Help! Reversed bottom bracket
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Help! Reversed bottom bracket
I was sitting in class about 10 minutes ago and all the sudden realized "OMG, I put my BB in backwards". I cant believe it. I mustve gotten confused because I had the bike upside down. Its an old 80's specialized. The cups threaded in fine but got tight. I thought it was because the frame saver that had gotten all over the threads. Is there any chance of me being able to save this bike??? I still cant believe this happened, i feel nauseous.
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What type bb? Certainly you aren't telling us you put left hand threads in right threaded shell and vise-versa. What exacty did you get backwards?
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I put the lockring/pin spanner cup on the drive-side. It threaded right in. Just got back and was able to switch everything with absolutely no problem. Im *hoping* things will be ok...
Last edited by Homebrew01; 06-21-19 at 06:56 AM.
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Velo orange has some fixes.
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1- Don't post on line if you can't handle a little feed back.
2- The Specialized would most likely have Eng threading (whether a b68 or 73mm shell width we don't know yet). So threading the cups in of the opposing sides means they are now "cross threaded".
3- Do no more hurt. Leave as is until it becomes an issue.
4- Plan on a proper repair when schedule and budget allows.
5- I strongly suggest you seek out a shop or "builder" who has the proper thread chasing tools and has a large experience bank to help you out. This is one of the situations where a bit too much ego and not enough prudence can do some serious harm to the frame. It might be that the crossed cups have done some shell damage that won't be corrected with simple chasing, or that the tap won't engage the thread and thus chasing isn't an option. Andy
2- The Specialized would most likely have Eng threading (whether a b68 or 73mm shell width we don't know yet). So threading the cups in of the opposing sides means they are now "cross threaded".
3- Do no more hurt. Leave as is until it becomes an issue.
4- Plan on a proper repair when schedule and budget allows.
5- I strongly suggest you seek out a shop or "builder" who has the proper thread chasing tools and has a large experience bank to help you out. This is one of the situations where a bit too much ego and not enough prudence can do some serious harm to the frame. It might be that the crossed cups have done some shell damage that won't be corrected with simple chasing, or that the tap won't engage the thread and thus chasing isn't an option. Andy
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...if that's your worst day ever, you're doing pretty good. Just sayin'.
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If they threaded in that easily, wrong way, I might keep checking that for tightness if I were you - Could be the BB threads are toast.
Just sayin'
Just sayin'
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Basic rule I follow on bicycles:
Install parts by hand, no wrench. Its easy to get cross threaded when you use a wrench. My hand strength is not able to cross thread. If I get resistance, I back the part out and try again, by hand. Use the tool to do the final snugging/tightening. Its particularly bad when threading a steel part onto an aluminum part, like pedals into cranks and freewheels onto hubs.
Get those threads chased by your LBS. There will be damage if you in fact put the bottom bracket in backwards. That takes some real force, as the threads are opposite.
Install parts by hand, no wrench. Its easy to get cross threaded when you use a wrench. My hand strength is not able to cross thread. If I get resistance, I back the part out and try again, by hand. Use the tool to do the final snugging/tightening. Its particularly bad when threading a steel part onto an aluminum part, like pedals into cranks and freewheels onto hubs.
Get those threads chased by your LBS. There will be damage if you in fact put the bottom bracket in backwards. That takes some real force, as the threads are opposite.
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This just doesn't make sense. If you have English threads and put the fixed cup in the wrong side, there's no way it isn't damaged... either the cup, the BB or both.
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Will there be obvious damage? I imagined stripped threads and and/or the threads looking like a crosshatch pattern. Everything looks straight...
#14
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a loose ball BB [British thread RH cup LH thread] , you could just have the axle in backwards ,, cups in right
.. cross threaded both ? they went in real hard? you are boned..
...
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Will there be obvious damage? I imagined stripped threads and and/or the threads looking like a crosshatch pattern. Everything looks straight...
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I don't think anyone has actually confirmed that the BB is English thread. OP - what is the thread on the BB - it'll be embossed in the cups.
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1.27 24t Its english. The thing is, whenever I crossthreaded something growing up, there was obvious damage. Stripped/smashed threads, crosshatch, metal shavings. There nothing here. I just dont understand it.
#18
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I just rebuilt a 1988 Bianchi Brava with a Shimano 105 drive train. After fighting with the RH BB cup for longer than I will admit, I decided to tighten it and it spun out. Both sides are RH thread on this bike. I had heard of it before on Italian bikes but with a Shimano Drive train I did not expect it.
I definitely would not think that is the case on am 80's Specialized though.
I definitely would not think that is the case on am 80's Specialized though.
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It is possible that the shell's threaded diameter is a tad larger then spec. This would both make threading in the wrong side's cup easier as well as reduce the likelihood of shell damage from said mistake. But the test is easy, reinstall the cups in the correct sides and see how nicely they thread in and how sloppy a fit they have within the shell.
Again, be very careful about how you go about this. Sure there are various paths to take if the shell is damaged but why force you choices to them. This is why I strongly suggested a visit with someone who has more experience with these problems. Andy
Again, be very careful about how you go about this. Sure there are various paths to take if the shell is damaged but why force you choices to them. This is why I strongly suggested a visit with someone who has more experience with these problems. Andy
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It is possible that the shell's threaded diameter is a tad larger then spec. This would both make threading in the wrong side's cup easier as well as reduce the likelihood of shell damage from said mistake. But the test is easy, reinstall the cups in the correct sides and see how nicely they thread in and how sloppy a fit they have within the shell.
Again, be very careful about how you go about this. Sure there are various paths to take if the shell is damaged but why force you choices to them. This is why I strongly suggested a visit with someone who has more experience with these problems. Andy
Again, be very careful about how you go about this. Sure there are various paths to take if the shell is damaged but why force you choices to them. This is why I strongly suggested a visit with someone who has more experience with these problems. Andy
Last edited by worstdayever; 06-22-19 at 08:44 PM. Reason: added picture
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....if you ride it around and it becomes evident you can't keep one or both cups in place and adjusted, the simplest and cheapest fix (that you can do yourself with minimal tooling), is to switch to a sealed unit BB with plastic retainers. Those babies will kind of form themselves around anything, and the actual bearing races and bearings remain in adjustment because of the sealed nature of the sealed unit.
You just need to buy the correct one in terms of length, shell size, and threading.
You just need to buy the correct one in terms of length, shell size, and threading.