Is the brake disc warped?

[kungfupoodle]

Hello

My front brake is feeling a bit 'sticky' and needs a bit of TLC - hopefully just some cleaning and lubing in the right places.

I have also noticed that dragging the braking lightly the braking force varies as the wheel rolls around.

It doesn't seem to judder under hard braking though as a previous bike did with warped discs.

Any ideas?

Thanks

[Kickstart]

Hi

What kind of disk is it?

Floating disks can sometimes stick on the bobbins, as they get caked in brake dust. Brake cleaner and rotating the bobbins in place should hopefully free them off.

I have had some cast iron disks that developed a raised section where the pads rusted to the disk. Short of gettting them lightly skimmed I am not sure of a way round this.

All the best

Keith
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[kungfupoodle]

Thanks. However, its a stainless non-floating disc on a CB500

[Blue_SV650S]

Warped discs are normally identified by a 'pulsing' at the leaver, can you feel any pulsing?

Also, to make sure, get the front elevated and spin the wheel, put a pencil from the fork pointing at and just touching the disc, you can then easily see if it is warped when the wheel spins - good luck
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[kungfupoodle]

[kungfupoodle]

Update:

I cleaned up the caliper. The pistons could be pushed back by finger pressure.

I did the pencil check and found the disc left the tip of the pencil for about half of its surface. Of course whether this is over the 0.1mm runout limit I can't say. It also drags against the caliper more in one part of the disc than the rest.

Went out for a test drive after cleaning the caliper and dragging the brake at low speed I could feel the weight coming on and off my arms as the braking force changed.

Still no judder in the lever though.

So.. definitely a warped disc?

[kungfupoodle]

I don't like to leave a thread unresolved.

I changed the disc tonight (5 minute job) and now it no longer feels like I'm trying to stop on the worlds bumpiest road.. so that must have been it.

Its a revelation!

Odd that there was no pulsing from the lever.

[Kickstart]

Hi

Think it probably depends on how it is warped. Ie, if it is a gently warp over the whole circumference of the disk or a warp limited to a small part of the circumference.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing