CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS
Non-Audio Stuff => Car Talk => Topic started by: Marvey on January 08, 2015, 03:44:13 AM
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How did this happen? Does the M4 not have limited slip or did this guy do something weird?
http://www.youtube.com/watch?v=miA5qj5ergM
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Turned off traction control to be a baddass and punched the throttle at the improper time as he was changing lanes. Don't ask how I know this.
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Actual Driver Explains
http://f80.bimmerpost.com/forums/showthread.php?p=17171373#post17171373
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Actual Driver Explains
http://f80.bimmerpost.com/forums/showthread.php?p=17171373#post17171373
I don't buy his claimed expertise and neither does he by the sound of it.
Reminds me of this:
https://www.youtube.com/watch?v=kzlg3oQMze4
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I did a something similar on a supercharged 5.0 Mustang acccelerating out of a turn, but I never jumped a curb. Hard to tell, but it looks like he suddenly lifted when he realized he was losing it. Or one of the tires could have run over a patch of spilled slurpy or dog poop. Gotta respect the power.
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Look at the steering action. None. He should have countered, but it seems we wasn't trying much.
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Looks like he tried from the video, but too little and way too late. Hard to a point finger at him as I'm sure many of us have done stupid shit like that and I'm not sure I could have corrected. Then again, I don't turn the computer 100% off (with cars so equipped) when I'm on the street.
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Talking of stupid shit.. well i have had lots with bikes. Once tried to drift my 650 enduro bike with dirt bike tiers on asphalt. Ended up sliding some 50 meters.. :)p6
From my experience, turning off the traction and stabilty is good, then i get a better feel for the car.
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Looks like he tried from the video, but too little and way too late. Hard to a point finger at him as I'm sure many of us have done stupid shit like that and I'm not sure I could have corrected. Then again, I don't turn the computer 100% off (with cars so equipped) when I'm on the street.
It's amazing how fast torquey cars (without nannies/nannies off) can bite you, especially if the air temps and tires are cold.
You don't need to ask me how I know--it's exactly what you expect.
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Few things could and probably need to be emphasized.
Tires: pressure, wear, road and weather conditions are absolutely crucial when there is so much power and no DSC. When you combine even a couple of those expect a lot of trouble while pressing on gas this hard. In the above case it looks like quite a few factors went into play at once; cold temperature combined with humidity and uneven tire pressure with possible uneven tire wear (as per driver car was pulling slightly to the right from day one). Still driver's main error was changing lanes but I could understand him not worrying about this too much as he used to drive AWD cars.
Audi especially allows much less attention paid to the back end during hard accelerations. Those things pretty much self correct most of the driver errors which develops a certain habits. Even 997tt being AWD is way more stable during hard accelerations then say 997cs despite having way less linear power and gobs more of nonlinear torque. But even then I personally and many others prefer to keep TPM screen on the dashboard at all times even though it looks quite awkward taking like 30% of its real estate (Porsche is actually doing the right thing by allowing you to keep that screen always on and in the center spot). I personally also don't trust high performance tires after first 10k and would rather go like a snail unless there is a lot of space for drifting which of course is the most fun. As for weather conditions, humidity is way more important then temperature and powerful car surely wiggles much more in the morning.
Back to the poor guy, looks like he didn't let go of gas but instead it seems like there was an automatic gear change and even though it's a dual clutch there still must have been be a slight loss of torque. Front wheels were already pointed to the left and so the skid started right there. At the point when skid was already developing so fast no counter-steer would help in such a tight spot, absolutely no way.
After that initial error driver actually did quite well IMO, he was trying to counter steer and was even able to later on straighten the wheels and avoid collision with the road sign. I actually totally believe in his past racing skills as most in this situation would probably end up not only hitting the curb with front wheels still counter-steering to the max but most likely flipping the car over after hitting the curb and a sign at a crazy angle.
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Yup Jason. That's why it takes more skill to drive properly on the street than on a track. Way more environmental factors in less than ideal conditions. People's psychology is usually reversed on this point.
Looking at the M4, looks like they use 'Active M Diff' which is highly reliant on electronics and DSC for input. Congratulations, the cheap ass Torsen in my Toyota is probably a better street diff than your $80,000 BMW's when the nannies are off (as long as the wheels are on the ground).
http://www.bimmerfile.com/2011/09/28/the-active-m-differential-in-detail/
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AWD doesn't have much to do with it. It's the relative torque distribution. Lambo uses pretty much the same AWD systems as Audi but they oversteer crash all the time due to the 90% to the rear bias under certain conditions. Most Audis are usually locked in around the 40/60F-40/60R bias range. This is why Lambo made the new Huracan understeer to keep their dumb poser clients from crashing all the time.
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Damn thing doesn't even have to be all that powerful. RWD is the key here. All owners of 500hp Civic's would confirm;-).
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AWD doesn't have much to do with it. It's the relative torque distribution. Lambo uses pretty much the same AWD systems as Audi but they oversteer crash all the time due to the 90% to the rear bias under certain conditions. Most Audis are usually locked in around the 40/60F-40/60R bias range. This is why Lambo made the new Huracan understeer to keep their dumb poser clients from crashing all the time.
lol..
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Doesn't need to be a 500hp Civic. I've spun a 100hp FWD Corolla before when I was young and knew shit about cars. Unequal length driveshafts+El Nino+lift off throttle=Hydroplaning 720.
When I was driving it home for the first time, I almost spun my old 6.0 V12 Jag into wall at 20mph around a 90 degree right hander due to old skinny rear tires and no rear stabilizer bar. Hooray for left foot braking. ;)
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What I'm wondering is if the electronic diff goes full retard and loses any limited slip capability once the computer is 100% off. Why I am thinking Airbus?
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What I'm wondering is if the electronic diff goes full retard and loses any limited slip capability once the computer is 100% off. Why I am thinking Airbus?
Even if it doesn't go full retard, it's obvious BMW engineered the performance package and overall balance to perform optimally with use of electronics. The only benefit of 'all off' on these modern BMW M's and AMG's seems to be for Chris Harris and Jeremy Clarkson to drift around a circuit for cool videos and ratings.
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You don't need fancy technology to "muck" up
https://www.youtube.com/watch?v=CUgN9ynu4qs
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You don't need fancy technology to "muck" up
I think that's exactly what we're saying.
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Low tech helps a lot. I had a lot of suspension work done on my Mustang including differential, subframe connectors, torque arm, panhard rod, 4-point cage, front K-frame, coil-over, brakes, before I added significant power. Gotta make sure you can put the power down.
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https://www.youtube.com/watch?v=1QJlL0zNdMA&index=7&list=PLHa6PXrV-yIgnXSYFT07BouKhEhyFuWnf
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If one can accomplish the same engineering outcome through mechanical means as they are getting through electronic means, then by all means, do it.
That's an old adage of mine. Electronics have lower engineering costs, weigh less, and cost less. But when they fail, things are often more detrimental to a positive experience. Think electronic steering or throttle.
The diff could be its own system with a certain amount of autonomy when the computer is off, or it can be full-slip. We'll have to dig more to find out.