Nissan SR20/CA18/KA24 gearbox info – FS5W71C

Nissan FS5W71C gearbox 3-4th gear selector fork problem

There are two types of 3-4th gear selector forks and synchros. Early models used small aluminum fork, small synchros, while later more powerfull models used uprated synchros and forks. Old/small design forks brake due to weak part material, design and hard gear changes.
broken_ca18_prefacelift_fork

S13 CA18DET prefacelift (1988-89), small aluminum 3-4th fork (not supported on other forks), small 3-4th synchros
32811-58S00, 32811-58S10

S13 CA18DET facelift (1990-93), big steel 3-4th fork, big synchros
32811-80S10, 32811-15U00

S14/S14A SR20DET (1994-99) – big 3-4 gear selector fork, big synchros
32811-15U00

S13 KA24E/DE (1988-1993), S14 KA24DE (94-98) – small 3-4th fork/synchros (same as prefacelift CA18)
32811-58S00, 32811-58S10

JDM S13 SR20DET uses uprated 3-4th fork/synchros

2011-08-04_00-14-31_603
S13 SR20DET blacktop on top, S13 KA24DE on bottom
pic from nissanroadracing.com

Center bearing/gear mounting plate

Center bearing/gear mounting plate seems to be the same part number on all EU/US S13/S14 CA18/SR20/KA24 gearboxes. There were rumors that late S14 models used uprated center plate with better oil passages to prevent oil accumulation in the rear housing on acceleration but I haven’t found anything different YET.