RX7Club.com - Mazda RX7 Forum - Advice from actual drag racer

Obviously "someone" is getting their panties nicely wadded becasue they don't like to be disagreed with. I'm clearly not discouraging anyone from doing whatever they need to feel safe in their own cars. I heartily encourage anyone competing in motorsports to carefully evaluate their own potential risks and take whatever action they can to minimize them and feel safe in their driving environment. You are right - I don't dragrace, I am a roadracer. I'm dealing with about 200 horsepower and a lightened flywheel and clutch that I install VERY carefully. Rx7 Carl is definitely right - people outside your car are the people who are threatened by a failure of this type. Now, as far as the points you TRIED to make:

1) Einstein was primarily a theoritician working at the upper end of physical chemistry. Atomic level structure, probability - you know, quantum mechanics stuff. My education is in Mechanical Engineering - the folks who design air conditioners, irrigation systems, and yes - cars.

2) Unfortunately, the failure mode on things like this IS for them to separate, at least initially, in large chunks. Most common is NOT because of high rotational speeds, but becasue of high acceleration of rotational speeds. Kind of a hard concept to easily picture, but any object that is spinning at speed, even if it is high speed, is relatively stable with the exception of the centripital acceleration that is making the flywheel itself want to fragment. Since flywheels are designed to resist exactly these forces, and they are a large and strong piece, this RARELY happens. What typically does happen is the extremely high amount of initial acceleration of the rotating mass puts the flywheel bolts, and clutch bolts into high shear loads. These are magnified if ANY amount of looseness or movement creates a dynamic shear on those bolts. When the clutch shears its bolts and takes off in the direction of the bellhousing it usually does so in a way that instantly unbalances the flywheel, which can cause it to also shear or fracture its mountings.

3) A smooth hard surface can only exert force perpendicular to it's surface. A bell housing bells toward the front of the car. A moving object can only rebound from that surface in a direction normal to that surface, which is forward - toward the front of the car unless redirected by a LARGE force.

4) After searching the internet, and some news databases, I could only find anecdotal evidence of one injury occuring as a result of a exploding clutch or flywheel. In that case a low level drag racer, who was NOT driving a Mazda, had a clutch disintigrate at the starting line and a piece flew into the spectators area hitting a woman in the forearm. In comparison, it is apparently not uncommon for there to be shootings among the participants and spectators at drag races. A very rough study would suggest that you are more than ten times more likely to be shot at a drag race than to be injured by an exploding clutch. Perhaps you should get TWO scattershields and wrap one around your transmission, and one around your torso. The one around your torso is much more likely to end up "saving lives".

5) Stand like a soldier on whatever you like. Speech is still free in this country, and it's up to the listeners to filter the B.S. You can stand like a soldier on the need to sacrifice chickens in your bedroom so the boogieman won't take you while you are sleeping as far as I care. It would have about the same factual backing as the arguement you are currently pursuing.

Perhaps you missed the part above where I encouraged you to do whatever your knowledge and experience tells you to do to make you feel safe. I'm not telling you not to safegaurd yourself in any reasonable way that makes you feel good. I am simply telling you why I do not take the precaution that you are describing. Don't take it so personally friend - good luck with your racing and be safe!