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ReverendCode posted:As I understand it, the brakes themselves are fine, but it is still hauling a pretty heavy car down from whatever ludicrous speed, which can quickly cause even decent brakes to heat soak. Because it is a 5-7 passenger sedan, not some track weapon. What would be a good car to compare it to in terms of stopping distance? Edmunds says "In Edmunds brake testing, a P85D with high-performance summer tires came to a stop from 60 mph in just 102 feet. To put that distance in perspective, most large luxury sedans take about 110 feet to stop, and even high-performance sports cars take about 106 feet. Considering the Tesla's significant mass, that is a truly impressive number." Shelby GT shows 104, but I'm not sure what people think of as a track weapon.
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Apr 8, 2016 17:06
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Subjunctive posted:What would be a good car to compare it to in terms of stopping distance? Edmunds says "In Edmunds brake testing, a P85D with high-performance summer tires came to a stop from 60 mph in just 102 feet. To put that distance in perspective, most large luxury sedans take about 110 feet to stop, and even high-performance sports cars take about 106 feet. Considering the Tesla's significant mass, that is a truly impressive number." Shelby GT shows 104, but I'm not sure what people think of as a track weapon. Here are the top 20 stopping distances tested by Motor Trend: http://www.motortrend.com/news/20-best-60-to-0-distances-recorded/ Model S comes within a foot of the worst cars on the list however you want to judge that. The best braking sedans are at the following spots: 18. 2014 Audi RS7 – 101 Feet 9. 2014 Jaguar XJR – 99 Feet 8. 2015 BMW M3 – 99 Feet 6. 2014 Cadillac CTS VSport – 98 Feet
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Apr 8, 2016 17:21
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A single attempt at short stopping distance isn't what defines good sports brakes though. It's stopping distance and heat management, a hard 100 - 30 once every 10 seconds repeated for several minutes without losing performance. And something Tesla rightly didn't prioritize.
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Apr 8, 2016 17:29
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eeenmachine posted:Here are the top 20 stopping distances tested by Motor Trend: http://www.motortrend.com/news/20-best-60-to-0-distances-recorded/ In Motor Trend testing the P90D was actually 109 feet, so a fair ways off. Thanks, I have learned things! E: Ola posted:A single attempt at short stopping distance isn't what defines good sports brakes though. It's stopping distance and heat management, a hard 100 - 30 once every 10 seconds repeated for several minutes without losing performance. And something Tesla rightly didn't prioritize. Are these really single measurement tests? I assumed they would do a bunch after warming up the brakes, but I can't find the details so far. Subjunctive fucked around with this message at 17:33 on Apr 8, 2016 |
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Apr 8, 2016 17:30
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Subjunctive posted:In Motor Trend testing the P90D was actually 109 feet, so a fair ways off. Thanks, I have learned things! When people who drive on race tracks talk about braking they mean how many times/how much cumulative braking force the system has, because on a race track you have to brake a lot which sends a lot of heat into the braking system. Making the brake system capable of withstanding/absorbing the heat requires a lot of expensive compromises like bigger brake parts which add unsprung mass, exotic materials like carbon ceramic brake discs, etc. This stuff is also useless for driving on the street since you don't do that much braking and so the average Porsche/Audi cock driver is unlikely to derive any benefit from it. The Tesla is a very heavy car and the amount of energy that needs to be dissipated by the brakes obviously goes up very quickly with increasing weight.
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Apr 8, 2016 17:36
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Throatwarbler posted:The Tesla is a very heavy car and the amount of energy that needs to be dissipated by the brakes obviously goes up very quickly with increasing weight. Doing a gradual slowdown from highway speed to a stop in a Prius recovers almost all of the kinetic energy, with the mechanical brakes only being used right at the end; in a crash stop, it's probably all mechanical brakes though. For this under-defined Model S track driving scenario, how much of the braking can be regenerative instead of lossy?
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Apr 8, 2016 17:41
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The first time some big sedan brakes from 100 to 50 on a track it might not take much longer than an M3. The tenth time in 3 minutes it brakes from 100 to 50 on a track it'll probably take a lot longer than an M3 unless it has a brake setup designed to dissipate heat quickly.
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Apr 8, 2016 17:43
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Probably very little regeneration will be used, since "gradual braking" isn't something you want to do in a track, all other things being equal. Either you're on the throttle, or you're braking at maximum effort.
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Apr 8, 2016 17:46
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I mean, in the general track case the S loses because the battery overheats and it has to limp along. https://www.quora.com/Has-a-Tesla-model-S-ever-been-put-on-a-track Sounds like until it stopped being able to, you know, go it was a good time!
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Apr 8, 2016 17:48
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Cocoa Crispies posted:
Not much. Regen braking works well for one foot driving in traffic which is fairly low braking effort. Track braking is max effort every time. The energy difference between the two is tremendous, shoving all those joules into the battery might not be possible, it might be way more than supercharger wattage. Subjunctive posted:
I don't see why they would. Stopping distance with cold brakes is what's relevant for the safety in traffic angle.
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Apr 8, 2016 17:50
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Isn't there a hybrid class that races in Le Mans every year?
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Apr 8, 2016 17:53
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Ola posted:I don't see why they would. Stopping distance with cold brakes is what's relevant for the safety in traffic angle. Bingo. If you want to do track work do your homework fist.
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Apr 8, 2016 17:53
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Ola posted:Not much. Regen braking works well for one foot driving in traffic which is fairly low braking effort. Track braking is max effort every time. The energy difference between the two is tremendous, shoving all those joules into the battery might not be possible, it might be way more than supercharger wattage. Ah, I was misremembering. CR does multiple tests with cool-down laps between them; pretty much the opposite! Regen braking is pretty strong in the S (like "lurch in seat, spill a drink" strong), and I usually only have to actually brake for the last 10 mph or so, but regen is more like tapping the brake than braking hard. One-pedal driving is pretty nice, though.
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Apr 8, 2016 18:03
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Throatwarbler posted:When people who drive on race tracks talk about braking they mean how many times/how much cumulative braking force the system has, because on a race track you have to brake a lot which sends a lot of heat into the braking system. Making the brake system capable of withstanding/absorbing the heat requires a lot of expensive compromises like bigger brake parts which add unsprung mass, exotic materials like carbon ceramic brake discs, etc. This stuff is also useless for driving on the street since you don't do that much braking and so the average Porsche/Audi cock driver is unlikely to derive any benefit from it. The Tesla is a very heavy car and the amount of energy that needs to be dissipated by the brakes obviously goes up very quickly with increasing weight. A far bigger problem is that super hard acceleration absolutely eats battery power and creates a ton of heat which overheats the batter, plus sinCe it takes hours to recharge youre only getting a limited number of hot laps before you are forced to stop
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Apr 8, 2016 18:55
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I wonder how long before someone starts selling a ricer-grade battery CAI mod You know it'll be a thing when the model 3 comes out, at least
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Apr 8, 2016 19:08
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Ola posted:A single attempt at short stopping distance isn't what defines good sports brakes though. It's stopping distance and heat management, a hard 100 - 30 once every 10 seconds repeated for several minutes without losing performance. And something Tesla rightly didn't prioritize.
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Apr 8, 2016 19:10
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Ola posted:I don't see why they would. Stopping distance with cold brakes is what's relevant for the safety in traffic angle. Look at this flatlander. Sagebrush posted:I wonder how long before someone starts selling a ricer-grade battery CAI mod Covering the floor in dry ice.
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Apr 8, 2016 23:13
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Godholio posted:Covering the floor in dry ice. Asphyxiating in my vehicle, just like a F-22 pilot 
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Apr 9, 2016 00:03
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canyoneer posted:Isn't there a hybrid class that races in Le Mans every year? Yes but they do not weigh more than 4000 lbs.
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Apr 9, 2016 01:30
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Godholio posted:Look at this flatlander. This bit of snark is geographically, conceptually and factually wrong. There is no better feature suited for regen than straight, long downhills and you'll search long and far to find better regen downhills than the subsea tunnels of western Norway, my dear home. Edit; I got so excited I forgot to argue against your actual point. Brakes get better when they are hot, until they suddenly get worse. So you want to test brakes when they are cold because that's the most statistical likely condition of a set of brakes as they go into an emergency situation. If you traverse long downhills by riding the brakes you are doing it so wrong. Ola fucked around with this message at 08:13 on Apr 9, 2016 |
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Apr 9, 2016 08:08
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If you're looking for meaningless magazine stats, sure. But I've had brakes overheat and fail, so that got me a bit more interested in how much abuse they can take than how short they can go from 60 mph to zero.
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Apr 9, 2016 17:59
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Godholio posted:If you're looking for meaningless magazine stats, sure. But I've had brakes overheat and fail, so that got me a bit more interested in how much abuse they can take than how short they can go from 60 mph to zero. If your brakes are overheating, you're driving poorly and/or speeding. (e: it's still an interesting test perhaps, but might be harder to repeat accurately) 60-0 is a more meaningful statistic in a consumer test than 0-60. Ola fucked around with this message at 20:39 on Apr 9, 2016 |
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Apr 9, 2016 20:36
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Or driving a commercial vehicle that's poorly maintained because hey, insurance. I don't think I've ever gone from 60-0 in a gnat's rear end situation. Even where wildlife jumps into the road, that's just never been the best maneuver available.
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Apr 9, 2016 20:42
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Godholio posted:
Me neither, but I've done 50-20 loads of times, a few times with wildlife as well. A car that does 60-0 well also does 50-20 well.
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Apr 10, 2016 01:10
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I've done 30-0 in a panic when a kid on a trike looked like they were going to roll into the street, albeit not in the S. I sure cared about that distance.
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Apr 10, 2016 01:25
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I've done 60-0 many times testing robotic control of braking systems, but that was on a closed course. If you've done that twice in the amount of time that your brakes stay hot, you're either racing, a bad driver, or incredibly unlucky.
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Apr 10, 2016 04:48
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Frinkahedron posted:I've done 60-0 many times testing robotic control of braking systems, but that was on a closed course. If you've done that twice in the amount of time that your brakes stay hot, you're either racing, a bad driver, or incredibly unlucky. Actually in racing you'd almost never slow to zero either. Even the slowest hairpin will still be 20-30mph.
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Apr 10, 2016 11:27
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Just stop riding your brakes on the steep downhill stretches, instead press them hard and decelerate a lot, like 30mph or so, all in one go, then let off and coast up back to whatever speed is borderline too fast before doing it again. Yes the people behind you will be annoyed if they are tourists, but it's ok to annoy tourists they are all miserable people from Connecticut or some awful place so they will be miserable no matter what you do.
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Apr 10, 2016 23:00
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Pryor on Fire posted:Just stop riding your brakes on the steep downhill stretches, instead press them hard and decelerate a lot, like 30mph or so, all in one go, then let off and coast up back to whatever speed is borderline too fast before doing it again. Yes the people behind you will be annoyed if they are tourists, but it's ok to annoy tourists they are all miserable people from Connecticut or some awful place so they will be miserable no matter what you do. Is this really the "correct" way to downhill brake? Seems strange. What's the reasoning / advantage behind it?
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Apr 11, 2016 04:45
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Gives your brakes a chance to cool off. This is a big deal in places like eastern California, where (e.g.) the the roads down from the Sierra Nevada to the Central Valley are like 80 miles of continuous downhills.
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Apr 11, 2016 04:58
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Sagebrush posted:Gives your brakes a chance to cool off. This is a big deal in places like eastern California, where (e.g.) the the roads down from the Sierra Nevada to the Central Valley are like 80 miles of continuous downhills.
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Apr 11, 2016 07:27
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Do you lose low mode regen braking strength if the battery is topped up?
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Apr 13, 2016 05:11
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kimbo305 posted:Do you lose low mode regen braking strength if the battery is topped up? Yes, it coasts like in neutral when the battery is full. And in the high 90s it will only accept small currents. Doesn't take much distance to make room for it though and many Tesla owners rarely charge to 100% anyway.
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Apr 13, 2016 08:52
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So how do you drive down a mountain then without cooking the brakes?
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Apr 13, 2016 14:25
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mobby_6kl posted:So how do you drive down a mountain then without cooking the brakes? By not having a 100% full battery at the top. Pretty easy in practice I should think.
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Apr 13, 2016 14:37
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Why won't Tesla let me trigger a software update from the app? Do they hate freedom? Unrelated: http://www.technobuffalo.com/2016/04/12/mario-kart-tesla-drive-easter-egg/
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Apr 13, 2016 16:45
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Subjunctive posted:Why won't Tesla let me trigger a software update from the app? Do they hate freedom? Tried it this morning, pretty distracting! 
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Apr 13, 2016 16:55
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Subjunctive posted:Why won't Tesla let me trigger a software update from the app? Do they hate freedom? Does the car work when its being updated? Could be to prevent malicious loving around.
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Apr 13, 2016 17:02
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Don Lapre posted:Does the car work when its being updated? Could be to prevent malicious loving around. Or just loving around at all because telsa is boring.
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Apr 14, 2016 03:31
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mobby_6kl posted:So how do you drive down a mountain then without cooking the brakes? Turn on the heater to draw some current?
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Apr 14, 2016 03:53
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