TLicense Posted February 24, 2008 Share Posted February 24, 2008 To be honest I've no idea whether you want a more open design wheel or a closed one. It depends so much on what the airflow is doing. Only by doing temperature tests would you be able to find out. Yes, wheel material will also be a factor in how effective the system is at getting rid of the heat, but to what degree with the Supra, I couldn't say. Within F1, it's becoming a much more important factor, specifically with using the heat generated from the brakes to heat the tyres. Quote Link to comment Share on other sites More sharing options...
juanchan Posted February 24, 2008 Share Posted February 24, 2008 To be honest I've no idea whether you want a more open design wheel or a closed one. It depends so much on what the airflow is doing. Only by doing temperature tests would you be able to find out. Yes, wheel material will also be a factor in how effective the system is at getting rid of the heat, but to what degree with the Supra, I couldn't say. Within F1, it's becoming a much more important factor, specifically with using the heat generated from the brakes to heat the tyres. I'm gonna have to look that up! How long has that been in practice? How long before regenerative braking is allowing in F1 do you think? Quote Link to comment Share on other sites More sharing options...
paul mac Posted February 24, 2008 Author Share Posted February 24, 2008 Excellent write up Tony, with regard to caliper stiffness i read an article that stated that bolted calipers were more rigid than cast one piece calipers but then read another article that said this was tosh and was simply a smokescreen by the smaller brake manufacturers because they did not make the volumes necesary to tool up or justify producing cast one piece calipers , i wont loose sleep over the subject though Quote Link to comment Share on other sites More sharing options...
Alex Posted February 24, 2008 Share Posted February 24, 2008 I'm gonna have to look that up! How long has that been in practice? How long before regenerative braking is allowing in F1 do you think? KERS is legal from next year. Kinetic Energy Recovery Systems Quote Link to comment Share on other sites More sharing options...
Steve Posted February 24, 2008 Share Posted February 24, 2008 KERS is legal from next year. Kinetic Energy Recovery Systems How does that work? Quote Link to comment Share on other sites More sharing options...
Alex Posted February 24, 2008 Share Posted February 24, 2008 How does that work? We've got to wait till next year to see how the teams interperate(sp?) the rules. But basically we're looking at hybrid F1 cars next year. Quote Link to comment Share on other sites More sharing options...
Steve Posted February 24, 2008 Share Posted February 24, 2008 We've got to wait till next year to see how the teams interperate(sp?) the rules. But basically we're looking at hybrid F1 cars next year. Could be interesting then Quote Link to comment Share on other sites More sharing options...
TLicense Posted February 24, 2008 Share Posted February 24, 2008 We've got to wait till next year to see how the teams interperate(sp?) the rules. But basically we're looking at hybrid F1 cars next year. Something like that Quote Link to comment Share on other sites More sharing options...
spiderpigcity Posted February 24, 2008 Share Posted February 24, 2008 There's quite a bit of confused logic being bandied around here. Right to start off with, let me tell you about my history with brake systems. For the last 10 years I've worked in developing aerodynamic attributes of F1 cars. Approximately 2 years of that (albeit spread over 8 years of that period) has been spent developing brake systems. Whilst the majority of the work I've been involved with has been to do with how to cool the brake system, I've also been involved in the design of the brake system from a clean sheet in an effort to produce a brake system design that is at worst sympathetic to the air flow, and at best utilises the air flow to improve vehicle performance. So in all, it's fair to say I've been around the block when it comes to brakes. The "brake horsepower" mentioned in the table posted refers to the amount of work done by the braking system to stop a car. Using my very rusty math's, to stop a 1600Kg Supra travelling at 100mph in 5 seconds would require an average of 708084 Joules / second of work to be done = 962 metric HP. This is basically the work done to convert 3540418.6 Joules of kinetic energy into other forms of energy (predominantly heat) in 5 seconds, which is exactly what the braking system is doing. According to the table given, if the TT 4 pots can do work at a rate of 1665HP, and the tyres were able to cope with the rate of deceleration, then it should be possible to stop the car from 100mph in a little under 3 seconds.... Anyway, the effective ability of the brake system to do this heat transfer is what we're essentially talking about. This is dependant on a number of things. Now there's plenty of resource available on line as to how brakes work, but to summarise:- Braking performance is a function of the friction coefficient of the pad, the clamping force placed upon the pad by the calliper pistons and the distance from the centre of the wheel to the centre of pressure generated by the pad. A secondary function is the ability of the system to transfer heat from the pad / disc mating face elsewhere. There's nothing less or nothing more to it. However optimising those functions is where things tend to get tricky. Increasing the area of the pad face will not increase the friction between the pad and the disc. Brake pads are the size they are as a function of other factors. Primarily to do with the size and number of calliper pistons. (Increasing the size of the piston increases the force that is being exerted on it by the hydraulic fluid, which increases the clamping force of the pad) However there are obvious geometric limitations as to how large a piston can be. Increasing the number of pistons does not necessarily mean better braking ability though. The clamping force on the pad is a function of the hydraulic pressure being exerted on the piston face, and the area of that piston face. Increasing either will increase the clamping force of a brake pad, and in turn increase the braking ability of the brake system. However the big problem is calliper stiffness. In fact it's not a big problem, it's a MASSIVE problem. As the callipers get bigger and bigger it becomes more and more difficult to make the calliper strong. Generally, unless you're willing to spend tens of thousands of pounds on callipers made from exotic aluminium alloys like MMC, you'll be left with standard aluminium, which is pretty weak. The problem with that is as the callipers get longer to fit more pistons in, you get more deflection of the calliper. Basically the force of the piston on the pad is equally exerted onto the calliper itself, and it tries to bend the calliper open. For years 6 pot callipers were believed to be the best compromise between the number of pistons vs the length of the calliper, but with modern design practices it's possible for more elaborate 8 pot callipers to have the same stiffness as 6 pots. 4 Pot callipers are inherently stiffer than 6 pot's, however the problem is getting enough piston area into the calliper to give sufficient clamping force. It's a fine balance..... If you look at most quality calliper designs you'll also notice that the pistons area not all the same size. Even the two outer pistons will be different sizes. This is to help reduce the amount of tapered wear that would exist of you had all 3 pistons the same size. It's a balance between performance and longevity. You'd be pretty hacked off if you had a fantastic brake set-up but had to change the pads every few thousand miles because one end of the pad was worn to the backing whilst the other end was only half worn. Where the largest confusion comes into play is to do with heat transfer and brake fade. Brake fade comes in two distinct forms. One is when the friction coefficient of the brake pad is reduced due to the pad material being outside of it's temperature range, the other is when the same thing happens to the brake fluid. Each have their own distinct symptoms, but have similar solutions. Pad fade is identified by the brake pedal going very hard, but giving no retardation. Boiling brake fluid is identified by the pedal going spongy as the boiled fluid which is now gas, compresses. The simplest solutions for both mean making sure that the compound of the pad, and the fluid is in the right heat range. The second solution is making sure that the components of the brake system are as capable as possible in removing the heat from the above critical areas. Solutions involve correct material choice for discs and associated components, and ensuring that they have sufficient cooling. Material choice is usually driven by suppliers. You want a disc that has as low a specific heat transfer as possible. You basically want the material to absorb as much energy as possible before it increases by 1 degree. (Remember all it's doing is converting energy to heat - you just want it to have to absorb lots of it before it actually increases by 1 degree C) If you have a poor quality disc, then the disc is going to get hot quickly and will soon approach the temperature of the pad. When that happens the rate of heat transfer from the pad to the disc get's smaller, which means the pad stays hotter for longer. Most discs nowadays have various "vented" designs. Vanes that pump the air through the inside of the disc in an attempt to cool it. However it's also possible to cool the disc from the outside by making cooling ducts. The problem with these is it's far, far, far easier to get them wrong than it is to get them right. A simple example is do you want air to go from the inside of the wheel to the outside, or do you want it to go from the outside to the inside? Which would be better for cooling? By producing a duct that aided the air to go in one of the directions will help the cooling, but if you get it wrong in all likely hood it will actually hinder it. Also where do you want to point the duct? At the disc face? At the calliper? Get it wrong and you can end up creating a higher pressure region in an area where you want a low pressure region to help pull air in from another area. Then there is how fitting a duct will affect the actual downforce / drag profile of the vehicle which is a whole story on itself. My honest opinion with regards to ducting... unless you really know what you're doing, leave it well alone. I know there's maybe a few area's here that I've skipped over, but there's only so much someone can type (and remember ) in one go. But if anyone has anything specific that they'd like to ask, then I'm more than happy to try and answer any questions if I know the answers. Hope that clears up a few things though..... i like it, in other words banging a set of 6 million pot brembos on your supra in your shed, is about as much use as a teagbag with no holes in it, unless you take all the cooling, wheel design etc into consideration. a more technical explanation of what i was trying to say earlier on. let the oem guys do the testing with the proper gear while you do it at home in your shed with a couple of fans and some duct tape. :D Quote Link to comment Share on other sites More sharing options...
spiderpigcity Posted February 24, 2008 Share Posted February 24, 2008 before you go out in your supra with your big 8 pots on, put a thin film of "sticks like edited" on your tyres. they sell it at screwfix. it works really well for sticking most materials it says. doesn't say anything about sticking rubber to concrete, but i reckon it would work well. :d Quote Link to comment Share on other sites More sharing options...
paul mac Posted February 25, 2008 Author Share Posted February 25, 2008 i like it, in other words banging a set of 6 million pot brembos on your supra in your shed :D directed at me by any chance ? Quote Link to comment Share on other sites More sharing options...
Alex Posted February 25, 2008 Share Posted February 25, 2008 directed at me by any chance ? If it was it a) wasn't funny and b) wasn't necessary. At least you've used a sensible sized system unlike those trying to do it with brakes from a smaller car. Quote Link to comment Share on other sites More sharing options...
Sean1933 Posted February 25, 2008 Share Posted February 25, 2008 This was quite an adult informative discussion....until those childish comments were thrown in there. Quite unnecessary. Out of interest Matt, where is/was you knowledge gained. Serious question, not piss taking. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 25, 2008 Share Posted February 25, 2008 I think Motorsport in general is losing the plot. It's all very well making these quasi political bows to the green lobby, what with unfair biasing for diesel powered cars at Le Mans, and now regenerative systems for F1, but if you look at the wider picture, in 10 years or so China will be so "dirty" that these pitiful saps to the carbon footprint, to use a sickeningly trendy term, will be even more laughable than they already are. The only realistic hope for mankind's world pollution is another real slap up world war, with LOTS of death and destruction. In the meantime I'm just off to burn a few tyres and de gas an A/C system. Racing SHOULD be noisy, dangerous, polluting and most of all FUN. With the last two DC3 (Dakota) planes to be de commissioned in the UK for passenger transport as they are too dangerous for people to fly in without cripplingly expensive `elf and safety mods, there's not much hope for F1, as far as I can see it. They are too tied up with politics to make a noble gesture of defiance, and at least lie down and die with dignity. Quote Link to comment Share on other sites More sharing options...
b_have Posted February 25, 2008 Share Posted February 25, 2008 I think Motorsport in general is losing the plot. It's all very well making these quasi political bows to the green lobby, what with unfair biasing for diesel powered cars at Le Mans, and now regenerative systems for F1, but if you look at the wider picture, in 10 years or so China will be so "dirty" that these pitiful saps to the carbon footprint, to use a sickeningly trendy term, will be even more laughable than they already are. The only realistic hope for mankind's world pollution is another real slap up world war, with LOTS of death and destruction. In the meantime I'm just off to burn a few tyres and de gas an A/C system. Racing SHOULD be noisy, dangerous, polluting and most of all FUN. With the last two DC3 (Dakota) planes to be de commissioned in the UK for passenger transport as they are too dangerous for people to fly in without cripplingly expensive `elf and safety mods, there's not much hope for F1, as far as I can see it. They are too tied up with politics to make a noble gesture of defiance, and at least lie down and die with dignity. Exactly that. Quote Link to comment Share on other sites More sharing options...
TLicense Posted February 25, 2008 Share Posted February 25, 2008 Massive thread hijack ahoy (feel free to split this off into a new thread in off topic....) I kind of see where you're coming from Chris. I really would like to have free reign to be able to use the very best materials and aerodynamic principles to make the car go literally as fast as we can design it. It really would be interesting work, and IMHO make for some amazing racing. The cars would be doing 250mph+ with full ground effect and moveable aerodynamic devices, utilising all the modern technology that they could to get to the chequered flag first. However the problem isn't the proposed rule changes for next year, but the rule changes that occured after Senna's death that channelled all our resources into "safe racing". Reduction in top speeds, reduction in cornering speeds, reduction in braking ability, reduction in electronic aids. All that was left is aerodynamics. The teams ploughed heavy investment into this area in order to try to gain the competetive edge. The problem with that is the aerodynamics on a modern F1 car bear no resemblance to any other vehicle. Personally though, I applaud the introduction of KERS (or hybrid engines). It's just a pity it's 10 years too late. We should have been spearheading the development of this, not playing catch-up. But who know's where development may lead in the next 10 years? Engine development has now been stopped completely, but now in addition to aero development with also have KERS. Perhaps KERS is the way forwards and we'll see massive performance increases from the use of KERS and the "push to pass" set-up. Should make for some interesting racing when you get two drivers side by side and when one of them brakes the other goes for the button. The sport is changing massively. It's not the old Mansell vs Senna, or Villeneuve vs Arnout days of old. But then that's the nature of Motorsport. Evolve or be left behind. The main question is how entertaining will the racing be, and for that I guess we'll have to wait and see. Quote Link to comment Share on other sites More sharing options...
paul mac Posted February 25, 2008 Author Share Posted February 25, 2008 Massive thread hijack ahoy (feel free to split this off into a new thread in off topic....) its all good comment, well most of it Quote Link to comment Share on other sites More sharing options...
Matt H Posted February 25, 2008 Share Posted February 25, 2008 I think Motorsport in general is losing the plot. It's all very well making these quasi political bows to the green lobby, what with unfair biasing for diesel powered cars at Le Mans, and now regenerative systems for F1, but if you look at the wider picture, in 10 years or so China will be so "dirty" that these pitiful saps to the carbon footprint, to use a sickeningly trendy term, will be even more laughable than they already are. The only realistic hope for mankind's world pollution is another real slap up world war, with LOTS of death and destruction. In the meantime I'm just off to burn a few tyres and de gas an A/C system. Racing SHOULD be noisy, dangerous, polluting and most of all FUN. With the last two DC3 (Dakota) planes to be de commissioned in the UK for passenger transport as they are too dangerous for people to fly in without cripplingly expensive `elf and safety mods, there's not much hope for F1, as far as I can see it. They are too tied up with politics to make a noble gesture of defiance, and at least lie down and die with dignity. Do you have children Chris? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 25, 2008 Share Posted February 25, 2008 Nope, I am already supporting too many other people's, and more by the day, so I couldn't afford to bring any of my own up properly. Quote Link to comment Share on other sites More sharing options...
bignum Posted February 25, 2008 Share Posted February 25, 2008 Do you have children Chris? Whats that got to do with it? Quote Link to comment Share on other sites More sharing options...
paul mac Posted February 25, 2008 Author Share Posted February 25, 2008 If it was it a) wasn't funny and b) wasn't necessary. At least you've used a sensible sized system unlike those trying to do it with brakes from a smaller car. never mind Alex, sticks and stones, what i find a bit hard to take is the guy pm'ed me to ask advise on auto coolers last night then he slags off my "garden shed" (btw i have a garage not a shed), it makes me wonder is this another 15 year old dreamer sat in his mums house or is he just a muppet, im sure time will tell either way, good thread none the less Quote Link to comment Share on other sites More sharing options...
Alex Posted February 25, 2008 Share Posted February 25, 2008 never mind Alex, sticks and stones, what i find a bit hard to take is the guy pm'ed me to ask advise on auto coolers last night then he slags off my "garden shed" (btw i have a garage not a shed), it makes me wonder is this another 15 year old dreamer sat in his mums house or is he just a muppet, im sure time will tell either way, good thread none the less We got to infract him for swearing Quote Link to comment Share on other sites More sharing options...
paul mac Posted February 25, 2008 Author Share Posted February 25, 2008 We got to infract him for swearing ahh nice one Quote Link to comment Share on other sites More sharing options...
Jspec Germany Posted February 25, 2008 Share Posted February 25, 2008 Interesting thread. I'm replacing my tired Jspecs with AP 6pots up front and US rears with upgraded rotors and pads, braided lines and I do have a brake bias valve. This set up was used on a big twin in the states with great success and I think it will serve me well at the Ring this summer. I just worry about the ABS issue. Now for those pads. Quote Link to comment Share on other sites More sharing options...
Matt H Posted February 25, 2008 Share Posted February 25, 2008 Nope, I am already supporting too many other people's, and more by the day, so I couldn't afford to bring any of my own up properly. that explains your lack of consideration to future generations then Quote Link to comment Share on other sites More sharing options...
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