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06 yamaha R6
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Discussion Starter · #1 ·
Hey there,

My front brake feels like it's pulsating when I am coming to a slow stop. I don't feel it in the lever but in the front end of the bike. When I'm hard braking I don't really notice it until the last couple of meters.

It does this since I bought it a couple of years ago but now it's annoying me. It doesn't feel right.

I checked the rotors/disks for warping but they seem to be straight although 1 may be slightly off... But it's really, REALLY hard to tell.

I cleaned the calipers, refreshed the brake fluid and made sure there was no air in the lines. But the issue remains.

During the cleaning I noticed the pistons aren't pushing out evenly.
Could this be causing the pulsating feel? Or is it more likely that my rotors are warped?

I'm kinda leaning towards buying a caliper rebuild kit but I am not sure if it will fix the "sticky" pistons and the pulsation.

Your thoughts will be greatly appreciated.
 

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Administrator
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Sounds like warped rotors? Take the rotors off, lay them on a flat surface and see if they are not flush to the surface. You said you checked them... how exactly did you do that?
 

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Just for testing purposes, do wild swings in tire pressure have an impact? (return to normal pressure after testing)

The handlebar clip-on bolt has been known to back out on 3rd Gens. May be time to retorque things.
 

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YZFR6... ooodles of HP
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Is this an abs model? Are there lines on the rotors? Does the wheel spin pretty freely in the air after a good squeeze and release? Run a fingernail from outside to inside, feel like glass or notchy? The semi metallic pads leave buildup on the rotors over time causing a grabby pulse type deal as the front comes to a stop. Just a side effect of stainless rotors. No non stainless available that I can find. So you have to lift the front and hold some 400 type sand paper and spin the swheel to get that crap off. I switch to ebc hh copper pads and the every few months rate of sanding got a lot longer.
 

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06 yamaha R6
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Discussion Starter · #5 ·
No abs. I will have to check for lines and the glass or notchy feel.
I will give the sanding down a go. Seems like a good idea. Thanks!

The handlebar clip-on bolt has been known to back out on 3rd Gens. May be time to retorque things.
Will this cause the feeling of the entire front end going over small waves you reckon? Do you by any chance know the torque settings? Never hurts to get them up to spec right.

Maybe pulsating isn't the right word (sorry not my native language). It feels like the brake grabs on and releases and grabs on and releases.
I don't feel anything in the brake lever. The entire bike is rocking back and forth like going over little waves.

The uneven piston pressure is not an issue?
 

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That's classic warped rotor. Need to download the PDF service manual for torque settings.
Mentioned tire only as another check but really really doubt that's it.

Admin had a comment about removing the rotors and setting them on a flat surface. Try that and if the rotors really are good then look at the floating mounts.
 

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Discussion Starter · #7 ·
Warped rotors would be a bummer!

Is there any other good (and preferably easy) way to check if they are warped. I taped a screwdriver to the front fork with the tip of the screwdriver grazing the rotor. Couldn't really tell if there was any side movement. If you can't see it with the naked eye will it still be noticeable when braking?

The floating mounts you are referring to are the round bobbins right? I checked if they were moving freely. Some of them were a little harder to turn then others. How easy are they supposed be turning?

I hope I get around to sanding them down tomorrow.

I don't need to worry about the caliper pistons? No need to rebuild them?
 

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YZFR6... ooodles of HP
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Did you lift the wheel and spin it?
 

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UR B-hind Da 8 Ball
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With the floating bobbins, if a warped rotor was your problem, it would have to be visibly warped using the screwdriver test you used.

Most likely you have some “hot spots” on the rotors. Take some scotchbrite pads and scuff the rotors with some brake cleaner. That will clean the surface. See if that helps.
 

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Discussion Starter · #11 ·
Tried the scotchbrite pads... Got a lot of dirt from the rotors but no bueno... I was really hoping it was the hot spots.

Should the bobbins spin easily (by hand) or is it normal that I need some tools to spin them around a bit?
 

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Wouldn't recommend used rotors like this guy. You could be buying a turd and a FleaBay seller would figure out a way to mess that sale even. Different bike, probably different torque settings, but the general procedure is pretty much the same.

 

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YZFR6... ooodles of HP
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Post a close up of a rotor area macro mode is excellent.
 

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Discussion Starter · #16 ·
Musical instrument Guitar accessory Wood Table String instrument


Musical instrument White Automotive tire Light Wood


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White Wood Circle Pattern Water


I made some pics.
The last one shows some black spots that I can't seem to brush off. It doesn't feel like it is on the disc but more embedded. It feels smooth.
Could this be causing the annoying feeling while braking?
 

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YZFR6... ooodles of HP
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Those show pad material build up on them. Sand with 400 sand paper to remove.
 

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YZFR6... ooodles of HP
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Hell even 120 would not leave scratches to deep in the stainless. Lighter grit is best depending on your technique. You could stone them if you have ever lapped or stoned gasket surfaces. Same idea.
 

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Discussion Starter · #20 ·
So it's not residue... It's actually little holes/dimples... It's not all the way through but pretty shallow. Has anyone ever seen this? Is this reason for concern?
It doesn't seem likely to me that it is causing the braking issue... or is it?
 
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