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From: AMuzi <am@yellowjersey.org>
Newsgroups: rec.bicycles.tech
Subject: Re: Stuck BB
Date: Wed, 18 Sep 2024 08:51:10 -0500
Organization: Yellow Jersey, Ltd.
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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.
>>>>>>>
>>>>>>> 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.
>>>>>>
>>>>>> I was going to suggest that.
>>>>>>
>>>>>>
>>>>>>> I have managed to chew the notches pretty good but it 
>>>>>>> will take the wrench at this point.
>>>>>>>
>>>>>>> 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. ]
>>>>>>
>>>>>>
>>>>>> 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.
>>>>>>
>>>>>> If you still want to DIY, get one of these to match 
>>>>>> your threading first.
>>>>>>
>>>>>> https://www.amazon.com/HOZAN-C-402-Bottom-Bracket-Tap/ 
>>>>>> dp/ B000BSBSLQ/
>>>>>>
>>>>>
>>>>> 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.
>>>>>
>>>>> In his aluminum shell, 
>>>>
>>>> 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.
>>>>
>>>> The question is, how do you tell if it's galled or just 
>>>> stuck from corrosion or some adhesive?
>>>>
>>>>> a small stainless brush is plenty for cleaning up crud 
>>>>> from the threads.
>>>>
>>>>>
>>>>> https://www.sears.com/forney-70488-wire-brush- 
>>>>> stainless- steel-with- plastic/p-00920078000P
>>>>>
>>>>
>>>
>>> Even with a lot of displaced material, a slit or at the 
>>> extreme two of them will relieve the pressure and allow 
>>> removal.
>>>
>>
>> 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