Harmonic dampers (aka harmonic balancers) are found on all Ford 90 degree V6 and V8 engines, so far as I know. They consist of a two cast iron discs with some kind of elastomer sandwiched between them, and they are mounted on the front end of the crankshaft to dampen or balance out crankshaft vibrations that occur at certain frequencies and rpm's. It suttles out the sound and the cars sound and vibrations inside of the car.
All of our 3.8L V6 engines have a harmonic balancer. On the 94-98 engines, the crank pulley bolts to the front of the harmonic balancer. On 99+ cars, Ford made the harmonic balancer and crank pulley one piece.
So. if you put an underdrive pully on a 94-98 car, all you have to do is remove the old crank pulleyand bolt on a new one. To put an underdrive pulleyon a 99+ car, you have to replace both the harmonic balancer and the crank pulley.
UD pulleys reduce the speed of accessories relative to the crankshaft speed. Therefore increasing horsepower, torque and gas mileage, and by turning the accessories slower, extend their life. Some people say that using UD pulleys isnt good for your car cause it takes some power away from your accesories.
Well The amount of power that it absourbes from your accesories really isnt that much. It wont harm your accesories in anyway.
It prolongs the life of them, ask people who have ud pulleys in there car they will tell you the dont see any difference in the way their ac works, heat, power steering, ect.
hope this helps
