Reply to "Driveline vibration after lowering car?"

The dynamics of a load going through a shaft with joints is fairly complex. The YouTube is a good starting point to better understand what happens when U-joints are used. There was no load on the demo rig. If the car's drive components were perfectly lined up then both systems would work about the same but it's a dynamic system. The further away from perfect alignment (an impossible arrangement) the less tolerant U-joints are. Don't forget about camber gain during suspension compression and the slip joint (splined joint) friction. SACC has two good CV systems worth considering.