Journals of universal joints are drilled and provided with lubrication fittings. Lubricant travels through the fittings to all 4 oil reservoirs, through a small hole inside of each reservoir, to the needle bearings. Seals protect the bearings against the following:

1. Lubricate the universal joints with chassis lubricant. Refer to Fluid and Lubricant Recommendations in Maintenance and Lubrication.



2. When greasing the joint, a flow of grease at all 4 trunnion seals must be visible in order to ensure lubrication of the joint.
3. If grease does not appear at all 4 trunnion seals, rotate the universal joint trunnion in all 4 directions while applying lubricant under pressure in order to relieve any airlock inside the joint. Air lock prevents the lubricant from reaching the bearing area.

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

4. If necessary, bend the lock strap out of the way and loosen the cap screws and cap enough in order to allow a flow of grease.

Tighten
Tighten the hex head bolts to specifications. Refer to Fastener Tightening Specifications .

Splines of the slip joint are lubricated through a lubrication fitting installed in the slip yoke. Apply grease gun pressure to the lubrication fitting until lubrication appears at the relief hole. Refer to Maintenance Schedule in Maintenance and Lubrication for specified times to lubricate slip yoke splines.

The center bearing is permanently lubricated. Do not add or change grease in the bearing. When installing a new center bearing, fill the entire cavity with chassis grease. The quantity should be sufficient to fill the cavity to the extreme edge of the slinger surrounding the bearing. Filling the cavity to the extreme edge shields the bearing from water and contaminants.