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Discussion Starter #1
Hi all -
I recently built up a new ride. It's my first run-around with hydraulic discs - sram XX to be precise. The front brake is mounted via post to a reba fork, and is running a 160mm rotor. I followed setup and bed-in procedures listed in the brake manual, as well as watched a number of videos and consulted various books to ensure I've installed them correctly. Apparently though, I've failed at that.

When riding, the front brake feels "rough" and sounds miserable. Almost like metal-to-metal grinding (in the worst way possible). I feel like you can hear every notch in the rotor go past the pad. The rear brake is fine, however.

Does anyone have thoughts? Have I "glazed" my pads by doing bed-in improperly? Should I just ride through it? I see no adverse effects on the rotor, it just affects my psyche on the bike!

Thanks for any tips!
 

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it will be obvious to see if the rotor is rubbing the top of the caliper. yes i have had to add a washer between the cps stack and mount. i have not been impressed with the elixir line from a qc stand point. pistons dont retract back in to the caliper well. mainly the rears the fronts seem to have huge pad and rotor clearance
 

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Discussion Starter #3
The rotor does not appear to be rubbing anything apart from the brake pads. I pulled the pads out, and they seem kinda grooved, and definitely not smooth. Haven't had any issue with pistons as of yet.
 

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Only one piston is moving and it's pushing the rotor to the side and hitting the caliper body? I mean, if the TOP of the rotor isn't touching the caliper, the it must be the sides since nothing else can give a metal-on-metal sound.

With the bike on a stand ... if you pull the lever, does anything metal contact anything metal? Almost everything on your bike should be either anodized or painted, so just look for what doesn't have any paint on it anymore and there's your problem.

What rotors are you using?
 

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Discussion Starter #5
I'm not seeing any metal-on-metal contact - the rotor doesn't move when the lever is squeezed. Both brake pads are moving, and seem to be contacting at the same point. It really looks to be *just* pad-to-rotor contact. If these were rim brakes, I might start looking at toe-in issues. I've also re-torqued everything in the front end to ensure that isnt causing wobble.

One thing I've noticed - the caliper body almost looks like it's mounted at an angle. I've re-mounted it a few times, and it always appears to be at an angle (to me).



I'm using the stock XX rotors, Avid Clean Sweep X, in 160mm format.

Thanks again for help!
 

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The two washers are concave/convex so the caliper can be rotated/moved to be lined up even if the fork tabs are poorly manufactured. You'll need to fully push the pads back first (lever carefully with a screwdriver or the red plastic 'fork' that came with the brakes) then loosen the two mounting screws until the caliper has a little bit of movement. Squeeze the brake lever so the rotor is held by the pads then tighten the bolts whilst the brake is on - this should align the brake both laterally and rotationally.
 

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Another thought, maybe your pads aren't riding on the entire braking surface? Like, maybe they're hitting the blades of the rotor a bit? Also possible you have the same "problem" I had with my Avid 203mm rotors; the front one had much sharper edges on one side ... I know i's normal, but it was quite pronounced on the front one. Taking a file to the edge of the entire rotor got rid of my turkey-gobble temporarily, but I suppose a similar problem could be manifesting itself as a metal-on-metal sound. Also possible that the combination of what you have is simply REALLY amplifying the normal braking sounds?

Good luck figuring it out, the metal on metal sound I think you're experiencing is not something I'd personally like to hear coming from my bike.
 

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Discussion Starter #8
Compared to the (smooth) rear wheel, the pad contact is nearly identical, so I dont think its that.
However, searching around, I found this technical bulletin.

Describes my problem to a T, and jives with what it feels like the brakes are doing. Looks like it could be time to take a trip to the shop, and see if its a warranty situation.
 

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Discussion Starter #9 (Edited)
also listed in this thread

Since the solution is apparently "don't ride your bike for a while" I'm thinking of trying to sand down the leading edge of the pad, to avoid catching on rotor holes. Thoughts?
 

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Can't see why that wouldn't work, though I don't think the problem is the same as you're having. Try searching youtube for noises (I can't do it now; this computer has no speakers) and link what you're experiencing. If you're experiencing the famous "brake howl", that's completely different to what I am imagining you are experiencing.
 

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I had to move up to 185MM rotors on front to quiet mine down. The back still grinds! I got Juicy 5's
 
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