Front brake pads glazing/brakes seem to drag

[toecutter]

Have an issue with my front brake pads glazing, if I sand them back good, a 20 mile run glazes them again.

With the front wheel in the air, spinning it seems stiff and like the brakes are dragging, rear spins freely.

Sure it's not a case of the calipers needing cleaned, they are the CBR600F ones with matching master cylinder, I stripped and cleaned them before fitting, and don't get out on bike much (and only in dry). Not sure if it's had this issue since I got it.

Could the discs/wheel be out of true? I have a DTI on a magnetic base, but as the fork lowers are aluminum it won't work, can't see anywhere else to attach it?

If it seemed like the discs were not true, how would I know it was the discs and not the wheel hub? There is no paint ect under the discs.

Can anyone help?

[Wicky]

Might need a more thorough brake calliper overhaul with new seals, and cleaning / replacing pistons, fluids and new pads. Check the disks are still within wear tolerances if brakes have been dragging.

[Jamoi]

Also, do you have aftermarket levers? And what pads are you running?

[Virt]

Check there is some play in your levers and that they aren't constantly applying pressure to the brake discs..

I lost a perfect set of wavey discs from that

[cheekykev]

To check for disc run out cable tie the mag base to the fork leg, but make sure you put some tape or rag on the fork leg first to stop it scratching the paint off
To be honest if you're not using it much then it could just be a case of the pistons sticking and not allowing the pads to retract properly
Another tip, I don't know what pads you are using but the original Honda Nissan pads are by far the best for road use plus

[Jamoi]

Hey toecutter, did you manage to investigate your pads?

[toecutter]

Got a chance to have a look earlier, cheers for the advice -

Discs are still within wear limit.

Levers are standard, plenty of play before the brakes start to work.

I think pads are EBC HH sintered.

Runout on left hand disc is 0.16mm, right hand disc is 0.28mm. Readings taken with pads fitted if it makes a difference.
The maximum runout is 0.3mm, so right disc seems pretty close?

When the wheel is spun, it feels tighter at some points than others.

[tony.mon]

Doubt if it's a disc runout problem.
This sounds like seized pistons, the only way to sort it is to pull off the calipers one at a time, and pump the brake to see if the pistons all move out at roughly the same pace, or at all, really.

[mattycoops43]

Runout will be felt by pulsing through the lever so it's pretty obvious normally. I stripped my calipers, it's easy on these, just order up some seals first.

[VTRDark]

When the wheel is spun, it feels tighter at some points than others.

Wheel maybe slightly warped. It's always a possibility.

As has been said service the callipers first, make sure the pistons all move freely. You may not need new seals and could just pull the pistons out, clean, re grease with a little smear of red rubber grease, put pistons back in, new pads and bleed. Even better if you split each calliper and give a thorough clean out.

(:-})

[toecutter]

Checked movement of pistons today, a couple of pistons didn't move until I held the others still.

Will order new seals, I cleaned up the new ones when I got the calipers and that didn't help.

Also, they are fitted with Galfer pads, don't know why I thought they were EBCs.

[toecutter]

Replaced seals today, hasn't made any difference.

Video of turning wheel - http://vid151.photobucket.com/albums/s1 ... f7b9fc.mp4

Is that how it should be or does it look like it's sticking?

[Wicky]

What was the condition of the pistons?

If they were okay then … Bobbins?

[toecutter]

Pistons had small amount of grime on them where they sat out past the seals.

Will try freeing up the bobbins but pretty sure I tried it a while ago.

[toecutter]

Bobbins are all free.

MOT'd it yesterday, got an advisory for 'front roller brake test indicates slight fluctuation of brake effort'

There is quite a bit of vibration when braking.

Think I'm going to have to buy new discs, if it was the wheel would the discs not have the same amount of runout?