BRAKE ROTORS 101

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ImStricken06
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BRAKE ROTORS 101

Postby ImStricken06 » Tue Jun 26, 2012 5:16 pm

I was having a discussion with someone elsewhere, and figured that my gigantic essay on different types of brake rotors should be posted on here for others to read up on if they wish too. This stuff is a lot to take in, but its pretty simple. I figured anyone on here interested, should have the info available if the need it. ENJOY :)
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Dimpled Rotors: dont do jack-poo. the only thing that dimpled rotors do, is release a tiny bit of the gasses that builds up between the rotor & pad. but since its such a tiny dimple each, its not even worth the extra money. think of how many CC's from a syringe would fill each tiny dimple. worthless. best to take that money and invest into better pads. its made to resemble cross drilled rotors - and thats about it. plus, as the rotor wears so does the size of the dimple. (see picture below)
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Cross-Drilled: is a whole different story. they actually vent any gasses between the pad & rotor, and also allow air to cool the rotor itself. the only problem with cross-drilled rotors is two fold. how its made (cast with hole, or drilled after casting). the more expensive rotors are cast with the holes, which are then refiled, and smoothed out. the cheaper rotors are all solid core, and THEN drilled. the drilling causing the metal to become more brittle. and you know brittle rotors spinning while heat cycling (contracting & expanding) is awful, and a disaster waiting to happen. IT CAUSES STRESS FRACTURES NEAR THE DRILL SITE(see pictures below)

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(cross-drilled continued)
now modern science has done plenty testing to state the follow: either casting, or drilling = it still produces stress fractures in the rotor itself because essentially its a full hole, through metal that goes through extreme pressures & heat cycles. In fact, I have a BRAND NEW BREMBO OVER-SIZED TWO-PIECE “FLOATING” ROTOR THAT HAS NEVER BEEN USED = STRESS FRACTURES SO LARGE, ITS NOT EVEN FUNNY. ITS BEEN MY MONITOR STAND FOR 5 YEARS NOW. WORTHLESS. So that tells you how sensitive these things are. somewhere in transport to and from its destination, it cracked while in the very well packaged box. (see pictures below)
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SLOTTED ROTORS: (can be found in curved, or straight) these in my book and in many books, is the best rotor for the buck to get. it causes a HUGE bite on the pad, (which causes faster pad wear, and more dust) but it works very well. its like sliding your finger across a cheese peeler. its unreal the stopping force these types of rotors will have. plus, they are not fully drilled through, and they vent because the actual slot extends PAST the break pad surface. (see pictures below) you can see that there is just a fraction of an inch on both ends of the slot that never comes into contact with the brake pad surface, so the slot not only aides in the bite, but it also works as a channel for the hot gasses to vent out - which helps the brake pads stay cooler and reducing glazing/melting/etc.
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JUST WHEN YOU THOUGHT THAT WAS IT?
J HOOK: this is a revised slotted design. its actually less appealing to the eye - but its THE BEST FOR PERFORMANCE, HANDS DOWN.
This design was used in Le Mans, Nascar, SUPERGT, etc. These are noisy, will make more brake dust, but this is BALLS TO THE WALL, TRACK STUFF. The idea is, that it cuts/shaves the brake pad face differently every millimeter as the J hook passes the surface of the pad. that reduces glazing, and the typical bump-bump-bump design in the rotor as the same spot touches the same portion of the pad, in the same way.
Slide your finger across the J Hook and you will see that at it will touch different parts of your finger, at different times - and the next hook wont pass the same spot anymore - but half will be cut in the same location. it basically acts like a confusing shaver to the brake pad. really cool physic's stuff.(see pictures below)
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ImStricken06
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Re: BRAKE ROTORS 101

Postby ImStricken06 » Tue Jun 26, 2012 6:48 pm

A LOT OF PEOPLE EXPERIENCE WARPED ROTORS NOW A DAYS, AND THEY CANT UNDERSTAND WHY ITS SO PREVALENT NOW A DAYS AND NEVER BEFORE. here you go:

if people are having warped rotors, its due to HEAT. remember these rotors WERE straight at one point in time. after YOU used them, they are no longer straight. brakes are a wear item. the more you drive = the more they wear. the more aggressively you drive = the faster they wear. you get the idea.

its no secret that people within the last 5years have been traveling faster, reducing the distance between the drive in front, and using their brakes more often. that causes your rotors to generate heat, and not have enough time to dissipate that collected heat, before the next brake application.

you also have to take into account, that the cars prior were bulkier, had more meat, were heavier, and any and all wear items where much larger - thus giving you more service life. THATS NOT THE IDEA ANYMORE. Auto manufacturers are pressed by the EPA to conform to standards they are not ready too. so they find ways to reduce weight in any possible way. and part of reducing weight, is going to involve reducing the weight of a rotor. rotors are heavy! and the only way you can reduce rotor weight - is by reducing its thickness. thus making it more pliable. and this goes across the whole board, not just asian cars. american too.

There are 3 more reasons rotors warp from heat:

1/ your calipers are seized, (stuck in the fully expanded position and never retract.)
explanation:
its often that it happens. the brake caliper gets stuck. they are also a wear item. they too are exposed to serious heat. the greater the heat = the more stress the rubber boot on the piston takes a beating. and if that boot gets a tiny tear/melt - then puddles and filth get into the cylinder, past the seals, past the now rusty piston and now into your break fluid. water, dirt, grime, that gets into the brake fluid will boil. that boiling will create steam. that steam will cause you to loose brake pressure, or will start to push against the caliper(or other calipers) = thus its like you driving around with the brake pedal pushed down on the specific calipers being effected = tremendous heat build up = warped rotor.

2/ or you have to much moisture/air pockets in your brake lines.
explanation:
people, i cant stress this enough. BRAKE FLUID IS HYGROSCOPIC! (Hygroscopy is the ability of a substance to attract and hold water molecules from the surrounding environment.) THAT MEANS EVERY TIME YOU OPEN THAT LID, ITS SUCKING IN MOISTURE. THAT ALSO MEANS THE FLUID NEEDS TO BE CHANGED WITH FRESH FLUID AT LEAST EVERY 2 YEARS. (its best to bleed your brakes every year, but with gentle driving every 2 is fine). The water molecules will need next to nothing to begin to boil & cause steam = seizing your piston, rusting your piston, and causing a seized piston that will warp your rotors. (or will stop working all together, not in nor out - and cause your car to pull to one side when you hit the brakes). i change my brake fluid in my race bike every season, often more times, and my car = every year & every brake service.

3/to aggressive of a brake pad for the rotor.
explanation: this one is simple. it happens with more of the beginner gear heads, tuners, etc. they keep the stock rotors or buy generic rotors that are OEM spec, and then invest in the best and most aggressive brake pads they can get. good idea, it will stop you faster & better = but it will eat up your rotors like hungry beast.

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Leo2005
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Re: BRAKE ROTORS 101

Postby Leo2005 » Tue Jun 26, 2012 7:13 pm

I'm using over 2 years slotted/cross-drilled rotors without problems. Still shiny. eBay seller doesn't sell them anymore but it was from trinet_motorsports. Price was about $250 for 4 rotors + semi-ceramic brake pads.
P.S. BTW these days there's like 100 different designs so it would be hard to choose. Some of them made for look and some for performance:
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ImStricken06
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Re: BRAKE ROTORS 101

Postby ImStricken06 » Tue Jun 26, 2012 7:33 pm

Leo2005 wrote:I'm using over 2 years slotted/cross-drilled rotors without problems. Still shiny. I can find a seller from ebay who I purchased it from if anyone interested. Price was about $250 for 4 rotors + semi-ceramic brake pads.
STILL SHINY? lol = totally irrelevant.

How often do you inspect every hole in your rotors? Drilled Discs must be regularly and frequently inspected for excessive heat glrazing and cracking. disks cracking on the vent holes is such a problem the worlds top rotor maker = AP Racing doesnt even make cross drilled rotors anymore. They clearly state: "Mainly used for aesthetic reasons on road applications."

The Engineers for the R35 GTR replaced the cross-drilled rotors on the GT500 race car with slotted ONLY due to finding that, the drilled style rotor wore out to fast, and cracked.
[youtube]http://www.youtube.com/watch?v=ar8jibQoAi0[/youtube]

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Leo2005
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Re: BRAKE ROTORS 101

Postby Leo2005 » Tue Jun 26, 2012 7:45 pm

Well...never checked the holes...lol. I'll check and makes some pics in the morning. And I lied...just checked the installation date of these rotors is: 08/15/2010 so it will be 2 years soon. Damn...gotta stop drinking on weekends also.

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ImStricken06
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Re: BRAKE ROTORS 101

Postby ImStricken06 » Tue Jun 26, 2012 7:53 pm

front rotors will require complete removal to check the inside disk of each rotor. With cross-drilled rotors any crack 7 mm or more radiating from the edge of the rotor OR between the cross-drilled holes makes the rotor unsafe and not reusable.
look carefully, some are VERY hard to spot
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