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Discussion Starter · #1 ·
Trying to work out an issue I'm having with a set of new Magura MT sport brakes .

I'm running the brakes with 203mm storm HC up front and 180mm in the rear. Front uses a magura 180-203 adapter, rear needs no adapter (spec enduro 29 2019). I went with the storm rotors to avoid any possible incompatibility.

I'm getting a strange noise/vibration under moderate to hard braking. Best way to describe it, sounds like the pads are catching a hard edge on the rotor. I'm not sure if this is just what they're meant to sound like but seems odd.

The rotors are 6 bolt mounted to DT Swiss wheels using the 6-bolt CL adapter. I'm wondering whether the adapter is the source of the issue?

Originally the bike had SRAM guide R brakes and I got the same sound running slx 6 bolt rotors. The SRAM centreline rotors on the stock wheels were dead silent.
 

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Discussion Starter · #2 ·
Trying to work this out logically.

Rear:

dT Swiss with bedded storm HC ... Ticking (almost a warble)
Use copper grease on back of pads and retaining pin ... Smooth for a while then back to warble
swap wheel to roval w/new storm HC ... smooth
Swap wheel to nukeproof W/old Shimano rt-56 ... Smooth
Use Shimano slx rotor on DT Swiss wheel ... Smooth
Use new storm HC rotor on DT Swiss wheel ... Smooth

Front:

dT Swiss with bedded storm HC ... Warble
Wet the caliper ... Quiet until dry then warble
Swap wheel to roval with new storm HC ... Warble
Use slx rotor with dt Swiss wheel ... Warble
Check piston movement and ensure all pistons moving equally ... Warble
Reface pads W/300 grit sandpaper ... Warble
Realign 203mm magura adapter and caliper ... Warble
Copper grease on back of pads and retaining pins ... Quiet for a while but not 100% smooth
Remove clean, reinstall CL adapter & Reface bedded storm HC W/180g sandpaper on DT Swiss wheel ... Smooth

Based on that I can come to a few conclusions:

Noise is created by pad movement rather than 'catching' and almost eliminated with the copper grease/lubrication
Irregular pad movement should be abnormal i.e. shouldn't need the copper grease to quiet them down.

Possible incorrect installation of the rotor/CL adapters although they're pretty straightforward can't imagine getting this wrong.

Possible incorrect bedding process seems most likely but I was getting pretty good power just noisey warble ticking noise. I would have thought incorrect bedding would affect braking efficiency rather than noise and feel?
 

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Interesting. I have HC and SL2 rotors that make a noise similar to what's described. The power is there, so it's more of an annoyance, again, as described above. Also with centerlock DT hubs, using six bolt rotors with Magura adapters.

Here is what's interesting. I get the exact same noise with two different brakes. Both Magura MT7s and Hayes Dominions warble and sound like the brake is catching once warmed up a bit.

Sent from my Pixel 3 XL using Tapatalk
 

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Discussion Starter · #4 ·
That is interesting, are you using the magura rotors with the Hayes also?

Common factors between us seem to be:

DT CL hubs
Magura rotors
Magura adapter
Poor bedding?

How did you bed your brakes?

I have always just ridden up and down my driveway (10m) braking progressively harder about 20 times from about 10kmh (about as fast as I can get in a tight space). I know this isn't what magura recommends, but 30-50 stops from 30kph seems way excessive. Had always worked with Shimano brakes (xt, deore, mt500, mt400) without a hint of uneven deposits.
 

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I am using Magura SL2 rotors with Hayes brakes.

As far as bedding in, I ride up and down my street. Get up to 10-15 mph, brake till barely moving, rinse and repeat. About 20 times per side.

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Discussion Starter · #6 ·
Hrm, you're probably bedding in better than I yet you still have the issue. Still less than the Magura recommendation, perhaps this is a bedding problem?

I wonder if it's the rotor design itself though. I noticed on both front (mt5) and rear (MT4) the pads hang over the brake track towards the rotor arms a fair amount for most of the time, only really engaging the rotor near the rotor arms. At its narrowest point the brake track on the storm HC is only12mm ... 2mm narrower than the Shimano 'narrow' (slx/xt) rotors and 4mm narrower than 'normal Shimano' rotors.

I'm thinking of getting a set of SRAM centreline rotors and trying that out.
 

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I read this somewhere but have not tried it but apparently if you flip your rotors it stops the noise. My Magura brakes make the noise too but it hasn't bothered me enough to try the rotor flip.
 

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Discussion Starter · #8 ·
I read this somewhere but have not tried it but apparently if you flip your rotors it stops the noise. My Magura brakes make the noise too but it hasn't bothered me enough to try the rotor flip.
Yeah I think I'd rather try different rotors than flip them. What rotors are you using?
 

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Discussion Starter · #10 ·
I threw my old slx rotors on and warbling is gone again, front and rear. I'll try take it out for a decent ride tomorrow and see if it stays that way.

I have some centreline rotors ordered anyway. Curious whether they will help having a wider track than my other rotors.

I have a 2nd set of mt trail sports I was going to put on my hardtail. I might put them on with different rotors again to see if I end up with a different result.
 

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Hrm, you're probably bedding in better than I yet you still have the issue. Still less than the Magura recommendation, perhaps this is a bedding problem?

I wonder if it's the rotor design itself though. I noticed on both front (mt5) and rear (MT4) the pads hang over the brake track towards the rotor arms a fair amount for most of the time, only really engaging the rotor near the rotor arms. At its narrowest point the brake track on the storm HC is only12mm ... 2mm narrower than the Shimano 'narrow' (slx/xt) rotors and 4mm narrower than 'normal Shimano' rotors.

I'm thinking of getting a set of SRAM centreline rotors and trying that out.
Possibly. I haven't had to do more than that in the past. I did try close to 40 stops on the rear, but it didn't seem to make any difference.

I'm in the process of building up a new wheelset, which will be six bolt, and was going to also try the Hayes rotors to see if that gets rid of the noise. To clarify, I'm not building the wheels to get rid of the noise, it's not that bad, but this will give me an opportunity to try something different.

Sent from my Pixel 3 XL using Tapatalk
 

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Discussion Starter · #12 ·
Possibly. I haven't had to do more than that in the past. I did try close to 40 stops on the rear, but it didn't seem to make any difference.

I'm in the process of building up a new wheelset, which will be six bolt, and was going to also try the Hayes rotors to see if that gets rid of the noise. To clarify, I'm not building the wheels to get rid of the noise, it's not that bad, but this will give me an opportunity to try something different.

Sent from my Pixel 3 XL using Tapatalk
That's good to know, maybe my bedding process isn't the culprit. Be interesting to see if the Hayes rotor makes any difference.
 

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Discussion Starter · #14 ·
Ok I'm pretty convinced this isn't bad bedding. A few more things I tried today. Warbling stopped with the slx rotors however braking action is not smooth at all, sort of on/off in rapid succession. It's bad enough that you can see the fork legs shifting back and forth.

Tried bleeding the calipers (holy crap what a mess that was) ... Juddering
Different wheelset ... Juddering
Baked and sanded pads and rotors again ... Juddering
Ran a 180mm storm rotor (no adapter) ... warbling
Reversed direction of rotor ... Warbling
Swapped to m8000 front brakes ... Smooth

I installed a 2nd set of magura trail sports on my hardtail using some entry level Shimano rotors (rt-56), and smooth sailing. So I moved that wheel/rotor combo across and boom ... Smooth. I'll add that these were not new rotors either.

Running out of ideas and patience tbh. From everything I've eliminated it looks like a rotor issue with narrow braking tracks, but I find it hard to believe there aren't more complaints about it online. Or maybe people just aren't as fussy as me 
 

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Discussion Starter · #17 ·
Just had a thought about what's going on here. One thing I forgot to mention, I'm only braking with the front or rear, not both at the same time for all this testing.

Could it be possible that what I'm experiencing with the juddering (not the warbling) is in fact caused by reaching some physical limit of the tyres/fork/brake combo?

I'm thinking in terms of the juddering (fork flexing rapidly back and forth) is manifested when braking hard on a concrete surface with big wide knobby tyres (butcher grid 29x2.6). In both cases the juddering ceased when I lowered the braking capability by running a weaker brake set (m8000) or smaller rotor (rt-56). The juddering also is not present right after refacing the pads and rotors, only as and after the brakes bed in.

I'm thinking of it didn't judder and simply gripped hard it may throw me over but instead, the fork flexes enough to relieve the braking force enough to keep the wheels moving. I'm also thinking if I was on a loose or wet surface I'd more than likely be sliding instead of juddering.

Just a thought.
 

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I have MT Trail Sports. When I first got them, I used them with the 180mm Centerline Rotors I already had that came with the original Guide T's. They worked pretty well. Had to get new pads recently and decided to upgrade to 203mm rotors front and rear along with the Performance Pads. This time I tried the Storm HC rotors.

Rotor to pad clearance is much, much tighter with the Storms. The rotors weren't completely true when I got them, but they're not too bad. The front rotor ticks the pads oh so slightly but I can only hear it when it's in the bike stand and not at all on the trail. Rear is fine.
 

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Discussion Starter · #19 ·
I have MT Trail Sports. When I first got them, I used them with the 180mm Centerline Rotors I already had that came with the original Guide T's. They worked pretty well. Had to get new pads recently and decided to upgrade to 203mm rotors front and rear along with the Performance Pads. This time I tried the Storm HC rotors.

Rotor to pad clearance is much, much tighter with the Storms. The rotors weren't completely true when I got them, but they're not too bad. The front rotor ticks the pads oh so slightly but I can only hear it when it's in the bike stand and not at all on the trail. Rear is fine.
Interesting, good to know about the SRAM rotors. Mine will take a few days to get here.

I didn't have too much trouble at all fitting them on the stand, 0 rubbing and pretty true. I actually quite like the robustness of them. It's too bad I don't seem to be getting along with them.
 
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