SlowestCat3 said:WD40 is just about the worst thing you could spray in your BB. If it were that easy, we'd buy a new BB every couple years. Just accept the fact that it's gone. I have an old style Campy BB (cup and bearings) on my winter bike. I just repack it and replace the loose bearings regularly and it works pretty well. Even the Record BB can die if it's exposed to water too often. The BB, IMO, is the only slight weak link in the Campy chain. It's worth it to me to deal with it and stick with Campy. I wouldn't even use Shi*mano to fish. That's just my take. Oh, I forgot... I don't fish.
BMC SL01 (2006 Chorus)
Trek OCLV (1995 Chorus...and still going strong)
Eddy Merckx Team 7-11 SLX (1994 Chorus)
Stupid GT Zaskar mountain bike gathering dust....
I "love" that remark ... it's a great parrot of what I've also read in BICYCLING magazine espousd by somone who probably didn't take high school chemistry/physics/whatever, yet aforementioned published mechanic is taken as Moses coming down from Mt Sinai!
Just trust me ... with SEALED cartridge bearing bottom brackets, the amount of WD-40 or Household Oil infiltration will be minimal ... but, it will probably be enough to move the grease around the ball bearings enough to smooth things out. There's no way on God's-green-Earth that enough WD-40 will enter the cartridge bearing to truly flush the grease out!
If anyone can get enough WD-40 (or, equivalent) into a sealed cartridge bottom bracket, then he-or-she can clean & regrease the cartridge bearings.
I'd elaborate, but it isn't my intent to "convert" anyone ... I was just relating a solution which I know has worked in the past for me when confronted with a cartridge bottom bracket which is no longer smooth.
IMO, the people who should worry about misusing solvents & lubes are the ones who use chain cleaners which scrub & flush the (cosmolene-type grease in the case of Shimano) "grease" that lubes their chain's pins ...
BTW. A properly maintained, vintage, "loose" Dura Ace (and, Shimano 600, too ... heck, include the Sugino & SunTour BBs, too, amongst others) bottom bracket will be as smooth as a vintage Campagnolo bottom bracket.