Are there any 3.63 gears that fit the FD's diff case?
I read about a 3.63 that fits the NB Miata's torsen but not sure if it works on the FD's...

 

FD is the 8" ring gear and the 1994-2005 miata (and 79-91 NA Rx7) uses a 7"

there probably is an 8" gear set with a ratio lower than 3.9, but its going to be in some dogmeat car like an 80's 929 or something

 

The old 626 had a 3.63 but Miata sized
Sigh... back to planning...

 

You'll have to find another way to pull that stump

Dale

 

Yep. It's probably more mental exercise at this point given how infrequently i drive the car...

 

I hear you. One of the local guys here (Jimmy) and I joke about how we're going to buy some mod or part for the car we never drive .

Dale

 

Yep. I'm even considering dumping a bunch of money into it for a repaint. At least the paint will stay nice in the garage. Unless I scratch it while working on my race car...

It's a sickness

 

my FC is like that too, and i have this idea that if a car is good, its hard to find a low mileage one.

so think like a Boss 302 vs a Boss 429, the Boss 302's always have 200k miles, and the 429's all have 2500 miles, why? the Boss 429 sucks, the 302 is fun.

whole bunch of cars like this, E30 BMW's, the 84-85 GSL-SE's, old miatae

so i've been trying to make my FC more fun to drive, and its helped

 

Not sure if it's been covered somewhere else, but why the need for taller gearing? I have the 3.9 rear end and the car is a dog until my EFR kicks in.

 

V8 dont like to rev

 

paul_3rdgen was running a 3.73 I believe from a Mazda MPV. I think there were some modifications needed to install

 

There is no need for taller gearing on a 13b rotary powered FD running the stock transmission IMO.
Unless you are contemplating a transmission swap to a 6 speed of some sort. I've been researching that and it seems like I would need to consider both the trans and the final drive gears in order to meet my goals of shorter gearing in gears 1-5 and an overdrive type 6th gear with a lower cruising RPM.

 

Thanks for that. Here is the old thread on the topic:
https://www.rx7club.com/3rd-generati...rs-fds-688203/

Seems like there may have been one or two fabricated at the time. I see that paul ultimately sold the diff with that gearing.

 

the Mazda 6 speeds are all close ratio boxes, so the top gear (6th) is actually shorter than the 5 speed. so in the Miata the 6 speed cars get a 3.9 diff and the 5 speed cars are 4.30, and i think top gear ends up being the same (or very close)

with the FD you have a big wide power band and don't need the gears as much

 

^Yep. I hated that 6 speed on the Miata. Buzzy **** with way too much shifting.

The FD does have a wide power band but it would be nice to have a bit extra oomf coming out of stop signs low in the RPM range in 2nd gear for example. The higher ratio 4.3, 4.4 etc help with that. The higher ratios effectively liven things up a bit at lower RPMs. But then the RPMs are higher and the exhaust is louder when cruising at 80 which annoys me.

First world problems...

 

moot point, supposedly there was a 3.638 available in 8” on the first year 929 and as best I can tell it was maybe in Europe, so likely lost to history and time

even the 3.727 is a hard find, but forget about the MPV, the best bet on that is the USDM 2WD 2600 truck because there were a lot more of them. They’re out there rusting away …

the reason to have one though is for the alternate transmission options such as the Nissan CD009, certain versions of the BMW DCT, and possibly others.
.

 

nm