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Discussion Starter · #1 ·
so im a first time user of Disk brake
bought new YBR 125, if i rotate front wheel it requires some force bec it is not completely free
the disk pads are sitting on disk and dragging along it. they make a sqees sound and are leaving black dust and marks on disk.

I think wheels should be completely free and rotate freely like drum brackes ?
it is a waste of hp !
 

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While the pads may slightly 'kiss' the rotor, there should not be a noticeable amount of drag. If this bike is still under warranty, take it back to the dealer and have them check it out.
BTW, how many miles/kilometers on it?
 

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Discussion Starter · #4 ·
yeh today i went to yamaha service center the guy inspected it by rotating it and said its normal all the bykes are same bec the pads are rubbing on it, after some time they will drag less.
 

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Can you sit on the bike and walk it around?
 

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Discussion Starter · #6 ·
Can you sit on the bike and walk it around?
yeh sure no problem in that without any force. its just that if i rotate the front wheel with normal force it stops after 5 rotations. Im used to drum brakes which never stop rotating. So i think disks waste a power and fuel
 

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yeh sure no problem in that without any force. its just that if i rotate the front wheel with normal force it stops after 5 rotations. Im used to drum brakes which never stop rotating. So i think disks waste a power and fuel
Another thing to consider: you must be raising and spinning the wheel right after using the front brake, meaning it is still extended against the rotor. Try this: go for a ride, but when you stop to test it, only use the rear brake. I suspect it will spin more freely, after the slave piston seals have had time to retract the pads.

After that many kilometers, there could be brake dust and other road [email protected] in the small gap between the piston and cylinder, causing to bind a little; vibration from riding it should overcome that friction, allowing the pads to retract that tiny amount.
 

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Discussion Starter · #8 ·
Another thing i just wanna share here is that i also have a Honda CG125 classic with euro 2 on it, 2017 manufactured.
What i noticed is that it is an old technology but still its engine dont make a sound its quieter than the new Yamaha YBR125 which i bought. CG engine is so quieter than YBR.

After ybr gets warmer it engine nose increases like a timing chain moving noise similar to valves movement sound.
 

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Discussion Starter · #9 ·
Yeh i put it on the stand and then rotate but with or without pressing front break before.

I checked a lot of videos about that and everyone is saying that there is no mechanism to retract pads from disk, they always sit on disk and have a bit of drag. One can experiment with them by gluing back of the pads to disk piston so that they retract with piston if there as that much space. I will check if they have space to backup or no.

Disk system is clean, nothing on it, not even dust.
 

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Yeh i put it on the stand and then rotate but with or without pressing front break before.
But, did you ride it some distance to the stop, or just roll it to the stand? There is a big difference, as just rolling it from where you parked will not help the pads retract.

I checked a lot of videos about that and everyone is saying that there is no mechanism to retract pads from disk, they always sit on disk and have a bit of drag. One can experiment with them by gluing back of the pads to disk piston so that they retract with piston if there as that much space. I will check if they have space to backup or no.
In fact, there is such a mechanism; the sealing ring around the piston flexes when the piston extends to apply the brake, and that small amount of flex pulls the piston back a few hundredths of an inch. This small distance removes most pressure from the pad, even though it may still lightly touch the rotor. In any case, there isn't enough drag to use up much power; I suspect your lights pull more power from the engine than your brake.

Disk system is clean, nothing on it, not even dust.
I'll take your word for it, but it is VERY hard to see into the gap between the piston and cylinder, so, unless you take the wheel or caliper off and look with a bright light, you can't really know if there is stuff stuck in there. If you do remove either, make sure to stick something between the pads, so they can't extend too far out.
 

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Discussion Starter · #11 ·
I have inspected it by rotating several times, like left for overnight than checked it in the morning without pressing break

after driving using brakes etc...

and for the dirt around the piston, there is really none bec i brought it brand new and drove only 80km so far on clean roads.

I will try to put a needle between pads and disk to know if there is space or not
 

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I suggested riding without using the front brake before testing for the drag. Any use of the front brake in the last few kilometers can change the test results

Using your brake creates a very fine dust, so even if your roads are always clean and dry when you ride, you are coating the brake caliper with that dust, which can get onto the surface of the brake slave piston.

The gap on normally operating brake pads is measured in thousandths of an inch; and needle is in hundredths of an inch. Sometimes the gap is effectively 0, but there is no pressure applied; it is the pressure that creates the drag, not the touch.
 

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Or you could just quite worring about something that is normal and get out there and ride.
 

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Discussion Starter · #14 ·
i did the needle test but no gap was there, i think the drag may be normal but i will rid without using disk than let u know
 

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Ya, agree with the above. If you can easily walk the bike around don't worry about it.
 
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