[Tuck4Bama]

I am very impressed with the expertise of the NASCAR experts. I have learned alot from all of you who have contributed techinical explainations. If there is a forum where the "ask the experts" will stay very busy This is the one. Great job to all of you.

[simple simon]

ok i have a question for you experts

since i believe the SC in NASCAR stands for Stock Car ..... just what exactly on these cars is still stock ?

[Racer Duck]

Originally Posted by simple simon

ok i have a question for you experts

since i believe the SC in NASCAR stands for Stock Car ..... just what exactly on these cars is still stock ?

the air they race in...

National Association for Stock Car Auto Racing originally raced "stock cars" on the beach at Daytona. Over the years, "improvements" have been made to every aspect of the car, and to the tracks and the drivers, such that no part of "stock car" racing is stock, or as it was in the beginning - except, that is, the competition between drivers (and the air they race in). Until the 80's the cars still appeared stock .. but even that has changed with the "aero" technologies available. The big deal back then was anyone could bring their (family) car to the track and race .. that's how "stock car" racing got it's start in NASCAR.

Compare it to the improvements in basketball or football or marathons or whatever sport you wish. Technologies have improved training, the equipment and the arenas (even the streets aren't the same now as for the original marathons...)

[Racer Duck]

Originally Posted by Racer X

How can any adjustment have one effect on the car at one point in the turn and another effect on the car at another point in the turn? It seems to me that any adjustment would make the car, on the whole, looser or tighter. The only thing that is variable is what the driver is doing in the car in terms of steering, gas, and brake. Along the same lines, how can a car be adjusted if they it is tight in Turn 2 but loose in Turn 4? Any adjustment, to me, would make the car looser or tighter on the whole…

I hope my question makes sense…. I have been struggling with this concept for years. Thanks for any insight you can give me.

Racer X,

I re-read your question(s) and realized we only gave a partial answer: that of "loose in and tight off" and the combinations there of... But you also raised two other questions that, I think, most folks are also having trouble with. So let me take each in turn.

How can any adjustment have one effect on the car at one point in the turn and another effect on the car at another point in the turn? Let's go back to the discussion in the "wedge" question about weight transfer. As I described there, the car's weight is "moving around" during the 3 primary parts of a turn (entry, middle, & exit.) First it goes forward, then to the right, then to the rear and finally back to the left. Different components on the car control how much weight transfers and how quickly. Some of those components are not adjustable during a race, such as shocks (how quickly), others are partially adjustable such as springs (spring rubbers increase or decrease the "stiffness" of the spring and changing the cross weight, or wedge, changes the static load on the spring - how much) and others are fully adjustable such as tire pressure and the panhard bar (track bar). Tires, in addition to gripping the pavement, also act as springs. Adjusting the pressure up or down adds or removes spring stiffness to that corner of the car thus decreasing or increasing traction respectively (but there's a point where too much or too little air pressure is detrimental to the safe operation of the tire.)

Tires also exhibit another characteristic: as they are inflated their circumference changes. But, contrary to popular belief, not all tires "grow" the same amount for a given air pressure. So two "identical" tires may actually be different sizes with the same air pressure. If I put the tire with the largest circumference on the right side and the "smaller" tire on the left side and each rolled exactly one revolution, the right side tire would roll farther than the one on the left. That difference is called "stagger" and is measured in inches. By varying the air pressure between the left side tire and the right side tire, I can manipulate the amount of stagger so that I get maximum benefit from the difference in tire sizes. This isn't as easily done with the radials the Cup cars run since they don't "grow" as much as the racing tires used at the local short track or by, for instance, the World of Outlaws.

Now that I've said all that, let me answer your question. When you make an adjustment to one component, the resultant action has two parts: when the component is loaded and when the component is unloaded. By knowing the actions of the associated components you can forecast the ultimate action and reaction of the "set". For instance springs and shocks are "hooked together" at each corner of the car (a set) so they act as a single assembly. If you change spring rate (stiffness), you change the way the assembly reacts. That assembly may be primary at one point in the turn but secondary at another point due to weight transfer so while it has major control at, say turn entry, it may not have as much control as another assembly at turn exit so the resulting action may be loosening the car on entry while having no or little affect on exit.

Sometimes that concept is hard to understand. It's not the single component that you adjust that's important, it's how you change the action of the assembly of components plus the importance of the assembly to the overall handling at that part of the track.. many times the same effect can be achieved with a different adjustment on a different assembly with better (or worse) side effects (tire runs cooler - or hotter!)

how can a car be adjusted if they it is tight in Turn 2 but loose in Turn 4? Any adjustment, to me, would make the car looser or tighter on the whole… You are absolutely correct. This is a problem many teams never find a solution for. But it's easy once you decide what's important to your car and driver. It all comes down to compromise. You set up the car to do best in which ever turn the driver is most uncomfortable in, or as close as you can without completely destroying the pair's abilities at the other turn. This means the driver will be more comfortable in the turn they don't like and still be able to navigate the turn they like. Drivers always perform better at tracks and parts of tracks they like so you maximize the the car for the bad and let the driver handle the good...

[Racer X]

RD, that is exactly what I was looking for!!! So my statement that an adjustment will have a single, constant effect on the car during the entire turn is not accurate. With the weight moving, as you said, to the front, then to the right, and then to the rear, you can adjust what happens in different parts of the turn. That is because the weight is dispersed in different places on the chassis at different times during the turn. So if you are “loose in the middle” you would make an adjustment on the right side of the car because that is where the weight is when the car is in the middle of the turn. And as for differences in the handling in Turn 2 versus Turn 4, your explanation makes sense. I had come to that conclusion myself, but it is great to get it finally validated.

I can’t tell you how much I appreciate this! I have been struggling with this ever since I started watching NASCAR. It now makes total sense to me. Thanks again!

[Racer Duck]

Originally Posted by Racer X

my statement that an adjustment will have a single, constant effect on the car during the entire turn is not accurate.

It is accurate .. to a point. That point is when other forces begin taking precedence. In some cases the effect on the car will increase as the car goes thru the turn .. it all depends on what the adjustment was, what the rest of the car is doing at that time, and any outside condtions such as track surface changes(dirt, "marbles", oil/water, hot dog wrappers, etc.), bumps, holes, wall, the draft, or any of a hundred other variables.

[hacksaw]

Originally Posted by simple simon

ok i have a question for you experts

since i believe the SC in NASCAR stands for Stock Car ..... just what exactly on these cars is still stock ?

On the COT the hood and the trunk lid are the only stock parts .......

[Racer Duck]

Originally Posted by hacksaw

On the COT the hood and the trunk lid are the only stock parts .......

are they really the stock parts that I can by at my local dealer, or are have they been modified? (sorry for the question, but I'm not up on the pieces and parts of the COT.)

[SpaceCadet]

I have seen some horrific crashes in open wheel racing, mostly involving my beloved supermodifieds. We all know that these cars are designed to basically disintegrate upon impact, absorbing the force so the drivers don't absorb it. There's nothing left but the roll cage with the driver sitting in it going "what the heck just happened right there?" Stock cars - well, Cup and Busch cars, stock or not, don't do that, at least not to anywhere near the extent open wheel cars do. I was at Pocono when Gordon hit the first turn at almost 200 mph, and while the car had stuff flying off everywhere, it was pretty much in tact. How is the engineering on these cars so very different? Why don't NASCAR type cars fall apart? And most importantly, it's obvious that the driver doesn't absorb the impact, so what does? Sorry for my total ignorance here, it's probably a pretty basic question.

[Bob Tanner]

Originally Posted by simple simon

ok i have a question for you experts

since i believe the SC in NASCAR stands for Stock Car ..... just what exactly on these cars is still stock ?

As usual, Duck is right on the money. Absolutely nothing of substance to add.

But, in the "Very Little Substance" category:

(a) Around 2002-2003 I read a report somewhere which addressed your exact question. Please don't laugh at this answer but in very close examination about the ONLY part of a NASCAR "Stock" car which met mfg. specs was a small section of the roof between the flaps. Nothing else was either a factory part, nor met a factory template.

(b) In the beginning Bill France Sr. featured modified racers and what we now know as "NASCAR" was a add-on event called the "Strictly Stock Division." People were intrigued at seeing cars off the street race each other and France held the first "Strictly Stock" major event at Charlotte. The rest is history.
As you probably know the winner of this first race was disqualified because his car wasn't strictly stock. Glen Dunnaway's '48 Ford coupe was an honest-to-God moonshine runner and had overload springs on the rear. For this he was awarded last place and Dean Roper was declared the winner.

[LSC9901]

I feel guilty for asking this question but it really baffles me how it is done. How exactly do the tire carriers set the new tire onto the hub without having to twist it to get the lugs properly lined up ? When I deal with my tires in my yard I have to fight much longer than 15 seconds to even get the lugs lined up with the hole. I know there is a tape mark on the tire and I assume that is part of the answer but I'm still amazed at the speed it is done.

[Racer Duck]

Originally Posted by SpaceCadet

I have seen some horrific crashes in open wheel racing, mostly involving my beloved supermodifieds. We all know that these cars are designed to basically disintegrate upon impact, absorbing the force so the drivers don't absorb it. There's nothing left but the roll cage with the driver sitting in it going "what the heck just happened right there?" Stock cars - well, Cup and Busch cars, stock or not, don't do that, at least not to anywhere near the extent open wheel cars do. I was at Pocono when Gordon hit the first turn at almost 200 mph, and while the car had stuff flying off everywhere, it was pretty much in tact. How is the engineering on these cars so very different? Why don't NASCAR type cars fall apart? And most importantly, it's obvious that the driver doesn't absorb the impact, so what does? Sorry for my total ignorance here, it's probably a pretty basic question.

Good question, SpaceCadet. There are two primary reasons:

1. the basic design of the cars. The open wheel cars use a lighter frame and cage assembly with a very strong driver's cell (F1 & Indy type cars usually have a driver's cell made from carbon fiber or the like while the supers have a small strong cage surrounding the driver.) The intent is for everything outside the driver's cell to separate, bend, or break thereby absorbing the crash energy and getting the large heavy components away from the driver. The NASCAR type cars use a different philosophy: build it as strong as possible. The core part of the car (the part within the roll cage) is built to withstand any type of crash and to keep the driver safely within its confines and is done utilizing reinforcement of the cage and devices which keep any part of the driver from getting outside the the protected area (window nets, etc.)
2. because of a horrific crash a number of years ago where some fans were killed and maimed by part of Bobby Allison's car flying into the stands, NASCAR instituted a requirement that all major components of the cars that can separate from the car have a "tether" that keeps them attached to the car. The parts that must have tethers include the hood, deck lid, and wheels. Also the engines, transmissions and rear ends are mounted into the car in such a way that they are "captured" within the frame and cage supports and reinforcements, i.e., they would have to go thru inch and a half steel pipe to be able to exit the car.

[Racer Duck]

Originally Posted by Bob Tanner

As usual, Duck is right on the money. Absolutely nothing of substance to add.

But, in the "Very Little Substance" category:

(a) Around 2002-2003 I read a report somewhere which addressed your exact question. Please don't laugh at this answer but in very close examination about the ONLY part of a NASCAR "Stock" car which met mfg. specs was a small section of the roof between the flaps. Nothing else was either a factory part, nor met a factory template.

(b) In the beginning Bill France Sr. featured modified racers and what we now know as "NASCAR" was a add-on event called the "Strictly Stock Division." People were intrigued at seeing cars off the street race each other and France held the first "Strictly Stock" major event at Charlotte. The rest is history.
As you probably know the winner of this first race was disqualified because his car wasn't strictly stock. Glen Dunnaway's '48 Ford coupe was an honest-to-God moonshine runner and had overload springs on the rear. For this he was awarded last place and Dean Roper was declared the winner.

I didn't know that. Thanks for the info, Bob.

[Racer Duck]

Originally Posted by LSC9901

I feel guilty for asking this question but it really baffles me how it is done. How exactly do the tire carriers set the new tire onto the hub without having to twist it to get the lugs properly lined up ? When I deal with my tires in my yard I have to fight much longer than 15 seconds to even get the lugs lined up with the hole. I know there is a tape mark on the tire and I assume that is part of the answer but I'm still amazed at the speed it is done.

Several parts to this answer:

• practice .. they practice as much as 20 hours a week to perfect their mechanics
• the tape on the tire lines up directly with a hole in the wheel so they simply line up the tape with a stud and put the wheel on
• the fender openings are very small and don't allow hands on the outside of the tire, i.e., they are already very close to centered because the fender openings force it
• watch how they position themselves as they are putting the wheel on .. you'll see that they aren't looking at the hub directly (like the tire changer does), but at an angle from above and they have their fingers in the "non-lug" holes in the wheel, and the wheel is hanging down .. all this gives them complete control of the wheel while requiring very little strength to hold it up and align the lug holes with the lugs.

[Racer Duck]

Originally Posted by hacksaw

On the COT the hood and the trunk lid are the only stock parts .......

Originally Posted by Racer Duck

are they really the stock parts that I can by at my local dealer, or are have they been modified? (sorry for the question, but I'm not up on the pieces and parts of the COT.)

hacksaw, ya got me.

when I actually thought about what you said I realized it was a bogus answer: the likelyhood of two auto manufacturers having identically shaped hoods and trunk lids is very remote, but it's out of the realm of possibilities that four manufacturers would. when I remembered that the only differences in the bodies of the COT are the front and rear bumpers, then I realized for your answer to be right a chevy hood had to fit a ford or a dodge or a yota body .. sorry, but the car manufacturers aren't gonna do that, not even for NASCAR.