GM Full-Size Trucks 1970-1979 Repair Guide

Pinion Seal



Except 8

  1. Raise and support the vehicle safely. Matchmark the driveshaft and the pinion flange.
  3. Disconnect the driveshaft from the rear differential. Position the driveshaft out of the way.
  5. Mark the position of the pinion flange, pinion shaft and nut. Using the proper flange removal tools, remove the pinion flange nut and washer.
  7. Remove the pinion flange. Position a drain pan under the assembly to catch any excess lubricant.
  9. Using a centerpunch, remove the seal from its mounting.
  11. Installation is the reverse of the removal procedure. Be sure to replace any lost lubricant. On all axles except those equipped with the Chevrolet 12 1 / 4 in. and the Rockwell 12 in. ring gears, tighten the nut flush, then tighten to the original line scribed during disassembly. On the Chevrolet 12 1 / 4 in. tighten the nut to 220 ft. lbs. (298 Nm) and on the Rockwell 12 in. tighten the nut to 350 ft. lbs. (474 Nm).

81/2, 87/8and 91/2in. Chevrolet Ring Gears

  1. Raise the vehicle and support it safely.
  3. Disconnect the driveshaft from the axle.
  5. Position the propeller shaft to one side and tie it to the frame side rail.
  7. Measure the torque required to rotate the pinion and record the torque for later reference.
  9. Mark the position of the pinion flange, pinion shaft and nut. Count the number of exposed threads on the pinion stem, and record for later reference.
  11. Install Tool No. J-8614-11 on the pinion flange and remove the pinion flange self-locking washer faced nut. Position the tool on the flange so that the four notches are toward the flange. Save the scribed nut for reinstallation.
  13. Thread the pilot end of Tool J-8614-3 into the small O.D. end of Tool J-8614-2. Then with Tool J-8614-11 installed as in step 6, insert J-8614-2 into J-8614-11 and turn 45° to the locked position. Remove the flange by turning J-8614-3 while turning J-8614-11.
  15. Using a suitable tool, pry the old seal out of the bore.
  17. To install, lubricate the cavity between the seal lips of the pinion flange oil seal with a lithium-base extreme pressure lubricant.
  19. Position the seal in the bore and place gauge plate J-22804-1 over the seal and against the seal flange. This tool assures proper seating of the seal.
  21. Using tool J-21057 or J-22388 for the 9 1 / 2 in. ring gear, to press the seal into the carrier bore until the gauge plate is flush with the carrier shoulder and seal flange. Turn the gauge plate 180° from the installed position; the seal must be square in the carrier bore to seal properly against the pinion flange.
  23. Pack the cavity between the ends of the pinion splines and pinion flange with a non-hardening sealer such as Permatex® Type A or equivalent prior to installing the washer and nut on the pinion.
  25. Using Tool J-8614-11, install the flange onto the pinion. Install the washer and nut and tighten the nut to the original position. Refer to the scribe nuts and number of threads recorded earlier.
  27. Measure the rotating torque of the pinion and compare with the torque recorded before removal. Tighten the pinion nut in additional small increments until the torque necessary to rotate the pinion exceeds the original figure by 1-5 inch lbs. (0.11-0.56 Nm) Do not exceed the original torque by more than 5 inch lbs. (0.56 Nm).
  29. Reattach the driveshaft, brake drums and wheels.