Quote:
Originally Posted by 51504bat
Balance issue as I understand it. All I know is that if its not phased properly there will be a noticeable vibration when driving.
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Well, not quite! Phasing really has nothing to do with balancing, as such. To understand the theory, one must first realize that any time a u-joint is at SOME angle (NOT in straight alignment), the drive shaft actually speeds-up and slows down four times per rotation. The greater the angle that the u-joint is deflected, the more pronounced the effect.
If both joints on a shaft are in phase, the slowing down and speeding-up should have an identical effect from EACH u-joint, making the function completely similar and complementary for BOTH joints. If the two u-joints are out of phase with each other, the two ends of the shaft will be trying to speed-up and slow down at different times in the cycle. That can only cause twisting and vibrating and all sorts of contortions going-on with the drive shaft in that situation.
In other words, EACH u-joint MUST speed-up and slow down at exactly the same time and rate. DD
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