Shuddering Front Brakes

[Moo.]

Started to notice my front brakes shuddering, or an on/off feel accompanied by a swoosh-swoosh-swoosh sound on the front rotors.

Typically i thought it may be warped discs.... But 3 pairs of front disks later, they all do the same thing. All discs will sit flat on a piece of glass

Also only scraped past the MOT as he said the braking power was fluctuating massively on/off but passed it because all the pads/rotors were new so could possibly be put down to not being bedded in...

So when pulling the lever, its more pronounced at slows speeds, but you can feel the brake power going on and off when it passes a certain point and creates a jerking braking movement when stopping...

Anyone have any ideas?
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A2 Passed 18/6/10

[P.addy]

New disks AND pads or just disks?

Have you considered overhauling the calipers?

[Wafer_Thin_Ham]

+1 to pointing the finger at calipers if the pads have also been changed.
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[Moo.]

New pads and discs. Calipers haven't been overhauled, they're blue spots... Seen a kit somewhere that let's me take the star blank plate off...
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A2 Passed 18/6/10

[stinkwheel]

Get a dial guage on the discs while they're on the wheel.

I had a problem with fluctuating brake effort on Mrs stinkwheels CB500 and it eventually turned out (after replacing/overhauling literally everything on the braking system) that there was an uneveness on the posts the disc bolted to.

I eventually sorted it by putting shims between the disc and wheel at the "low" points. Very thin (0.1mm) shims at that. Doesn't take much to make the runout exceed tolerances.

This probably wouldn't have been a problem with floating discs.

Mind you, a sticking piston can cause the pads to chatter too but if you have accfess to a DGI, it's free and easy to check the runout.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.