Driveshaft Question??????

on the panther platform cars, once the rear gear goes over 3.55 you have to swap out to an aluminum driveshaft. the nice thing is that the newer police interceptors have a very good AL driveshaft from the factory. also keep in mind that these are a lot longer so there is more vibration involved.

cold96snake said:

I thought they were swapped more to reduce vibration and therefore allow removal of the dampener as well as the previously stated reasons.

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All driveshafts will vibrate to a certain degree, any rotating mass will vibrate to a certain degree, even a "balanced" item will vibrate once it gets past a certain speed or rpm. All driveshafts, however, are balanced (unless a weight was removed by some means) and should produce no noticable vibration during normal operation, with aluminum being able to withstand the higher rpms before giving off a noticable vibration (this mainly has to do with the fact that aluminum can be made much thicker than its steel counterpart, making it harder to flex and cause a vibration due to the lightness of the material). The dampener cannot be removed, because it does not smooth out any vibrations from the driveshaft. The harmonic balancer, or vibration damper, is a device connected to the crankshaft to lessen the torsional vibration. When the cylinders fire, power gets transmitted through the crankshaft. The front of the crankshaft takes the brunt of this power, so it often moves before the rear of the crankshaft. This causes a twisting motion. Then, when the power is removed from the front, the halfway twisted shaft unwinds and snaps back in the opposite direction. Although this unwinding process is quite small, it causes "torsional vibration." To prevent this vibration, a harmonic balancer is attached to the front part of the crankshaft that's causing all the trouble. The balancer is made of two pieces connected by rubber plugs, spring loaded friction discs, or both. When the power from the cylinder hits the front of the crankshaft, it tries to twist the heavy part of the damper, but ends up twisting the rubber or discs connecting the two parts of the damper. The front of the crank can't speed up as much with the damper attached; the force is used to twist the rubber and speed up the damper wheel. This keeps the crankshaft operation calm.