Bicycle Mechanics - Hub seizing after a few rotations -- is the dustcap tightening the cone?

I was trying to overhaul my rear hub which I found to be seized up, I get the cones to sit right and then tighten the locknut. When I spin it it spins great for a few rotations but then suddenly seizes up until I spin it the other direction, it will spin in that direction for a few rotations then seize up again. I am guessing that the dust caps are hitting the cone and tightening it down but I am not sure of this. Any ideas?

If the cone/locknut interface is tight enough, nothing the dustcap can do will move the cone. Torque them together very firmly.

Ah ok I was under the impression that the locknut only prevented the cone from loosening and not tightening, I will try this.

I have had good luck using a 'three wrench' aproach. I use a cone wrench and adjustable wrench on one side, and adjust the other side with a cone wrench. When I get the adjustment right, I hold all three wrenches, and tighten the locknut on the adjusting side with another adjustable wrench. Might seem kind of 'kludgey' but it has worked well once I got used to it.

The side with the cone/adjustable wrench is kept tight.

Ah ok I was under the impression that the locknut only prevented the cone from loosening and not tightening, I will try this.

Then you missed out on a fundemental issue for hubs. The cone needs to be torqued tight to the locknut, along with any in between spacers, to ensure neither moves. So you need a set of cone wrenches to hold it while tightening the locknut. You will also need to do this with an eye to achieving the correct bearing preload so that the bearings are neither tight and "coggy" feeling nor loose enough that they just barely don't have any noticable wiggle at the rim. Ideally with the QR skewer pinching on the axle with it's normal tension the axle should spin with just a very little drag due to the preload.

Ah ok I was under the impression that the locknut only prevented the cone from loosening and not tightening, I will try this.
+2 You were mistaken. I do the three wrench trick as well.

Three wrenches? I would think the money for an axle vise would be well worth avoiding such gyrations. In any case I don't really see the advantage. If the opposite cone and locknut are properly locked together with a lockwasher in between they are not going to move in my experience.

Three wrenches? ...I don't really see the advantage. If the opposite cone and locknut are properly locked together with a lockwasher in between they are not going to move in my experience.

It's not about the other side cone + locknut moving WRT each other, it's the cone + locknut on the side you're working on moving WRT the axle, messing up the adjustment you're trying to achieve.

get a axle vise or just clamp the lock nut on a front hub in a vise. at the very least use the park tool method to clamp one side of the hub in the frame/fork to hold it stationary. ideally clamp it to a junker frame/fork, the drop outs can bend

It's not about the other side cone + locknut moving WRT each other, it's the cone + locknut on the side you're working on moving WRT the axle, messing up the adjustment you're trying to achieve.

k, was not entirely clear but an axle vise is still a lot less awkward.

k, was not entirely clear but an axle vise is still a lot less awkward.
+1 I don't know why these aren't a universal tool for anyone who overhauls hubs.

I have a slot on my workbench where a 3/8 inch ratchet wrench is held in place. Otherwise, I would go the vise route. Axle tends to turn, which loosens your cone while you are trying to secure it. Do it a couple of times, and you will see the axle move on you.

That axle vise (more accurately a set of fitted soft jaws to use in a regular vise) doesn't look like it would get a good secure hold on the stubby bit sticking out of a QR axle. But for then you've got the other locknut that you can grab with the regular vise jaws.

Either way when adjusting the cone and locknut to get just the right preload I pinch the side that's already locked down into the vise. Otherwise it could be a very frustrating experience.

..when adjusting the cone and locknut to get just the right preload I pinch the side that's already locked down into the vise. Otherwise it could be a very frustrating experience.

+1

I do the same. The force required to position the axle is minimal.

That axle vise (more accurately a set of fitted soft jaws to use in a regular vise) doesn't look like it would get a good secure hold on the stubby bit sticking out of a QR axle.
Ahhhh, but they do. I have a Park AV-4 that has three recessed "holes". One is for front axles, a slightly larger one for rear axles and a third even larger one for pedal axles. Clamped in a good bench vise it does indeed hold the wheel/hub assembly very steady just by griping the stub sticking out past the locknut. I used to have a smaller Park AV-1 that only fit front and rear axles, not pedals, and it too did a plenty good job of holding the wheel steady while the hub was adjusted.

Now, if you cheat and respace a 126 mm hub to 130 mm without changing the axle, maybe the shorter stub wouldn't be enough but the standard 5.5 mm stub is plenty to give good firm support.