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Jeep CJ/Scrambler 1971-1986 Repair Guide

T-90C 3-Speed Overhaul



See Figure 1

  1. Drain the lubricant.
  3. Remove the transfer case rear cover.
  5. If so equipped, remove the pto shift unit.
  7. Remove the cotter pin, nut and washer and remove the transfer case main drive gear.
  9. Remove the transmission shift cover.
  11. Loop a piece of wire around the mainshaft just behind 2nd gear. Twist the wire and attach one end to the right front cover screw and the other end to the left front cover screw. Tighten the wire to prevent the mainshaft from pulling out of the case when the transfer case is removed. If the mainshaft pulls out, the synchronizer parts will drop to the bottom of the case.
  13. Remove the transfer case screws, then tap lightly on the end of the mainshaft to separate the two units. The transmission mainshaft bearing should slide out of the transfer case and stay with the mainshaft.
  15. Remove the front main drive gear bearing retainer and gasket.
  17. Remove the oil collector screws.
  19. Remove the lockplate from the reverse idler shaft and countershaft at the rear of the case.
  21. Using a dummy shaft and hammer, drive the countershaft out through the rear of the case.
  23. Remove the mainshaft assembly through the rear opening, followed by the main drive gear.
  25. Remove the countershaft gear set and 3 thrust washers from the case. Dismantle the countershaft gear assembly.
  27. Drive out the reverse idler shaft and gear.

Click image to see an enlarged view

Fig. Fig. 1: Exploded view of the T-90 transmission


  1. Drive in the reverse idler shaft and gear.
  3. Assemble the countershaft gear set. End-play, controlled by the thickness of the rear steel thrust washer, should be 0.012-0.018 in. (0.30-0.45mm). Assemble the large bronze washer with the lip entered in the slot in the case. The bronze-faced steel washer is placed next to the gear at the rear end and the steel washer is next to the case. Use a dummy shaft to assemble the countershaft bearing rollers. Hold the rollers in place