On a car as small as the CRX, heat dissipation is as important as surface area, after-all, baking is nothing more than converting kinetic energy into waste heat energy, right? Therefore, efficiently expelling that heat will lead to increased barking performance. Measure the surface area lost by cross-drilling the rotor and you'll see that you've lost barely 5% of the total surface area. Also, under hard braking, gasses will build between the rotor and pad, which is one of the main causes of fade (that, and boiling your fluid.) Drilled rotors help to evacuate these gasses. I don't know if you've ever tried-out the AEM Big Brake upgrades, but they're designed to use a larger rotor with stock calipers. We installed many sets of them on cars at the shop where I worked and even with stock calipers and rotors (which, by your argument, should not result in increased braking performance) the cars stopped on a dime when braking hard! Those big rotors dissipate heat more efficiently.
As far as stress cracks, that's a rumor that all drilled-rotor oponents like to bring-up, yet, on all the cars I've ever had drilled rotors on, I've never experienced a single crack - and I get on the brakes, believe me! And I'm a Chemical Engineer with lots and lots of physics, thermodynamics, and fluid-transport classes under my belt! Brian ----- Original Message ----- From: "Ricky Crow" <[EMAIL PROTECTED]> To: "Brian-SubCultureNM" <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Friday, January 31, 2003 10:32 AM Subject: Re: CRX: Re: Physics lesson, and a stop to all this bickering about tires and sizes and hydroplaning. > On Fri, 31 Jan 2003, Brian-SubCultureNM wrote: > > > Anyway, I agree completely with what you have to say. It's also quite > > evident that larger wheels/tires will take longer to stop (higher inertia), > > Yes > > > which is why I run drilled rotors with a good carbon/kevlar pad (probably > > overkill on the street), braided-stainless brake lines, and the Ford Super > > More flawed reasoning... Man, your engineering background must be in > electrical engineering, because it really doesn't help you much when it > comes to mechanics and physics, does it? > > Unless you live in an area where you get massive flash-floods, > cross-drilled rotors are ONLY good for developing stress cracks when > driven hard. > > Cross-drilled rotors have less surface area, therefore less ability to > make contact with the pad, therefore less braking coefficient of friction. > > Cross-drilled rotors have less mass, therefore, less ability to absorb and > dissipate heat through the vents in the center of the rotor > > Cross-drilled rotors are only good for evacuating water. Many people have > the flawed thinking that the holes are there for outgassing the pads. Let > me tell you -- if your pads are outgassing that badly (to the point where > you are seeing pad fade), you are using the wrong type of pads for your > application. > > Talk to the engineers at Porsche. They put cross-drilled rotors on their > cars, but it's not for heat dissipation. It's for water evacuation. > > Talk to any motorcycle rider that races bikes, they'll tell you the same > thing. > > > Blue brake fluid. Ask any grass-roots race enthusiast and they'll tell you > > to save your money on the expensive fluids and use the stuff from Ford! > > Yes... Something we do agree on. > It's cheap and has a high boiling point. > > I use Ford brake fluid, as well. > > Ricky > > > > See ya, > > > > BRian > > ----- Original Message ----- > > From: "David Miller" <[EMAIL PROTECTED]> > > To: "Ricky Crow" <[EMAIL PROTECTED]>; "Brian-SubCultureNM" > > <[EMAIL PROTECTED]> > > Cc: "Jeremy Bass" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> > > Sent: Friday, January 31, 2003 8:52 AM > > Subject: RE: CRX: Re: Physics lesson, and a stop to all this bickering about > > tires and sizes and hydroplaning. > > > > > > Just for fun here -- it is not the size of the wheel that matters. > > > > For performance, there are two factors involved -- first, there is the > > weight of the wheel/tire combination. Then, there is the location of the > > mass in relationship to the diameter. > > > > Let's say that you have a wheel/tire combination that weighs 25 pounds. > > Now, running a 175/70-13 vs. 205/30-18 (within 0.2 inch in diameter) you can > > see that on the 18 the entire tire portion is located beyond 9 inches from > > the center of the wheel. Where with the 13 it is located beyond 6.5 inches > > from the center of the wheel. Therefore the 18 inch wheel has a greater > > rotational force to overcome. > > > > This, in essence, means that everything else being equal, a car with 13" > > wheels will accelerate faster than one with 18" wheels. It is a simple > > matter of physics. > > > > IF this is what you are referring to as performance. > > > > Personal experience. My '89 DX (we must keep CRX content, right?) > > accelerates faster with 195/60-14's than it does with 175/70-14's because > > the tire/wheel combination is probably 8 pounds heavier per corner. Greater > > rotational mass. > > > > TTFN! > > > > David > > > > -----Original Message----- > > From: Ricky Crow [mailto:[EMAIL PROTECTED]] > > Sent: Friday, January 31, 2003 9:44 AM > > To: Brian-SubCultureNM > > Cc: Jeremy Bass; [EMAIL PROTECTED] > > Subject: Re: CRX: Re: Physics lesson, and a stop to all this bickering > > about tires and sizes and hydroplaning. > > > > > > You're the one that brought some pickup truck into the equation. This is > > a CRX List, and he was stating numbers about a stock CRX. All CRXs have > > the close to the same weight distribution, for the most part. Therefore > > his numbers apply to the vast majority of CRX's out there. Your CRX's > > suspension can't be much different than what my CRX is (I have one CRX on > > each end of the spectrum, from almost-stock to heavily-modified with > > various suspension braces, sway bars, roll-cage, etc). > > > > And yes, he was oversimplifying, because you didn't seem to understand. > > Bottom line is, no street tire will help you from hydroplaning over > > 50-55mph, no matter how good the tread pattern is. If you were really an > > engineer like you say you are, you'd realize that bigger wheels have a > > diminishing return on performance increase (and gets to the point where it > > actually is a detriment to performance). > > > > Ricky > > > > > > > > > > On Fri, 31 Jan 2003, Brian-SubCultureNM wrote: > > > > > Hey Ricky, > > > > > > You ever heard of a discussion? That's all this is, my man. If you can't > > > take it, then you have no business being in a public forum where > > discussions > > > take place. You obviously can't handle anyone disagreeing with you, my > > > friend (which is the statement you issue towards me, as if it's an > > insult.) > > > I don't care - I like the discussions; they're thought-provoking and get > > my > > > blood boiling sometimes. Besides, when someone's thinking is flawed, > > there's > > > no harm in pointing-out the error, especially if it's done in a > > constructive > > > way. The fact is, his thinking did not take some critical factors into > > > play - he assumed that all vehicles handle and drive alike. His formulas > > > were also over-simplified. Sometimes my Engineering education rears its > > ugly > > > head, that's all. > > > > > > Anyway, like the previous threads, you have nothing positive nor anything > > > constructive to add, so your point is irrelevant. Notice, I still haven't > > > become negative, even in the face of your insults. > > > > > > Take care, > > > > > > Brian > > > ----- Original Message ----- > > > From: "Ricky Crow" <[EMAIL PROTECTED]> > > > To: "Brian-SubCultureNM" <[EMAIL PROTECTED]> > > > Cc: "Jeremy Bass" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> > > > Sent: Friday, January 31, 2003 7:53 AM > > > Subject: Re: CRX: Re: Physics lesson, and a stop to all this bickering > > about > > > tires and sizes and hydroplaning. > > > > > > > > > > Exactly why I stopped discussing this with you -- you will argue with > > > > anybody that doesn't agree with you, no matter what they say or how they > > > > prove what they're talking about (hence the reason why I didn't bother > > to > > > > give you any 'scientific' evidence, because you'd have tried to discount > > > > it as well). > > > > > > > > Sadly, your thought process is way too typical these days. > > > > > > > > Ricky > > > > > > > > > > > > > > > > > > > > > > > > On Fri, 31 Jan 2003, Brian-SubCultureNM wrote: > > > > > > > > > You've made some decent points, but haven't taken all the variables > > into > > > consideration. Your formulas assume a perfectly flat tire, one with no > > tread > > > pattern at all (tread pattern will, of course, take precious square-inches > > > away from your total contact patch.) However, a well designed tread > > pattern > > > will evacuate water from underneath its contact patch, thus nullifying a > > > large portion of your assumptions. > > > > > > > > > > Anyway, I'm not an advocate for driving as you would on dry pavement > > > when it's wet. Of course, here in NM, rarely do we have to worry about > > > anything more than a few rain drops on the pavement. Also, as far as the > > > truck is concerned, 1) it has an air-bag suspension which allows for a lot > > > of slop in its handling - in other words, it doesn not maintain constant > > > down-force on any surface; 2) it's body-dropped and has had a large > > portion > > > of its bed structure removed, so the weight over the drive wheels is > > > probably no heavier than a CRX; 3) as mentioned, it is front-heavy RWD, > > > which lends itself to more handling problems (and less predictable > > handling > > > problems with the 'bags) than a FWD CRX. Therefore, when you take all this > > > into consideration, it should handle even worse on wet pavement than the > > > CRX. It didn't, and the tire tread and compound has a lot to do with that. > > > > > > > > > > Finally, congratulations on your door handles (seriously.) I would be > > > curious as to how long you've had them done and whether-or-not you've > > > started to experience shrinking of the JB Weld. If you haven't, you will. > > > Believe me, having a lot of experience with custom body mods, there's > > rarely > > > a time that they are 100% trouble-free. THis isn't a critique of your > > work, > > > it's just a fact. We've had to have one door and the tailgate handle on > > our > > > truck re-done because of cracking. It happens to the best of them! > > > > > > > > > > Brian > > > > > ----- Original Message ----- > > > > > From: Jeremy Bass > > > > > To: [EMAIL PROTECTED] > > > > > Sent: Friday, January 31, 2003 3:54 AM > > > > > Subject: CRX: Physics lesson, and a stop to all this bickering about > > > tires and sizes and hydroplaning. > > > > > > > > > > > > > > > An end to all of this hydroplaning crapola... Welcome to Jeremy's > > > weird world of physics... > > > > > > > > > > Exibit A: > > > > > Frontal Resistance... The more surface area you present in the > > > direction of the movement, the more resistance you create and the more > > force > > > you need to overcome that resistance. > > > > > > > > > > The surface area is the contact patch of the tires. The direction > > of > > > the movement is the tires penetrating the water. The resistance is how > > hard > > > it is for the contact patch of the tires to penetrate that water. More > > > force would mean more weight pushing down on the tire or traveling at a > > > lower speed so that the tire has less water to penetrate. > > > > > > > > > > In other words... If you were in a 1990 Honda CRX si, and hit a > > > puddle with a depth of .40 in. or greater of water at 50mph with stock > > > 185/60/14 tires you would be less likely to hydroplane than if you were to > > > hit water with 205/40/16s. I use .40 inches of water because it rids me > > of > > > variables such as tire tread pattern and road surface, because your tire > > is > > > as good as slick in water that deep. If your tread is deeper than .40 > > inches > > > on your crx you need to buy tires that are not for off-road use.... > > > > > > > > > > Now, a stock 1990 Honda CRX si with 185/60/14 tires at 28psi weighs > > > 2174lbs, and has a weight distribution of 62% front and 38% rear. > > Therefore, > > > the front tires are putting 1396.2 lbs to the pavement which is a scant > > > 698.1 lbs each. So, in exactly .40 in. of water and a contact patch of > > 32.8 > > > sq. inches, it would take water pressurized to anything above 21.28 psi to > > > lift the car from the surface of the road. ( I think that is around > > 51mph??, > > > but that doesn't matter right now ) > > > > > > > > > > SO, if the tire variables increase the contact patch of the tire, it > > > lowers the water psi needed to lift the vehicle, and increases the > > > likelyhood of hydroplaning. > > > > > > > > > > THEREFORE THESE STATEMENTS ARE FACTS: > > > > > Tire outside diameter DIRECTLY affects hydroplaning. (minimaly) (18 > > > inch rims must use larger than stock OD) > > > > > The width of the tire DIRECTLY affects hydroplaning. > > > > > Tire pressure DIRECTLY affects hydroplaning. > > > > > The weight of the car DIRECTLY affects hydroplaning. > > > > > Speed... Duh. > > > > > > > > > > Thank you ladies and gentlemen.. > > > > > > > > > > (I'm sure my english is not perfect, nor spelling. But the numbers > > can > > > be checked with a fine tooth comb.) oh, and your canyon carving truck > > with > > > the big fat tires weighs way more than our lil rexes so your example is > > null > > > because you have more "FORCE"... nanny nanny boo boo.... > > > > > > > > > > So, may we please quit bickering??! : ) > > > > > > > > > > > > > > > > > > > > > >
