Miata rearend for MG swap
 

Hey guys,

I was wandering the junkyard yesterday and noticed that the miatas have a 4-100 bolt pattern. I am also in the process of doing a rotary swap into my '78 MG Midget.

My question is... Is the miata rear end strong enough to handle the rotary, even a street ported 12a? And also, will it be a problem mating the driveshaft to the rearend?

I guess i didnt even look to see, but the miata isn't IRS is it?

Thanks a lot,

Josh

every miatas have double wishbones on the 4 corners

they will handle alot more than your 12A will give it..

they have a stock torsen LSD (97+ are better..) and the ring/pinion is the SAME THING as from an RX-7.. if you want to replace your gear ratio.. it would even be the same part number between the Miata and RX-7.

I have been wanting to convert my RX-3 to the miata IRS.
I bought my Fiance a really nice 97 M Edition.. and have been eye-balling it ever since.. she may come home to the car up on blocks some day.

more over a friend of mine here in town has a 399.xx rear wheel hp FE3 turbo powered miata.. the rear diff is holding up well.

i'd convert the 4 corner on my Fb to double wishbones and i'd manage to get the steering rack from a miata too. with a full tubed front.. and very lightened rear..

The Miata diff and axles are more than tough enough to handle a 12A or 13B. I'm currently building a 12A powered Triumph Spitfire, and I'm using Miata and 2nd gen stuff to build a custom rear suspension (building my own control arms, etc). The only reason I'm doing that is the Spit already has a (primitive) independent rear suspension.

The Miata diff and rear suspension comes mounted inside a large 'shroud' that is way too big to fit under a Spridget without major body surgery. It would be easier under an MGB. For a Spridget, I'd suggest using a GSL limited slip, narrow the housing and axles to fit under your car, redrill the rotors and hubs for the Spridget bolt pattern, then mount that to the stock leaf springs. Even that's a lot of work, but easier than the Miata suspension swap.

Sounds like you need no help with technical stuff, but welcome to the ro-spit club. It sounds like yours will be alot more engineered and take alot more time to build. FYI, no trouble with my stock rear end so far, I hope that it stays that way. With my 16" rims, the rear suspension problems seem to disappear quite a bit. I love my wide rubber.
Too bad you aren't running a late MGB midgrix, they can handle quite a bit of power stock, probably enough for your purposes. You should see a set of stock axles on those cars, huge!

I know this maybe a dead thread but I wanted to do the same thing with my midget. How did it turn out with the Miata rear suspension swap? What did you keep (I.e spring)? I was thinking of shortening the axles to make my midget look more stock.

Thanks
Shem