Nissan Fifth Gear Popout Info & Images

A service of the SE-R Mailing List

The Poll

If you own a Nissan Sentra SE-R, 200SX SE-R, NX2000, or Infiniti G20, and haven't taken the Fifth Gear Popout poll, do it now! To see the results of the poll, click here.

About Fifth Gear Popout

A large number of owners of Nissan Sentra SE-Rs, NX2000s, and some Infiniti G20s have experienced failure of the fifth gear synchronizer, leading to fifth gear popping out while driving, or becoming completely disabled. See the poll results mentioned above to see how many of the poll sampling were affected.

My 1991 NX2000 developed the problem, and I repaired the transmission myself. In the process, I found that the fifth input gear, a part of the fifth gear synchronizer in Nissan's RS5F32V manual transmission, was redesigned at some point by Nissan. I took the images and measurements mentioned below during the repair process. You can also see a table of the parts I used.

To date, Nissan has not acknowledged that this was a general design defect, and has not made any effort to correct the problem other than repair the transmission of those fortunate enough to develop the problem during their warranty period. While Nissan is within its rights to do this, it has embittered a great many owners of what are otherwise excellent vehicles. After being completely rebuffed by Nissan, many of these owners have sworn to never purchase a Nissan vehicle again.

• The old fifth input gear. Note the wear on the teeth. (51681 bytes)
• The new fifth input gear. (58776 bytes)
• A comparison of the old versus the new. The new gear is on the left, the old on the right. Note that the main difference is a increase in the width of the groove in the new gear. This is because the lower portion of the gear, the input teeth, has been made smaller. This makes the inset synchro teeth "taller" and lets them mate deeper into the synchronizer sleeve. Precisely, the overall height of the gears is unchanged at 1.162 inches (29.5148 mm). The height of the old input teeth portion is 0.588 inches (14.9352 mm), while the new, reduced height is 0.545 inches (13.843 mm). The height of the input gear teeth + synchro teeth is unchanged, at 0.778 inches (19.7612 mm). (49955 bytes)
• The transmission assembled just prior to putting the case back together. (40073 bytes)
• The limited slip differential from the SE-R/NX2000/etc. transmission. (10836 bytes)
• Assembled tranny (87852 bytes)
• Fifth synchro baulk ring (26126 bytes)
• Interior of case cover (13110 bytes)
• Stripped tranny case (22662 bytes)
• Stripped tranny case, on side (20318 bytes)
• Clutch housing side of case (12565 bytes)
• Control assembly (5751 bytes)
• Differential side view of assembled tranny (84311 bytes)
• Fifth synchro stopper with snap ring (23312 bytes)
• Input shaft (9217 bytes)
• Main shaft with reverse idler gear (12993 bytes)
• New fifth input gear (173671 bytes)
• Reverse idler and shift fork shafts (34637 bytes)
• Shift forks (7177 bytes)
• Control assembly striking area (34464 bytes)
• Control striker with shaft and pins (40909 bytes)
• 1st gear synchro, disengaged (18704 bytes)
• 1st gear synchro, engaged (19527 bytes)
• Various tranny components (26966 bytes)
• Reverse idler gear in place (44037 bytes)
• Reverse idler gear and shaft removed (50290 bytes)
• Worn fifth input gear (161357 bytes)