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07-21-2009, 12:22 PM | #26 | |
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07-21-2009, 03:21 PM | #27 |
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Drilled are always bling and always a bad idea. Cross drilling can and will lead to premature cracking of the rotor.
Slotted only are even remotely reasonable if the brake pads are having issues with hydroplaning. I've heard this can happen to the STi Brembos but I've never experienced it myself. In other words, get blanks. |
07-21-2009, 03:44 PM | #28 |
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So how come Mercedes and other high-end companies use drilled rotors?
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07-21-2009, 04:00 PM | #29 |
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Bling.
Uninformed consumers equate cross-drilled rotors with performance. |
07-21-2009, 09:43 PM | #30 |
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Actully, crossdrilled discs offers improved performance over non-crossdrilled discs. They not only help to remove the brake gases produced under hard/extreme braking, but also help to lower disc and pad temps as a result, which helps to keep pads at their optimal operating temps and limit them from fading due to excess heat. There is also the benefits of less rotational mass.
BUT, and it is a big but, the biggest problem is that they tend to crack from irregular expansion from all this hard/extreme braking - so if you use them on the track, you'll need to have the budget to replace them when cracks appear. Also, some manufacturers do try to limit cracks by reducing the drilled hole count and not drilling too close to the edges, as well as drilling after the discs are heat treated, and although these steps may prolong the life of the crossdrilled discs, eventually cracks can (and still do) form. Leslie. Last edited by wrxsti.l; 07-21-2009 at 10:27 PM. |
07-21-2009, 10:18 PM | #31 | |
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Additionally, reduced mass, in an iron rotor, is a bad thing. Rotors exist for the purpose of storing and then dissipating heat. For a given rotor material (iron, ceramic, carbon, etc), the heavier rotor ALWAYS can store more heat meaning it ALWAYS offers better performance. |
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07-21-2009, 10:20 PM | #32 | |
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http://forums.nasioc.com/forums/show...85&postcount=4 It's all there, from smarter people than me. Baer answers the gas thing. Wilwood says they reduce cooling capacity. Stoptech says they don't take abuse and don't work on track. http://corner-carvers.com/altimathread.php.html Carbotech engineer arguing the same points. "far greater performance", definitely not. |
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07-21-2009, 10:27 PM | #33 |
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Sorry about wording (fixed it btw), but there are performance gains to be had.
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07-21-2009, 10:29 PM | #34 |
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07-21-2009, 10:57 PM | #35 | ||||
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Also, just so you know, only about 20% of your brakes cooling comes from conduction (ie, the ability of the rotor to remove heat), however over double the amount is removed from convection - so the more surface area and better the airflow around the brakes, the better the cooling Quote:
I changed the wording, but regardless, it still imrpoves performance. Leslie. |
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07-21-2009, 10:58 PM | #36 |
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07-21-2009, 11:06 PM | #37 |
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07-21-2009, 11:46 PM | #38 |
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You have to look at it from their perspective to see why they would suggest general consumers to not use them.
In all probability, the main reason they recommend against them is for longevity - ie. they don't want to suggest customers use crossdrilled rotors on a track and have to deal with an influx of complaints because of cracking and/or warping after a short period and/or incorrect cooling down proceedures. From a cooling point of view, it is a fact that cross-drilled rotors have greater cooling ability (somewhere in the region of upto 20%) over non-drilled rotors. Go ask any one of those manufacturers and they will have to agree. And from a performance point of view, improved cooling equates to improved braking performance. What I hope you understand from my posts is that my comments are purely focused on the misunderstanding across the web that crossdrilled rotors offer no improvement to braking performance, when in fact they do. And that I do understand that even though their are improvements to braking performance, that alone doesn't make them suitable for the weekend track star or low budget race team looking for suitable brake package. Leslie. P.S. Regardless of what Baer, Wilwood, stoptech reps may post, their top of the line rotors are still crossdrilled, which says to me they still offer an improvement over non-crossdrilled or slotted only rotors |
07-21-2009, 11:50 PM | #39 |
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Considering that all the major players in the braking industry are contradicting you, the burden of proof is on you (I'll even accept you getting someone from StopTech or Baer to post here). Until then, you're just some crazy guy clinging to outdated ideas.
Seriously, some dude on the internet vs MechE's that design brakes for a living? |
07-21-2009, 11:59 PM | #40 |
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lol, but you have to admit, crazy ppl are fun
I guess physics doesn't rate high as proof these days And as I posted above (P.S comment), the top of the line rotors from those manufacturers, who comments you hold dear, are still crossdrilled - and I'm not talking just the "street" rotors, I'm talking race, track, and drag rotors too - where the look or bling means sfa over braking performance. If it wasn't of any benefit, they wouldn't have it. So I guess I'll use that as proof too. |
07-22-2009, 07:39 PM | #41 |
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There are benefits of drilled rotors but they dont really have anything to do with reduced weight or cooling since those are minimal at best. Drilled rotors will add more bite to a brake system by offering an increased number of leading edges for the pads to bite into. Drilled rotors also offer improved performance in wet weather by allowing an evactuation point for water and steam. A place you may not expect to see drilled rotors is on carbon ceramic systems on vehicles like Porsches and Ferraris. This is again to aid in adding bite to the system since the pads used in those applications need heat to operate properly. Without the drilled surface, the cold performance is pretty dismal.
As far as the "drilled rotors are evil" mantra that gets spewed so often, its mostly caused by the influx of inferior quality parts that are sold online and on ebay for rock bottom prices. These parts are most often crap and should be avoided but high quality parts should not offer any issues, especially on a car that will never see a racetrack. As a StopTech employee since 2005, I will go on record as saying that on an autocross car where brake temps are never really an issue and getting heat into the system can be difficult, I would purposely run drilled rotors for their added bite. Since the runs arent long enough to cause any kind of temperature issues, I would not have any problems with the parts prematurely cracking. On a street car that might see some canyon runs or performance use, maybe 1 or 2 light track days a year, I would go with what I preferred the look of most as that will have the biggest impact. In most cases, the driver would not be able to notice any difference in feel between blanks, slotted, drilled or drilled/slotted rotors becuase the tires dont offer enough grip and the pads dont have high enough levels of friction. On a track driven car, I would only run slotted rotors. They add bite to the system and keep the pad suraface from glazing with no discernable difference in crack related failures. To those who claim that blank rotors are the only way to go, I disagree as the added performance of the slots are well worth it. There is a reason that all of the top level race teams in World Challenge, GrandAm Cup and LeMans use some sort of a slotted rotor in their brake systems, they really do work. That being said, there are some teams that also have great experience with drilled rotors. For example, TriPoint Mazda who have been champions in World Challenge TC and are always top contenders prefer to run drilled rotors in their Mazda 6 race cars for the added bite. These cars can run a full season on one set of our drilled rotors and not experience any kind of cracking issues..this includes all of their practices and qualifying. The same can be said about the StopTech time attack EVOX which his drilled rotors for the sole purpose of proving they can be run on track successfully without premature cracking issues. Other than a small group of people on this message board, these cars are faster on the track than yours, driven by better drivers than you, and put through more abuse than you have the ability to match. Not all drilled rotors are evil and they do have their merits. Theres a lot of misinformation for and against drilled rotors, and way too much of the "I saw it on the internet so it must be true" followers in both camps. My recommendation is to go with what you prefer knowing possible risks involved. Be realistic...if you plan on doing a lot of track days, dont get drilled rotors since yes, they are more prone to cracking at extended high temperatures. Are you going to die in a fireball on your way to work in your daily driver because your drilled rotors cracked while getting off the freeway, not very likely unless you ended up with some really low quality garbage. |
07-22-2009, 07:46 PM | #42 | |
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Kudo's Erik - well wrote
1 - You have too much time on your hands 2 - You forgot the worst part about drilled rotors - getting harassed on NASIOC. Quote:
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07-22-2009, 08:05 PM | #43 |
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Aye, thanks Erik. I figured you would get the bat-signal eventually. I was actually going to try drilled rotors when my first set of Stoptech BBK rotors wore out but I needed them *that weekend* and couldn't wait, JSC had the slotted ones in stock. I was hoping to experiment.
I will say that, given the fact that most people do buy the crappy ebay ones (as evidenced by the weekly "hey guys, I found these rotors on ebay, what do you think" posts) I would think the general rule would be to avoid them unless you have a real reason to run them or you buy them from a reputable manufacturer. And in williaty's defense, hearing about drilled rotors being better because of pad gas does get a little old john |
08-20-2009, 01:59 PM | #44 | |
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I understand that brakes are only as good as how much grip your tires get with the road. However, if the car with the less sticky tires was equipped with better brakes, won't it stop in a shorter distance than the other car with stickier tires assuming that the tires don't loose grip? Thanks. Gerald. |
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08-20-2009, 02:10 PM | #45 | |
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What Luke was saying is that 99% of factory braking systems can deliver more brake torque than 99% of the typical tires people buy can hold. If the tires can't grip the road any harder, then upgrading the brake hardware won't make a damned bit of difference. However, if you picked up the drum brakes off of a 1940s British roadster and then put R-compound tires on it, yes, upgrading the braking hardware can make a difference because the R-comps would have more grip than the crappy old drum brakes can overcome. This is why you need to focus on the tires, and on keeping the tires in proper contact with the ground (suspension), rather than on making the braking system develop more braking torque. The point of upgrading brake hardware is to better deal with the heat of repeated stopping, not to make a single stop shorter. |
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08-20-2009, 02:33 PM | #46 | |
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Cheers. Gerald. |
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12-24-2009, 02:10 AM | #47 |
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Great thread. Answered many of my questions. Now I just have to decide which pads to get! I've been eyeing the Akebono ProACT pads. Anyone with these care to share their opinion?
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12-27-2009, 03:39 PM | #48 |
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hi just need some help i bought some drilled and slotted rotors and just was wondering , should i leave the brake shield on or have them removed?? any help would help.
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02-11-2010, 11:23 AM | #49 |
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In my quest to find good rotors/break pads I came across this article.. It seems very informative:
http://www.zeckhausen.com/bedding_in_brakes.htm |
03-18-2010, 08:06 PM | #50 |
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Bought my drilled & slotted rotors & ceramic pads from ebay for $180 shipped.
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