I have an opportunity to go in with a buddy to buy a '79 car with some interesting spare parts, like 2 4 speed trannies. I was considering going with a 4 speed in the Abomination (my rotary Spitfire) since they are lighter and I never use 5th gear anyway.

1) What are the gear ratios for the early 4 speed box?

2) Can the Miata cluster etc be used in the 4 speed box to get the higher 1st gear? I realize 5 speed Miata guts will go into a 5 speed RX7 box, but how about into a 4 speed?

TIA.

 

1) 79-83
1st 3.674
2nd 2.218
3rd 1.433
4th 1.000

2) Don't know.

I have question for you. Why is a taller 1st gear better for racing? Actually, I think a better question to ask is what is your rear diff gearing?

 

i think the miata gears will go into the 4 speed, essentially the 4 speeds are a 5speed with no 5th gear.

 

You may need the shift rails and such from a '79-early 80 5 speed. No info on what interchanges between the 80.5-up and the early units.

Jeff, it's not that a taller first is better, it's that putting the gears closer together is better.