to be if properly assembled... Top nut on base side It doesn't show but the nuts are the same size. Only difference is the threaded part is a wee bit longer on the base nut. Now that is out better grind/file the edge of flat bit as below and shorten the nut so I get more thread in. Still fixing the damaged thread on the base. Nice unwanted project for the xmas break Quote Link to comment Share on other sites More sharing options...
MikeHorton Posted December 21, 2021 Share Posted December 21, 2021 1 hour ago, Mr Fro said: You mean this kind of stuff? What's the diameter of the arm? 14 mm ish? You'd probably need a press or a good bit of heat to get the bend right. Just out of interest - have you unscrewed the mirror end and had a look at the thread on that? Is that a Bridgeport on the right? I have some fond memories of my toolmaking days Quote Link to comment Share on other sites More sharing options...
husoi Posted December 21, 2021 Author Share Posted December 21, 2021 4 minutes ago, MikeHorton said: Is that a Bridgeport on the right? I have some fond memories of my toolmaking days I have no idea what you mean. Quote Link to comment Share on other sites More sharing options...
Mr Fro Posted December 21, 2021 Share Posted December 21, 2021 12 minutes ago, MikeHorton said: Is that a Bridgeport on the right? I have some fond memories of my toolmaking days Yeah, I lucked out and got one with X & Y powerfeed. I fancy something a bit beefier though. Space might become a bit of an issue though! @husoi - do you really need to fix the thread if you're getting loads more engagement? It looks like you're going to have 3 x the amount of thread in there once you're done. 1 Quote Link to comment Share on other sites More sharing options...
husoi Posted December 21, 2021 Author Share Posted December 21, 2021 6 minutes ago, Mr Fro said: Yeah, I lucked out and got one with X & Y powerfeed. I fancy something a bit beefier though. Space might become a bit of an issue though! @husoi - do you really need to fix the thread if you're getting loads more engagement? It looks like you're going to have 3 x the amount of thread in there once you're done. The stripped thread is 3 turns at least, even if I double the length I would stay with the same 3 turns of good thread. If I'm getting the trouble of take it out and fix it better doing it properly. Then I'll double check the other side mirror as good measure. Quote Link to comment Share on other sites More sharing options...
husoi Posted January 7, 2022 Author Share Posted January 7, 2022 Forgot that I created the thread Tools in hand. Everything ready for action tomorrow. Need to remember to charge the camera's battery and find the tripod 1 Quote Link to comment Share on other sites More sharing options...
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