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Its not up to me to prove a damn thing. The burden of proof is on those who are trying to prove that UD pulleys are safe. You guys are the one's deviating from the norm ("norm" meaning, deviating from those little brilliant people in Japan who put the damn thing there to start with). In fact, every auto manufacturer uses them. I guess they are all just idiots, eh? Your argument isn't with me, I'm not using an UD pulley because I know what could potentially happen. You are choosing to ignore what's being stated, probably because you are ignorant to the factors at work. You bearings looked fine? Sure they did, the damage caused by tortional vibration is microscopic. It is a shearing of the bonds between the atoms in which the bearing is made of. It is not bearing face wear like you are thinking. Here's where I'll bring your brain up to speed. By using an UD pulley, you are adding an additional avenue for the bearings to be stressed. Typical bearing wear is face wear, where the bearing rides the crank. It gets worn primarily when the cylinder enters its power stroke and the oil is squeezed out of the small gap between the bearing and crank, and a little bit of the bearing gets worn off. If you jack up the boost, this will wear the bearing face quicker as you are applying more pressure. Combustion is a smooth transitional force (in most cases, exception: detonation,preignition,etc), one that does not deliver shocking blows. Now, throw an UD pulley into that mix. You will still have bearing face wear, but now you have added an additional factor of wear. Its called fatigue wear, not frictional wear. When a piston fires, the crank loads and twists a little and when the exhaust valve opens, the crank unloads and "springs" backwards. (backwards meaning slower angular velocity of the crank, not actually rotating in the opposite direction) At a certain RPM (unknown to me) the timing of the power strokes will match the natural frequency of the crank. This is when you need an UD pulley to dampen this vibration. But dont be fooled into thinking that "well, if its only at one specific RPM, I just wont hit it".. First off, I dont know what that frequency is, and secondly, the crank doesn't only need that one frequency to resonate. Harmonics of that same frequency will cause the crank to resonate. When the crank vibrates, the connecting rods in effect get accellerated and decellerated very quickly through their rotations with the crank. This accelleration-decelleration is because of tortional vibration of the crank. Now in a perfect UD pulley world, the crank would be a solid, non twisting piece of metal. Problem is, we dont live in a perfect UD pulley world and metals do flex and bend, no matter how hard they are. (If they dont flex, they aren't metals, most likely metalloids like silicon for you buttholes thinking, "some metals are brittle", yah, they are brittle, but they still flex before breaking, just not as much as, say, lead - WHATEVER) This accelleration-decelleration energy is transmitted through the connecting rod bearing where most of it is absorbed by both the oil inbetween the crank and bearing, and then the bearing itself once that oil layer has been squeezed. This is shocking force to the bearing. Much different than smooth pushing fore. Ever seen the thing where someone breaks a glass with their voice? Typically it is a woman hitting some god-forsaken high note... This is not an actuality, but it certainly is possible. The natural frequency of a wine glass is higher than a woman can sing, but, if you had a source of sound that could generate sufficient sound levels at the resonant frequency of the glass, it would break. Granted, wine glasses and crank bearings are two totally different things as far as purpose goes, but they are both made of matter which follows a very simple and well known set of rules (simple rules are those within the context of what were discussing here). UD pulley or not, you will still have bearing face wear, but what the UD pulley adds to this, as demonstrated here, is an additional avenue for stresses to make their way to your bearings. It may not fail in 10K miles, or 20K, give it 50K or so and lets see what happens. The UD pulley is kindof like smoking cigarettes. Its a long term effect. People who have never smoked in their life have died of lung cancer, couldn't say then that it was because they smoked, because they didnt. But the point is, if you smoke, and smoke, and smoke, you're odds of lung cancer increase. Likewise with the UD pulley. The UD pulley doesn't give you horsepower either, it eliminates a lot of parasitic and inertial drag. Kinda disappointing thinking that it doesnt add any horsepower at all and causes premature failure of bearings. I say Leave it on and turn up the boost another psi, at least that way you arent introducing another wear factor into the equation, just a little bit more of one you already had.
: There isn't any concrete hard evidence that supports Ashe's theory that the UD pulley cause premature bearing failure.
: The UD pulley has been used on Z for the past 5 or 6 years . There hasn't been any single instance of bearing failure attributed to the pulley. There have been spun bearings, but these occur on cars with our w/out the UD pulley.
: BTW, I when I rebuilt my engine @ 60K for internal mods. My bearings looked immacutlate. No abnormal wear on the main or rod bearings. They almost looked new. I drove my car hard the last 20K with the UD pulley.
: So there is more evidence that UFO's and BigFoot exists than the alleged problem with the UD pulley on the Z. Can't speak for other engines or cars. Just going from personal experience and track history of the UD pulley on Z the past five years.
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