Boardman MTX rear hub wear

[ArtVandelay]

I have been trying to service the rear hub on my boardman MTX 8.8 because i noticed a bit of friction.

When it was back together i noticed it would catch on a rough spot every rotation. So after a few more attempts decided to take the driveside apart.

All the bearings look fine but i noticed some unusual wear on the cone. First thing i noticed is it has two flat sides which i think is how it is manufactured. Also that there gouging and pitting around those areas. What i wanted to try and work out, is this purely wear or was it intended to have two flat spots?







I also noticed there was very little thread coming out on one side of the axle, it only sits a couple of mm on the bike as is. Should i be concerned about this too?

[531colin]

I don't know what that part is, but it isn't the bearing surface of the cone.
Give us some more photos to give the context of where it is.

[Eyebrox]

That's the left side cone. It's shaped that way so you can attach a cone spanner. The number of threads showing at each side after all the bits are fitted (washers, dust cover etc) should be equal. If one side is shorter than the other you just work the axle further through the hub using cone spanners until it is properly centred.

[ArtVandelay]

I don't know what that part is, but it isn't the bearing surface of the cone.
Give us some more photos to give the context of where it is.

Thank you, it looks unfamiliar to me too, i thought perhaps it was just this hub.

i have placed it back on the axle as i took it apart. It sits flush with the small rubber gasket and the cone part fits neatly into it, but it does not look like it should be a surface for the bearings like you say.



Edit* i have just realized posting this that it is supposed to sit on the other side of the cone. I feel like that was so obvious but it wasn't until typing this out that i realized. I couldn't see past the way i took it apart. I bought this second hand and fortunately decided to service it before putting too many miles on it

[slowster]

I think that that is a Formula DC-22 rear hub. If so, the exploded diagram for it can be viewed here. The part you have referred to as a cone looks like part 14, and it looks like you have incorrectly re-assembled the hub (which might explain why you no longer have 5mm of exposed axle on the right hand side).

[ArtVandelay]

Thank you. The advice here has been incredible. I would've been scratching my heads for hours more without it

[gregoryoftours]

That part is a kind of a top hat shield/washer. It's a piece of bad design that I have also come across recently. It goes between the cone and the locknut on the drive side. It is a bit like a washer in between those two parts except that it cups the flats of the cone itself, blocking access to them.

So to lock the cone against the locknut on the driveside you can only use the flats on the top hat shaped washer, not on the cone itself. This means that the cone can't be securely locked off and it's likely to precess into the hub and cause problems.

I used some high strength threadlock on the ds cone before fitting the top hat washer and locknut. Hopefully that way it will stay put.

And yes you could do with evening the axle out so that the same number of threads are protruding on both sides of the hub.

[Brucey]

just in case it isn't obvious by now the two flats on the 'top hat' part are so that the RH cone fits inside snugly, and still permits the cone to be tightened using a suitable cones spanner (16 mm or 17mm ?). As noted above this is a poor design in that for the hub to be reliable, the RH cone and locknut need to be perfectly secure i.e. locked hard against one another. if they are not then in use they will loosen and wind themselves (precess) into the hub and wreck the bearings. I think that a cone spanner is liable to slip on the top hat part, making it difficult (if not impossible) to tighten the cone and locknut against one another properly.

So the procedure is to assemble the RH cone and locknut securely (eg using permanent threadlocking compound) at the correct distance (typically leaving ~5mm of axle thread showing). Then leave the RHS parts alone; assemble the hub by inserting the axle assembly from the RHS, then adjust the hub bearings using the LH cone and locknut.

The correct adjustment is a little free play in the bearings, that just disappears when the QR is used to secure the wheel in the frame. If there is no free play at all (with the QR loose) then the bearings are set too tight and will be subject to premature wear.

FWIW I think Slowster did well to find a diagram of this hub. IME a major source of drag in these hubs is often the RH seal. For the seal to work properly, the freehub to last and there to be low drag , I find the use of a semi-fluid grease in the RH bearing is best. With other greases the seal runs dry too soon for my liking and then of course gets torn up.

cheers