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Floaty at Speed???

 
Old 10-22-2013, 05:51 AM
  #61  
Rainier_991
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Chuck,
nice writeup. Like it.
If you think THAT is the limit of instructor terror - try instructing landing an airplane.
Would LOVE to read your write-up after that. I'm sure there will be many more words in capitals !

Rainier

Originally Posted by chuck911 View Post
The DE advice is as much for you as my way of repaying all the Instructors who helped me to learn, advance, eventually become an Instructor myself. Like every Novice, I thought I already knew how to drive, just needed track time. Wrong. If you have not had real one on one instruction and seat time you do not know what you're doing. Literally. Its like the Donald Rumsfeld line about "known knowns.... unknown unknowns." You literally don't even know what you don't know! So you get in a car that does 140 like nobody's business, go around a curve, feeling fine and dandy in your blissful ignorance. Meanwhile your Instructor sitting beside you is having a near-death experience, gripping the armrest so hard his fingernails are about THIS CLOSE to ripping through the leather, because HE knows you're off-line, apexing way early, lifting where you shouldn't be, and if you make just ONE MORE error we're gonna be praying that PSM is all its cracked up to be. Oh God! Did I just say cracked up! Please God! No! NOOOO!!!! That anyway is exactly what its like with a lot of novices. But take the same novice, first time on the track, but this ones done Driver Skills first- well you would not believe the difference. Night and day. Better line. Better eyes. Better inputs. More at ease, more attentive and more receptive.

I like big beers. A good local Porter or Dunkelweizen.
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Old 10-23-2013, 04:11 AM
  #62  
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Originally Posted by Rainier_991 View Post
Chuck,
nice writeup. Like it.
If you think THAT is the limit of instructor terror - try instructing landing an airplane.
Would LOVE to read your write-up after that. I'm sure there will be many more words in capitals !

Rainier
I was just about to say what are you crazy teach someone to fly but then noticed you skipped right past FLY and went straight to LAND!
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Old 10-23-2013, 05:15 AM
  #63  
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Originally Posted by chuck911 View Post
I was just about to say what are you crazy teach someone to fly but then noticed you skipped right past FLY and went straight to LAND!
Ha ! I was thinking you're crazy teaching somebody to drive a Porsche around a corner !
BTW, like "driving", "flying" is dead easy. Including getting into the air. It's the landing where things fall apart. This is the hardest thing to learn for any new pilot. Not unlike going fast through a corner in many ways - mind you.
It's just that it hurts more if you get it wrong.
And yes - instructing to land can be very, very entertaining. The feeling you get when at the last split second the student does something unexpected is classic...

Rainier
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Old 10-23-2013, 06:26 AM
  #64  
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Originally Posted by chuck911 View Post
Uh,... er....
Forgot to mention, instruction cars were abs disabled. So degressive (not progressive) braking. I'm sure that will clear your confusion, right ? ;-)
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Old 10-23-2013, 01:55 PM
  #65  
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Originally Posted by bccars View Post
Forgot to mention, instruction cars were abs disabled. So degressive (not progressive) braking. I'm sure that will clear your confusion, right ? ;-)
Progressive means applying the brakes progressively. Braking causes weight transfer froward, with the increased weight resulting in increased front tire grip, which allows for increased braking. Progressively squeezing on the brakes this way eventually gets you to a point of maximum weight transfer, maximum grip and maximum braking at the threshold of tire traction- which is why its also called threshold braking.

Lets just tool around up here in the sky a while longer. I don't we're ready to try landing just yet....
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Old 10-23-2013, 03:25 PM
  #66  
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Originally Posted by chuck911 View Post
Progressive means applying the brakes progressively. Braking causes weight transfer froward, with the increased weight resulting in increased front tire grip, which allows for increased braking. Progressively squeezing on the brakes this way eventually gets you to a point of maximum weight transfer, maximum grip and maximum braking at the threshold of tire traction- which is why its also called threshold braking.
Ah, interesting, didn't expect that, good to know, you are one of those misguided progressive brakers ;-)

Nice reasoning, but you are completely forgetting that the slower you go (you are braking), the less braking force is needed to lock up the wheels ! Hence degressive !
I'm not saying the weight transfer issue isn't there, but it is only a fraction of the whole braking maneuvre, so you are taking it out of proportion in your reasoning !

Time to google some brake telemetry graphs of toplevel professional drivers as I'm sure you will not believe me ! ;-)

http://world2talkabout.wordpress.com...ving-analysis/
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Old 10-23-2013, 04:06 PM
  #67  
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No kidding. That's because I was only giving you part of the story- the progressive threshold braking part. Which your link describes as "wheel lock not far away". The next part of the story: modulation. Once having reached threshold braking lots of things can happen. Slight dip lowers weight hence traction causing lockup, you don't lift off the brakes but quickly modulate just enough to regain traction then go right back to braking.

What you're talking about, braking less as you go slower, actually is due to rotational inertia not tire grip. At high speeds a significant amount of braking is required just to slow the wheels rotation. Nice to know, and helps you understand why light wheels and PCCB are worth the cost after all. But in terms of being able to stop fast and in control its really only necessary to know how to use weight transfer and modulation to achieve and maintain threshold braking.
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Old 10-24-2013, 06:04 AM
  #68  
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Originally Posted by chuck911 View Post
No kidding. That's because I was only giving you part of the story- the progressive threshold braking part. Which your link describes as "wheel lock not far away". The next part of the story: modulation. Once having reached threshold braking lots of things can happen. Slight dip lowers weight hence traction causing lockup, you don't lift off the brakes but quickly modulate just enough to regain traction then go right back to braking.

What you're talking about, braking less as you go slower, actually is due to rotational inertia not tire grip. At high speeds a significant amount of braking is required just to slow the wheels rotation. Nice to know, and helps you understand why light wheels and PCCB are worth the cost after all. But in terms of being able to stop fast and in control its really only necessary to know how to use weight transfer and modulation to achieve and maintain threshold braking.
Well and that modulation is a diminishing force if you look at telemetry, hence degressive !
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Old 10-24-2013, 09:32 AM
  #69  
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Originally Posted by Pazzo009 View Post
... I had the car on brand new pavement at hit around 140mph. The car felt floaty and light at that speed. I am used to my M at those speeds it feel glued and comfortable.
Originally Posted by Pazzo009 View Post
Alignment? Okay, but I just picked up the car Tuesday night brand new. I do not want to add any suspension mods because I am leasing the car for 27 months. The only option the car is equipped with as far as beneficial in this matter would be the PDCC.
Originally Posted by ny991 View Post
Two days to 140mph. Not bad!
Wow... you would be very welcome in the "should I observe the run-in / break-in periods of my new 911" thread!

Clearly you are on the side of the spectrum that claims you should take the car from the dealership straight to the track
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Old 10-24-2013, 02:23 PM
  #70  
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Originally Posted by MacAna View Post
Clearly you are on the side of the spectrum that claims you should take the car from the dealership straight to the track
Best thing you can do for it. But take it easy on the tires. Unlike the engine that needs to be run hard asap, tires do need to be heat-cycled before hard track use. So use all the throttle and revs you can, but take it easy cornering and braking, at least until they've cycled.
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Old 10-24-2013, 07:43 PM
  #71  
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Yeah, I agree. I haven't beat on the tires...But nowadays engines have their owns maps for break in...or atleast that is what I am told.
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Old 10-24-2013, 07:50 PM
  #72  
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Originally Posted by Pazzo009 View Post
Yeah, I agree. I haven't beat on the tires...But nowadays engines have their owns maps for break in...or atleast that is what I am told.
Maps?!?

Nevermind. Yours was done a week ago.
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Old 04-24-2014, 01:48 AM
  #73  
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What is the top speed of a M5?
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Old 04-24-2014, 02:03 AM
  #74  
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Old 04-24-2014, 02:18 AM
  #75  
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U.S.
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