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Traction? What's that?

Old 09-23-2018, 03:19 PM
  #1  
FastAgain
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Default Traction? What's that?

Sorry I asked....

Last edited by FastAgain; 09-23-2018 at 09:15 PM.
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Old 09-23-2018, 04:59 PM
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Nothing is amiss, and I am not sure why it took you an entire book and arbitrary pictures to explain a simple condition. Here is a tip, if you want help with something limit your question to a few lines as no one is reading all that crap you wrote. Further, you are way over thinking this, and clearly have no experience in this area. So stop trying to use physics that you don't understand in your search for such a simple answer. I have a competition racing license, am a racing instructor and study these things literally every day, and not even I would spend more than 5 seconds on this topic. You simply went to 3rd gear too early. This causes a shock to the rear (where power is delivered) as the engine must spool back up very rapidly to reach the speed of the driveline and the tires, which in turn causes a violent shock to the driveline/tires and loss of traction. The solution is to either slow down more before you go to third gear, or blip the throttle prior to entering third gear. By blipping the throttle you can better match the revs of the engine to the speed you are at and avoid this shock to the driveline and tires.

With what you did, the rear WILL lose traction. One tire will lose traction first, due to a wide variety of reasons (road surface irregularities, crown of the road, weight distribution of the chassis, the direction of torque of the engine, small and minute variations in mechanical grip of each tire etc etc) and cause the car to step-out in one direction.

So, stop shifting to third so early, or learn how to rev match. The End. Nice car though. I suggest you take your road racing escapades to your local circle track or road course. You will learn (with an instructor in the car with you) how to control the car when driven in anger. You will "un-learn" all of these bad habits and be better for it. Good luck.
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Old 09-23-2018, 05:04 PM
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Originally Posted by Mordeth View Post
Nothing is amiss, and I am not sure why it took you an entire book and arbitrary pictures to explain a simple condition. Here is a tip, if you want help with something limit your question to a few lines as no one is reading all that crap you wrote. Further, you are way over thinking this, and clearly have no experience in this area. So stop trying to use physics that you don't understand in your search for such a simple answer. I have a competition racing license, am a racing instructor and study these things literally every day, and not even I would spend more than 5 seconds on this topic. You simply went to 3rd gear too early. This causes a shock to the rear (where power is delivered) as the engine must spool back up very rapidly to reach the speed of the driveline and the tires, which in turn causes a violent shock to the driveline/tires and loss of traction. The solution is to either slow down more before you go to third gear, or blip the throttle prior to entering third gear. By blipping the throttle you can better match the revs of the engine to the speed you are at and avoid this shock to the driveline and tires.

With what you did, the rear WILL lose traction. One tire will lose traction first, due to a wide variety of reasons (road surface irregularities, crown of the road, weight distribution of the chassis, the direction of torque of the engine, small and minute variations in mechanical grip of each tire etc etc) and cause the car to step-out in one direction.

So, stop shifting to third so early, or learn how to rev match. The End. Nice car though. I suggest you take your road racing escapades to your local circle track or road course. You will learn (with an instructor in the car with you) how to control the car when driven in anger. You will "un-learn" all of these bad habits and be better for it. Good luck.
I braved the read, needed to rev-match or use the brakes more instead of probably almost over-revving the engine to slow down. +1 on track experience and you will learn the importance of what Mordeth explained and what I just said.

Cliffs: Suspension fine, do not over-rev engine.
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Old 09-23-2018, 08:36 PM
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Its apparent almost anyone can own a z06...but maybe not everyone should.

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Old 09-23-2018, 08:42 PM
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Peace

Last edited by FastAgain; 09-23-2018 at 09:16 PM.
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Old 09-23-2018, 09:17 PM
  #6  
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Originally Posted by FastAgain View Post
I had written out an answer, and somehow lost it, and really don't feel like re-writing it. But it's weird when someone goes on a forum, says (in simple words) "...I'm here because you guys know more than I do, and I value your opinion...", and gets flamed as not knowing what he's talking about. Either there's an echo in this forum, or somebody missed something. Also, the yaw story shouldn't have even been included; the original question was about the fact that I can't get traction to save my life, and if anyone might have any idea why. I thought there might have been something wrong with my suspension, which is why I included that account.

In the end, the yaw had to do with angular momentum; increasing the angular momentum of the motor (r.p.m.) induced a roll moment, which in turn put more force on one rear tire than another, which caused the yaw.

Mordeth; you may be an accomplished driver, but you're not a physicist, which I am. If there's anyone who shouldn't talk about things they don't understand, it's you.

But thanks for the nice thoughts about my car; if you know any good driving schools in south Florida, please pass that info on.

Peace.
Not sure about the mods, but my R888R's same size as stock, are incredible.

From a roll around 5 mph, they will break lose for about the first 10 feet... but barely... then it's gone. It won't spin anywhere else, at any rpm, in any gear.

However, the dump to third gear at a very high RPM as you did, having tires that don't get traction could have saved your drivetrain if it spun... Not sure you want better traction if you're dumping it into third gear at upwards of 170... I likely could have read your post wrong, I'm also trying to save my kids from killing each other right now over some legos. So I apologize if I missed something.
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Old 09-23-2018, 09:51 PM
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This thread delivers
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Old 09-24-2018, 07:48 AM
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Shock loading a dynamic system is never a good idea...especially when slowing down.


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Old 09-24-2018, 08:08 AM
  #9  
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Originally Posted by FastAgain View Post
Thank you for your input. I erased my original post, as it seemed to be inappropriate to state that you weren't informed about what was going on with your Z06, admit that others knew more, and ask for their advice. I see now how stupid that was. Though Mordeth did, by the end of his post, provide sage advice.

In my original post, I stated that I "aerobraked" before going into third. If my Reynolds calculations are correct ( I am a physicist specialized in thermo, and fluid dynamics), and yes, I know that air isn't a perfect fluid, at 170, the atmosphere makes for a 318 horsepower brake, on a car with a 22 square-foot frontal section, and a Cd of .33. I didn't give a speed, but I went to third AFTER I aerobraked for a few seconds; I was still going fast enough to wind the engine up very quickly, as I was in a hurry to slow down. I didn't rev match because I wanted maximum braking effect from the engine, and the force applied to cause the sudden increase in the rotating assembly's angular momentum, resulted in a roll moment that planted one of the rear tires more firmly than the other, and probably caused some slight flexure in the chassis, all resulting in the yaw. Sorry for not stating that more clearly.

I'll look into the R88s; thanks for your suggestion!
Horseshit. If you hadn't deleted your rambling post then this horseshit would be more evident - although I don't blame you, considering the content. And all of my advice was sage advice, considering what you wrote, what you claimed you did and how you incorrectly interpreted it all.

So let's again, get to the point:

1) Don't over-rev your car and shock the suspension and tires.
2) Don't use the engine to brake, especially from those speeds. It is dangerous and stupid, especially for an untrained driver like yourself. That's what the brakes are for.
3) Learn how to rev match when appropriate.
4) Seek out proper training on how to operate your vehicle in a high speed environment. Road racing at 170mph on public streets is not only dangerous, but extremely stupid considering your glaring inability to control the car and lack of training on the proper inputs to achieve the desired effect. These proper inputs are learned behaviors, and so you must study them and train for them.

Additionally, it was the car's nannies that saved you (not your slow reaction to events, which were self induced). So you should be grateful for them, as they saved your life (assuming your initial rambling and now deleted post was even true).

And finally, if you are a physicist, then you understand the importance of using accurate data when performing calculations. Your data and assumptions are wrong (not surprising). The coefficient of drag for a C6Z, as published by the manufacturer is .34. The frontal area of a C6Z is 22.3 sq ft. I am surprised at your glaring lack of accuracy, especially when preciseness is critical when considering the nature of fluid dynamics.

The proper equation for drag is as follows: D = Cd * A * .5 * r * V^2. Whereby D = drag, Cd = Coefficient of drag, A = the reference area, r = density and V = velocity. Typed out by me and taken directly from page 47 of the book I have in front of me titled: "Race Car Aerodynamics: Designing for Speed (Engineering and Performance) by Joseph Katz (as a reference and citation).

So when we plug this example into the proper equation in meters using the correct assumptions we have D = .34 * 2.071738 * .5 * 1.22 * 75.9968^2 = 2481.6138006 N

And get better tires.
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Old 09-24-2018, 08:27 AM
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Originally Posted by Mordeth View Post
Horseshit. If you hadn't deleted your rambling post then this horseshit would be more evident - although I don't blame you, considering the content. And all of my advice was sage advice, considering what you wrote, what you claimed you did and how you incorrectly interpreted it all.

So let's again, get to the point:

1) Don't over-rev your car and shock the suspension and tires.
2) Don't use the engine to brake, especially from those speeds. It is dangerous and stupid, especially for an untrained driver like yourself. That's what the brakes are for.
3) Learn how to rev match when appropriate.
4) Seek out proper training on how to operate your vehicle in a high speed environment. Road racing at 170mph on public streets is not only dangerous, but extremely stupid considering your glaring inability to control the car and lack of training on the proper inputs to achieve the desired effect. These proper inputs are learned behaviors, and so you must study them and train for them.

Additionally, it was the car's nannies that saved you (not your slow reaction to events, which were self induced). So you should be grateful for them, as they saved your life (assuming your initial rambling and now deleted post was even true).

And finally, if you are a physicist, then you understand the importance of using accurate data when performing calculations. Your data and assumptions are wrong (not surprising). The coefficient of drag for a C6Z, as published by the manufacturer is .34. The frontal area of a C6Z is 22.3 sq ft. I am surprised at your glaring lack of accuracy, especially when preciseness is critical when considering the nature of fluid dynamics.

The proper equation for drag is as follows: D = Cd * A * .5 * r * V^2. Whereby D = drag, Cd = Coefficient of drag, A = the reference area, r = density and V = velocity. Typed out by me and taken directly from page 47 of the book I have in front of me titled: "Race Car Aerodynamics: Designing for Speed (Engineering and Performance) by Joseph Katz (as a reference and citation).

So when we plug this example into the proper equation in meters using the correct assumptions we have D = .34 * 2.071738 * .5 * 1.22 * 75.9968^2 = 2481.6138006 N

And get better tires.
*mic drop*
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Old 09-24-2018, 09:20 AM
  #11  
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Originally Posted by FastAgain View Post
Yes.

But first you guys flame me when I OVER state information, then call me inaccurate when I give approximate values for the Cd and frontal area; sorry about 22 vs 22.3 , and .33 vs .34; it was a quick reply. If had written out the entire Reynolds transfer function with the associated Taylor series to describe it, and the kinematics necessary to prove the energy requirements I stated, I would have gotten yet another flaming for an excessively long post. In a few words, damned if I do, damned if I don't.

Like I said; forget I asked.

Y'all have a nice day.
I mean, if you are going to boast about yourself, you should put enough effort to, at least, state accurate figures.
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Old 09-24-2018, 09:50 AM
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Anthony at his best in APA format... The initial post needed a Thesis.
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Old 09-24-2018, 09:58 AM
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I did not see the unedited first post, but advice to the OP (and to the rest of the posters - who I value). Don't let this thread prevent you from participating in the forum. All of us have our areas of expertise outside the forum. Don't try to impress with high level technical stuff unless it is absolutely necessary to answer the question.

The answers addressing tires, when to downshift (less than 122 MPH into 3rd) and rev matching are the solutions to the problem I think was asked.
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Old 09-24-2018, 11:38 AM
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this thread makes me think i should have applied myself more in school...
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Old 09-24-2018, 12:02 PM
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Originally Posted by jammeejamm View Post
this thread makes me think i should have applied myself more in school...
I'm with you on that one. I though all you had to do was mash the gas, shift, turn the steering wheel and hit the brakes.
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Old 09-24-2018, 12:36 PM
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Originally Posted by AzDave47 View Post
I did not see the unedited first post, but advice to the OP (and to the rest of the posters - who I value). Don't let this thread prevent you from participating in the forum.
Thanks but, no danger of that ever happening again.


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Old 09-24-2018, 01:00 PM
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The initial post was a joke, or so it seemed.

Mordeth was spot on. I didn't feel like wasting time responding when he summed it up so well.
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Old 09-24-2018, 04:12 PM
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This is LMM worthy.
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Old 09-24-2018, 06:11 PM
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Originally Posted by Texasthunder View Post
I'm with you on that one. I though all you had to do was mash the gas, shift, turn the steering wheel and hit the brakes.
wait .....thats not what you do????
God Ive been doing it wrong

Clif
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