I have several 5 speeds out of the 1st gen rx-7's laying around, they are all from the 12A motors. Now i was looking at the gear ratios on the two and it appears that the 1st gen 1985 model year tranny would lead to faster acceleration on my 87 if i swapped them out. I am planning on putting a new clutch in sson and i figured while i had the tranny out i could swap them... Anyone done this or any ideas on it? will the 12A tranny bolt to the 13b? i think it will i'm just not really sure.... any info would be great.

1st gen tranny

1st- 3.622
2nd- 2.186
3rd-1.419
4th-1.00
5th-0.758
final- 4.076

2nd gen

1st-3.475
2nd-2.002
3rd-1.366
4th-1.000
5th-0.711
final-4.100

wouldn't the 1st gen tranny lead to higher accel?

thanks

trevor

 

Yes, 1st gen tranny is slightly lower geared. Be warned that they are slightly weaker than the already fragile N/A FC tranny though. You will need to swap the FC bell and tail housings for it to fit properly. A few people have done it before, and I looked into it when I was still N/A.