Holy crap! Between barking and baking, I've started a whole new discussion!
Brian ----- Original Message ----- From: "Brian-SubCultureNM" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Friday, January 31, 2003 10:38 AM Subject: Re: CRX: Re: Physics lesson, and a stop to all this bickering about tires and sizes and hydroplaning. > 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??! : ) > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
