Trying to remove the bottom bracket on a '92 Marin Bear Valley. Right side has a plastic cup that's broken since over a decade. Left side seems metal. Wouldn't budge, neither with a wrench nor an impact. Tried fixing the tool in a vice and turning the frame for leverage, as it's often recommended here. What now?
by random_word_sequence
14 Comments
Did you try a big socket, 1/2 inch with a 1/2 inch big breaker bar? Leverage it
Heat
Penetrating oil
~~If the drive side cup is one piece with the cartridge (as it is on a UN-55, for example), this will work fine.~~ lol ignore that part this is on the NDS
If it is a separate piece, you could be fighting yourself with this setup. Add a very strong compression spring on your bolt between the bolt head and the washer. Or loosen it up a bit – still tight enough to hold engagement on the bottom bracket tool to the cup splines, but also loose enough that as the cup is loosening, your apparatus isn’t fighting you.
you have to allow some freeplay in your fixing bolt, or you’re just trying to stretch the big ass bolt and break free. So make sure it’s loose enough to jiggle, but not loose enouge to let the tool out. Once you get slight rotation, then re-loosen the fixing bolt a little more…repeat as needed. Apply penetrating oil, heat (careful to not thrash paint), taps and 24 hours, then be extra sure youre rotating correctly (top of BB rotates forward to loosen-opposite of pedals)
Not to be condescending in anyway, but are you turning it the right way?
I recently dealt with the most stuck bottom bracket I’ve encountered and this tool: [https://pedros.com/collections/pedal-crank-bottom-bracket-tools/products/bb-socket-holder-ii](https://pedros.com/collections/pedal-crank-bottom-bracket-tools/products/bb-socket-holder-ii) worked for me. It essentially holds the bottom bracket tool in place. I was able to get a big ass pipe clamp on the bb tool and free the bb.
Following this with baited breathe as I am attempting an identical job with a ‘95 Marin Shoreline Trail!
Same problems, same progress!
I know bike mechanics don’t believe in power tools but I’d use a cordless impact driver (not an impact wrench for automotive lug nuts; an impact driver like for driving screws).
I once drilled a BB out, with the largest drill i could find. Took an eternity. When only the shell was left of the BB, i cut it out with a saw.
Might have to mention that I had a complete workshop for trucks and forklifts at my disposal. Heavy tools….
You need to have a little play in the bolt that fixing BB tool to BB. It just won’t go without it. And tou need to keep this play when unscrewing.
There were some Shimano unit bottom brackets that were plastic support cup on the driveside and the unit screwed into the non-driveside. You’re doing the right thing with bolting the tool into the bottom bracket, the lowest cost option is to put a 12″ adjustable spanner onto the tool, then slide a scaffold pole over the spanner. Heat and oil will help, once you’ve got it moving spin it back half a turn every now and then
Keep oiling it, return once a week to try again. If you can lock the BB tool onto the BB, then attach a long, sturdy, arm for leverage and use a hammer to whack the arm. Usually it will start to move eventually.
I’d try heat… not crazy heat, but everything I’ve seen suggested in this thread should have worked before your vice cracked. Unless your Marin is actually a Peugeot with a French BB snuck in there or something (actually that’s worth a shot…) you should get some movement out of it by now.
If you’re getting literally nothing, not even so much as a creak, with the methods you’re describing, then maybe someone popped some red loctite in there or even krazy glue or something. If that’s the case then heat will soften it. Even epoxies start to soften as low as 70C, so even a dump of boiling water might be enough to make some progress without trashing your paint.
I’d actually try the opposite direction just to get some movement. Maybe the face of the cartridge BB might crack off, but even that would release the tension and you’d still have teeth on the inside for removal. OR, you find out that you got one of 10 frames that Marin experimentally manufactured in Paris between Tuesday and Thursday the third week of March of 1992… (to be clear I’m not suggesting that’s the case, but stranger things have happened)
Use the longest lever you can find! Idealy a least 35 to 40 inches.