What started as a joke has turned into a very real idea. With the off road Exocet, it got me thinking about how to make a 4wd version. In all the googling I could do, it seems no one once had ever made a 4wd Miata. There have been several jokes made about them but generally every single 4wd discussion thread turns into a childish debate about why you should not do it and how the benefits aren't worth while. Me being me, someone telling me not to do something only motivates me to want to do it more.
In my searches, I did find an FC RX7 someone built using a Mitsubishi transmission out of a fuso pickup.
There have been guys doing Mitsubishi RWD conversions for the 4G series engines (DSM/EVO motor) and they use an RX7 trans which literally bolts right up, so it's no surprise they found a Mitsubishi trans to bolt to the rotary.
All I could find on Mazda 4wd transmissions was the M50D and the M5R1 which came in the ford Rangers and Mazda B-series pick ups. The difference between this trans and the Mitsubishi Fuso trans is the gearing and the transfer case being on the passenger side vs the drivers side.
I don't know if any of the transmissions will bolt up to the Miata engine but if it doesn't, I would bet a 12 pack of tacos the bell housing or even the shifter housing (which contains the transfer case to power the front wheels) swaps on right to the stock Miata trans (which we would want for the shorter gearing anyway).
Tempted to track one down and find out.
So assuming the trans will bolt in, the next hurdle is getting power to the front wheels. The motor itself and the suspension block the way an axle would need to get to the hubs but I think I found a solution to that using the OEM front control arms and hubs out of the B-series truck itself. It has the same style upper and lower control arm features as the Miata.
Note the truck uses a 6 lug hub vs a 4 lug. Again, going out on a limb and will say any Mazda FWD hub and bearing will swap into this housing. Say from a Mazda 3 or even a 6. Obviously I would need to get one in my hands to measure and find out. Worst case, I would machine one.
Also note how the strut bolts to the lower arm like a Miata but obviously this arm won't bolt to the Miata front subframe. That's okay though because for the next bit, I can't use the stock Miata subframe anyway.
So with the Arms setup to accept the front axles, the motor then needs to get pushed back. By my measurements, it only needs to come back 4-5" (or course this is only a guess). This can be done using the generic front subframe from V8 roadsters with no motor mounts.
v8roadsters.com/shop/mount-less-subframe/The mounts for the control arms would probably need to be relocated to allow the B series front hubs and then I need to weld in the motor mounts for the engine to sit further back.
In an Exocet, this (probably) means cutting away some of the firewall and moving it back a couple inches which isn't hard with square tubing. It also means a custom shifter turret which hopefully will only need to be cut in the trans cover and not the frame itself.
The next hurdle is eliminating the PPF which is easy as all I need to do is create a mount for the front part of the rear diff to hold it in place. Then it's a matter of getting custom rear drive shaft, custom front drive shaft and custom front axles. All of which can be measured out and ordered from
www.axle-exchange.com Worst case, I make them myself by scouring the junk yard then swapping the cups and joints to make it all bolt in....
Final challenge is mounting the front diff but again, if I had the stock B-series's setup, it's a matter of just creating custom mounts to hold it in place. The drive gear itself is the same size as the Miata rear diff so I can swap that in to match the rear end so they are identical in terms of gearing.
While much of this is speculation, I'm starting to think more and more about doing this in the future. Maybe not to my Exocet but ordering another to try it out. I've already got a spare donor Miata to play with...
I'm honestly amazed no one has thought of any of this before... At least I can't find any discussions about it online anywhere.
