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Brakes make scratching sound after excessive use on downhills

1K views 14 replies 8 participants last post by  sturge 
#1 ·
Apologies If this has been asked.

Im running hope m4s and the rear brakes tend to have a low scratching sound that is a little irritating. (its different to the high pitched screeching sound that most experience). The sound only happens after I pull the brake a lot on downhills and becomes normal again after a period of time.

Im running metallic brake pads and am wondering if this is related to heat?

thanks.
 
#3 ·
IS it a "Schwing" type noise? If so, could mean you need a good bleed, could be that there's air in the system and when it gets heated up and expands it's pushing the pistons out some and then when it cool, it contracts and everything is good again.
 
#13 ·
[QUOTE

My understanding is that the setup process for Hopes is a touch different than what's usually recommended by other brake manufacturers

Hi, can you please give a simple outline of how to true the brake rotor? I have pliers and an adjustable wrench that I may use to bend it.
 
#14 ·
IS mounted calipers can be aligned using shims. Back in the day they were supplied with a pack of shims that typically look like very thin washers* that you use to space the caliper inboard of the frame or fork mount.

They’re a bit fiddly to set up but simple, cheap and effective.

I’d try straightening* the rotor first if it is obviously wobbling

Steve

They can be “fork shaped” and just push over the bolt without fully undoing it which is easier to set up.
 
#15 ·
I use a 6" crescent wrench which has smooth jaw surfaces that won't scratch rotor. I do it with wheels still on bike. Adjust wrench so it's snug but easy to slip over the rotor and slide it all the way into rotor. Then gently bend in areas that show a slight wobble (do it 180 deg away from caliper). You want to focus on bending the whole radius of rotor from center to outer diameter so any bend is a smooth transition. Start with gentle pressure and check for true after each attempt. Usually any bends are very small so it does not take much to true it up.

I hit it with a spray can of auto brake cleaner when done to clean off any contamination.
 
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