A Question About New Rotors
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Tourer
Joined: May 2013
Posts: 297
Likes: 12
From: Los Angeles County
A Question About New Rotors
Your thoughts please,
One of my otherwise perfect looking front rotors has .038 runout (yes, no kidding). So I'm planning to put a pair of new EBCs on.
My question is ... Can I keep the also perfect looking pads on, or must I change them too? If I scuff them up with some emery cloth will they seat with the new rotors, or is that a lost cause?
Thanks for your feedback.
One of my otherwise perfect looking front rotors has .038 runout (yes, no kidding). So I'm planning to put a pair of new EBCs on.
My question is ... Can I keep the also perfect looking pads on, or must I change them too? If I scuff them up with some emery cloth will they seat with the new rotors, or is that a lost cause?
Thanks for your feedback.
Stellar HDF Member
Joined: Nov 2008
Posts: 2,432
Likes: 290
From: FL
Pads will be fine. I'm amazed at the runout on your rotors. Have you had tires changed recently? I'm just trying to understand what caused the runout? How old are the rotors? I assume 6 years.
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Joined: May 2014
Posts: 89
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From: Eastern PA
Warped rotors
It's not difficult to warp a set of rotors. A splash in a puddle after a long downhill, or even simply keeping the brakes squeezed after a long stop will cause uneven cooling of the rotors and warping usually results.
There's nothing you can do about the puddles, but it is a good practice to release the brakes and roll forward or back a little to expose the entire rotor to the air. That will prevent the uneven cooling of the part of the rotor under the pads. Obviously, this is for hard stops that get the rotor hot. The occasional stop doesn't get the rotor hot enough.
There's nothing you can do about the puddles, but it is a good practice to release the brakes and roll forward or back a little to expose the entire rotor to the air. That will prevent the uneven cooling of the part of the rotor under the pads. Obviously, this is for hard stops that get the rotor hot. The occasional stop doesn't get the rotor hot enough.
Last edited by HD-Gyro; Mar 26, 2016 at 02:18 PM.
Stellar HDF Member
Joined: Nov 2008
Posts: 2,432
Likes: 290
From: FL
This is my thinking. I've been riding for over 35 years and I've never had a rotor just warp on its own. Not saying it not possible, just not likely.
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Tourer
Joined: May 2013
Posts: 297
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From: Los Angeles County
I am amazed too at that much runout. And only one rotor, the other one is within +/-.003.
It did not happen with any single event I can think of. It kind of gradually got worse over about 5000 miles. At first it only was noticeable after riding a while, but then got bad all the time. I measured the .038 runout cold, no telling what it is when warmed up.
It did not happen with any single event I can think of. It kind of gradually got worse over about 5000 miles. At first it only was noticeable after riding a while, but then got bad all the time. I measured the .038 runout cold, no telling what it is when warmed up.
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Stellar HDF Member
Joined: Nov 2008
Posts: 2,432
Likes: 290
From: FL
I'm sure our riding environments or differences has a lot to do with the fact that I've never had rotor issues. We do stray into the north Georgia mountains from time to time but the majority of my riding is in Florida where my brake use is nothing out of ordinary.
Have you checked the pistons in your brake calipers?? Maybe they're not fully retracting which is causing slight pressure against your rotor, in turn causing it to overheat and warp?? Another cause I've heard of from other technicians is that infrequent changing of the brake fluid in our DOT4 systems. Since DOT4 is highly hygroscopic, the buildup of moisture in our lines can create boiling effect and again, cause slight pressure of your pads against your rotors and over heat them.
Hope you get it figured out. It's one thing to fix the symptom but unless you discover and correct the cause, you'll be doing this again.
Have you checked the pistons in your brake calipers?? Maybe they're not fully retracting which is causing slight pressure against your rotor, in turn causing it to overheat and warp?? Another cause I've heard of from other technicians is that infrequent changing of the brake fluid in our DOT4 systems. Since DOT4 is highly hygroscopic, the buildup of moisture in our lines can create boiling effect and again, cause slight pressure of your pads against your rotors and over heat them.
Hope you get it figured out. It's one thing to fix the symptom but unless you discover and correct the cause, you'll be doing this again.
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Joined: Jun 2007
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From: Bedford UK
Changing a tyre is a likely time. Remove the rotors before doing so, to avoid the risk of damage.