Author Topic: Rotor problem  (Read 560 times)

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Offline The Doctor

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Rotor problem
« on: March 23, 2019, 02:33:31 am »
Hey all,

So I was riding to class tonight and noticed a bit of lurching when I was on the breaks. Immediately thought one of my rotors might be a little wonky. After getting home I felt them to see if there was any concerning temperatures that might indicate rubbing etc. The front right one was totally fine and cool(ish) to the touch. The front left one was kinda hot. And the rear one was HOT.

I know this is a problem, but not sure where to go from here (aside from taking the OTHER bike to class tomorrow). Take the rotors off and see if they're warped at all? Worry about the brake calipers? I did a rebuild on the rear caliper just recently so I think it should be okay (unless I inadvertently messed it up?). What, if not excessive heat from a messed up caliper, would cause a rotor to warp? How worried do I need to be?

Ride safe!
It all started on a 250...


Offline Bob_C_CT

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Re: Rotor problem
« Reply #1 on: March 23, 2019, 10:18:14 am »
Make sure your right bag isn't droopy and resting on the rear caliper causing the drag.

IMO it is easier to get the wheel off the ground and spin it to see if rotor is warped.
If you don't have a dial indicator to see how much it runs out, tape a drinking straw or pencil to the fork/rear swing arm so it just touches the rotor then spin wheel while seeing how much the runout is.
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Offline RWulf

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Re: Rotor problem
« Reply #2 on: March 23, 2019, 02:30:30 pm »
If when you finished the rebuild of the rear caliper, the wheel rotated without any drag, and
stopped the wheel when the brake was applied, I would start by bleeding the system.
The front indicates the pads are dragging. Even if the rotor is warped the pad should not be
dragging. Most likely needs to be rebuilt.

Offline GeorgeRYoung

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Re: Rotor problem
« Reply #3 on: March 23, 2019, 07:47:16 pm »
This is worth thinking about:

https://www.randols.net/Connie/RotorTweak/RotorTweak.html

Worked for me.

Offline m in sc

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Re: Rotor problem
« Reply #4 on: March 26, 2019, 02:30:05 pm »
also make sure the tiny bleedback hole in the master cylinder isn't clogged.
I break stuff. I fix stuff. (rinse & repeat as necessary)

Offline The Doctor

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Re: Rotor problem
« Reply #5 on: March 31, 2019, 04:04:36 pm »
If when you finished the rebuild of the rear caliper, the wheel rotated without any drag, and
stopped the wheel when the brake was applied, I would start by bleeding the system.
The front indicates the pads are dragging. Even if the rotor is warped the pad should not be
dragging. Most likely needs to be rebuilt.

It wasn't dreading, at least not appreciably. It's just a build up of heat when at speed. I've read up somewhere about the seals maybe bunching up, so I took the calipers off, took the pads out, and pushes the piston in and out a few times. That seemed to help, but not cure it. I've been testing by running up and down the streets near my house, not utilizing whatever brake is in question (will mess with the front and then only use rear brake on that run). When I get back to the garage the right one is nice and cool, the left one is not cool, but I wouldn't go so far as to say it's warm or hot. But there's definitely a temperature differential there. Same thing with the rear now.
It all started on a 250...


Offline RWulf

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Re: Rotor problem
« Reply #6 on: March 31, 2019, 05:11:05 pm »
The 2 ways that can happen are the wheel bearing on that side is really bad and the other
way is the brake pads are dragging. The seal around the piston, when new, has just enough
ability to pull the piston back just a few mm's. This keeps the pads from touching the disk.
You most likely need new seals. The good side is you know the pistons are free to move.

Offline mnbikeguy

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Re: Rotor problem
« Reply #7 on: March 31, 2019, 05:37:29 pm »
This is worth thinking about:

https://www.randols.net/Connie/RotorTweak/RotorTweak.html

Worked for me.

Can someone explain how bending the carrier can have any impact on a floating rotor? On a number of levels this seems crazy to me.

Offline RWulf

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Re: Rotor problem
« Reply #8 on: April 01, 2019, 02:08:58 pm »
If I understand it (I could be way off) the float is in the forward/ aft direction.
Not left/right direction. Unless hit by something the rotors warp from heat.
If I have this wrong,educate me.

Offline Old Man on a Connie

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Re: Rotor problem
« Reply #9 on: April 02, 2019, 01:31:29 am »
I have dial indicators if you need them Matt.
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