Parts interchange with other Aisin AZ6 transmissions
 

Would be very useful if we can figure out if any of the other AZ6 Aisin transmissions share parts with our transmission. The cars that i know have this tranny are: S2000, Miata, Silvia S15, RX8

Sixth gear on the Miata looks like a good short ratio replacement at 0.843 vs 0.767 if it would fit.

Why would you want a shorter sixth? :confused:

For circuit racing. From experience with the Honda I used to race, the stock brz 6th is long.

Youre trying to fix a power problem with a gear swap?

Which is usually what we do in road racing, yes.

just wondering, it sounds, reading in between the lines, that you want a shorter 6th or more top end power (I'm usually only in 6th AFTER i have wound out 5th)

sadly the tracks by me dont let me use 5th or 6th much, but I could see in a circuit that being possible

any reason you wouldnt consider FI as a way to add power instead? not trolling, just askin seriously

if tranny mods and interchangeability can be found, that would be very neat

Yeah I'm wondering which tracks you are driving on where you are in need of a marginally shorter 6th gear?

There are a number of final drive kits to raise the overal final drive ratio. At least one company (Monster sport I think) has also made a kit with a longer 1st and 2nd gear.

For me i would say that in the area where i live, i know there would be more racing class open if i am staying N/A compare to F/I.

honestly in N/A form you don't need a 6th gear in this car unless you have already put a shorter gear out back.

just change the final gear

What exactly is the name of the Manual Transmission? If its the same one in the s2000 then we have a very strong transmission to work with. S2k run 600hp without touching the tranny or rear

anybody know what is our final drive i haven't seen it.

4.10

You could use shorter 6th + higher final drive to get the 6th close to the old 5th, giving you an extra gear. A 0.83 6th would be "effective" for reaching top speed (might need a few aero tweaks to hit high 150s) but sorta useless on the track due to lack of power, but with a slightly higher final drive bumping it up to effectively 0.9 or so could make it useful.

But then, after you've put a higher final drive in, 6th will automatically become "more useful" and so whether or not the effort it takes to change 6th gear out becomes more questionable, since it'll only gain you very little speed for the short amount of time you can spend above 140mph, and make your car less practical for the highway. Additionally, considering the powerband of this motor (plateaus pretty hard at the top end), a shorter 6th only gives you marginally more power (look at any dyno chart and keep in mind that shifting out of 5th lands you at 5700rpm-6000rpm if the rev limit has been increased).

For example with 10% higher final drive, your 6th is effectively a 0.8437, and 6th would top out at about 162mph, power peak with tune arrives at perhaps 155mph or so. It should take somewhere around 200hp (ecomodder calculator says 170hp, but I just punched in 2 square meters and 0.27 Cd, I don't know what the actual CdA is) to go 160mph, so you should be able to just top out 6th gear. Assuming the engine has a tune, you have about 50-80hp "reserve power" after topping out 5th gear for accelerating after drag is accounted for. Shortening 6th would reduce the top speed, but let you reach the top speed faster.