Bastard squealing disc brake

[red997]

OK
so I've got a squealing disc brake.
Had the bike for a couple of years, never had an issue
moved house recently, got the bike out of storage & went for a ride
bugger me the rear brake squeals; front is fine

Got home & took a look today.
no obvious oils, or other crap on pads / disc
stripped it all down
forgot to mention - its a Shimano Deore disc brake system.
no obvious contamination, but to be sure I isopropyl the pads & paper roll dry.
Also chamfer the pad edges slightly, rough up & re-clean with a diamond file, clean disk with isopropyl, re-centre the calliper to the disk, thinking all will be ok.
Clean (isopropyl) and very fine wet/dry sand the disk surface, re-clean.
went out for a test ride....

if anything, it's worse !
Double checked everything, & all looks perfect.

I've never had an issue with this setup, and had the bike from new.
However, this is my first Shimano disk system - previously had Hope all round on a Pace (until some nicked that bike)

Worth trying new pads first ?

anything else to try ?

[jesusbuiltmycar]

is there a slight bend in the disc?

failing that is teh disc centra between the pads?

I had this issue recently and it was caused by a brake rub on one of the pads

I resolved it by:

1. loosening the bolts that hold the the caliper to the frame
2. place some card between the pad and the disc on the side where it was rubbing
3. sqeezing the brake lever hard
4. re-tightening the bolts that hold the the caliper to the frame whislt keeping the brakes applied

[red997]

no - tried that too
just bought a new set of pads to try - only 7 quid !

[Flippin' Kipper]

Shimano seals often start to leak miniscule amounts of mineral oil from the caliper seals which ends up on the pad. You may be able to improve things by sanding and degreasing the pads and disc, but if this is the issue it will just come back. You can replace the caliper for not too much money, but rebuild kits are not available.

[red997]

It was the pads.
Fitted a new set and all good
Bedded in nicely no squeal and more bite
I’m guessing that I got some chain oil on the old set at some stage.
Nice and cheap too !

[red997]

forgot to mention - bought the pads from Halfords - cheaper than any of the online retailers !
snd they had them in stock, at the local store.
Not often I say this, but well done Halfords!

[S13_Alan]

I often have a similar issue (standard resin pads on a set of Shimano Zee brakes) where they just squeal and have no stopping power.

Cleaning and sanding doesn't help and it doesn't seem to be proportionate to use or overspray from anything, they went like that after sitting all winter in the house having been fine before.

I just pop the pads in the oven at 200 for 20 min or so, problem goes away and brakes work great. Suppose using a torch would help but I don't know how far to go with that.

Worked multiple times with the same set and no issues.