How to install Bearings and Cups in Bicycle one piece Crank

Frequently, when a crank bearing tears up, the inside lip of the  cup has cracked and is bent.  This will cause new bearings to tear up soon after you put them in.  Sometimes, the inside lip of a cup has a crack in it and has not yet become bent.  You can probably see that crack by looking through the inside of the bottom bracket shell with a flashlight.  If the inside lip of a cup is cracked and  not bent, it might be several days, months, or years before it bends and causes the bearing to tear up.  Most bicycle mechanics advise to replace cracked cups. 

If you want to remove the old cups, just get something long enough that you can hit with something to knock the cups out.   Don't hit the cup so hard  that it comes out the first time you hit it.  Instead, hit the cup a few times in different places until it comes out. 

To put in new cups, get a flat piece of wood almost as wide as the cup.  Put the cup on the bottom bracket shell and place the piece of wood on the top of the cup so the cup will go straight into the shell when you hit the piece of wood with something.  Or, you could use a cup press if you have one. 

Take both of the old bearings out of the cups before you try to pull the left side of the crank through the bottom bracket shell.  It will be easier to pull the crank through the shell with the bearings out of the way.  Also, if you want to save the old bearings, it might damage them if you try to pull the crank arm through the shell while either of the bearings is in the cup. 

If you put the bearing in backwards, it will tear up as soon as someone rides the bicycle.   The side of the bearing retainer that has several curved pieces that hold the balls in the retainer goes toward the inside of the cup.  

IF YOU WANT TO USE THE OLD KEYED NO-TURN WASHER FOR THE LEFT SIDE:
The washer goes under the lock nut and the nib goes in the groove on the crank arm which prevents the washer from turning when you tighten the lock nut.  Sometimes the nib has become damaged in the past and is now shorter that it was when new and one  of the edges of the nib has become slanted..   This causes the nib to come completely out of the groove when you start tightening the lock nut, which allows the washer to turn, which causes the cone to turn.     So, before you start to tighten the lock nut, put the flat part of a screwdriver on the washer just over the nib and push on it while you are tightening the lock nut so the nib will stay down in the groove as far as it will go.  Or, stop tightening a few times to push the nib back down in the groove in case it has come part of the way out.  Even if the nib is so short that it will come completely out of the groove, it can still prevent the washer from turning if you push on it to keep the nib down in the groove as far as it will go.  This can also be done with a new washer to prevent the end of the nib from   getting damaged.  Be careful because the screwdriver will frequently slip off the washer while you are pushing on it and could cause you to be seriously injured.     

Sometimes, after you put a new bearing in the right side of the bicycle (the side that has the sprocket), the crank will slide out a little on that side, dragging the bearing with it when you start to work putting the bearing in the left side.  Then, when you pull the right side back in against the bearing, the bearing may be slanted and part of the bearing will be all the way down in the cup and part of it will not be all the way down in the cup.  So, before you tighten the lock nut on the left side, turn the sprocket to see if it wobbles.  If it wobbles, the bearing on the right side moved out of place and has become slanted.  To straighten the bearing, just loosen the left cone enough so you can move the crank up and down a little on the right side, moving the bearing so it will be straight.  Then, hold the right side against the bearing to keep the bearing from getting out of place while you tighten the left cone. 

Most of the articles on how to adjust crank bearings say that you need to leave a little play (looseness) in the bearing before you tighten the lock nut because the lock nut will compress the bearing cone closer to the bearing and it will be too tight if there was not enough "play" in it before tightening the lock nut.  Most articles say to tighten the adjusting cone until it is against the bearing, then back off about one-fourth turn or one-eighth turn.  This will often give close  to the right amount of play in the bearing before you tighten the lock nut.  Tightening the lock nut will remove most or all of the play.  After tightening the lock nut, turn the crank slowly and lightly with your hand to see if there is any binding anywhere.  If you come to a place where it binds, stop, and loosen the adjusting cone slightly and retighten the lock nut, then try it again.  If there is too much play everywhere except at the spot that is binding, something else is wrong. 

This is a guide I wrote.  It is on Google's blogger.com website.    It is a list of articles  and videos on youtube  by several different people.   To see it,  click the link below, or put the title in the Google SEARCH. 

You can see videos on youtube showing how to install and adjust cups and bearings in a one-piece crank.... 

How to install Bicycle Parts, all kinds. See videos on youtube


DISCLAIMER:
I am not responsible if anyone is injured because they followed the instructions in any of the articles that I wrote, or in any video or article by others that I recommend.  Some of the information in the articles I wrote and in the videos and articles by others that I recommend may be dangerous if someone tries to follow the instructions in those articles and videos.  Repairing or servicing bicycles can be dangerous.