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Discussion Starter #1
this doesn't relate to me, but this topic arose between a friend and myself. the question is essentially, if you constantly experience the cracking of rotors, would that have any relationship to what calipers are being run?
from my understanding, whether a rotor cracks or not should be solely dependent on the rotor itself and not the calipers. my reasoning is because it's the rotor's job to disperses the heat created by stopping, where it is the calipers job to turn the kinetic energy of the moving car into heat for the rotor to disperse. therefore any cracking should just be related to the materials used to produce the rotor, along with the quality of the rotor itself.
can any of you guys give me some feed back on the mechanics of it all?
 

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Re: cracking of rotors: rotor issue or caliper issue? (munkey)

My rotors have hairline cracks... Im interested too! I need new rotorseses.
I did make a post about it, but I forgot to follow up, and the thread died before much info was provided.


Modified by SebringMGB at 1:05 AM 1-12-2008
 

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Re: cracking of rotors: rotor issue or caliper issue? (munkey)

||Bump||
I'm curious too. I have hairline cracks on my front rotors. Could this somehow be related to the torque on wheel bolts? I run stock calipers.
 

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Discussion Starter #4
Re: cracking of rotors: rotor issue or caliper issue? (QuackDuck)

c'moooon materials engineers/physicists/chemists of the car lounge, don't fail us now!
 

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Re: cracking of rotors: rotor issue or caliper issue? (munkey)

It's a rotor issue, but the thing to remember is that if there isn't enough air flow in the wheel well, where's all the heat going to go?? Install good cooling ducts all the way to the hub of the rotor to provide the airflow your rotors need. If you go for a brake intensive drive, cruise around for a little while to allow the rotors to cool before parking it.
Even doing that could make it worse because of quick temperature changes, so it's best to find good deals on replacement rotors. I'm fortunate that I can get rotors for ~$25 from Napa or Rockauto, so if the cracking concerns me, I can simply swap out rotors. That said, if you're not driving extremely hard, you probably have nothing to worry about, especially if the cracks don't extend more than half way out.
 

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Re: cracking of rotors: rotor issue or caliper issue? (leaftye)

I'm no expert, but I'd say the issue is definitely with the rotors, not the calipers. The calipers are just doing their job.
One thing that wasn't mentioned- are the rotors cross drilled? A lot of aftermarket cross drilled rotors are just plain rotors that were drilled, unlike REAL crossdrilled rotors which were cast with the holes in them. The process of drilling rotors weakens them and they tend to get stress fractures near the drilled holes. Just a note...
Calling osbornsm to the thread! This guy is the self-proclaimed brake whore of the vortex- he knows his stuff!



Modified by VRsexxy at 8:30 AM 1-12-2008
 

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Re: cracking of rotors: rotor issue or caliper issue? (munkey)

It would come down to the pad choice, rotor quality, and driving style.
I get countless numbers of cracks and deep bluing on my rotors when they get old after they've seen some track duty. I consider it normal.
 

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Discussion Starter #8
Re: cracking of rotors: rotor issue or caliper issue? (TabulaVicious)

sweet, thanks for the replies guys! i'm glad to hear that i was somewhat on the right track. I'm not sure if my friend's friend's car's rotors were drilled or not, but i'll definitely pass this thread forward. It hadn't even occurred to me that it was the abrupt change in temperatures that'll cause the fractures.
 

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I'm not sure about the brake rotor cracks but I can chime in on a recent experience with rapid heating and cooling and what it can do...
Earlier this week I preheated my oven to 400. once it was pre heated I went to put my pizza in only to find out my GF had been storing glass baking dishes in there ( about 16x8x2 ). So I took them out and set them on the top of our glass top stove. ( I had also been using the left front burner but had just turned it off. ) So one baking dish went onto each front burner, I put in the pizza, set the timer and left the kitchen. Well 15 mins later the timer went off so I went to the kitchen, opened the oven and realized there was no where on the stove to put the pizza. SO, not thinking I pushed the dish from the left front burner ( had been set on 6 15 mins ago ) to the left rear burner ( room temp ). When I did this I immediately heard a slight hiss, just enough for me to think WTF, then, BAM the dish exploded!! Scared the Sh** out of me. Glass was everywhere. I didn't get hit with any but there were little shards of glass stuck in the wall next to the stove and the pieces on the floor were melting the polyurethane off the wooden floor and smoking. Biggest piece of glass I found was about 2"x2".
I never thought this would happen, but it was kinda cool, if anyones willing to try and youtube it, I'd love to see it in slow motion.
 

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Re: (NARDO)

You'd need a very special camera to capture something like that in slo-mo....and that camera hasn't been released for sale yet....but has been formally announced.
 

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Re: (leaftye)

here are pics of the aftermath


and heres the spot where a the biggest chunk melted the polyurethane
[URL]http://i118.photobucket.com/albums/o114/amydaim/P1120195.jpg[/IMG[/URL]]

[IMG]http://www.vwvortex.com/vwbb/eek.gif
 
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