The truck developed a nasty driveline vibration at about 2000 RPM going down the freeway, causing the dashboard in particular to rattle and resonate.
Stabbing the accelerator up to 2500 RPM, or simply lifting and coming off the pedal, would bring the truck out of resonance with an audible metallic clanking as the driveline unloads.
These are symptoms of a worn universal joint (u-joint) in the rear driveshaft. Mine was the link to the locked 10.25″ Sterling rear axle pinion yoke.
Thankfully when caught, the u-joint hadn’t completely sheared apart. The cups first wear into the u-joint crossshaft, causing the needle bearings to fall out and for the crossshaft to wedge itself off-center in the yoke under the u-joint straps.
Single rear wheel 4×4, double cardon front and single u-joint rear driveshaft, regular cab long bed.
Found a replacement in stock at a local parts store and changed the u-joint right in their parking lot.
Napa Auto Parts p/n UJ331
Torx T-45 bit to remove the 4x driveshaft strap bolts,
Pliers to squeeze and remove the inner retaining clips,
Large socket as a drift and
Hammer to extract and reinstall the ujoint caps.
- Mark relationship between balanced driveshaft and pinion yoke, to reinstall in the same orientation.
- Apply penetrating oil to the ujoint caps at the yoke ears
- The u-joint only has internal retaining clips outboard of the caps. Remove with pliers, and knock out the caps with the large socket and hammer.
- Knock out one u-joint cup at a time, in the same direction. The u-joint comes out between the yoke ears.
- Install new cups one at a time, using u-joint cross shafts to hold needle bearings in place.
- Strike hammer against socket only, do not hit the new u-joint cap directly with a metal hammer.
- Insert new retaining clips and ensure u-joint pivots smoothly.
- Smack driveshaft yoke ears with the hammer if u-joint is tight and binds.
- Reattach balanced driveshaft in marked positive relative to rear axle yoke.
- Retorque bolts after test drive and wear in.