Icon Vehicle Dynamics Suspension Question: What is drive line shutter and how can I prevent this?
There are several factors which contribute to this issue. Mechanically what is happening is under acceleration the pinion tries to climb the ring gear causing the springs to bow. This is because this is the path of least resistance as opposed to quickly accelerating an 8000 lbs object. With lift blocks the leverage working against the springs is increased allowing the pinion to climb further. When the pinion rises above the angle of the driveline the u-joints go out of phase causing an oscillation. This oscillation deflects the rubber in the carrier bearing thereby transmitting vibration to the cab. Carrier bearing shims reduce the differences in the effective angles seen by the upper and lower u-joints. This minimizes the oscillation but is typically not eliminated 100%. Flat rear lift blocks help by placing the pinion lower relative to the angle of the driveline which allows for a bit more pinion rotation before low speed oscillation occurs. A CV rear driveline is more tolerant of th
