Working on bottom brackets requires special tools.  At the very least, the selection should include: 12" adjustable wrench with sharp jaws, good lubricant, ring wrench, grease scraper/applicator, soft wire brush, aluminum foil and a Big Bolt.  It is also very useful to have a small magnet on hand to help with pulling the slippery ball bearings out of the cavity, but it is only a help, not a necessity.

Start by using the correct tool to loosen the bottom bracket's lock nut.  The picture shows the wrench position for tightening the BB lock nut.  Turn it the other way to remove the nut and be careful.  The nut is narrow and the tool can easily slip off of its purchase.  I always wear gloves when loosening or tightening the lock nut.

There are other methods that will allow for removal of the lock nut, however; most prove to be somewhat destructive or damaging to the soft metal that makes up the lock nut.  It is easy to distort, crush or otherwise disfigure this component.

Once the BB lock nut is removed, it is a fairly straight forward task to loosen and unscrew the adjustable bearing cup on the left hand side of the bottom bracket.  It is quite possible that you will need a special tool for this job also but I don't have one.  I just use whatever works and I exercise caution when doing so.  I do not want to damage the component.

Be careful when removing non-drive side (adjustable) cup since the little ball bearings, if of the loose design, are likely to fall out and, if your luck is anything like mine, get lost for as long as it takes you to find them.  Try to ensure that you can catch the bearings if and/or when they start to tumble out.  Count the bearings and ensure that you keep the set together.  Mixing bearing up is not a good idea!

Once the adjustable cup is unthreaded and removed, carefully pull the spindle out the left side and try to catch the bearings in your hand.  Try also to avoid mixing the fixed cup bearings (drive side) with the adjustable cup bearings (non-drive side).  Ball bearings need to go back into their original locations, if at all possible.

There are two ball bearing arrangements that you are likely to come across.  The loose ball assembly which is just that.  All of the ball bearings are installed individually in the bearing cup.  This is a bit of a pain to work with but you just might be forced to do so.  The second arrangement which is much more user friendly when removal and insertion are the issues is the caged bearing assemble.  Each set of bearings are held together in a brass or steel cage.  The complete set comes out together and goes back in together.  The only drawback to this assemble is that it is a bit more difficult to clean up.  A small concern, all other things taken into consideration.

Next, and this part can be the mother of all tasks, the fixed bearing cup on the right side of the bottom bracket needs to be removed.  A few issues surround this task and most of them will cause grief.

The fixed bearing cup is usually left hand thread.  It will have to be turned clockwise to loosen it off.  How do you know if your bottom bracket fixed cup is left or right hand thread?  Usually, you don't and you will have to feel for the movement when and if the darn thing will loosen off.  More often than not, the fixed cup will have to be turned clockwise to loosen it off for removal.

Before attempting to remove the drive side bearing cup, the bearings will have to come out.  These little guys can be difficult to reach and a magnet will prove to be a useful tool for the task.  It is also possible that there will be a plastic sleeve inside of the bottom bracket cavity.  If so, remove this first and then go for the bearings.

If you do not have the proper tool for to remove the drive side bearing cup, a 12" adjustable wrench with sharp jaws will do the job.  The edges of the jaws must not be all chipped up and rounded off.  If the jaw edges are not square and crisp, the wrench will slip and damage to the bottom bracket, the wrench and possibly your hand will result.  Even if the wrench is in excellent condition, there is still the possibility of it slipping off, since the area that it has to grip is so narrow.  With that in mind, it is wise to use the Big Bolt to help hold the wrench in position when force is being applied.

With the adjustable cup reinstalled the full depth of its threads, insert the Big Bolt through both cups, allowing the threaded end to protrude through the drive side or fixed cup.  Snug the adjustable wrench up on the narrow flats of the fixed cup.  Now, slide the Big Bolt's washer up to the wrench face and finger tighten the nut into place.  This set-up will only help to prevent the wrench from slipping.

Once this set-up is ready, put on a pair of work gloves.  You may have to apply a good deal of pressure to loosen the fixed cup.  If you do slip, at least the gloves will offer a small degree of protection to delicate skin.

Now try to turn the fixed cup in a clockwise direction first and look for movement.  Do not allow the adjustable wrench to flop one way or the other.  Keep it absolutely square to the work.  Failure to do this will probably cause the wrench to slip.  If the fixed cup moves, great.  Try a little more movement and then loosen off the Big Bolt nut just a wee bit to allow room for the fixed cup to be unscrewed.  Loosen the fixed cup some more, and so on until the fixed cup is free of the housing.

If the fixed cup does not move, try loosening in the counter-clockwise direction.  Before doing so, ensure that the adjustable wrench jaws are tightened up again and that the Big Bolt nut is still snug.  In fact it is a good idea to check each of these things before any application of pressure to the wrench.  Now try the turning in the other direction.  It might be necessary to try turning one way then the other until things loosen off.  A bit of WD 40 applied might also be a good idea.  Sooner or later, the fixed cup will release and out it will come.  The key to all of this is patience, coupled with know how.

Removing the fixed cup and be a difficult task and the cup will not always come out.  If it was improperly installed, it might be seized into place thanks to oxidized threads and fits.  It just might be necessary to take the frame to a local bike shop and ask for help.  You might also decide to clean the fixed cup in place, inspect it very carefully and, if the cup is still serviceable, leave it where it is.  As long as the fixed cup is clean and in good condition, it does not absolutely have to be removed.