Rear brakes rubbing sound / feel

Saint rob

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May 26, 2019
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Yes, the washer is in the right place, but it is a little odd how the caliper piston is shiny. Something may not be right in there, because the piston is out further than it has was. (that is why it is shiny)
It could be my eyes, but I don't see a shiny calliper piston. The only shiny bit I see is the wheel spindle (axle) and the pinch bolt
 

Cantab

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Christchurch NZ
Yes, the washer is in the right place, but it is a little odd how the caliper piston is shiny. Something may not be right in there, because the piston is out further than it has was. (that is why it is shiny)
Old pads were put back in so the pistons had to travel further back out ?
 

cavenger

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If it is a damaged brake disc it can be difficult to detect and almost impossible just looking at it. You'd need a DTI to measure possible runout or you may be able to use an engineering straight edge and feeler blades. Easy fix though if that's what it turns out to be
A new disk would probably be cheaper than having someone even glance at it.
 

cavenger

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Yes, the washer is in the right place, but it is a little odd how the caliper piston is shiny. Something may not be right in there, because the piston is out further than it has was. (that is why it is shiny)
My anxiety about this is ever increasing. I hope its not the caliper.
 

cavenger

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For what its worth the piston and seals are only about $35 (new caliper is $200) Rear rotor is $75. I'd throw the $100 in parts at it along with new pads to remove the "easy and cheap" options for a fix.
I am probably going to remove the tire and take a little sand paper to the disc to see if it helps.


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Kurgan

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Dec 11, 2015
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SE Michigan
I am probably going to remove the tire and take a little sand paper to the disc to see if it helps.


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Leave the wheel and tire on the bike, put it on the center stand and run it in 1st gear. Do it when the bike is cold so that first startup has a bit higher idle speed and you can sit to the side with some sandpaper, emery cloth, etc. and have a go at it. Best bet would be to wrap the sandpaper or emery cloth around a small block of wood so you can scuff the entire swept braking area evenly.

Do be aware that running the bike in gear on the centerstand will set off some warning lights on your dash but those will go away after your first ride.
 
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cavenger

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Leave the wheel and tire on the bike, put it on the center stand and run it in 1st gear. Do it when the bike is cold so that first startup has a bit higher idle speed and you can sit to the side with some sandpaper, emery cloth, etc. and have a go at it. Best bet would be to wrap the sandpaper or emery cloth around a small block of wood so you can scuff the entire swept braking area evenly.

Do be aware that running the bike in gear on the centerstand will set off some warning lights on your dash but those will go away after your first ride.
Thanks! Any idea the grit of sandpaper I should use?


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cavenger

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So I went down the road of cleaning the rotor with sand paper. That didn't make any change. I then replaced ALL of my brake pads both front and back. I still have the same issue. This is really frustrating. Something is very odd about that brake. It does not feel right, like it doesn't feel like it has enough pressure yet it has some pressure. Fluid is showing in the rear reservoir. Its hard to assess based on brake strength because most of the braking power comes from the front. I have 3 options of what to try next as best as I can tell. Either replace the brake disc, flush and fill the brake fluid or do whatever I have to do to fix the caliper. I am open to any suggestions you guys may have.
 

Saint rob

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Can you get the bike onto a roller brake tester?
If you can then with light pressure on the brake pedal you'd be able to tell if the disc is warped as the gauge will fluctuate.
Fluid change/flush is cheap and easy to do, but I can't really see it would create the noise, but it would certainly make a difference to how the brakes feel
 

Saint rob

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Do the easy/cheap things first if the roller test doesn't show up a warped disc and changing the brake fluid along with Revz suggestion of checking the wheel bearing doesn't show anything, I'd then be looking at caliper seals and slides. Over time caliper seals deteriorate and their ability to retract the piston to provide a running clearance between the pad and disc diminishes, potentially causing your problem
 

cavenger

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Listen to my bike on the center stand. Does this sound normal? This was running it in first gear:



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Don in Lodi

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The clank clank is the drive train lash. You don't do that on a centerstand and expect silence, she's going to argue with you about it.
 

WJBertrand

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Listen to my bike on the center stand. Does this sound normal? This was running it in first gear:



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Remember that the 270 degree crankshaft has an uneven firing order, so will tend to accelerate and decelerate in speed, not perfectly uniform. Those speed changes will cause all of the lash normally built into the drive line to rattle back and forth as the whole driveline follows the varying speed of the crank. This would not be heard with the tire on the ground and rolling.
 
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