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#46
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i know my driving style on the course isnt the ideal one, however my friend that is leading points with his WRX agreed with me on all of my complaints about the brake system, so i dont think that a person thats been to 2 driving schools and leads points is wrong either. dont get me wrong, i think they are great for daily driving and street use, and on the track the only times i have any problems is in places where is on and off alot in a short period of time followed by a fast stop for the finish.
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98 Impreza Wago-O-Doom & Datsun Roadsters |
#47
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British vehicles are my last ditch attempt to keep the nasty Italian thoughts in my mind at bay. So far its working. |
#48
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i beg to differ, not about the car stuff but the course, you come through the cicane and have to come to damn near a dead stop before a 90* turn out of the course always, its basiacally a coned shoot that you have to come to almost a stop in before you turn out. but yeah, i think i will buy some wilwood fluid and some different pads then go from there
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98 Impreza Wago-O-Doom & Datsun Roadsters |
#49
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I guess I don't understand. Do we have 2 alternate realities here. I've never experienced significant fade, except for some minor fluid fade. I would have to guess that my 20 to 30 minute sessions on a road course would be more stressful on the brakes than a 30 second autocross run. I know that one of the functions of slotting or even drilling the rotors is to relieve gas from the pads which might otherwise decrease pad rotor contact. I'm wondering if that is the cause of your fade.
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____________________________________________ 95 LS-i Red, 31,xxx; bone stock for now; Daily Driver 94 LS-i Emerald Pearl, 106,xxx,; 246 whp; Tomyx snorkus and HKS Cold air intake; PWR aluminum radiator, silicone hoses; Inline thermostat; enhanced coolant routing; external power steering and oil coolers; Phenolic intake manifold spacers; 2004 WRX 5 speed transmission; ACT Clutch Kit, Heavy Duty Pressure Plate, Lightweight flywheel, performance disc; Group N motor mounts; ‘07 WRX 4-pot front calipers, cryo-treated slotted Tribeca rotors; Hawk HPS ferro-carbon pads; Frozenrotor rear slotted rotors; SS brake lines, Axxis Ultimate pads; Rota Torque 17x8 wheels; 245/40-17 Bridgestone RE01-R's; Koni inserts with Ground Control coilovers, Eibach springs; K-Mac camber/caster adjustable strut mounts; Urethane swaybar bushings; Bontrager rear sway bar; Urethane differential bushing; Custom Whiteline adjustable rear lateral links; Outlaw Engineering forged underdrive pulley; custom grind Web intake and exhaust cams (11 mm lift, 250° duration); solid lifters; CP custom aluminum forged 11 to 1 pistons, Brian Crower coated SS intake & exhaust valves; Brian Crower upgraded springs w/ titanium retainers; NGK sparkplugs; RallyBob (Bob Legere) ported and polished cylinder heads; Eagle H-beam rods; ACL Bearings; Cometic Head gaskets; ARP head studs & fasteners; Hydra Nemesis EMS; Wideband O2 sensor; 740cc Injectors; Walbro 255lph fuel pump; Upgraded WRX starter; Equal length SS headers (3 into 1); dual Magnaflow cat converters; 2 into 1 into 2 SS exhaust with Bullet muffler; OT Fiberglass hood; Oil pressure gauge; Programmable shift light, 2017 Subaru Forester XT, metallic dark gray, 29,xxx 2005 Porsche 911 Turbo S Cabrio, 24,xxx 2006 Subaru Outback LL Bean, 166,xxx sold 92 LSL Dark Teal, Smallcar Shift Kit - sold |
#50
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British vehicles are my last ditch attempt to keep the nasty Italian thoughts in my mind at bay. So far its working. |
#51
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"Driving right" uses a LOT of braking. The idea is to spend as little time braking as possible, but braking as hard as possible during those times. You spend more time traveling at a higher rate of speed. The whole concept of late-braking in a nutshell. Some tracks have nothing but high-speed corners and require relatively little braking while the rest of the time is throttle-open driving with plenty of cooling time. Other tracks are little more than a series of straightaways and hard stops followed by an abrupt corner. The correct way to brake on a track like that will kill your brakes. |
#52
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Obviously you're smarter than anybody else here that doesn't have the issues you complain of. Sorry to insult such an excellent drive. Just don't kill anybody with your excellence.
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British vehicles are my last ditch attempt to keep the nasty Italian thoughts in my mind at bay. So far its working. |
#53
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#54
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As often as you change brake fluid, you must have a favorite. What is your favorite fluid and who makes your favorite svx brake pads.
Thanks again, great thread. Quote:
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#55
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It might be interesting to see what braking performance is actually required required to stop a standard SVX from various speeds.
These are only ‘rough and ready’ calculations, someone else can refine them further, if they feel the need, but I feel that they are fairly representative. Lets assume that the standard car weighs around 1590 kilograms and that the total weight of all four brake disks is 20 kilograms, and that the specific heat of iron is 449 Joules per kilogram per degree centigrade. We will brake the car from 3 different speeds at 0.8g deceleration. Firstly a 60 mph stop. (26.6 m/s). Code:
Kinetic energy dissipated (½mv²) = 565333 joules Time to stop = (37.5/9.8)/0.8= 4.78 seconds Average brake power dissipation = 166 kW. Average brake disc temperature rise = 63° C. Code:
Assuming a 70:30 braking bias. Front brake temperature rise = 88 ° C Rear brake temperature rise = 38° C Code:
Kinetic energy dissipated (½mv²) = 1570370 joules Time to stop = (44.4/9.8)/0.8= 5.66 seconds Average brake power dissipation = 277 kW. Average brake disc temperature rise = 175° C. Assuming a 70:30 braking bias. Front brake temperature rise = 245 ° C Rear brake temperature rise = 105° C Code:
Kinetic energy dissipated (½mv²) = 3533333.333 joules Time to stop = (66.7/9.8)/0.8= 8.5 seconds Average brake power dissipation = 415.5 kW. Average brake disc temperature rise = 393° C. Assuming a 70:30 braking bias. Front brake temperature rise = 551 ° C Rear brake temperature rise = 236° C So what does this tell us? We can be reasonably confident that Subaru designed the standard braking system to cope with at least one 150 mph stop. Stops from more reasonable speeds put considerably less energy into the braking system. Repeated stops and the capacity of the braking system to recover from them is perhaps a more worrying feature. I can envisage no disc venting system being able to dissipate meaningful quantities of heat in short time periods. I suspect that many brake upgrades are more for show than for go (or should that be stop?). So what upgrade would work? Well there really is only one that can make a significant difference, and that is to fit a larger and heavier disc. Its additional mass will mean less temperature rise, and its larger surface area will provide greater heat dissipation. There are downsides to this approach too, more unsprung weight and more expense being the most important ones. If you think you have braking problems then it is probably due to a defect in the standard setup. Finally, boiling brake fluid is not brake fade, it is catastrophic brake system failure.
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I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the state of Science, whatever the matter may be. Sir William Thomson |
#56
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British vehicles are my last ditch attempt to keep the nasty Italian thoughts in my mind at bay. So far its working. |
#57
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Then you obviously can't read. You're a waste of my time so enjoy being an idiot.
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British vehicles are my last ditch attempt to keep the nasty Italian thoughts in my mind at bay. So far its working. |
#58
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The feeling is mutual.
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#59
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British vehicles are my last ditch attempt to keep the nasty Italian thoughts in my mind at bay. So far its working. |
#60
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to sum it up with personal feelings aside, the brakes on the SVX are adequate enough even for racing. Just set the system up best that works for you... If you still warp brakes or experience brake fade(not a tired leg) then go ahead and upgrade to something else. I have a feeling you will not find the thousands of dollars invested in bigger brakes worth it
A good piece of advice from a very knowledgable racer, quiet and smooth is almost always faster than loud and rough Tom |
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