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Old 03-28-2008, 11:17 PM   #31
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Derrick drill bits are made of steel & cost pennies compared to expensive machined aluminum chassis'.I would consider using an old chassis as a test bed though.
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Old 03-28-2008, 11:27 PM   #32
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i know, i was just replying. Too stiff in a crash can be bad also. Bad comparison i guess. If you really want to find out Go from one extreme to the other? Ultra Soft to Ultra stiff. And keep notes. every change write down what you did and what effect it had on the car.
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Old 03-29-2008, 07:26 AM   #33
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what if you had a really stiff chassis? Ever seen a drill bit break? If its really still, the force is transfered thought the whole car, if it flexes, it takes energy away.
I think the thing is. We are not setting the car up for crashing.......or to survive crashes. We are setting the car up to race and to get fast lap times.
I'm not saying we should ignore damage prevention etc
But its a question of priorities.
Is it better to have a slower car that will survive a "possible" crash better, or a faster car that "may" be damaged easier.
Guess it would depend on how good you are and how much you do crash, or intend to crash.

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Old 03-29-2008, 07:55 AM   #34
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I think the thing is. We are not setting the car up for crashing.......or to survive crashes. We are setting the car up to race and to get fast lap times.
I'm not saying we should ignore damage prevention etc
But its a question of priorities.
Is it better to have a slower car that will survive a "possible" crash better, or a faster car that "may" be damaged easier.
Guess it would depend on how good you are and how much you do crash, or intend to crash.

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that answer would depend on the driver, if you suck and crash all the time, or if you're a pretty good at not crashing
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Old 03-30-2008, 07:24 PM   #35
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I think, like all cars, full scale or not, it all comes down to driver preference. If you can drive faster with flex, drive it. If you need super rigid, drive it. What matters is what is fast for you, not what is right.
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Old 03-31-2008, 01:51 AM   #36
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I think, like all cars, full scale or not, it all comes down to driver preference. If you can drive faster with flex, drive it. If you need super rigid, drive it. What matters is what is fast for you, not what is right.
well some of the comments on here.. well some people are on crack.. the reason a drill bit breaks is because its hardened steel.. the harder a metal is the more brittle it is... Race cars are made with mild steel or chromeolly steel neither of which are hardened..

chassis flex on real cars is not desirable ... not in the capacity you think.. A#1 example: Today my test driver had a race at Infineon raceway with another teams car (wanted to drive a shitbox for some fun) and the car was all over the place, when you crack the throttle mid corner it would randomly either dart inside or dart outside.. sometimes would hold the line... WHY? the chassis was cracked (flexing). in "real cars" the chassis flex idea is mostly confined to cars that don't have dampers and springs.. like Funnycars/ top fuel, and karts.... they tune with flex..

race car based on production or tube chassis, Seam welding, cages. its the stiffening and the structure that work two fold, they don't just crumble and colapse on itself whereby squishing your driver.. and at the same time make the chassis a more ridged assembly.

and if your tuning a chassis on a real car and flex helps, you should shoot the shock guy in the face.. along with the engineer.. you really think formula car engineers want more flex in the chassis? Yeah, thats why they use the most ridged material they can reasonably use. Carbon Fiber, not play dough kids..
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Old 03-31-2008, 11:21 AM   #37
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I think, like all cars, full scale or not, it all comes down to driver preference. If you can drive faster with flex, drive it. If you need super rigid, drive it. What matters is what is fast for you, not what is right.
I think your right to a large degree............but only as exactly as you have written it!
I mean, if you are FASTER with a chassis with more flex, then use it. Not if you like it with more or less flex. Thats the key. Sometimes you wont like the way your car handles, it will be a handful, or you may have to really concentrate really hard just to keep the thing on the black stuff............the thing is, is it faster that way? Thats the key question here.

Also, what has just been said about real cars is somewhat true for our scale cars also. If flex in the chassis is working, or making the car/driver faster, the suspension is not set optimally.
Now, you may not be able to get the optimum suspension set up for the track and for maximum mechanical grip, why? cause we only have single adjuster dampers to work with at the moment. So as Motorman pointed out, the use of flex with our scale cars can be used as a secondary suspension medium, to be used as a tuning aid.

I think the best way to use flex in our scale cars is to make the chassis as stiff as possible, COG as low as possible and Mass should be on the legal limit. Wings in a mid' position if adjustable. Sway bars off.Or full soft.

Tune suspension and get the car as good as possible, then add Sway bars, flex and more wing as needed.

Add lots of time none of us have and loads of money to get to tracks, a patient/understanding wife/girlfriend and your all set......lol

Regards all,
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Old 03-31-2008, 11:22 AM   #38
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When i raced karts, you're right the flex WAS the suspension (and the tires, but thats besides the point). When i moved up into formula 500, and then legends cars, the name of the game was eliminate flex. I was refering to scale cars in terms of flex. Some full scale drivers like a bit of push in their cars, some like a free rear end. Some scale drivers like flex, some like stiff. Opinions are like buttholes, everyones got their own, haha.
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Old 03-31-2008, 12:05 PM   #39
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lol
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Old 03-31-2008, 12:51 PM   #40
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OK, I have one.. of you people that say flex in a 1:1 car is good. How many race cars have you built? How many races have you driven? Driven a car that had problem with the chassis stiffness (a soft chassis, cracked chassis or something that affects handling) How much experience do you really have with real cars? How many of you have ANY motorsports engineering background? to that end.. how many of you have even welded a cage in your own car? The forces involved are very different and the tire/ chassis and suspension charicteristics are different.

Me: 8 years in motorsports
3 national titles (IMSA, SCCA, and Pro formula mazda)
26 straight regional titles from 2005-2008 (various SCCA, NASA and rally america races/ rally) Lost my first race in SCCA yesterday.. 3rd place..
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Old 03-31-2008, 12:54 PM   #41
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Wings in a mid' position if adjustable. Sway bars off.Or full soft.? so your telling me, you would go to PIR, firebird, road atlanta with a Formula Atlantic with no swaybars on it and wings at 18*F and 37*R? The track day you did with your miata at willow springs doesn't count old buddy...
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Old 03-31-2008, 12:56 PM   #42
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Originally Posted by rx7ttlm View Post
OK, I have one.. of you people that say flex in a 1:1 car is good. How many race cars have you built? How many races have you driven? Driven a car that had problem with the chassis stiffness (a soft chassis, cracked chassis or something that affects handling) How much experience do you really have with real cars? How many of you have ANY motorsports engineering background? to that end.. how many of you have even welded a cage in your own car? The forces involved are very different and the tire/ chassis and suspension charicteristics are different.

Me: 8 years in motorsports
3 national titles (IMSA, SCCA, and Pro formula mazda)
26 straight regional titles from 2005-2008 (various SCCA, NASA and rally america races/ rally) Lost my first race in SCCA yesterday.. 3rd place..
Come on now, this is suppose to be an informative post, no need to slap people with credentials. Like stated, everyone has some say be it wrong or not, collective thoughts help more then the "who has bigger pee pee" posts.... and this is not just directed at rx7ttlm, this goes for the whole FORUM.
lets keep this informative and not argumentative.
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Old 03-31-2008, 01:58 PM   #43
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Originally Posted by Baedarlboo View Post
Come on now, this is suppose to be an informative post, no need to slap people with credentials. Like stated, everyone has some say be it wrong or not, collective thoughts help more then the "who has bigger pee pee" posts.... and this is not just directed at rx7ttlm, this goes for the whole FORUM.
lets keep this informative and not argumentative.
On my end, I threw that out there because I am 99% sure the people that are talking about chassis flex in 1:1 cars have NO idea what they are talking about.. its not an aircraft wing subjected to 594,000 Lbs of load (F/A 18C in a 9G turn)Thats where you want the structure to flex.

Vehicle designers balance weight, stiffness(stiffness of X component is taken into consideration but is not desired save for springs, swaybars and tires), suspension/ chassis component deflection is accounted for but not desired, CG, Moments, safety, and serviceability.

So some guy saying that chassis flex in 1:1 car is good that has no practical experience is very interesting to me.. I could say how well the serpent 120 handles under certain conditions.. but I haven't driven it so how would I know? same concept.. so how informative is a post by someone about how the serpent 120 drives that hasn't driven one..
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Old 03-31-2008, 02:12 PM   #44
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On my end, I threw that out there because I am 99% sure the people that are talking about chassis flex in 1:1 cars have NO idea what they are talking about.. its not an aircraft wing subjected to 594,000 Lbs of load (F/A 18C in a 9G turn)Thats where you want the structure to flex.

Vehicle designers balance weight, stiffness(stiffness of X component is taken into consideration but is not desired save for springs, swaybars and tires), suspension/ chassis component deflection is accounted for but not desired, CG, Moments, safety, and serviceability.

So some guy saying that chassis flex in 1:1 car is good that has no practical experience is very interesting to me.. I could say how well the serpent 120 handles under certain conditions.. but I haven't driven it so how would I know? same concept.. so how informative is a post by someone about how the serpent 120 drives that hasn't driven one..
And I understand where you're coming from, and correct info is even more helpful, but what i'm trying to say, is lets keep things civil and not let this thread go up in flames with back and forth arguments. Thats all....
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Old 03-31-2008, 02:28 PM   #45
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And I understand where you're coming from, and correct info is even more helpful, but what i'm trying to say, is lets keep things civil and not let this thread go up in flames with back and forth arguments. Thats all....
if they really wanted to prove me wrong, they would sawzall their cars chassis down the middle for "flex tuning" and provide some data as to how great it was... lol

its also not about grip or balance.. chassis flex on a real car intruduces and inconsistent variable, and the car will become unpredictable..
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