Re: Stuck BB

On 9/17/2024 9:11 PM, Frank Krygowski wrote:

On 9/17/2024 3:59 PM, Zen Cycle wrote:

On 9/17/2024 9:10 AM, AMuzi wrote:

On 9/17/2024 7:36 AM, Zen Cycle wrote:

On 9/16/2024 4:16 PM, AMuzi wrote:

On 9/16/2024 2:00 PM, Zen Cycle wrote:

On 9/16/2024 1:57 PM, Mark J cleary wrote:

My Wilier has a stuck right cup BB. At the moment the cranks spin fine. It has an FSA Mega Exp crankset that is the one that is not pinch bolts but uses self extracting allen key to put on drive side crank arm. Has the wavy washer in the set up. I think that is why the bearings went bad because it allows moisture to get in not sealed like a regular shimano crank and external BB.
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The BB is of course and external BB from FSA. The let side cup bearings went bad so I used a Shimano BB60  cup because I had a spare one. The crankset works beautiful now. However I would like to simply try and use the whole Shimano BB60 bracket. I cannot however get the right side cup off. I realize it is left hand threaded but it is really stuck. I tried putting in a vice and using the bike to turn but no luck.

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I was going to suggest that.
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I have managed to chew the notches pretty good but it will take the wrench at this point.
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Any suggestions on how to get the cup free. I actually think it would be easier to simply hacksaw the cup and take it out but I don't want to mess up the treads in BB of the bike. I will take any and all suggestions on how to get this cup off. At the moment the cranks spin fine because the bearings are fine on the right side cup but I just don't like the set up. I may even go to a shimano R7000 crankset. ]

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I'm sure Andrew may have some sage advice, but if you're beginning to see damage to the cup, I'd suggest taking it to a shop.
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If you still want to DIY, get one of these to match your threading first.
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https://www.amazon.com/HOZAN-C-402-Bottom-Bracket-Tap/ dp/ B000BSBSLQ/
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Some people do like owning esoteric tools but I strongly dissuade most customers from buying dies, reamers, mills, taps. They are only and always subtractive, that is, they can (and often do) damage material but they cannot add material.
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In his aluminum shell,

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Something else just occurred to me - If his frame is aluminum and the bearing cup is aluminum, it may have galled. In that case, even notching the cup isn't going to work. In fact, doing so may damage the cup such that it won't be possible to replace the bearing, you'll basically have to toss the thing.
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The question is, how do you tell if it's galled or just stuck from corrosion or some adhesive?
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a small stainless brush is plenty for cleaning up crud from the threads.

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https://www.sears.com/forney-70488-wire-brush- stainless- steel-with- plastic/p-00920078000P
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Even with a lot of displaced material, a slit or at the extreme two of them will relieve the pressure and allow removal.
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I'm not an ME, but that's not how I understood galling works. I was told the two surfaces bond on the molecular level, I suppose one might be able to 'peel' the two components apart, but that would either leave and/or remove enough material such that the remaining threads would be likely damaged beyond use.
Not being an expert in this area, I might have some misunderstanding.

 I'm a Mechanical Engineer, but I think we need a Metallurgical Engineer at this point. But we've been talking about parts that are not in motion. As I understand it, galling requires relative motion.
 The problem with aluminum and steel, as in this situation, is different. It's a layer of aluminum oxide forming at the interface, which adds thickness to the aluminum and causes the aluminum component to essentially clamp onto the steel component. AFAIK there's no metal-to-metal bonding. But it's a famous problem with aluminum seatposts in steel frames. Searching online will show that problem is pretty common and quite difficult.
 

That's true but OPs problem is an aluminum cup in the aluminum shell of a carbon frame.
--
Andrew Muzi
am@yellowjersey.org
Open every day since 1 April, 1971