Originally Posted by pierce

my guess is, you either got the wrong sized balls in the wrong place, or you didn't have the locknuts setup right against the cones.

is there a Shimano part number on these hubs? it will likely be FB-Mxxx or similar. for instance, a HB-M585 is a Deore LX front hub for disc brakes, and the parts diagram is here, https://techdocs.shimano.com/media/te...9830637979.pdf

the index to all shimano parts is here,
https://techdocs.shimano.com/techdocs/index.jsp

and you can enter a part number in that search box on the upper left to find it. or, go to mountain or road bike, and select a 'group' and scan the list of all parts in that group.

re: cleaning with WD-40... Not having a professional parts cleaner machine, I use that all the time, I buy it by the gallon can (a gallon lasts me /years/). don't waste your time with aerosol cans. I'll just take some 'rubbing alcohol' (Isopropyl aka isopropanol) and wipe off the brake surfaces when I'm done. or you could use a paint thinner for this, anything that will dissolve grease and leave a clean metal surface. small parts like axles, cones, bearings go into a jar or can and get covered with WD40 to soak out the old crud, then wiped clean on a rag and left out to dry for a bit. hubs, I have a squirt bottle (the kind with a trigger) filled with WD40, and will squirt it into the fully diassembled hub cups and wipe clean with a rag, repeat until shiny clean.

re: grease, I generally use green 'marine' waterproof ball bearing grease, this should be available at any auto parts store. its nice and clean, lasts a long time. bicycles don't need a high temperature lithium or moly grease (the black stuff is probably moly, the yellow-white stuff lithium). When you reassemble a ball bearing, you want to pretty much FILL the area the balls are in with grease such that it oozes out when you assemble the cone + seal. wipe away any excess on the outside of the seal, of course.

Originally Posted by pierce

ok, here's your hub.
https://techdocs.shimano.com/media/te...9830647993.pdf

the stack of parts under the '3', from left to right, that's the cone, a couple seal rings (4), a washer and the lock nut. on the other side, under '7', its the same thing the other way (cone on the right, then seals, spacer washers, and the outside lock nut on the left side of the drawing.)

you need a special thin 'cone wrench' to fit on the flats of the cone, to hold it while you tighten the lock nut with an ordinary wrench. the cone has to be set just the right against the bearings when you do this. if things are loosening up, its not assembled right, and the locknuts aren't tight enough against the cones. Usually, you set and tighten one cone before you even assemble the bearings on that side, insert the axle into the hub, and thread the other cone over its bearings.

either the Park Tool site, or Sheldon's, should have pictorials on how you do this.

Originally Posted by pierce

oh. when you get the cassette off, it will come apart in several pieces, depending on exactly what model. Typically, most of the larger cogs are riveted together, but the small ones just sit on the splines, then the lock holds them together. there probably are some spacers between some of these. the cogs have to be aligned a specific way when they are reassembled, its its very important to keep track of how it came apart.

the cassette is fitted over a 'freehub' which has a spline on it.... one tooth of that spline is winder than the others, thats the alignment mark. the cogs that come loose, also have one wider tooth that has to be aligned with the one on the freehub, and its very important that you put the cogs on right side out.

if its a Shimano freehub, it probably has markings to aid in reassembly, like this example one:

https://techdocs.shimano.com/media/te...9830700115.pdf

if its another brand, well, there's less documentation.