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Initial D World - Discussion Board / Forums > Technical Discussion > Myth Busting: Crossdrilled Rotors |
Posted by: But she looked 18 officer May 15 2005, 03:52 PM | ||||||||||||||||
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Posted by: sideways May 15 2005, 05:43 PM |
Pin worthy but this should probably be in the Tech section, ill let it get some attention here then pin her up in the tech |
Posted by: WRX DEMON Type R May 15 2005, 05:59 PM |
im too lazy to read all that. i am looking to completely replace my car's pads and rotors... Suggestion please? |
Posted by: But she looked 18 officer May 15 2005, 06:24 PM |
I will suggest you quit being lazy and do some research. There is a LOT more to getting the right braket setup then what many people go by which is "bigger is better". Think about exactly what it is about your current brakes that you are not satisfied with and what type of driving will your car be experiencing. FWIW When Brad Bedell's mk2 mr2 won the Sport Compact Car Magazine, Ultimate Street Car Challenge, he was using 94/95turbo mr2 brakes with real good pads and had the lowest stopping distance of any car they had ever tested. A good set of brake pads can do wonders for your car. Also remember, brakes dont stop the car, the tires do. *edit: If your really set on spending money I would suggest going with STi brake setup. They have had a lot of testing done for those cars. You could probably get a good set of 2nd hand brakes from someone with out too much money. |
Posted by: Nd4SpdSe May 15 2005, 07:26 PM |
I've always wondered then, why do high-performance cars have them? Lamborghini Murcielago http://www.swisscarsightings.com/lamborghini/Lamborghini%20Murcielago%20340.jpg Porsche 911 GT3 http://images.automotive.com/cob/factory_automotive/images/Features/auto_shows/2004_CIAS/2004_Porsche_911_GT3_wheels.jpg 2006 Corvette http://www.canadiandriver.com/discus/messages/1490/24053.jpg Enzo Ferrari http://www-personal.engin.umich.edu/~dixitp/photos/autoshow03/P1180880.jpg |
Posted by: sideways May 15 2005, 07:36 PM |
To keep it simple because they look good. Nicks post was dead on and used a number of resources, common sense with physics will also support the claims made. They want a car the looks and performs good. As nick touched, hands down the BEST way to increase your braking ability are the pads. If your getting brake fade due to overheating you need to flush out your system and upgrade your fluid. If you want to upgrade your rotors, sloted is the best path to go. Any thing that builds up between the rotor and the pad has a place to go, plus the egde gives the slicing effect should the pads start to glaze. They suppoedly bring the life of your pads down but its minimal, so no worries- small price to pay for the advantage imo. NFS i still suggest you upgrade your fluid as well, its not a sin to mix fluid, and as long as you flush it properly youll do fine. Bleed the rear passenger until your getting the new fluid going through, rear driver, front passenger, then front driver (from the furthest to closest). |
Posted by: WRX DEMON Type R May 15 2005, 08:25 PM |
my brake rotors are rusted (what i get for keeping the car locked up for nearly 3 moths) and the car makes noises when i press the brakes. hey, anyone know if Monroe brakes are any good? www.monroebrakes.com I can grab these at Canadian Tire. Rotors and pads. ATM the car is just for transportation. No fancy NAWZ or drifting for me. LOL. |
Posted by: Cubits May 15 2005, 09:10 PM |
Slots-b-good. Even the most uber-modern pads will glaze from light pedal use etc, and slots don't really diminish the pad life much. The slots may weaken the disc slightly, but it is quite an insignificant amount in most cases. Drilled are pretty bad. If you don't get hole-cast discs, it will create issues. If you say, got the brakes nice and hot on a mountain road, then hit a puddle, you'd probably warp or even crack the discs (badness). I've seen semi-drilled discs (EBC make em) that are slotted too. Pretty sure the hemispherical dents are only for street appeal, but at least they'll be stronger than fully-drilled discs. They're cast holes. |
Posted by: Jabberwocky May 15 2005, 10:21 PM |
Let me start off by saying that what nick posted was true. Cross drilled rotors are not without their application. It is a viable way to reduce unsprung weight/rotational mass. Usually a cross drilled rotor of the same thickness will have less mass. Thus be a worst heatsink. In some cases, this trade off is worth it, especially is the car already has more than adequate braking. Eg. if the car can lock all 4 wheels at any time. The other way to reduce the rotational mass of the rotor is to make it thinner. Which can make it more prone to warping. Or decrease the size of the rotor. Which also reduces the surface area. Reducing the mass of the rotor usually involves some kind of trade off no matter how you look at it. From what I've seen, high price cars with drilled rotors usually also have massively powerful braking systems. A slight reduction in unsprung weight could very well be worth the tradeoff since the braking system far exceeds the traction of the tires anyways. I think only cheap pads glaze. The good ones aren't suppose to. |
Posted by: Cubits May 15 2005, 11:47 PM |
If i had more than sufficient braking, i would rather go to a smaller disc than have holes drilled in them. The saving in rotational inertia is worth a buttload more than the saving in unsprung mass. |
Posted by: Jabberwocky May 16 2005, 06:49 PM |
I dont want to get too deeply into it, but going with a smaller diameter usually means a small pad. Also the braking force depends partially on the velocity of the rotor relative to the pad. There are tradeoffs to everything. I'm not saying that crossdrilling is better or worse, but that it is another valid way to lowering rotational mass. |
Posted by: MidnightViper88 May 16 2005, 07:18 PM |
I like the drag racing cue of parachutes... |
Posted by: vhsfootball_82 May 16 2005, 07:18 PM |
so sloted rotors are better than having crossed-drilled rotors------In heavy racing i think......... and Having Bigger rotors and Bigger Brake pads, give u better braking........ crossed-drilled rotors look nice, but are more for street/light racing........ and i dont think having a smaller rotor and smaller pads would help u brake better.......well from what i read in the first post.......Having a bigger rotor surface, will dissipate and dispense heat faster......... you would have less surface for heat to dissipate into the rotors and heat wont dispense as fast as a bigger one would......i think correct me if im wrong, im still trying to figure it out, trying to make it easy for others........got to learn this stuff.....its interesting....... |
Posted by: Jabberwocky May 16 2005, 08:18 PM |
It can't be oversimplified too much. I'd just wanted to point out that crossdrill rotors arent complete junk. I use regular blanks myself because they are cheaper and work just as well. Here's a bunch of factors to consider (generally true): With larger diameter rotors, you have more rotational inertia, which is very bad. With larger diameter rotors, you also generally have more mass to resist fad, good. With larger diameter rotors, you generally have a the pad engage the rotor at a higher velocity, good. With larger diameter rotors, you generally have the air vanes in the rotor working at a higher velocity to dissapate heat, good. With holes/slot drilled in, you generally have less pad to rotor contact, bad. With holes/slot drilled in, you generally have less rotational inertia, good. With holes/slot drilled in, you generally have less mass to resist fade, bad. With holes/slot drilled in, you generally have a weaker rotor prone to cracking, bad. With thinner rotors, you generally have less rotational inertia, good. With thinner rotors, you generally have less mass to resist fade, bad. With thinner rotors, you generally have a weaker rotor prone to warping, bad. That barely scratches the surface. Then there's the tires effect on braking, the caliper design, the brake pad material, the rotor's material, rotor vane design, antisquat and antidive and their effect on weight transfer during braking and more. I know that I'm not that knowledgeable on brakes either. There is probably plenty of stuff that I haven't even mentioned. For those looking for more braking power, I'll say this. The biggest factor IMO is brake pad, the difference between el cheapo autozone pads and something like HP+ is just astounding. |
Posted by: vhsfootball_82 May 16 2005, 08:36 PM | ||
very true.......... autozone pads,,,,,,cheapo.......brake pads do make a difference in braking.......big time |
Posted by: TaksPandaHatch Sep 10 2005, 12:26 AM |
Alright. The bigger the rotor, the more heat you will disipate, which means less brake fade and not having to turn your rotors because of warpage. Pads do make a difference. I heard some dumb a$$ at Kragen say that ceramic pads will stop squeeking. BS The squeeking is the brake pads moving in the caliper while braking causing a high pitch sound. Ceramic work better at a high heat range and that is why more cars are using them. While Semi Metallic pads work better at a low heat range. Now, cross drilled rotors and slotted rotors. Prectically the same. Cross drilled CAN disipate heat better because the air hits them, but they are taking away metal mass and brake surface area they cannot disipate heat as well because its NOT there. SO you can stop better but you can't either. YOU GAIN and lose. Some Slotted rotors have more pad surface area, some have less,but for the most part, but you have more metal to help disipate the heat than drilled rotors. They also BOTH help remove gasses that build up on the pad surface. Better braking can be achieved by removing the heat, that is the goal of the rotors. You can also increase the rotor size to achieve better braking because you have more brake pad surface area. |
Posted by: RandRace Sep 12 2005, 08:50 AM | ||
Greater surface area. Not neccessarily true in regards to drilled rotors where you're not getting any more surface area, but true in a general sense. Look at the heatsink in your computer. A heavily vaned chunk of aluminum. A solid lump of aluminum would have greater mass and a better ability to absorb heat but far less ability to dissipate that heat since the air flowing over it would pass over a far smaller surface area. I want rotors with a fractal surface. To the pads it would be just like a normal solid disk. To the air though the surface area would be simply immense. Orders of magnitude greater than the flat surface of the rotor. |
Posted by: Pearce Sep 19 2005, 08:36 AM |
someone mighta said this...that's too much to read...but i heard hey warp more easier when they're crossed drilled because they heat up really hot and then cool so quickly...heard it from some street racer...not to sure on the validity of his statement, but it does kinda make since |
Posted by: MidnightViper88 Sep 19 2005, 03:01 PM | ||
It's taken quite a few months for me to ponder over this post, but sports and supercars have more than just large-ass brakes...They also have large-ass pads to go with them, large-ass wheels, and wide/sticky-ass tires, so their braking capabilities are not soley on brakes alone... |
Posted by: InitialE Sep 19 2005, 03:17 PM |
Tire compound/size are more or just as important as brakes when it comes to stopping power, it's the only thing that touches the road surface |
Posted by: sideways Sep 19 2005, 03:25 PM |
Exotics drill their rotors for one reason. It looks nice, how often do u think those owners are REALLY pushing those cars aroudn tracks? (granted some of them actually DO). That and then of course they dont use the same material to make their rotors. |
Posted by: Wheels84ss Sep 21 2005, 06:22 PM | ||
Unfortunately anti-rice is down so i can't get the link to the actual reason because we did one of these threads a while ago... But it was explained something like this.... The exotics use crossdrilled for astetics and less rotational mass.... Usually exotic setups have more braking capacity then is actually required for the vehicle.... So you can crossdrill the rotors to lighten the load and appeal to the eye without actually decreasing the max braking the car can do... (because the system itself far surpasses what the tires and the suspension will allow) So short answer, it looks cool.... |
Posted by: Nd4SpdSe Sep 23 2005, 05:09 AM |
Well, I've been runing Brembo Cross-Drilled and Slotted with PBR ULX Ceramic pads. I kept the Dot3 Fluid (cause I would need to change all the parts to make sure the system is clean) and want with new steel lines, although I wanted to get stainless steel/teflon braided lines, a miscommunication between me and the guy ordering the lines would have put them beyond my available timeframe, fortunately I found out that they are not DOT approved in Canada, so I don't feel do bad Although I can&!39;t give a blank rotor vs XD/S rotor comparison because of the upgrades in pads, I will say that the combo I'm working with is amazing and hasn't decreased in the several months I've ran them. It's neat, me and a friend were driving about on the highway and were playing around, I was behind him and he saw a cop way up ahead and slammed on the brakes. Now, I don't slam on them cause I know they would lock up, but I was pretty hard on them and not only did it feel like my heart was going to come out of my chest, but it almost felt like my rear wheels wanted to come off the ground. We did some touge "crusing" with the Rx-7 club in spring and they performed great, even when my rear wheels were 2" off the ground (literally, as the Rx-8 driver behind me witnessed). I can't wait until next year I did a tune up and I was checking the rotors, they are acually worn in about 1-2mm, so there's some good friction going on, and I can't see the XD/S rotors being anything but beneficial at this point. I know last time I went on the Rx-7 cruise, that my rotors literally burned blue from overheating, how, my car, although it didn't have as much power, it didn't handle as well either do I was doing more braking, but even this year, it wasn't a walk-in-the-park either, although I'm happy that I kept up with the Turbo FD's no problem And they were really impressed as well. My setup was only a few days old at the time, but next year, I'll push her alot more, I'll show them what my Mx-3 truely can do |
Posted by: sideways Sep 23 2005, 06:36 AM |
Braided lines often dont pass dot approval because they rarely pass the "spin" test (which has jack to do with braking anyways- so who gives a crap) |
Posted by: Batmanbeyon Sep 28 2005, 10:55 PM |
i recomend the SS lines they will make the pedal more stiff and under extreme preasure they wont blow unlike the fatory lines. |
Posted by: BOZZ Savage Jul 21 2006, 11:07 PM |
wow thanks for clearing that up... my dad and i actually had a discussion on this cross drilled slotted rotors thing and now i actually now the true answer... sorry for reviving an old thread. |
Posted by: DALAZ_68 Aug 21 2006, 12:35 PM |
stupid question but..... is the surface of the disk increased (from say a 7 diamater to a 10 diameter ) becuase of the decrease in the surface due to the slotted/ crossdrilled ?!!? in other words because u have gaps/ holes, u compensate by increasing the surface amount??!!? i wonder if anyone understands my queston |
Posted by: Frost Aug 21 2006, 05:40 PM |
Well, mathematically if you drill holes into the surface, you lose that surface area. So when you increase the disc diameter and keep the hole density (holes per unit surface area) the same, you will increase the surface area. Frost |
Posted by: DALAZ_68 Aug 22 2006, 04:09 PM | ||
so... is that a yes to wut i said lol |
Posted by: BOZZ Savage Aug 26 2006, 02:00 PM |
lol |
Posted by: Batmanbeyon Aug 26 2006, 02:36 PM |
that is a long first post all i have to say is that i seen the cracking happen before on corss drilled back when i was in cali doing the canyon thing some peoples brakes got so hot from going from no braking to full braking on and off and since it's not like at the track your on them a lot so a lot so that cooling and extreme heat was bad of people just have slotted. |
Posted by: Rudy Sep 18 2006, 06:22 PM | ||
Essentially, yes. Check out sport bikes with "pepperoni pizza" rotors as evidence. |
Posted by: sideways Sep 19 2006, 12:40 AM | ||
http://dictionary.reference.com/search?q=Punctuation |
Posted by: sideways Sep 19 2006, 12:41 AM | ||
http://dictionary.reference.com/search?q=Punctuation |
Posted by: HorizontalMitsubishi Sep 19 2006, 10:01 AM |
THE DOUBLE POST, ITS SOOO ANGRY!!! |
Posted by: sideways Sep 19 2006, 01:27 PM |
Posted by: TRD-hachi-roku Sep 23 2006, 01:07 PM |
you want more good braking power? replace your old jankyass master cylinder, and brake booster, then get yourself some nice new blank rotors, sport/ street pads (if it is still a street driven vehicle), ss brake lines, good brake fluid, bleed the shit out of the system. that way you will have refresh most of the components on your braking system, not only will you have better brakes, but safer ones too...what good is 3000$ big brake kits...when your master cylinder is leaking like a lil bit**? |
Posted by: DALAZ_68 Oct 10 2006, 12:57 PM | ||
i du get it ? |
Posted by: Force Fed Mopar Oct 17 2006, 09:54 AM |
So, what I've heard of cars w/ blanks out-braking the same cars w/ X-drilled rotors because the XD'd rotors wouldn't come up to temp enough could be true? or false? I agree that good pads and fluid make a much bigger difference than drilled rotors. |
Posted by: sideways Oct 17 2006, 02:42 PM |
Xd'ed rotors also have less surface area in contact with the pad |
Posted by: Akira Jan 1 2007, 06:57 PM |
So I imagien then, because according to physcis.., having cross drilled and slotted rotors just adds the effects? Sounds like amazing braking but maximum pad wear.. Not exactly what we all need... |
Posted by: Inygknok Jun 13 2007, 10:08 PM |
Okay, got sleepy half way through. Kudos to Nick for posting all that info (first time in my life I have seen that much info about brakes in one place, and I have seen a lot of info). I'm sure everyone already understands the purpose of drilling brakes. Unsprung weight, but they crack, yadda yadda. EOS. Now, slotted rotors. I don't know if someone mentioned this after I stopped reading, but here is a little factoid. The little slots act like a very fine knife cutting away the pads bit by bit. You can barely notice it, but it's true. As for the brake fluid. ALWAYS study up on the fluid you want to use and NEVER mix it with old fluid. They all have different operating temps and quite a few of them get easily contaminated with humidity. Yes. Everytime you open up the cap, even if just to have a look, a little bit of humidity mixes with the fluid and it ruins it. As easy as it sounds, as easy as it gets ruined. Some are very well made and don't get spoiled that easily, but it still happens. Companies should have charts of how their products stand up to these conditions. Give them a call. And if the bastards won't say, Google is your friend. As for pads glazing, it's generally due to their materials. Other times, the pads and discs themselves aren't up to the work of constant hard braking and glaze, and may even catch on fire (seen it in person, what a riot). This is why super cars usually opt for ceramics, and why F1 cars use carbon fiber. Someone said that using smaller discs meant using smaller pads...... not completely true. You do need to use a pad that won't actually overshadow the disc, but doesn't always have to be the case. Some people get slightly larger discs while still using the stock caliper/pad. It really depends. TRD-hachi-roku: Replace the brake booster? Do you know how much those cost? It is generally rare for one to actually break. Replacing parts that are still functioning properly is just throwing money into the garbage due to lack the ability to inspect things properly. No offense. Also, you forgot to mention obtaining brake calipers with more clamping force. Better pads and better/new discs help, but they won't work as well as some people would like to believe without opting for a stronger caliper Only problem.... buying aftermarket calipers is one, f**king expensive ordeal..... so, people wanting to get stronger calipers, just use Google and try to see what better calipers from other cars can mount up to your current one with some mild mods |
Posted by: SR5Sedan Jun 22 2007, 08:31 AM |
Gimme a brake! I'm cheap. Rather than think about slotted vs. drilled, think about this: 1) Brake fluid is the most important part of a braking system. Change it and upgrade it, and make sure you bleed it properly, hammer it, and check it again. 2) A good tool is available from your local Radio Shack. It's an infrared thermometer. Point it at your left brake and right brake after a session of hard driving and the temps should be the same. 3) Your rim choice affects your brakes more than your rotor choice. 4) Both slotted and drilled rotors use more pads that a fat woman during her period. 5) For most reasonable (even race) circumstances of the time, smooth rotors only lose on a cold, wet, rainy course to the other two. 6) Proper brake bias is more important than slotted vs. drilled. 7) I know a fanboy who can prove w/a lot of finite element analysis that slotted+drilled is the "ultimate." |
Posted by: Dakai Jun 22 2007, 08:46 AM |
What about wave? It's a new type of rotor used on racebikes. |
Posted by: SR5Sedan Jun 27 2007, 01:15 AM |
I'll ask my bike mechanic about the wave thing. It looks like it's good for show, or maybe on bikes, but my eyeballs scream that there's not enough material there to do the job. Bike rotors get a lot more air than car rotors, so the wave thing might work on bikes. I'd be surprised if they ever show up on cars because of warpage and durability issues. |
Posted by: But she looked 18 officer Jun 27 2007, 07:32 AM | ||||||||||||||||||
http://www.corner-carvers.com/forums/showthread.php?t=2630&highlight=revolution+rotor excerpt:
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Posted by: Möbius Jun 27 2007, 07:38 AM |
Time for me to google this "wave" technology. |
Posted by: But she looked 18 officer Jun 27 2007, 08:40 AM | ||
be wary of fine print. |
Posted by: Inygknok Jun 27 2007, 01:56 PM | ||
I think I'll tag along. I hadn't heard of this before. Then again, I'm not a bike guy. |
Posted by: But she looked 18 officer Jun 27 2007, 04:25 PM |
What no reply or thoughts on what I posted? |
Posted by: MidnightViper88 Jun 27 2007, 08:20 PM |
Some of us have ADD and can't even get past the patent numbers... |
Posted by: Inygknok Jun 28 2007, 10:45 AM | ||
He pretty much summed it up. I'll be honest, I just bothered reading a bit and saw the pictures..... in all honesty, those little waves will reduce contact area. People might think it's just a bit, but take into consideration the amount of contact area provided by an 11.5" rotor vs a BBK disc of about 13.5". The increase is massive. Those little "waves" seem to be a factor that just MIGHT reduce the extra surface area provided by the extra 2 inches of the bigger brake disc. I can see the pros and cons just by looking at the design, but honestly, I believe the cons outweigh the pros on this. For racing applications, modified discs have worked just fine up until today by using cross-drilling, vents (which are found in almost every modern car today), specials coatings, and using different materials. For street applications, how many of you honestly drive so hard in the streets to cause the brakes to catch on fire? Before anyone gets clever, I am speaking realistically and legally. Race on the streets, and catch you brakes on fire, I'll laugh. But yeah, there's just no way to make the brake upgrade kits we can already buy overheat on the streets in a realistic scenario, unless you screwed up mounting them up and following protocol (brake fluid choice, materials, etc). Also, if you're using your weekend track car as a daily driver, here's what's done in your case: carry an extra set of brakes. 1 for every day, and swap it out at the track on the weekends. So in summary: CONS: a) Sacrifices contact area to lose weight should cause uneven pad wear c) Traps water wherever the hell it was that it got trapped, which is a horrible thing to happen, since those things need to maintain their shape to actually work. Warping on these things has to be fatal. d) Might cause uneven pad wear e) Probably more expensive to buy due to it's shape. f) More expensive to maintain due to the latter. g) and is probably cosmetically unappealing to the majority. PROS: a) Reduces weight by eliminating contact area Allegedly provides better cooling (I can actually imagine how it works, so I have no reason to doubt it, but I still question the method in terms of practicality). c) Might be appealing to the minority (kids still like going against the majority, right?) |
Posted by: But she looked 18 officer Jun 28 2007, 02:06 PM | ||
skip pass the patent part and he brakes it down and explains everything. actually f**k it. I dont even know why I bother to post shit here anyway. |
Posted by: MidnightViper88 Jun 28 2007, 02:13 PM | ||
Damn, I'm gonna have to remember that statement so I can use it as a pun... |
Posted by: But she looked 18 officer Jun 28 2007, 02:40 PM | ||
zing! I meant to do it.. really |
Posted by: SR5Sedan Jun 29 2007, 07:59 AM |
Nice updates to the thread... The "wave" thing looks to be good for getting mud out of your brakes. I thought of a good application though: True: When you're riding dirt bikes with friends and "leading" and there's a pile of horse dung in front of you, it's a lot of fun to not dodge it. If you clutch, over-rev, and release perfectly, you will spray your pal behind you with manure. It keeps them off of your line. Sometimes the eyeballs are right. The physics behind off-road two-wheel braking vs. on-road four-wheel braking are immense. Wave might work in muddy conditions (and might not even be worth it then), but not on cars. Nice to see that braking is important to some folks though. |
Posted by: snoro Jun 23 2008, 03:39 PM |
braking will be alway important when you see a corner after going trough a straight at 150mph. |