Originally Posted by
joe_mn
Please, no rips on bike quality. 1yr old schwinn trailway bike. Not my bike. Bottom bracket is loose. Or specifically, the crank axle feels loose thru the bottom bracket. I took off pedal crank arm. Took off lock ring on side opposite chain ring. The "cone" nut is shaped like a "double D". It has approx 16mm flats. I do not have the special wrench a mechanic might use to remove the cone. I do have 2 separate 16mm wrenches and I am using both to try and loosen the cone nut. It will not budge. Should this cone turn with no lock ring installed? Sorry if I refer to this adjustable nut as a "cone". Since I cannot remove it, I cannot see beneath it so I do not know for sure if I have a caged bearing or sealed bearing.
........as a volunteer at the bike coop, I end up working on a lot of lower end mart bikes.
A lot of them (and I cannot say for certain yours is one) have something called a "semi sealed unit BB"
which is apparently installed on the assembly line with power tools, and can be very difficult to remove
without proper tools. On the outside, it looks like a regular loose ball BB unit, but it is virtually
impossible to service and readjust so that it will work properly because it is very difficult to adjust
the bearing play upon reassembly.
If that is what you have, the standard fix is to replace it with a new sealed unit BB of the proper length.
Again, this can be very hard to do, given the tools you've listed as available to you.