Stripped bottom bracket threads -solutions please

[pigman]

Just a couple questions from me, if someone knows

1. If you're inserting the English thread coil into Italian threads, then that goes in clockwise. When you then thread in the English cup anticlockwise, it will never satisfactorily tighten as the coil will undo. This leads me to think that the coil has to be somehow "fixed" in. Is that correct?

2. Why do those threadless units have a bevel on, thus needing the frame to be chamfered on the edges. If it was made without the bevel, it would make installation a simple DIY job. There must be a sound reason

 

[jim haseltine]

I think its so they can bed into whatever remains of the BB threads so fix more securely to avoid the possibility of pedalling action causing the unit to rock in the BB shell in much the same way that press-fit BB cups can do in badly sizes frames. The retaining ring on Nadax BB units had a long bevel which was cut into by the left side BB threads as it was tightened to help lock the unit in place.

 

[danson67]

Just a couple questions from me, if someone knows

1. If you're inserting the English thread coil into Italian threads, then that goes in clockwise. When you then thread in the English cup anticlockwise, it will never satisfactorily tighten as the coil will undo. This leads me to think that the coil has to be somehow "fixed" in. Is that correct?

2. Why do those threadless units have a bevel on, thus needing the frame to be chamfered on the edges. If it was made without the bevel, it would make installation a simple DIY job. There must be a sound reason

1: Yes, usually something such as Loctite 638 Retainer, or an epoxy resin. I have even seen them silver soldered in.

2: The chamfer holds the bottom bracket unit straight and central on the BB shell. The 45° interface is better able to manage the axial, radial and precessional forces from pedalling. Without the chamfer, the bearing unit would be free to float radially within the shell, only being held axially by contact with the external faces of the bottom bracket shell.

All the best,

 

[pigman]

cheers Danson, makes sense

 

[danson67]

I have the MAVIC chamfer tool, too...



All the best,

 

[Nabeaquam]

If you guys have Locktite try the red permanent stuff. This can be removed later, for repacking, by heating with a torch. If that doesn’t hold, use JB Weld slow set steel reinforced epoxy. That might be impossible to remove later, but it will hold. Assuming there’s still some threads remaining to get it a little tight and adjusted before the stripped threads slip. I don’t know exactly what the precise problem is but if it goes in and can be clamped or held tight then I might drill and tap through the BB and cup put a grade 8 bolt in there. It might be impossible to drill and tap the hardened cup. Depends on which side is stripped. Or, drill and tap the BB for grease jerks, adjust it with new bearings and tack weld the cup to the BB . Then load it with grease. I’ve done this fix twice. Let the next guy swear at you. You could try and grind, file and hacksaw through the tacks to get it apart later. I’ve fixed a head tube in a similar manner. All these fixes are a real hack.

 

[paton]

Edco bottom bracket with eccentric cups might work.

https://www.ebay.co.uk/itm/23521332...chdOj306/ST7K5s5bjw4L+TQ==|tkp:Bk9SR9KC64OUYw

 

[Midlife]

Edco bottom bracket with eccentric cups might work.

https://www.ebay.co.uk/itm/23521332...chdOj306/ST7K5s5bjw4L+TQ==|tkp:Bk9SR9KC64OUYw

Trying to get my head around how that works.....

 

[jim haseltine]

Though I never fitted one, from what I remember the cups were unthreaded and the socket for the cartridge inside the cups was offset slightly from the centre of the cup diameter. The unit and cups had a set of marked datums which when aligned matched a 35mm diameter. To fit it the cartridge was placed in the BB shell with one of the cups and rotated until the pair wedged against the shell. The other cup was then pushed in and with pressure applied towards the other cup was rotated to fully lock the unit and both cups into the shell. Imagine the cups pressing against the inside of the front of the BB shell and the cartridge pressing against the rear of the shell. If I'm mixing things up with other units and that wasn't how they worked I'd be interested to know the exact way they fitted. The cup offset from the true centre line didn't have to be much to cover BSA, French and Italian BB diameters as the difference between them is only a touch over 1.2mm.
Always considered that there would be a strong likelyhood the centre line of the BB spindle ending up being canted slightly instead of being concentric with the centre line of the BB shell. Mind you, considering the wide tolerances in most frames it'd probably be no worse than any other BB.
I do remember hearing that they were highly dependant on being locked tightly - if left a little loose they would gradually move in service until a rider could find the entire unit rattling around inside the BB shell.

 

[Nabeaquam]

Though I never fitted one, from what I remember the cups were unthreaded and the socket for the cartridge inside the cups was offset slightly from the centre of the cup diameter. The unit and cups had a set of marked datums which when aligned matched a 35mm diameter. To fit it the cartridge was placed in the BB shell with one of the cups and rotated until the pair wedged against the shell. The other cup was then pushed in and with pressure applied towards the other cup was rotated to fully lock the unit and both cups into the shell. Imagine the cups pressing against the inside of the front of the BB shell and the cartridge pressing against the rear of the shell. If I'm mixing things up with other units and that wasn't how they worked I'd be interested to know the exact way they fitted. The cup offset from the true centre line didn't have to be much to cover BSA, French and Italian BB diameters as the difference between them is only a touch over 1.2mm.
Always considered that there would be a strong likelyhood the centre line of the BB spindle ending up being canted slightly instead of being concentric with the centre line of the BB shell. Mind you, considering the wide tolerances in most frames it'd probably be no worse than any other BB.
I do remember hearing that they were highly dependant on being locked tightly - if left a little loose they would gradually move in service until a rider could find the entire unit rattling around inside the BB shell.

Jury rigged. Piss poor solution, there is already a good solution that doesn’t require quantum physics. Use JB weld, let the next owner use use a torch to get the JB loose down the road.