Stripped bottom bracket threads -solutions please

[minutemat]

I will post before, during and after photos if Dan is able to take some.

 

[stephan]

I will post before, during and after photos if Dan is able to take some.

Thank you so much, would be great to see for myself and also the retrobike community this done, my guess a lot of frames could be saved this way with it "tapped up to Italian, but then the bonded helicoil's that will take the thread back down to BSA" @danson67 @minutemat

Thank you both, Stephan.

 

[minutemat]

Praise be to @danson67 who completely fixed my frame through his method explained above!

See photos of grinding out the remaining damaged thread using this tool, then inserting the Italian thread, then the finished result! All done in around an hour.

Thoroughly nice chap, and nice to admire all the retro bikes hanging around his workshop awaiting their turn too!

 

[minutemat]

 

[hubar1565]

Depending on how bad it is, and how much you value the frame:

The Loctite Form-a-thread kit (#28654, or PC 3967) is a good basic thread repair system, and should be OK for a large diameter, low load fine thread like a BB shell. You spray a release compound on the male thread (cup), and a cleaner/primer on the female thread (BB shell), then mix and apply the epoxy into the thread and assemble. The release compound allows the cup to still be screwed out as normal.

I also have the 45° cutting tool for putting the appropriate chamfer on the BB faces if you're going down the threadless BB route, such as Mavic YST, or M-wave.

A quick and nasty repair (only for frames that you're not too attached to, probably) is to take a 2-3 mm straight cut across the underside of the BB shell. Close up the shell with a combination of brute force and heating, then weld or braze up the gap, then retap the threade into the fresh metal of the now slightly smaller diameter shell.

As @Peachy! mentioned above, I have repaired several BB shells by reaming out the old thread to a larger diameter, tapping out to Italian spec,

View attachment 598535

then fitting a pair of thread repair helicoils.

View attachment 598534

These are steel inserts that are screwed into the Italian thread, held in with Loctite 638 Retainer, with a standard BSA thread on the inside.
This is the best way to sort it out.

PM for more details if you're interested.

View attachment 598536

All the best,

This looks like the perfect solution to my issue I'm having with a bike I just bought. How can I get more info from you on this?

 

[Jonny69]

This looks like the perfect solution to my issue I'm having with a bike I just bought. How can I get more info from you on this?

Messaging the user is best, but because you’re newly signed up you might not be able to message anyone directly until you’ve made a few posts. If I tag @danson67 it should get their attention.

 

[The Muppet]

Depending on how bad it is, and how much you value the frame:

The Loctite Form-a-thread kit (#28654, or PC 3967) is a good basic thread repair system, and should be OK for a large diameter, low load fine thread like a BB shell. You spray a release compound on the male thread (cup), and a cleaner/primer on the female thread (BB shell), then mix and apply the epoxy into the thread and assemble. The release compound allows the cup to still be screwed out as normal.

I also have the 45° cutting tool for putting the appropriate chamfer on the BB faces if you're going down the threadless BB route, such as Mavic YST, or M-wave.

A quick and nasty repair (only for frames that you're not too attached to, probably) is to take a 2-3 mm straight cut across the underside of the BB shell. Close up the shell with a combination of brute force and heating, then weld or braze up the gap, then retap the threade into the fresh metal of the now slightly smaller diameter shell.

As @Peachy! mentioned above, I have repaired several BB shells by reaming out the old thread to a larger diameter, tapping out to Italian spec,

View attachment 598535

then fitting a pair of thread repair helicoils.

View attachment 598534

These are steel inserts that are screwed into the Italian thread, held in with Loctite 638 Retainer, with a standard BSA thread on the inside.
This is the best way to sort it out.

PM for more details if you're interested.

View attachment 598536

All the best,

Depending on how bad it is, and how much you value the frame:

The Loctite Form-a-thread kit (#28654, or PC 3967) is a good basic thread repair system, and should be OK for a large diameter, low load fine thread like a BB shell. You spray a release compound on the male thread (cup), and a cleaner/primer on the female thread (BB shell), then mix and apply the epoxy into the thread and assemble. The release compound allows the cup to still be screwed out as normal.

I also have the 45° cutting tool for putting the appropriate chamfer on the BB faces if you're going down the threadless BB route, such as Mavic YST, or M-wave.

A quick and nasty repair (only for frames that you're not too attached to, probably) is to take a 2-3 mm straight cut across the underside of the BB shell. Close up the shell with a combination of brute force and heating, then weld or braze up the gap, then retap the threade into the fresh metal of the now slightly smaller diameter shell.

As @Peachy! mentioned above, I have repaired several BB shells by reaming out the old thread to a larger diameter, tapping out to Italian spec,

View attachment 598535

then fitting a pair of thread repair helicoils.

View attachment 598534

These are steel inserts that are screwed into the Italian thread, held in with Loctite 638 Retainer, with a standard BSA thread on the inside.
This is the best way to sort it out.

PM for more details if you're interested.

View attachment 598536

All the best,

Hi , I was wondering if you could tell me where to get these Italian thread to BSA helicoils, they might just be the answer to my problem. Thanks in advance.

 

[danson67]

I have them along with the Italian BB taps and BB facing cutters that are also needed.
Get them from Peter at Ceeway..Silva Art 616: https://www.ceeway.com/Sundry-Components.htm

All the best,