BB shell thread repair

[Miguel75]

Apologies if this has been discussed before: my phone is a spud and the search feature doesn’t work for me on this site, on my phone.

I recently purchased a 2nd hand frame and during the strip down portion of the process I removed the BB to find the drive side threads are in very poor shape while the NDS threads are in poor shape. (Pics below).

It’s a Banshee Rune V2 (2018?) so Aluminium I believe. Can anyone recommend a mechanic (Astroboy racer etc) who is good at chasing/retapping threads?

My worry is there’s not enough thread remaining...

Thanks in advance.

 

[Oddjob]

Most good lbs will have a good bb chasing and facing tool, this should clean up the threads but you will want to replace bb cups as little as possible.

I would then invest in a CK bb which has very good serviceable bearings or get an old school shimano bb52 and some good blind bearing pullers and treat the bb52 shell as a press fit bb for these Enduro kits https://www.mtbdirect.com.au/enduro...tzLnV9sigqv7n5V3cSHPF--30t5yqfIRoCn5YQAvD_BwE

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[link1896]

Or Hope BB at 160ish.

See the little notch in the cups behind the bearing, thats for bearing removal. another at 180 degrees. You use a screw driver or punch to knock out the old bearings.

Once threads in shell are repaired and the shell is faced on both sides, I'd loctite in the new cups.

 

[Oddjob]

Or Hope BB at 160ish.

See the little notch in the cups behind the bearing, thats for bearing removal. another at 180 degrees. You use a screw driver or punch to knock out the old bearings.

Once threads in shell are repaired and the shell is faced on both sides, I'd loctite in the new cups.

Dear god no. Hope bbs are the absolute worst! The oem bearings are shit and they don't leave enough clearance between the bearings and shell on the inboard side leading to friction. The notches only help if you have the bb shell out of the frame as well.

Get a Shimano bb52 for 24mm cranks or a Rotor bsa30 for 30mm cranks, or a Sram dub bsa setup if you're unfortunate enough to have sram cranks as they use the same bearings as bsa30 just with a plastic cup.

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[Miguel75]

Thanks for the help so far team. As far as blind bearing pullers, is something like this good?

https://www.cleanskinmtb.com/blind-bearing-puller

Any other blind bearing pullers out there I should look at? I prefer to get the best tools I can afford, especially ones that I’ll use often.

 

[ozzybmx]

I was a big believer in CK, Hope, Hope ceramic and other blingy stuff at one stage... once its chased and the threads are right, just go a Shimano XT BB. Best bang for buck every time.

I've fitted them to bikes as new and sold the same bikes with the BB fitted.

 

[Plankosaurus]

I was a big believer in CK, Hope, Hope ceramic and other blingy stuff at one stage... once its chased and the threads are right, just go a Shimano XT BB. Best bang for buck every time.

I've fitted them to bikes as new and sold the same bikes with the BB fitted.

Still haven't had a bb70 fail on me. Bb56 have gone a little crunchy on me, but the bb70 is rock solid . I've tried the xtr (bb90?) But doesn't seem any better for the extra dollars.

I've got an FSA that's done a phenomenal job for near a decade on my cx bike too. Rain, mud, creek crossings, and thousands of KMs on the trainer and it just keeps ticking.

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[ozzybmx]

I've got an FSA that's done a phenomenal job for near a decade on my cx bike too. Rain, mud, creek crossings, and thousands of KMs on the trainer and it just keeps ticking.

I've had a BB386EVO Kogel ceramic press in BB on my Cervelo roadie do 15,500km when I sold it. I have had a CK BB do 750km before creaking. Same with Hope Ceramic, still big $$$ and shithouse.

These days I'm DT hubs and Shimano BB... now Hope hubs are also awesome too, just no supply.

 

[hellmansam]

Get the threads re tapped, and a new Shimano BB. Fit the cups with out tightening them as much as you normally would, then add the green "super wick-in" variety of Loctite to the threads from the inside end of each BB cup. I'd lay the frame on it's side and do them one at a time, waiting for it to set enough that you can turn the frame over to do the other side.
I have done this with some pretty munted BB threads, most notably on a Cannondale road frame which had a lot of thread damage.

Alternatively clean the threads, fill with Devcon and retap.

 

[Oddjob]

Still haven't had a bb70 fail on me. Bb56 have gone a little crunchy on me, but the bb70 is rock solid . I've tried the xtr (bb90?) But doesn't seem any better for the extra dollars.

I've got an FSA that's done a phenomenal job for near a decade on my cx bike too. Rain, mud, creek crossings, and thousands of KMs on the trainer and it just keeps ticking.

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But bb70s have been discontinued in favour of the mt-800. The mt-800 is an excellent bb but it uses a smaller bearing than the old bb70 and bb52 so it can't accept the MRA2437 bearings that the Enduro kit uses. The goal here is to essentially use the bb52 shell as a press fit shell and avoid taking it out if possible. But you should get a few good years out of a bb52 before the bearings need to be replaced.

The cleanskin blind bearing pullers are fine, the ebay ones can be a bit variable so just pay the extra. Just remember to use grip paste on the collet. It might also be easier to use a brass punch to knock the collet out then use the slide hammer. The shimano bbs use a plastic sleeve which needs to be removed with a flathead screwdriver before attaching the collet to the bearing.

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[PJO]

I know that there is a threadless external BB for munted BSA threads but unfortunately it is for a 68mm shell.
Banshee's are 73mm and I haven't yet seen one for the wider mtb shell.

Here is the 68mm shell version:

Threadless External Repair Bottom Bracket Hollowtech BB YST BB-0901 | eBay

The patented bottom bracket is sealed and maintenance-free. Suitable for Shimano Hollowtech II cranks (24mm axle) and bb shell width 68mm (not suitable for 73mm shell width!)., colour: black, weight: 138g.

www.ebay.com.au

 

[blacksp20]

I know that there is a threadless external BB for munted BSA threads but unfortunately it is for a 68mm shell.
Banshee's are 73mm and I haven't yet seen one for the wider mtb shell.

Here is the 68mm shell version:

Threadless External Repair Bottom Bracket Hollowtech BB YST BB-0901 | eBay

The patented bottom bracket is sealed and maintenance-free. Suitable for Shimano Hollowtech II cranks (24mm axle) and bb shell width 68mm (not suitable for 73mm shell width!)., colour: black, weight: 138g.

www.ebay.com.au

My Prime has a 68mm shell, I just measured it. I’m running BB spacers as I have on every other bike I’ve owned with threaded BB.

I think that item you linked will be the answer if chasing the BB threads doesn’t work.

I found this thread from a few years ago from a guy that used one and it looks like they might be spaced for 73mm cranks on a 68mm shell out of the box.
https://www.bikeforums.net/20818247-post14.html

 

[PJO]

My Prime has a 68mm shell, I just measured it. I’m running BB spacers as I have on every other bike I’ve owned with threaded BB.

I think that item you linked will be the answer if chasing the BB threads doesn’t work.

I found this thread from a few years ago from a guy that used one and it looks like they might be spaced for 73mm cranks on a 68mm shell out of the box.
https://www.bikeforums.net/20818247-post14.html

Yeah it is only if your threads are toast.
Which year is your Prime?
There is a 2016 Spitfire in our collection and it's 73mm, pretty sure the later model V2s and new V3s are all 73mm...

BB shell for the guy in the forum you linked is 68mm, says here: https://www.bikeforums.net/20790681-post4.html.

Not sure how well that YST corp threadless BB would work for a 73mm shell, reckon there wouldn't be enough thread overlap, you can play with the 3D model here, looks like there is only 10mm of threads (so extending it beyond the 68mm would not leave enough).

 

[blacksp20]

Yeah it is only if your threads are toast.
Which year is your Prime?
There is a 2016 Spitfire in our collection and it's 73mm, pretty sure the later model V2s and new V3s are all 73mm...

BB shell for the guy in the forum you linked is 68mm, says here: https://www.bikeforums.net/20790681-post4.html.

Not sure how well that YST corp threadless BB would work for a 73mm shell, reckon there wouldn't be enough thread overlap, you can play with the 3D model here, looks like there is only 10mm of threads (so extending it beyond the 68mm would not leave enough).

I stand corrected, it is 73mm. I forgot the measure the ISCG mount.
Guess that YST won’t work on 73mm BB shell anyway as it seems like they have been made to fit a 68 without the need for BB spacers. Cranks likely won’t fit.

 

[PJO]

Cranks likely won’t fit.

Yeah that too, forgot about that!

 

[Miguel75]

I stand corrected, it is 73mm. I forgot the measure the ISCG mount.
Guess that YST won’t work on 73mm BB shell anyway as it seems like they have been made to fit a 68 without the need for BB spacers. Cranks likely won’t fit.

Thanks anyway team. I’ll likely get the threads cleaned up and pop in the BB52 and green loctite, as suggested. If all else fails I’ll get the Devcon and re cut threads...