6 spd cars came with a 3.9 ratio rear, some crazy overseas models were 3.636. Your 92 has a 4.3 ratio rear. (then 4.1 in the 1.8 NA, and back to 4.3 for the 5 spd NB) You'd want to source a numerically lower gear if you got a 6 speed. It's really not that hard, you can find what you need out of a number of mazda trucks and rx7s. Someone has a cool list of other mazda gears compatible with the 7" miata diff, maybe they'll post it up.

 

The 6th gear in a 6 spd is shorter than the 5th gear in a standard 5 spd. The 6spd is a stronger transmission and was mated with a 3.9 rearend(correct?). If i was to swap in a 6 spd I would do some research and have a taller 6th gear installed to get some gasmileage and top end out of it other wise the only benefit is strength over the 5 spd.

 

Yeah, I was planning on getting a higher rear as well. Good to know on the 6speed, thanks for spoon feeding my non-searching lazy ***.

 

Is anyone actually looking for a 4.3 Torsen out of a 5 spd NB? I'd gladly drop to a 3.9 or better yet a 3.63 Torsen for a swap.

Frank

 

Sure, 4.3 would probably be a great gear for track duty. But if I were looking, I would probably go 4.10 with the rx7 5th gear.

 

here's your 3.9. That's about half the price of a new 3.63 from mazdaspeed. I'd still spend double for the 3.6 though. It may slow the accleration, but not enough to notice (only on the timeslip) and the lowered cruise rpm would be worth it IMO.

 

better yet, call 915racing.com in TX and I bet you can source a 84-85 GSL 3.909 cheaper.

or try the:

3.700 - 808/72-75 RX-3
3.636 - RWD 626
3.727 - 76+ RX-3
3.308 - 82-84 B2000/Courier Diesel


here these guys: http://cgi.ebay.com/ebaymotors/Mazda...2328QQtcZphoto

just call them, they can get the 3.909

 

is that where you got the one that you sold to yates?

 

I have a low milaage 6 speed w/ 47200 miles available for $695. Located in Alabama. See www.partsgroup.com.
Tom

 

I'm currently running a 5-speed and 3.636 gears in my 2000. I really like that gearset. If you do the math on the custom FM gears, my first gear w/ the stock 5 speed is very close to their tall 1st gear w/ stock 4.30's. All that to say I like my setup. Now if I can just fix the speedo.....