Hydraulic disc pads... whats going on ...

enc

Senior Retro Guru
... Deore XT BR-M775 front caliper the trailing edge of the pad is sticking. can this be fixed? I'm new to hydraulic discs.

Kg5QBic.jpg


5c1M8gQ.jpg
 
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mk one

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Has the spring snapped or popped out of place?
 
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mk one

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Should have a spring similar to this between the pads, sometimes one of the arms snaps or bends, which lets the pad fall inwards.

Also is the pad pin screwed all the way in, it is hard to tell from your pictures but looks like the bolt is not fully in, in which case the pad could be moving.

spring.jpg
 
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dyna-ti

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The pin that secures the pads will have a safety clip on it. It is imperative that safety clip is there and the retaining pin also. the pin will need to be all the way through the caliper for the safety clip to fit onto the end of it.
Without the safety clip, the pin slips out and then the pads fall out and then you'll be in a world of hurt to discover as you enter that busy junction at 20 mph to find you have zero brakes.
I have done this, and near knackered the caliper pistons trying to stop using them as i cranked down on the levers wondering what the hell was happening. It's a lesson you learn once and only if youre lucky.
 
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enc

Senior Retro Guru
Has the spring snapped or popped out of place?
you were right ;)

this is what i found ....

hJynkNH.jpg


after comparing with the rear brake caliper it was obvious the clip was not seated correctly..

this is the rear caliper ...the clip is more central...

AEQ8hYR.jpg



and after removing the pin and faffing the clip with needle nose pliers...

rV9ncm1.jpg


fiddly but got there eventually ... buzzing :cool:
 

hookooekoo

Retro Guru
you were right ;)

this is what i found ....

hJynkNH.jpg


after comparing with the rear brake caliper it was obvious the clip was not seated correctly..

this is the rear caliper ...the clip is more central...

AEQ8hYR.jpg



and after removing the pin and faffing the clip with needle nose pliers...

rV9ncm1.jpg


fiddly but got there eventually ... buzzing

I could very well be wrong*, but the pin securing the brake pads in place has a groove at one end. I suspect that groove is meant to have some kind of circlip or other type of clip to stop the brake pad retaining pin from falling/rattling out.

If the brake pad retaining pin falls out, followed by the brake pads, you could end up in a very nasty no-brakes situation. On the M8000 brake caliper, you can see that there's some kind of retaining clip where the groove is.

Maybe someone who is more familiar with these calipers could confirm if it should have a clip, and whether there is also a thread on the brake pad retaining pin.

* I don't own a single bike with disc brakes!
 

hookooekoo

Retro Guru
The pin that secures the pads will have a safety clip on it. It is imperative that safety clip is there and the retaining pin also. the pin will need to be all the way through the caliper for the safety clip to fit onto the end of it.
Without the safety clip, the pin slips out and then the pads fall out and then you'll be in a world of hurt to discover as you enter that busy junction at 20 mph to find you have zero brakes.
I have done this, and near knackered the caliper pistons trying to stop using them as i cranked down on the levers wondering what the hell was happening. It's a lesson you learn once and only if youre lucky.
Ahh. I see someone else already raised this. But the latest pictures of the caliper with the spring issue fixed don't appear to show a safety clip installed.

Please take care out there, and don't ride this bike until the retaining clip is in place on the brake pad retaining pin.
 
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mk one

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Yeah, most have clips of some sort, though the pins are usually threaded in. Never reused the clips myself, just made sure the pins were tightened properly.

Always a good idea to check the brake bolts regularly, along with the rotor bolts.

And @enc it is easier to take the pads and clip out and slide them all in as a unit, even easier with the wheel out, just make sure you push the pistons back in otherwise you wont be able to fit the disc between the pads.

Glad you got it sorted in the end though 👍
 
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