Shimano FH-M525A - buy spare or another?

[mikeymo]

Although in theory the drive side is wider than the non-drive side its not by much (12.5 vs 14mm). So pushing out the bearings in one go with a single 14mm drift would risk bending the race in the middle I think ? The YouTube method of gradually knocking it out at four points might be safer ?? What do people think ?

If you have access to a big enough vise, I would try pressing it out. Something 14mm in diameter through the hub, and a bit of tube about 40mm diameter to push the cup into? (tube bears on disc mounts?)

Thanks, excellent idea. If not a vice, a G-clamp or similar perhaps. An accurately cut drift of some sort, with the end perfectly square, should do it. And avoids the potential damage from hammering.

This is probably theoretical because, as others have pointed out, a reasonably well maintained hub should last, and the final bearing surfaces to go are the hub shell cups. Still, it's good to have an idea how to do it, if necessary.

[531colin]

G clamp can go cocked but a vise will push straight?

[mikeymo]

G clamp can go cocked but a vise will push straight?

You're right, quite possibly. I was mainly thinking of what I personally have. Though there are plenty of facilities I can "borrow" if this situation ever occurs.

[Brucey]

FWIW in the bad old days we needed a mushroom-headed drift or a fancy tool if we wanted to knock the cups out of tullio's finest, and in lesser hubs (which was pretty much everything else) access to the back of the cup was often obstructed by the hubshell. Fortunately Al is fairly soft, so it wan't too difficult to find a way of getting the job done. However in recent years two things have happened. First, I have concluded that there ought to be a much faster way, and second, I have finally realised that old pedal spindles are an excellent resource for anyone wanting a hard steel.The net result was that I found that it took just a few minutes to make a new cutting tool from an old pedal spindle, using an angle grinder and a drill. The new tool goes into an ordinary drill and removes Al very quickly, so a hubshell can be modified in just a few seconds if needs be.
I also think that although they might start out as an interference fit, most cups would benefit from having a slightly smaller OD and being bonded into place using epoxy resin. This (along with appropriate filler pieces) would help support the cup from behind, thus preventing bad cracking of the cup as well as making the whole bearing a bit smoother because it should allow the cup to be reground too.