sanford traction issues?

Chuck Branscomb · **Posted:** Wed May 03, 2006 9:29 pm

Brian Herring wrote:

(considering you have been autoXing longer than I have been alive

.

LOL. Yeah, my first auto-x was in the fall of 1975 at Perimeter Mall in Atlanta. Northside Porsche brought one of the "new" 924's to the event. Other cars there I remember were Datsun 510's, 911's, and a Shelby 427 Cobra. It was the beginning of my learning curve that I couldn't treat a car like my motocross bike if I was going to achieve the fastest time.

I took a big hiatus from auto-x from 1989 until last year except for a couple of events.

AdamBreakey · **Posted:** Thu May 04, 2006 9:32 am

steve remchak wrote:

AND WHY IS IT ALWAYS GOTTA BE A CORVETTE THAT RAN OFF COURSE AND NEARLY etc. etc. etc. etc. . sorry Keith just being a d***. damn corvette guys.

HEY

adamb

MarcusMcRae · **Posted:** Thu May 04, 2006 10:49 am

Chuck Branscomb wrote:

Perhaps the correct answer is to simply tell the novice the truth?

[conversation]

Novice: "Hey, that 330i in front of me just launched like a drag racer off the line."
Insturctor: "Yep, when you are attempting to squeeze tenths of a second out of an auto-x course, the launch becomes an important part of the equation. Don't worry about it now. We'll talk about it back in the pits later. Just do a nice firm launch and focus on the course ahead."

[later, in the pits] Did you know that a typical car will take about 0.4 seconds to move the first 12 inches off the line? This is the only spot on the auto-x course where your car will use up the most time per unit of distance traveled. So in fact, at the competitive level, a proper launch can be extremely important.

[/conversation]

No more granny launches for me. :twisted:

ChuckNelson · **Posted:** Thu May 04, 2006 10:56 am

It was my first time and I saw some guys scrubbing their tires and wondered why they bothered, you still sit for a few minutes before you start.
The spinning the tires off the line thing is very easy to avoid, use a car without enough power to spin them. Works for me.

My wife came over to the work station and I was pretty sure she was not supposed to be there, but as I want to continue doing this and also want to continue my mostly strife free marriage, I did not say anything to her. She was just standing behind us taking pictures and I figured it was safer than her wandering around.

About the spectators standing close to the course. Most, if not all, of the spectators were not around for the driver meeting. So they did not know to not stand past the ditch. Most of them did seem to have the sense to stay on the inside of the faster "turns", when they were closer to the course Maybe placing cones, every fifty feet, in a line down the course to show the no pass point would help.
The guys working are(should be) busy paying attention to the course, and don't need to be running off spectators, and everybody else is either driving, prepping or waiting.

Chris Landi · **Joined:** Mon Mar 08, 2004 6:31 pm **Posts:** 579

MarcusMcRae wrote:

Chuck Branscomb wrote:

Perhaps the correct answer is to simply tell the novice the truth?

[conversation]

Novice: "Hey, that 330i in front of me just launched like a drag racer off the line."
Insturctor: "Yep, when you are attempting to squeeze tenths of a second out of an auto-x course, the launch becomes an important part of the equation. Don't worry about it now. We'll talk about it back in the pits later. Just do a nice firm launch and focus on the course ahead."

[later, in the pits] Did you know that a typical car will take about 0.4 seconds to move the first 12 inches off the line? This is the only spot on the auto-x course where your car will use up the most time per unit of distance traveled. So in fact, at the competitive level, a proper launch can be extremely important.

[/conversation]

No more granny launches for me. :twisted:

WHAT??!!?? I've been telling you this for 2 years! You can have a lot of fun during that first 30 feet you know. It's become my 'tire cleaning/heating ritual'.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Chuck Branscomb wrote:

Perhaps the correct answer is to simply tell the novice the truth?

[conversation]

Novice: "Hey, that weaving looks like fun. I think I'll do that."
Insturctor: " No, you're not going to do that. R-compound tires pick up debris like sticky tape, and these guys are attempting to get some of that off their tires before they hit that first slalom. What they are doing has no effect on non-R-compound tires. Don't worry about it until you have learned enough to spend a couple thousand bucks on wheels and tires and know how to use them properly."

Novice: "Hey, that 330i in front of me just launched like a drag racer off the line."
Insturctor: "Yep, when you are attempting to squeeze tenths of a second out of an auto-x course, the launch becomes an important part of the equation. Don't worry about it now. We'll talk about it back in the pits later. Just do a nice firm launch and focus on the course ahead."

[later, in the pits] Did you know that a typical car will take about 0.4 seconds to move the first 12 inches off the line? This is the only spot on the auto-x course where your car will use up the most time per unit of distance traveled. So in fact, at the competitive level, a proper launch can be extremely important.

The difference between a so-so launch and a great one can be as much as 0.5 seconds or even more if the driver is not taking complete advantage of the starting line configuration. The point is not to "light them up" off the line but to "hook them up" as soon as possible. On most RWD cars you will need to work hard to find the right combination of starting rpm, clutch engagement speed and throttle application in order to spin the tires "just right" in the process of hooking them up and getting the car in its powerband. It is a delicate balance, especially in a high horsepower car, and takes a lot of skill/practice to execute properly.

If you want to practice launching, you may want to go to a drag strip’s test 'n tune night; however, this is one of the last things you need to worry about now since until you have advanced to the level of extracting 95% or more of what your car can give in terms of the friction circle versus the track you are driving, focusing on gaining a few tenths at the launch is not where your energies should be focused. Remember what I said before...just do a nice firm launch while focusing on the course ahead."

[/conversation]

Don't forget that the start light trigger is usually about 5-10 feet ahead of the start line. Those first 12 inches mean nada in terms of time. How fast the car is travelling after the beam is tripped is all that matters. And how fast it's accelerating thereafter.

I think you're overstating the importance of the launch a little bit for our typical course. I'd love to see some calculations for a "good" and "bad" launch with some reasonable assumptions. I'd bet $20 that the difference is less than 0.1 sec.

Wes Eargle · **Joined:** Mon Oct 27, 2003 9:47 am **Posts:** 3683

Chris Landi wrote:

WHAT??!!?? I've been telling you this for 2 years! You can have a lot of fun during that first 30 feet you know. It's become my 'tire cleaning/heating ritual'.

Yeah, starters love being hit with gravel and water being spit out of the exhaust. :roll:

Brian Herring · **Posted:** Thu May 04, 2006 11:33 am

MikeWhitney wrote:

Chuck Branscomb wrote:

Perhaps the correct answer is to simply tell the novice the truth?

[conversation]

Novice: "Hey, that weaving looks like fun. I think I'll do that."
Insturctor: " No, you're not going to do that. R-compound tires pick up debris like sticky tape, and these guys are attempting to get some of that off their tires before they hit that first slalom. What they are doing has no effect on non-R-compound tires. Don't worry about it until you have learned enough to spend a couple thousand bucks on wheels and tires and know how to use them properly."

Novice: "Hey, that 330i in front of me just launched like a drag racer off the line."
Insturctor: "Yep, when you are attempting to squeeze tenths of a second out of an auto-x course, the launch becomes an important part of the equation. Don't worry about it now. We'll talk about it back in the pits later. Just do a nice firm launch and focus on the course ahead."

[later, in the pits] Did you know that a typical car will take about 0.4 seconds to move the first 12 inches off the line? This is the only spot on the auto-x course where your car will use up the most time per unit of distance traveled. So in fact, at the competitive level, a proper launch can be extremely important.

The difference between a so-so launch and a great one can be as much as 0.5 seconds or even more if the driver is not taking complete advantage of the starting line configuration. The point is not to "light them up" off the line but to "hook them up" as soon as possible. On most RWD cars you will need to work hard to find the right combination of starting rpm, clutch engagement speed and throttle application in order to spin the tires "just right" in the process of hooking them up and getting the car in its powerband. It is a delicate balance, especially in a high horsepower car, and takes a lot of skill/practice to execute properly.

If you want to practice launching, you may want to go to a drag strip’s test 'n tune night; however, this is one of the last things you need to worry about now since until you have advanced to the level of extracting 95% or more of what your car can give in terms of the friction circle versus the track you are driving, focusing on gaining a few tenths at the launch is not where your energies should be focused. Remember what I said before...just do a nice firm launch while focusing on the course ahead."

[/conversation]

Don't forget that the start light trigger is usually about 5-10 feet ahead of the start line. Those first 12 inches mean nada in terms of time. How fast the car is travelling after the beam is tripped is all that matters. And how fast it's accelerating thereafter.

I think you're overstating the importance of the launch a little bit for our typical course. I'd love to see some calculations for a "good" and "bad" launch with some reasonable assumptions. I'd bet $20 that the difference is less than 0.1 sec.

AWD, RWD, FWD, MR.... you think that statement still applies for an AWD car? I don't think launch means *that* much either, but it would be interesting to know.

- dow

Chuck Branscomb · **Posted:** Thu May 04, 2006 11:35 am

MikeWhitney wrote:

Don't forget that the start light trigger is usually about 5-10 feet ahead of the start line. Those first 12 inches mean nada in terms of time. How fast the car is travelling after the beam is tripped is all that matters. And how fast it's accelerating thereafter.

Sorry, but this is completely false Mike. Where the start beam is located is irrelevant to how fast you launch the car. If you get a "perfect" launch, you will just arrive at the start beam with a higher velocity -- what professional autocrosser would want to give up speed at the start? Those first 12 inches, first 3 feet, first 10 feet can make a win/loss difference in many classes at the pro level.

Years ago, I used to hear people use this argument for just easing off the line and then punching it once they got to the lights since "what was the point of taking off hard since the light hasn't even been triggered yet?" It's all a matter of how much velocity you want to be carrying when you trip the starting beam. At the dragstip, if they created a timer start beam 10 feet out from the staged beam, do you think pro drivers would think that it wasn't essential to cover that first 10 feet in the shortest time possible so that they arrive at that timer trigger with the highest velocity? I don't know of any who would gladly give up a few tenths in that way. The same actually applies at an autocross. We just end up turning a bunch on the way to the end, but distance x time doesn't change.

Cheers,

Chuck

Chuck Branscomb · **Posted:** Thu May 04, 2006 11:42 am

MikeWhitney wrote:

I think you're overstating the importance of the launch a little bit for our typical course. I'd love to see some calculations for a "good" and "bad" launch with some reasonable assumptions. I'd bet $20 that the difference is less than 0.1 sec.

One way to do this is just look at 60' times from the strip. From my experience, a poor launch versus a fantastic launch can easily be 0.3 seconds or even more if you really mess up the start.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Chuck Branscomb wrote:

MikeWhitney wrote:

Don't forget that the start light trigger is usually about 5-10 feet ahead of the start line. Those first 12 inches mean nada in terms of time. How fast the car is travelling after the beam is tripped is all that matters. And how fast it's accelerating thereafter.

Sorry, but this is completely false Mike. Where the start beam is located is irrelevant to how fast you launch the car. If you get a "perfect" launch, you will just arrive at the start beam with a higher velocity -- what professional autocrosser would want to give up speed at the start? Those first 12 inches, first 3 feet, first 10 feet can make a win/loss difference in many classes at the pro level.

Sorry what I said there was a little misleading. You're not being timed for the first 12 inches, that was my point. Maximizing the launch is important, yes. But your time starts after you cross the beam. I just wanted everyone to know that.

I'm not disagreeing. I'm just wondering how big of a deal it really is -- 0.5 sec would be a big deal, 0.05 would not in my book.

I'm not convinced about the 60' times ... since the start lights are 10' away. How much of the time is between 10-60 feet and how much is in the first 10'?

I would need to haul out my Physics 101 books and copy a few equations to do that

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Chuck Branscomb wrote:

Years ago, I used to hear people use this argument for just easing off the line and then punching it once they got to the lights since "what was the point of taking off hard since the light hasn't even been triggered yet?" It's all a matter of how much velocity you want to be carrying when you trip the starting beam. At the dragstip, if they created a timer start beam 10 feet out from the staged beam, do you think pro drivers would think that it wasn't essential to cover that first 10 feet in the shortest time possible so that they arrive at that timer trigger with the highest velocity? I don't know of any who would gladly give up a few tenths in that way. The same actually applies at an autocross. We just end up turning a bunch on the way to the end, but distance x time doesn't change.

Easy there Chuck ... I completely agree that those "people" are full of it. Don't read too much into what I said. Get off the jumping to conclusions mat.

MarcusMcRae · **Posted:** Thu May 04, 2006 12:15 pm

Wes Eargle wrote:

Chris Landi wrote:

WHAT??!!?? I've been telling you this for 2 years! You can have a lot of fun during that first 30 feet you know. It's become my 'tire cleaning/heating ritual'.

Yeah, starters love being hit with gravel and water being spit out of the exhaust. :roll:

Don't worry muffin, I'll granny launch for you when you're starting. :kisses:

Donnie Barnes · **Posted:** Thu May 04, 2006 12:48 pm

While you're right that in ProSolo (or drag racing in general) the 60' time can be that far off from good to bad launches, the fact is that most Solo events (outside ProSolo) never have a 60' drag start. You're turning long before that. That's why Mike's point is pretty much valid...I'd say you could have probably seen around .1s, maybe a *tad* more than that on the course due to launch in Sanford, but even that course had a relatively atypical start as far as speed. We're often doing hard turns out of the start rather than feeding into a slalom that just required a light brake touch (at least in an r-compound STi).

Remember that's it is that later 20' of the 60' where the real time is "made up" on the fast versus "slow" start. Well, for most car types, anyway.

--Donnie

Wes Eargle · **Joined:** Mon Oct 27, 2003 9:47 am **Posts:** 3683

MarcusMcRae wrote:

Wes Eargle wrote:

Chris Landi wrote:

WHAT??!!?? I've been telling you this for 2 years! You can have a lot of fun during that first 30 feet you know. It's become my 'tire cleaning/heating ritual'.

Yeah, starters love being hit with gravel and water being spit out of the exhaust. :roll:

Don't worry muffin, I'll granny launch for you when you're starting. :kisses:

I turn my back to the car after letting AWD cars and Walter start. So what's there to kiss is ... :shock:

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