Rear disc brake issue

jimmysplash

Ive been having this problem for a while now and i cant seem to get to the bottom of it....
I have shimano deore disc brakes with resin pads.
The rear brake is the issue. I buy resin pads, bed them in as best i can and everything seems fine. The pads engage on the (new) rotor well, they're quiet and dont shriek when i come to a stop. I hardly ever take my bike off road anymore. Just urban riding.
After about two weeks i notice a deterioration in the perfromance. when i bring the bike to a stop, about 2 seconds before standstill, the brakes starts squealing. The pads arent gripping the rotor very well.
My lbs says there isnt a leak anywhere.
I do clean my rotor with alcohol (not after every sodding ride though) and i keep any degreaser i use well away.

Is this not a problem? The amount of pads ive gone through thinking there is a problem

swod1

Sounds like they have not bedded in correctly and you've glazed them, I've done it loads before with shimano resin pads. i had to change from them as they aren't great in my experience.

Otherwise the brake caliper may have a leak around one of the pistons, only way to find out is take out the pads and use some tissue paper etc in there and press the lever a few times so the pistons come out and retract and you'll easily see if there is any mineral oil on the paper.

Not sure if you can service the calipers and replace any seals so you might have to buy a new caliper or full brake.

One other thing your not over spraying chain oil this is bad if gets on brake pads

cooldad

If it's used on the road, very possibly just road crud. Personally I never bother with actual bedding in, just ride and brake. But it is recommended.

Can also depend on your braking. If you drag the rear a lot it can also cause glazing.

Chain lube can also be a problem, especially if you use any sort of aerosol.

david7m

Check for a leak as already said.
These are awesome!
https://www.uberbikecomponents.com/cate ... Brake-Pads
Dave

swod1

david7m wrote:

Check for a leak as already said.
These are awesome!
https://www.uberbikecomponents.com/cate ... Brake-Pads
Dave

I've just ordered some more as they've got a 25% off sale this weekend. Thought i'd give the foaming bike cleaner a try too.

david7m

Didn't see the discount, think I'll get a spare set and another for the road
Dave

jimmysplash

I do use Muc Off chain cleaner spray but ive been assured this wont affect the pads
Maybe they were talking utter, utter bollocks

swod1

JimmySplash wrote:

I do use Muc Off chain cleaner spray but i've been assured this wont affect the pads
Maybe they were talking utter, utter ****

yeah its safe for bike use but i don't like it, leaves a film residue on the bike after. if your brakes aren't dirty just don't clean them and leave be.

I'm sure its the shimano pads your using i think they are s^&* i had nothing but issues with them until i switched to aftermarket from uberbike.

EBC make some organic (resin)pads for shimano but never tried them, maybe easier to bed in etc.

The code on uberbike to use is "NEWYEAR25" got 4 packs of pads and bike cleaner for 24 quid.

jimmysplash

The pads are Shimano Deore M515.
I went by the reviews on Chain Reaction.
I wouldnt know which are adequate pads and which are sh*t hot pads

david7m

I've the race matrix on mtb and road - huge improvement over original sram and Shimano kit.
Dave

FishFish

I've found that the brakes don't squeal when the bike has been in the garage overnight and certainly do when wet. Humidity also seems to affect it. I have, a few times, scored the surface of the pads with the edge of the file because the squeal is driven by a resonance set up on the disk by the pads - similar to a violin bow on a string. Has worked.

I tried an experiment with one organic and one kevlar on each disk just out of interest and strangely that seems to work too.

jimmysplash

well i cleaned the pads, used fine sandpaper on them, cleaned the pistons (in situ) went for ride in dry weather and things improved.
Im not doing that after every shitty weather though...