Why are my MTB brakes noisy?

[bmwmike]

Hi

Bought a cube 'TM Pro' bike last october and ran the brakes in properly (or at least as i normally do on prior MTB) and after they bed in, they get noisy when braking hard. Its almost like a grinding noise.

I sanded the brake pads lightly and the disk friction surface and they were silent until they re-bedded in, and they are noisy again.

Its not a squeal but a grinding on/off noise as the disc rotates, mostly on the front.

180mm discs, Magura MT thirty brakes. Stopping is fine, just doesn't sound too healthy. Perhaps is normal for these "resin/organic" pads (type 9.c)?

Thanks
Mike

[lickatysplit]

are you riding off road in the mud? sounds to me like that there is grit stuck in the pads, remove the wheels and pads and clean them to remove any grit. TBH if there is any grit in there you may hear a slight whine when the wheel is spinning anyway.

[bmwmike]

Its the angry goose noise:

https://www.youtube.com/watch?v=oRGUJi-UQgg

I've replaced the front pads and its still doing it. Aligned the caliper - still doing it. Cleaned the disc, still doing it. Driving me mad, like an angry goose

Anyone else had this? It seems common, but i'm not sure of any permanent fixes. I'll try replacing the discs next, but seems a bit extreme.

Thanks
Mike

[youngricharduk]

bmwmike said:

Its the angry goose noise:

https://www.youtube.com/watch?v=oRGUJi-UQgg

I've replaced the front pads and its still doing it. Aligned the caliper - still doing it. Cleaned the disc, still doing it. Driving me mad, like an angry goose

Anyone else had this? It seems common, but i'm not sure of any permanent fixes. I'll try replacing the discs next, but seems a bit extreme.

Thanks
Mike

If you feel you've ruled everything else out, it's likely the discs are contaminated, take the discs to you LBS and get them to skim the discs to give them a new surface. I tried everything else including sanding the discs but my LBS charged £5 per disc to give them a new surface instead of pulling out for new ones and it finally cured them. Good luck!

[bmwmike]

youngricharduk said:

If you feel you've ruled everything else out, it's likely the discs are contaminated, take the discs to you LBS and get them to skim the discs to give them a new surface. I tried everything else including sanding the discs but my LBS charged £5 per disc to give them a new surface instead of pulling out for new ones and it finally cured them. Good luck!

Ah didnt think of that. I had sanded them (forgot to mention) and it does cure it for a while but the angry goose comes back.

Will see if my LBS does that - thanks.

[Watchman]

It's the difference between sintered metallic pads and resin-based pads. The former grind but work better in the wet and mud. The latter are quiet but slightly less effective in those conditions.

Edited by Watchman on Tuesday 30th April 11:11

[bmwmike]

Watchman said:

It's the difference between sintered metallic pads and resin-based pads. The former grind but work better in the wet and mud. The latter are quiet but slightly less effective in those conditions.

Edited by Watchman on Tuesday 30th April 11:11

So you reckon it's normal?

My bike store are going to look at the bike for me but honestly I don't hold much hope.

I've since tried a different disc and the noise came back after bedding in (approx 6 miles). Today I refitted the original storm HC disc, cleaned with meth spirit, and abraded the pads with 180 grit. Silent until they bedded back in at 5.5 miles and that fooking gobblin turkey is back.

ETA I am not sure why I get Geese and Turkeys mixed up, I just do. Hahaha

Edited by bmwmike on Tuesday 7th May 21:02

[Watchman]

bmwmike said:

So you reckon it's normal?

Normal... Not sure I'd use that word but it is common for that type of pad.

It can be mitigated on cars with anti squeal shims - all they do is change the resonant frequency of the assembly. Sometimes coating the back of the pad with copper slip is enough.

It can be worse with some calipers than others. I find Avids are particularly bad, Shimanos and Tektros are OK. That's a bit of a generalisation but I work on a fair few bikes and it's something I've noticed.

I'd consider resin pads unless you specifically need the sintered metal ones for wet and muddy rides. Even then, you might find resin pads are OK. The difference between them isn't as night & day as the difference between rim brakes and disks.

[bmwmike]

Thanks. That makes a lot of sense. I am not sure if the pads are sintered or resin as the rear have copper flecks in them but the fronts don't. The thing is though the fronts are worse than the rears but both get noisy when toasty.

Magura suggested sanding the pads every few rides as a solution. They have offered to send me a free set of pads though so not all bad.

My mate suggested the front four pot calipers are too much for the 180 discs and perhaps upgrading to 203mm might be the way to go. I'm considering ditching the magura for shimano XT as another option. Perhaps a different type of pad as you suggest is a good next step.

Cheers

Edit. I've got 9p pads fitted to front (pic) and from what I can tell these are sintered. The 9c type are resin. Might be worth getting those.

|https://thumbsnap.com/yjv56hfj[/url]

Edited by bmwmike on Wednesday 8th May 11:29

[bmwmike]

In case it helps anyone the issue turned out to be a sticky piston:

https://m.pinkbike.com/news/tech-spotlight-brake-c...