Diagnosing brake disc/hub not spinning 'true'/wobbly...

[TeddyRuxpin]

Video spinning just the hub for what it's worth. Appears to spin true:

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[TeddyRuxpin]

You need the disc clamped to the hub. The wheel bolts are too long to do that without fouling the strut if wound in sufficiently to clamp with out the wheel being mounted.
Either, use shorter bolts (awkward) or spacers on the existing ones. Improvise - sockets, bits of metal tube, etc.

You're right as I can still feel some play when the disc is on. Perhaps I could try the space saver wheel? Probably a bit big...

I'd like to figure out a way to test this, for curiosity's sake if nothing else...

 

[TeddyRuxpin]

Could you bolt the wheel to the hub without the brake disc, you'll definitely see any run off then?

Yes, I think I'll try with the space saver as the caliper is still there hanging off to the side and the full size wheel will probably foul it.

(I meant with the disc on though to see if having the bolts pressing the wheel into the disc and hub corrects the run out)

 

[Bellow]

You're right as I can still feel some play when the disc is on. Perhaps I could try the space saver wheel? Probably a bit big...

I'd like to figure out a way to test this, for curiosity's sake if nothing else...

Where you have the disc mounted on two bolts - is that as far in as they will go? Looking at your vid in post # 41, there doesn't seem to be anything for them to foul.

Disc needs to be clamped as it would be in use to ascertain run-out.

 

[TeddyRuxpin]

Yes, that's as far as they would go. I tried with 5 too and they just 'stop'

 

[Bellow]

Yes, that's as far as they would go. I tried with 5 too and they just 'stop'

Spacers required. Even timber will do. Just enough clamping is all that is needed.

 

[Will]

Even just two bolts would do, but to be honest that runout is so great you could probably see it with the wheel mounted anyway

 

[TeddyRuxpin]

BEHOLD!!!!

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[TeddyRuxpin]

Note in the video the wheel still isn't really clamped with decent force as only one bolt is gripping but good enough for me to know that the problem is down to the bolts not being tightened enough...

Thanks in particular to Bellow for persisting with this line of enquiry

 

[Trickythemerc]

When you consider how thin the hub is compared to mass of the disc, it is not hard to understand how distortion can take place. When I did mine I cleaned the hub face till it was like a mirror and gave it a squirt of dry lube before mounting the new disc. Given the environment that the disc's live in corrosion could creep between the mating face's over time.

 

[Bellow]

Looking at the photos in post # 26, what I suspect has happened is that due to the seized calliper pins, the disc has been under force from only one side which has allowed the much thinner mounting face of the disc to (recoverably) distort during braking allowing moisture in and corrosion to occur at the hub periphery.
There is no heat related distortion. The heat required would leave witness discolouration and there's none.

 

[TeddyRuxpin]

Thanks again!

Does anybody know the correct torque settings of the caliper bracket bolts? Some places seem to say 115nm and some 180nm.

I believe the caliper slider bolts are 25nm.

Thanks!