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Brakes Grabbing/Pulsing Warped?

battleshaft

battleshaft

2017-04-05 07:58:00 UTC

Hello all,

Had my 990 for a couple of weeks now. Noticed this as soon as I rode it away - brakes grab harder at certain points in the rotation of the wheel.

I've had the calipers off and cleaned pistons and pads - they all seem fine.

I've spun the front wheel on a paddock stand to see if I can see anything by eye - can't really detect anything out of true.

The buttons on the disc do seem a bit crusty - but don't think it's those... any techniques for freeing them up?

Bike has never been down - all I can think is that a disc has been knocked out of true at some point? Just looking for some other things to try before I bite the bullet and go for new discs and pads!

The bike has only done 9k so still loads of life left in the discs and pads.

Any suggestions appreciated!

battleshaft

battleshaft

2017-04-05 07:59:00 UTC

P.S. It's most noticeable at low speeds - approaching a junction light on the brakes. It grabs on/off and the suspension compresses etc. At high speed emergency stops you can't really detect it.

Scotty

Scotty

2017-04-05 11:58:00 UTC

I described a method of freeing off sticking disc buttons in this thread (scroll down the page a way to see it):
viewtopic.php?f=10&t=27002&p=329594#p329594

Hope it helps, sounds a bit like a warped disc, but try freeing the buttons first....

battleshaft

battleshaft

2017-04-05 12:54:00 UTC

Thanks Scotty, that's very helpful - I'll give your technique a go.

CEREC1

CEREC1

2017-04-05 17:47:00 UTC

I had the same. Discs warped. Switched wheels problem went away.