2nd Gen 4Runner Driveline Vibration: U-Joints & Carrier Bearing
Reading the vibration
Driveline vibration has a vocabulary. A clunk on throttle tip-in or shifting between drive and reverse says u-joint play. A vibration that grows with road speed regardless of gear says balance or a failing joint. A shudder concentrated under acceleration around town — especially on trucks with the two-piece rear shaft — points at the center carrier bearing, whose rubber cushion softens and lets the shaft orbit.
First test costs nothing: with the truck safely on stands and in neutral, grab each side of every u-joint and try to twist. Any detectable play, or rust powder around the caps, is your answer. Then push up and side-to-side on the shaft near the carrier bearing — mush or visible sag in the rubber means it's done.
The fix and the smart extras
U-joints are cheap and a satisfying driveway job if the old ones press out cooperatively. While the shaft is out, have a driveline shop check the balance — a shaft that's thrown a weight will never feel right no matter how fresh the joints are. On high-mile trucks, doing joints, carrier bearing, and a rebalance as one visit turns a shaky driveline back into the tight truck you remember.
One more 2nd gen quirk while you're under there: these trucks came with a mechanical speedometer cable, and a bouncing needle is its death rattle — different system, same afternoon on the creeper. We cover that one separately in the speedometer fix guide.
