Juddery/Rubbing discs

evilzed · Scooby Slapper Joined: 05 Oct 2013 Karma :

Bit of a strange one for me, got the tyres changed on my FZ1 when I replaced the wheel the front discs where rubbing noticeably more than they were before taking the wheel off (tested on an Abba stand with the front raised up) after the cleaning up the brakes with brake cleaner and few rags it was a little better. Everything was tightened up at this point

So today loosened the pinch bolt on the axle, sat on the bike while lifted on the Abba stand and I pushed up on the yoke to pump the forks and hopefully align the wheel accurately. Torqued the pinch bolt up to spec, then loosened the caliper bolts and gently moved them side to side a touch to back off the pads slightly.

spun the wheel which was spinning fine with no contact then pumped the brakes up to pressure and held the brakes shut with a cable tie on the lever and torqued the calipers. After this the wheel spins quite free however I'm now getting this weird judder/catching when I push down on the wheel to spin it if I use any decent force. I thought it may be warped discs but if I do it slowly it's completely fine and nothing catches.

Is this something to do with floating discs or have I totally bodged something up? I'm a bit paranoid as I would rather not have the front lock up when accelerating away. I did take it for a ride and it seemed fine for the most part but it's an odd one.

Thanks for any help!

MCN · Super Spammer Joined: 22 Jul 2015 Karma :

Are the spacer/s fitted properly?

Is the tyre catching on your support/paddock stand? Embarassed

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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

evilzed · Scooby Slapper Joined: 05 Oct 2013 Karma :

I thought it was catching something so I did take a good look around and there's nothing I can see :S I did install a fender extender few weeks back and double checked and the clearance is plenty.

All cables etc are out the way I'll probably try setting the caliper pistons again, the front brake lever bites very fast noticeably more than before I realigned the wheel etc I don't think it's a stuck piston though as it spins find until I use a bit of force.

Wafer_Thin_Ham · Super Spammer Joined: 18 Nov 2005 Karma :

Are you putting it in the right way around? Discs will have a rotation arrow on them.

+1 to all spacers being in the right place.

You can't be unalign the front wheel in relation to the forks if you're just changing the front wheel. There's no scope for forwards and backwards adjustment built into the wheel, or the forks themselves.

What do you mean by a judder/catch? If it feels fine when you're riding I wouldn't worry too much. You'll always get a bit of dragging from the brakes anyway as they're always in contact with the disc slightly even when no pressure is applied.
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Matt B · World Chat Champion Joined: 01 May 2012 Karma :

Everything above ^^^

Check the wheel or tyre for a rotation arrow. Also have you had the pads out of the calipers? If so, did they go back in the same sides and same way round? Pads back in the wrong place will rub more until they have bedded to the disc.

If everything is where it should be then just go ride ita nd use the front brake. Try it again after.
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Taught2BCauti... · World Chat Champion Joined: 12 Jan 2012 Karma :

Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

evilzed · Scooby Slapper Joined: 05 Oct 2013 Karma :

Yeah I thought it may be the bearings as it's really the only thing that would explain it happening under force, The spacers are in right and so is the orientation as it's an ABS bike I also noticed whoever installed the wheel before me routed the ABS cables wrong which was interesting.

I'll double check everything and re-mount the calipers etc and see if I find the culprit.

MCN · Super Spammer Joined: 22 Jul 2015 Karma :

Process of 'illumination' now.

Thumbs Up

Hypothesis Mode/Laterally thinking mode on
One of both races (of each bearing assy.) will be in rotation and one will be 'fixed' (between the spindle nuts).

The wear will be most prominent on the loaded portion of the fixed race.

When you otherwise support the wheel the weight will act on the normally non-loaded portion. If there is no wear on that then it will not vibrate.

Hypothesis Mode off.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.