Grabby brakes?

[slofox]

So the front brake has developed a little pulsing grabby action when applied, mild enough but annoying - as is common enough with disc brakes. I'm sure you know what I mean...

If it was the cage, I'd just say to the mech at the next service, "fix that brake willya".

What would they actually do to the brake? "Skim" the disc? Which means what? Or is there some arcane art known only to them wot 'as been inducted into the secret fraternity of mechanicism an' they can't tell on pain of castration at dawn on an empty stomach?

Just wondering...

[kwaka_crasher]

So the front brake has developed a little pulsing grabby action when applied, mild enough but annoying - as is common enough with disc brakes. I'm sure you know what I mean...

If it was the cage, I'd just say to the mech at the next service, "fix that brake willya".

What would they actually do to the brake? "Skim" the disc? Which means what? Or is there some arcane art known only to them wot 'as been inducted into the secret fraternity of mechanicism an' they can't tell on pain of castration at dawn on an empty stomach?

Just wondering...

Not much to 'skim' on 'em which is basically removing runout by removing material.

Even then, this whole culture we have now of skimming discs every time the pads are replaced (mostly by shonky outfits like Midas & Pitstop) is ridiculous. It only needs to be done if there are obvious serious ridge issues.

In your case, the cause of the runout could be many things.

Most likely:

Seized rivets on the hub if it's a floating disc... give them a spin to see it they're stuck (easier said than done). But the mechanical damage to the rotor may already be done.

Warpage due to internal stresses being relieved through a combination of over heating causing normalising of the material and then wear. Best bet then is to replace them.

[CookMySock]

I'd whip the disc off and get it magnafluxed. Last thing you want to deal with is a cracked disc - or else most likely it will deal to you before long.. I read about some fella who had a cracked disc lock his front wheel and end-over him on the motorway. Not nice.

Steve

[Squiggles]

Skimming them will almost certainly put them under their wear limit, given they're at least 40k old and i suspect you arent too gentle on them...

[vifferman]

Don't panic! It may be nothing to do with the disk - my VFR had a bad pulsing at low speed when I got it. It turned out to be a badly and unevenly worn pad.

[quickbuck]

Don't panic! It may be nothing to do with the disk - my VFR had a bad pulsing at low speed when I got it. It turned out to be a badly and unevenly worn pad.

And that would abtually be caused by a piston not actuating at the same rate as it's mate.....

[nallac]

Could be one of the already mentioned problems,
or as in my case a suspected warped rotor turned out to be wheel bearings going bad.

[slofox]

... i suspect you arent too gentle on them...

Waddaya mean? COURSE I'm gentle with them...always totally smooth, unhurried and in control is me...

[cowboyz]

common feeling if your headset bearings are worn... Have you had brake problems before? A worn headset will feel like pulsing through under hard braking.

[slofox]

common feeling if your headset bearings are worn... Have you had brake problems before? A worn headset will feel like pulsing through under hard braking.

Headset checks out fine. No previous brake problems.

[Coldrider]

I've warped a disc, as much as i wanted to find another reason for the pulsing (cheaper) it wasn't to be.