There are other forces that are important (like aerodynamic lift, drag, yaw, etc..), but they are beyond our present discussion. The torque on the rear axles results in a forward acceleration at the pavement level, the car can either launch hard, or spin its tires violently. In drag racing, most would agree that a hard launch is preferable. At the corner supermarket, impressing friends by having the car "smoke" its tires may be more valuable to some, but rarely wins drag races, and annoys snobby women like myself who do not condone such behavior outside of a legitimate racetrack. There are several relationships (read: Physics, not Soap Operas), involved in chassis fundamentals that need to be understood. They are:

1. Burning rubber is not the way to win drag races. The relationship between traction and force is important, maximum traction is obtained just prior to wheel spin w/100% of the vehicle weight on the rear tires.
2. A car subjected to an inertial force during launch is responding to a basic action/reaction principle. The inertial force is an action opposite to the force accelerating the car. This inertial force is what pushes you back into the seat during acceleration. The effect of this inertial force is to lift the front end of the car. What is important to understand is the "wave" of weight transfer from the front of the car to the back of it. This can GREATLY increase traction if harnessed and used advantageously. This "wave" or "loading" of the chassis helps to plant the rear tires more firmly into the pavement, thus reducing ET's.
3. The maximum possible acceleration of your car is at an acceleration rate = to the maximum coefficient of friction the tires can provide against the pavement. Inertial "loading" of a tire will increase the "traction" of the tire somewhat, though the relationship is not linear, in other words a 10% increase in "loading" of a tire will not give a 10% increase in traction. Many things affect the "traction" of the tires: temperature, rubber compound, size, wheel rim width, etc.. However, as a general rule, please keep in mind that once you have both of the front wheels up in the air, 100% of the weight available to load the tires is there, maximum possible traction has been reached. If there was a way to somehow increase the load above 100%, traction would in theory be reduced.
4. The coefficient of friction available from any tire will vary not just with the tires construction but also with the surface it is being tested (raced) on, and several other variables.
5. IMPORTANT: Finally, it should be understood that there are physical limitations to how wide a tire can be installed in a car. AND that a wider tire has less of an effect on performance at any given level of performance than a properly setup chassis and proper suspension tuning. The loading of a tire is inverse to the contact patch, so good tuning pays off when you consider the additional rotational weight and rolling resistance inherent in just putting the "largest meat under da car", which can slow you down.

Shock, Load, effects of trans-brakes, stutter boxes, line-locks, etc..

OK, so where do all of those neato torpedo gizmos like the above come into play?

You can DRAMATICALLY increase the traction available and consequently reduce ET's by "shocking" the chassis upon launch of the car. This shock has to do with the inertial forces previously mentioned, along with its effect on just brutally planting the tires to the pavement in one instant... This "shock" can be produced by the common Trans-Brake, or 4 wheel Line-Lock, or stutter box.. There is an important difference between these mechanisms however. First, you must understand the difference between a "preloaded" chassis launch, and an "unloaded" chassis launch. The Trans-Brake is of the former variety, a switch is used to instantaneously engage the transmission upon launch without the "preload" inherent in something like a Line-Lock, or stutter box mechanism. The effect is amazing to watch, a study in pure forward motion: You have a "hit" when the car loads immediately, then "launch" when the car just takes off.

For those that are wondering why I chose the word "hit", it is because the action/reaction time is so quick, that the shock in the chassis provides a tremendously powerful impulse load to the driveline...Consequently, this leads many to respell "Trans-Brake" to "Trans-Break", the loads are often so great that some of the most spectacular driveline failures occur upon use. However, longevity of parts is not necessarily congruent with the use of Trans-Brakes, or just about ANY performance enhancement. This high impulse load literally shoots the tires into the pavement, thus increasing traction and reducing ET's.

In case anyone is wondering, there is NO WAY a footbraked car will out "hit" a Trans-Brake, two different mechanisms, one can be used on the street, the other.. ??? Stutter boxes and other similar mechanisms are "preload" type launchers. That is, they actively load the chassis in such a way as to "positively" locate the rear axle. It is important to first understand the mechanism behind the stock Turbo Regal rear suspension setup. It is essentially a mass produced 4 link, consisting of 4 control arms, 8 rubber bushings, 2 coil springs, connected to the body of the car. The theory behind the 4 link is both interesting and extremely complex. Suffice to say that those 4 control arms holding the rear end on your car are extremely important in the potential launching capability of the car.

The following explanation of how the control arms work will probably cause several of you more experienced drag racers experienced with 4-link suspension theory to wince and twitch uncontrollably due to its oversimplification, this was done on purpose, so stop twitching.. :)

Anyway, think of the control arms as an incomplete triangle, that is, if you were to extend both arms they would intersect at a point known as the "intersecting point" (duh..). It is extremely important to understand that this intersection point is based in relation to the cars center of gravity and therefore has a PROFOUND influence on the way your car launches. GM engineers did an excellent job designing this system, it is cheap to produce, comfortable, exceptionally reliable, and unfortunately, non-adjustable. The non adjustability can be a blessing in disguise, as it is quite good for most mild performance applications (down to 10.50 ET's, yes this ET is still mild..).

During launch, in the attempt of the rear end housing to rotate upwards, the upper and lower arms are affected because they are connected to the rear end (I know, duh..), the upper arms are PULLED, while the lower ones are PUSHED. The result is a leverage action that causes the upper arms to try and lift the car while the lowers attempt to push it forward, while also lifting.. This is once again an Action/Reaction phenomenon. Adjusting the instant center (the imaginary intersection point, remember?), by moving the upper and lower arms up or down (if they were adjustable), would affect the leverage provided by the arms. This is the basis behind the popular "lift" bars, and other mechanisms marketed by companies. These arms relocate the instant center on the car thus affecting traction positively or negatively (the ready made bars with no adjustability are a compromise based on research into what most performance applications require. It MAY or MAY NOT be correct for you..

The theory behind center of gravity, instant center, and the 4 control arms (4 link) are complex, this discussion is grossly incomplete but should educate most people on the fundamentals.. Anyway, the reason a stutter box, chip, or other device increases "traction" is due to shocking the chassis. An advantage of a "loaded" setup is that the inherent sloppiness in the stock factory rubber bushings, flimsy lower control arms, etc.. is partially removed because there is an active "load" on the chassis. This system can work very well if some mechanism is designed to control boost. Either way, it will outperform the traditional foot braking method most Turbo Regal owners use to launch their cars. The chassis "shock" is not the same super high impulse load in the absence of chassis "preload" like a trans-brake, but quite effective nonetheless.

Basic chassis performance enhancements for stock to mild (11.50 car) performance applications on the Turbo Regals.