One Piece Bottom Bracket Overhaul

Most old American made bikes have one piece cranks. These cranks are a solid steel bar with two 90 degree (ish) bends which the pedals attach to. They're primitive, heavy, and fantastically durable. This procedure will show you how to overhaul these bearings. No special bike specific tools are needed, but you will need a big wrench that can fit a 1-1/4" large nut. If you don't have the wrench and your cranks don't have any play in them then dripping motor oil into each cup can get you by, but whats the fun in that? The bike shown here is a Schwinn Continental.

First remove the left side pedal. I often have good luck using a thin adjustable wrench. Remember it's reverse threaded:

Now remove the large nut on the left hand side. This is also reverse threaded:

Remove the keyed washer, then use a screwdriver to unscrew the cone (reverse threaded):

The next step is a little tricky. You have to slide the crank out through the bottom bracket shell. You'll need to remove the bearings from the frame cups first before the cranks can come out:

Now clean and grease the bearing surfaces:

Reassembly is the opposite of removal:

Once the crank is back in place, rethread the cone back onto the left side. Leave some play in the bearings for now:

Now replace the keyed washer, then the lock nut:

Here comes the trickiest part. You need to dial in the bearing's adjustment. There must not be any play, but the cranks should spin freely too. For some bikes, tightening the lock nut will dramatically increase the preload on the bearing, so be sure to spin the cranks after tightening. Make adjustments by loosening the nut, then turning the cone until you get the desired setting:

Again, there definitely should not be any play here once the lock nut is tightened, since the bearing cups are merely a press fit into the frame. Finally, retighten the left pedal and you're set.