Brake issues thread

H

HamboCairns

Thanks for all the bananas
Hey all,

Did a long descent and my heard a scraping from my rear brake.

Smelt burnt and I have black marks on the rear discs.

Also, any way to centre the disc between pads (Shimano MT 400 brakes)?

 
dirtdad

dirtdad

Wants to be special but is too shy
Looks pretty centered. You mean a way other than loosening caliper bolts and adjusting? You can shim the disc/pad spaces with something on either side to help?
[Edit: do you mean center laterally or vertically?]

What pads are you running?
 
C

creaky

XMAS Plumper
Looks like you need a washer under one of the caliper mounting bolts to raise the pads up a bit higher on the rotor.

To align the caliper you loosen the bolts where they attach to the frame/fork, squeeze and hold the brake lever and then tighten the bolts up. If that doesn't work then you have to align them more manually by eye, but that method seems to work pretty well with shimano brake IME so long as the pistons are both moving freely.

Remember when tightening the caliper bolts up, you keep going until the thread in the frame just starts to strip, then loosen half a turn.
 
H

HamboCairns

Thanks for all the bananas
The Duckmeister said:
Resin pads as specced in the MT400s don't like extended use; the surface gets really hot, melts, and then forms a hardened, glassy surface that almost directly replaces power with noise. You need to let them breathe every so often to stop them cooking.
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I do think I need better brakes. Rotors and pads then actual brakes next year!
 
Flow-Rider

Flow-Rider

Burner
HamboCairns said:
I do think I need better brakes. Rotors and pads then actual brakes next year!
Click to expand...
Give the rotors and pads a quick sand with coarse sandpaper and then re-bed the brakes on flat ground before you go riding again. If you keep the left and right brake pad in their original orientation they'll bed-in faster. I usually mark the outside pad with a white marker. If you don't make the rotors too black, most times you can get away with just giving the pads a sand every 10 or so rides. I don't think your weight, Smithfield park steeps and the heat in Cairns will help any.
 
ozzybmx

ozzybmx

taking a shit with my boobs out
Got XTR M9000 race brakes on the Yoinkers Trek.

He informs me yesterday that the rear lever is flopping around and the brake is not working.

Looks like the master cylinder piston is stuck :rolleyes:

Has anyone came across this with Shimano brakes as I have never had or heard of it before.

Is this worth a rebuild and clean ?

The brakes were new in 2016 so they are 5 yrs old.

Cheers
 
frenchman

frenchman

Eats cheese. Sells crack.
ozzybmx said:
Got XTR M9000 race brakes on the Yoinkers Trek.

He informs me yesterday that the rear lever is flopping around and the brake is not working.

Looks like the master cylinder piston is stuck :rolleyes:

Has anyone came across this with Shimano brakes as I have never had or heard of it before.

Is this worth a rebuild and clean ?

The brakes were new in 2016 so they are 5 yrs old.

Cheers
Click to expand...
It’s worth a try. Put in another set of seals and it could be good (only place I’ve seen them is on AliExpress). However If there is scoring on the inside of the cylinder, it’s dead.
 
ozzybmx

ozzybmx

taking a shit with my boobs out
frenchman said:
It’s worth a try. Put in another set of seals and it could be good (only place I’ve seen them is on AliExpress). However If there is scoring on the inside of the cylinder, it’s dead.
Click to expand...
Sorted ! stripped the lever down, sanded the 2 plastic rings, lever bleed and she's working like a new brake.

Shimano didn't want people stripping these, that's why there are no Shimano spares and that fckn circlip was a chunt :D

I seen the Ali replacement Ti pistons, might order a set as spares in case it happens again and I'll drop the Ali pistons in.

380264
 
Labcanary

Labcanary

One potato, two potato, click
ozzybmx said:
Sorted ! stripped the lever down, sanded the 2 plastic rings, lever bleed and she's working like a new brake.

Shimano didn't want people stripping these, that's why there are no Shimano spares and that fckn circlip was a chunt :D

I seen the Ali replacement Ti pistons, might order a set as spares in case it happens again and I'll drop the Ali pistons in.

View attachment 380264
Click to expand...
Nice work @ozzybmx!

Hey, if you do happen to order some Ali pistons, could I possibly get you to grab a set for me and I'll transfer you the funds? I have NFI how to order from them!
 
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