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Is my fram toast? Stripped BB threads

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endoMaster

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Discussion starter · #1 ·
Tonight while removing my bottom bracket to replace it I ran into trouble. When I tried to remove the bottom bracket from the drive side it was extremely tight. I pretty much had to use a skewer to hold the tool in place and a HUGE crescent wrench to get enough leverage to turn the bracket.

Once it was off I saw all the extra material on the bottom bracket threads and also all the missing material inside the bottom bracket cup. It looks like a full 1/4 inch of the threads are gone, essentially the full area that the bottom bracket screws onto.

So, like the title reads, Is my frame toast? I can't see how the bottom bracket cup could be retapped since all the material there is gone. Is there somethinglike a heli-coil that could be used to repair the bottom bracket.

The frame in question is a 2004 Specialized Hardrock frame.
 
#2 ·
shot in the dark...

I believe that somewhere along the line I remember seeing a "Threadless Bottom Bracket" It kinda clamped the frame from each side rather than threading into it, but I think it only fits 68mm bb's. Not too sure tho, it was a while back. Mebbe worth lookin for instead of tossing the frame in the trash? (biketoolsetc.com maybe?) Otherwise a machine shop might be able to make a custom spindle, and bearing cups that thread into eachother through the frame, bypassing the stripped threads, that would work with regular cartridge bearings. Proble the most costly option, but if you know a machinist it might work in yer favor? Good luck!
 
#4 ·
Yeah, let your bike shop handel it. Nothing a good tap and a steady hand usually can't fix. You could consider having a welder slap another bb shell on the frame if it's that bad.

I'm not sure if anyone does one now, but I used to have a Mavic bottom bracket that was tightened and pressed into the frame. You had to angle the BB shell with a special tool that enabled it to mate with the BB cups that pressed into them via tightening the cups onto the BB (did not use the threads on the frame at all). I had external BB berrings on my bike back in 1991, and I went that rout because I knew the further out the berrings were the better power transfer I would get. Funny how things come full circle almost 15 years later.
 
Discussion starter · #5 ·
Well, took the frame to my LBS and they told me it wasn't repairable. I think I'm going to take it elsewhere and get a second opinion. When i got home I used a different bottom bracket that I had around and tried screwing it in. Lots of resistance obviously but it's making me thing there is enough material left to retap it.
 
#6 ·
2 Options Really

#1 as mentioned already would be to locate a Mavic BB. You would have to run square taper cranks (which is a plus in my opinion) and have to find a well established bike shop that has the Mavic BB tool to face your BB shell.

#2 would be to throw the frame away. Since we're talking a Specialized Hardrock frame pretty much any time your bike shop puts into repairing the damage will be equal to the value of the frame. Also you may be able to get a warranty replacement. Some reps will replace anything even if it shouldnt be covered under warranty just to keep you loyal to their brand.
 
#7 ·
options

the other replies have already touched on some of them.
we're assuming there's not enough meat left to be salvaged by just chasing the threads.
1. re-cut BB to Italian. Requires a skilled shop with the special cutting tool, but possible, as Italian thread is slightly larger. Then you need to track down a square-taper BB, probably a Campy from the late 80s, early 90s. Actually, come to think of it, if you can locate a pair of shitmano Italian cups, you can fit pretty much any length or series of shitmano spindle, most all the older shitmano cup and cone stuff was interchangeable, and old road lengths would be appropriate for modern compact mtb cranks. probably easiest to track down. shitmano italian cups for road bikes are not uncommon
remember, even though you've now got Italian threads, you still have a 68mm shell (unless it's a 73mm) and not the Italian-standard 70mm shell, so english spindles for 68mm shells are the ones you want, even with the italian cups.
2. Locate a cartridge bearing BB set that has its cartridge bearings facing outboard, where you can access them without removing the cups. Then PC-7 or similar epoxy the cups right into the shell. I used an Alpinestars ti BB set, which has out-facing bearings, to rescue an old Viscount road frame I found in the trash, turning it into a road fixed gear. The epoxy has held for like 6-7 years so far, and I haven't even had to service the bearings so far. Dunno what other BB sets have outboard bearings, look around I know there are some.
Or if you're willing to part with the frame once the cartridge bearings wear out, you could do this with any BB set. In which case maybe upgrade to Phil Wood bearings so at least they last a long time before you have to trash the frame.
3. Mavic BB: Good luck finding one, not sure what lengths were available though they did have both road and mtb versions. you need the special cutting tool to chamfer the edges of the shell to fit the lockrings. They were really sweet sealed cartridge units, way better made than today's shitmano crap. If you could find one and the tool (which goes in your shop's cutting tool, not a home job) it would serve you well.
4. an idea I never tried that may work. determine the ID of the shell, then locate sealed cartridge bearins with that OD and a 17mm ID for a standard straight Phil Wood or ActionTec spindle. Force-install the bearings into the shell with a liberal dose of LocTite sleeve retainer, 609 or 640 I believe, it's green. www.aebike.com or www.bocabearings.com lists bearings by ID and OD.
 
Discussion starter · #8 ·
It looks like it might be salvagable regardless of what my LBS said. I've been cleaning out inside of the cup as best as I can to get rid of any loose material and have managed to screw in an old bottom bracket i had laying around. It caught onto what remained of the threads closest to the outside of the cup and I slowly screwed it in. I pulled it out occasionally to see if I was crossthreading it and it all looked fine. The bottom bracket also screwed onto a section of the good remaining threads so I might be able to torque it down once I get a hold of a good bottom bracket again.

I'm going to still take it to a different bike shop and have them clean out the threads that are in there.

On the plus side it gave me a reason to go bike shopping. I found an '03 Enduro Comp, brand new but I was curious about the price. I have a feeling I will be told it's a good deal; Is 1300 out the door a good price for this bike. I was going to buy a used full suspension bike but this seemed a bit irresistable to me especially while I was sitting on it in the sales floor.

I wanted to thank everyone for their advice but if I couldn't get the threads repaired then I was just going to trash the frame. Someone mentioned cost of repair being a factor and I agree, no point in paying more for repairs than what it's worth. Nevertheless, great advice and recommendations that I'll keep in mind if this ever happens to me again with a much more expensive frame.
 
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endoMaster
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