Bicycle Mechanics - Possible to Lube an Installed Cartridge BB?
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I have an old cro-moly MTB frame that I have built into a beater/kid-trailer towing bike, got the frame for $10 used. It came with a Shimano cartridge BB installed. The BB is getting pretty rough and crunchy. After using most of a can of penetrating fluid and a 4' breaker bar, I've come to the conclusion that this BB is staying in there. Yes, I know the DS is left threaded. I can't budge either cup. I've tried giving the breaker bar a few raps, I've tried giving it a pull in the tightening direction before trying to loosen it. I've been applying the penetrant for about a week now (not WD-40), both to the outside and through the cable guide screw hole.
Has any-one ever attempted to force new grease into a sealed BB while it was still installed? How would you go about it?
If I can't service this, then I guess the frame is toast. I don't mind scrapping it in principle, but there's not many suitably cheap replacements available around here in my size.
05-12-10, 01:01 PM
A small needle such as a soccer ball inflation needle MAY be able to get past the seal and allow a slow injection of grease. But if it's already actually crunchy then grit or rust is present in the bearings so whatever you do will be borrowed time at best or not effective at all at worst. If it's crunchy then at best you'll get a couple of thousand klicks out of it before the bearings wear and you have excessive play in the pedals.
Since it's sort of toast already try some heat applied to the BB shell along with a good strong breaker bar. Play a propane torch over the area enough to get it hot but not enough to scorch the paint. This should cause the shell to expand enough that you will have a better chance of getting the cups to break loose.
you might try some heat, but given all the oil you have applied you might want to do it outside away from any buildings if you plan using an open flame like a propane torch. for sure you need to get at least the non drive side off to get the bearings out. you might get some light oil past the bearing seals but the grit is not going to wash out past the seals.
edit; you might take the frame and tool to a tire shop and see if they would put a rattle gun on it.
05-12-10, 09:28 PM
The frame is ALWAYS serviceable since you told us that
b) you don't care about the paint
Hold the BB tool in place with the appropriate tool or a DIY thingy. Heat up the bb shell with a propane torch, and have at it with a large wrench and breaker bar.
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