noisy disk rotors...

[ianfitz]

Maintenance Saturday troubles:

I finally got round to getting a second hand (QR version so fingers crossed!) SP hub built up into a wheel, for road use. Popped on an old rotor and stuck in in my forks. Disk rotor was rubbing, adjusted caliper, but realised it was rubbing due to side-to-side movement. Hmm...

Ok, maybe it is warped. It's an old one after all. Replaced with a brand new one - same thing. Side-to-side wobble. So tried one that works perfectly on another bike - same thing with all three.

Can anyone think of anything other than the tabs on the hub are not lined up?

And if so what can be done...

[whitestone]

What does the SP hub (with any rotor) do in another set of forks?

[MuddyPete]

Does the wheel rim wobble parallel to the disc wobble (i.e. off-centre axle)?
Is the rotor mounting surface on the hub parallel to the wheel rim (i.e. machined evenly)?

[ianfitz]

What does the SP hub (with any rotor) do in another set of forks?

Good point. Just tried and yes same issue.

[ianfitz]

Does the wheel rim wobble parallel to the disc wobble (i.e. off-centre axle)?
Is the rotor mounting surface on the hub parallel to the wheel rim (i.e. machined evenly)?

The rim is spot on.

But have just now removed the rotor and bolts there's a similar thing going on with the flange the bolt holes are in.

Does anyone know how to face a hub!

[slarge]

Easy in a lathe Ian, but the wheel will need to unbuilt. I would either set to with a file or see if the hub is twisted

[ianfitz]

Easy in a lathe Ian, but the wheel will need to unbuilt. I would either set to with a file or see if the hub is twisted

How do you mean twisted steve? In what way? I was sure to check, in both forks, that the wheel was in straight

[whitestone]

From your description it sounds like the rotor mount on the hub isn't perpendicular to the axle implying it's been damaged in some way.

To verify this you need to remove the rotor and axle and place the hub rotor mount on something like an old turntable, anything that is properly horizontal and can rotate will do. Shine a light from underneath the turntable through the axle hole. turn off the lights in the room and spin the turntable. If everything is correct then the spot of light on the ceiling won't move. If the rotor mount has been twisted then it will describe a small circle on the ceiling.

[PaulE]

You might be able to use a few 0.1mm spacer washers behind some of the rotor to line it up? Otherwise, I can probably skim it on a lathe for you if the hub is unlaced.

[ianfitz]

From your description it sounds like the rotor mount on the hub isn't perpendicular to the axle implying it's been damaged in some way.

To verify this you need to remove the rotor and axle and place the hub rotor mount on something like an old turntable, anything that is properly horizontal and can rotate will do. Shine a light from underneath the turntable through the axle hole. turn off the lights in the room and spin the turntable. If everything is correct then the spot of light on the ceiling won't move. If the rotor mount has been twisted then it will describe a small circle on the ceiling.

I'm pretty sure that's the case. With rotor and bolts off I can see a variation on the bolt tabs as it spins in the fork. Holding a metal point to it.

The continuing failings of SP products! I did say I'd never have another but was tempted by a secondhand one...

I'll have a look at it with a file as steve suggests.

[ianfitz]

You might be able to use a few 0.1mm spacer washers behind some of the rotor to line it up? Otherwise, I can probably skim it on a lathe for you if the hub is unlaced.

Can I make some out of beer cans?

Not that I need any excuse to have a beer!

[slarge]

Ian, by "twisted" I mean the 2 halves of the hub have moved. The hub outer shell is made up of 2 cups that are pressed together - the join is the ridge in the centre of the wheel. If during the wheel build the 2 halves got moved relative to each other then you would see the symptom you have. If this is true then the magnet inside may not be true either, and you may have a very notchy hub when you spin it.

Do you have any of the old Hope IS caliper spacer washers? They may help to get the disk a bit more true.

[ianfitz]

Ian, by "twisted" I mean the 2 halves of the hub have moved. The hub outer shell is made up of 2 cups that are pressed together - the join is the ridge in the centre of the wheel. If during the wheel build the 2 halves got moved relative to each other then you would see the symptom you have. If this is true then the magnet inside may not be true either, and you may have a very notchy hub when you spin it.

Do you have any of the old Hope IS caliper spacer washers? They may help to get the disk a bit more true.

Ah, not thought of that. I also wonder if that is implicated in the failure of some (many) units. Would it impact waterproofness? If that's a word!

Don't think I've any IS stuff left.

[fatbikephil]

Check the trueness of the spoke flange as this will show if the hub shell is squint. Trying to machine it square may not work as the rotor bolt holes will also be squint. I'd be tempted to get the hub shell apart and line it up properly.

[slarge]

Ian, don't split the shell, it won't go back together cleanly. Try and adjust it with a few taps on the disc flange with a small hammer. At this stage you have very little to lose.

[dlovett]

Fingers crossed you sort it out