Lubrication of the Universal Joint

cen mm 41.02.000

Note: Vehicles equipped with Meritor RPL Series drivelines do not require periodic lubrication.

  1. Park the vehicle on a flat surface, apply the parking brakes, and chock the tires.
  2. Wipe all old grease and dirt from each U-joint grease fitting. See Fig., Ref. 8.

    • After grease appears, cover the pressure-relief hole while continuing to lubricate.

    1. Slip Joint Grease Fitting (with grease gun attached)

    2. Yoke Plug

    3. Grease

    4. Half-Round Yoke

    5. Yoke Plug Pressure-Relief Hole

    6. Slip Joint Seal

    7. Full-Round Yoke

    8. U-Joint Grease Fitting

    Fig. 1, Slip Joint and U-Joint Lubrication

  3. Use a hand-type grease gun, or a high-pressure gun with a low-pressure adapter, to lubricate U-joints. If a low-pressure adapter is not used, U-joints may not receive enough grease.
    Using lithium 12-Hydroxy stearate grease (NLGI Grade 1 or Grade 2, with EP additives), lubricate until new grease can be seen at all four U-joint seals. Fresh grease must be seen escaping from all four bearing-cap seals of each U-joint. On yokes equipped with a yoke-bearing cap, if most of the grease being added to a U-joint can be seen escaping from just one of the U-joint seals, check the torque on the capscrews at that seal.
  4. Tighten the bearing-cap capscrews 43 lbf·ft (49 N·m). If the capscrews were already tight, or all of the U-joint seals still do not purge, remove the bearing cap at that seal, and examine the seal for damage. If the seal is damaged, replace the complete U-joint.
  5. If grease does not appear at one seal, use a prying tool to pry the U-joint trunnion away from the non-purging seal, or tap the driveshaft or yoke with a plastic or rawhide mallet on the side opposite the dry seal, while continuing to lubricate. If grease still does not appear, loosen the capscrews at the bearing with the dry seal, to relieve seal tension. Lubricate the U-joint until new grease is seen at the seal, then tighten the capscrews to the correct torque specifications. If the bearing will not take grease, replace the U-joint. See of the Century Class Trucks Workshop Manual for replacement instructions.
  6. Check the purged grease. If it appears rusty, gritty, or burned, replace the U-joint.
  7. Wipe the purged grease from the seals, and any excess grease from the grease fitting.
Note:
Parent topic: Lubrication of the Driveline
Document Number: 0000122392
Manual Publication Date: 2025-02-11
Topic Publication Date: 2024-06-04