Mangled BB threads.

gofasterstripes

Posts: 8161

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Topic starter

[#9382243]

Hey.

Partly for me and partly for a friend (we both have bikes with this problem).

Damaged driveside thread.

Mines a steel frame, his is ally.

Can I flood my thread with brazing brass, fit a LH self-aligning thread tool, align to that and recut my thread? I'll try to match the start point by leaving the very last outer end of the original thread visible. It's a chromolly MK1 BluePig, so I'm guessing my frame won't lose its temper?

For his ally frame, are there any decent deep threaded BB's around? I tried to find a deep threaded RaceFace previously, but I couldn't actually get one anymore (successfully found and ordered but was helpfully delivered a newer non-deepthreaded version.... as a "free upgrade" :/

I don't want to tell him to spend a fortune, so maybe there is a Superstar or similar value BB that has a good deep thread?

Posted : 14/06/2017 4:58 pm

akira

Posts: 953

Full Member

Saint bottom brackets used to be a lot deeper than most, might be worth a look.

Posted : 14/06/2017 6:03 pm

matt_outandabout

Posts: 46085

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Use a threadless replacement BB.

https://www.google.co.uk/search?client=ms-android-motorola&biw=360&bih=263&tbm=isch&sa=1&ei=n3tBWY-oM531gAaFhIn4Cw&q=mavic+threadless+bottom+bracket&oq=Threadless+bott&gs_l=mobile-gws-img.1.1.0j0i5i30k1j0i24k1l3.18835.27089.0.27717.28.24.4.0.0.0.1068.6141.2j15j2j6-1j2.22.0....0...1.1j4.64.mobile-gws-img..5.23.5332.3..35i39k1j0i67k1j0i10i67k1j0i13k1j0i30k1.7R0vxcxa3CI#tbm=isch&q=threadless+bottom+bracket

Posted : 14/06/2017 7:10 pm

nickdavies

Posts: 1299

Free Member

Have you tried a bike shop first? I had a c456 that was really badly cut - my lbs recut the frame without filling it - the only issue was whenever I changed the bb it was a nightmare to get in straight. I had it recut a couple of times in the end before cracking it. Using something like a hope with replaceable bearings would have made it a lot easier, you might be able to get away with it.

Posted : 14/06/2017 8:08 pm

gofasterstripes

Posts: 8161

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Topic starter

"replaceable bearings" - good call...if the BB stays tight.

"Threadless BB" - were both on Hollowtech, and I'm not giving up my M960!

Posted : 14/06/2017 8:23 pm

gofasterstripes

Posts: 8161

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Topic starter

"Saint" - good call, will check

"Recut" - perhaps... Not holding much hope our for mine though.

Posted : 14/06/2017 8:25 pm

Speshpaul

Posts: 3394

Full Member

Recut the thread, then either Saint or a replaceable bearing BB
If its loose, Locite bearing fit.

Posted : 14/06/2017 10:19 pm

mick_r

Posts: 3643

Full Member

Years ago I had to get a warranty replacement for a fillet brazed Kili Flyer. During building they blobbed a 2cm x 1cm drip of brass on the bb threads. They ran a tap through to "fix" it, but it left a raised and now threaded bit of brass, and also removed excessive amounts of steel thread from the opposite side. Tightening the bb cup made it skew out of parallel due to the wonky thread.

So I guess you'll have to get a minimal amount of brass quite uniformly around the whole diameter for it to work.

Or get it tapped out to Italian thread which is a bigger diameter (not a clue if you can get Italian thread ht2 cups).

Posted : 14/06/2017 10:37 pm

gofasterstripes

Posts: 8161

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Topic starter

Thanks again 🙂

What is a good BB to buy with replaceable bearings? All I know is that it's just about impossible to do with Shimano ones!

Posted : 15/06/2017 10:20 pm

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[Closed] Mangled BB threads.