Help with Shimano disc brakes (BR-M445)

[eddiemee]

I was hoping someone might be able to give me some advice on a very annoying problem with my disc brakes.

I have Shimano BR-M445 hydraulics front and rear. A month or so ago I replaced the front pads and they worked fine for about a week. Then they started shrieking (a real ear-piercing squeal even when perfectly dry) but more worryingly they started losing power. Within a few days the front brake was more or less useless so I couldn't rely on it. During that time I checked the alignment, cleaned the pads and rotor with Muc-Off disc brake cleaner but it didn't seem to make any difference. So, on with a new set of pads, and exactly the same thing has happened. There is also a dark band appearing on the rotor where the pads connect, and it doesn't seem to disappear with cleaning. I'm using my other bike for the time being as I don't feel safe riding when there is obviously a problem with my brakes.

I bought the pads off Amazon, but they are (at least appear to be) genuine Shimano products and the seller had very high positive feedback. I have triple checked that they are the correct (resin) pads and the packaging clearly states they are compatible with the brake system I have.

Has anyone had a problem like this, or have any idea what might be causing it and how I go about solving it? I'd appreciate any help.

Thanks,

Ed

 

[rusky]

Is the calliper leaking & contaminating the pad??

 

[compo]

Did you buy both sets of pads from the same Amazon seller? If there is no leak of hydraulic fluid then you may have answered your own problem when you say I bought the pads off Amazon, but they are (at least appear to be) genuine Shimano products.

 

[eddiemee]

Is the calliper leaking & contaminating the pad??

Ah ha. I think you might have nailed it. I took the pads out last night and sure enough there was oil on the back, and a little of it seemed to have seeped round to the front of the pads. Not a huge amount, but I guess it only takes a trace to destroy the friction.

So, new question - is it worth trying to fix a leaking caliper? If so, how? Or should I just fork out for a new one, they're only £20 (which possibly explains why it's leaking after 18 months).

Compo, good point about the source of my pads. For the time being I'll work on the assumption that it's the oil though.

Thanks to both of you for the replies.

 

[rusty bearing]

I don't believe Shimano do service kits for their brakes, means you have to replace the whole calliper, bleeding is simple tho'

 

[eddiemee]

Ho hum. Not to worry. I've ordered a new caliper so should be here by the weekend. I've bled and replaced the rear caliper before (unrelated problem) - one of those many bike-related jobs that is daunting when you've never done it but then you realise it's fairly simple when you know how.

 

[Cubist]

Did you check to see where it was leaking from before you ordered the new one? Sometimes the banjo or union joint comes loose, or you may even have forgotten to close the bleed nipple completely when you bled it.

 

[eddiemee]

Good point. I checked it and there doesn't appear to be anything coming from the joints or bleed nipple and the area around them is dry. There is a very thin film of oil on the area around the pistons though which makes me think that's where the oil is coming from. New calliper should be here today hopefully.

Thanks everyone for your help.