how to Shorten independant axels???

I am in the process of a complete restoration on a 1960 Nash Metropolitan.  While I was inspecting the suspension I noticed that one of the A arms was bent (probably from an accident, suggested by replaced body panel). I decided that I would replace the whole suspension and drive train with the suspension and Drive train of a Mazda Miata, favoring the stiff suspension of the Miata over the Metropolitan’s looser suspension.  I have already bought a Miata to use as parts and I have a lot of experience in machining parts so creating custom parts is not a problem.  The problem is that the Miata’s wheel base is 4.4 inches wider that the Metropolitan and so either the suspension will need to be pulled in or I will have to cut into the fenders and create space.  I would like to try and change the suspension to keep the classic look of the car.  I will also be replacing the stock engine with one from the Miata.  It will have independent suspension all the way around and I was wondering what problems this might create and how I could solve them before they happen.  

All positive comments and suggestions are appreciated.  

The axle shafts are the easy part.   Just take them to an axle / driveline shop and have them cut by 2.2" each and they can machine new splines after.

If the shape of the shaft wont allow that it's not complicated for the same shop to machine custom axles out of metal stock they will have.

The control arms are a bot more complicated.  You can narrow the subframe a bit but going too far puts a lot of stress on the axle shafts.  The CV joints need to stay fairly close to the A arm pivot points.

You can modify the arms but custom is your best bet.  Keep in mind that arm legnth effects the camber curve (even if the difference between top and bottom arms are kept identical), ride quality and other important aspects.

The front will proabably require the same work as the rear but moving the A arm mounting points in-board can cause problems with engine clearance.

You'll also need to shorten the Miata steering linkage on either side and that can cause bump steer issues among others if it's to extreme.


It might be simpler to fabricate entirely new subframes and arms around the Miata diff, knuckles and brakes.

Are you going to swap the Miata drivetrain in also?  They can make a whole lot of power when built right or you can swap the bellhousing with one from a B2000 or 2200 pickup truck and run the Mazda F series engine.

The cream of the crop would be the FE3N motor.  2.0L (vs 1.6-1.8L for the Miata) with about 170 CHP.  It's a solid engine that'll do over 800 WHP with boost.  Then theres the 2.2L SOHC MX6/Probe GT motor.  145 CHP but with a factory turbo for tons of torque.

That crank can be fitted to the DOHC motor for as much as 2.3L.

Then theres the Mazda 929 V6.   3.0L and 200 HP and a very solid motor.  Get the bellhousing from an early SOHC 929 and it'ss bolt up.

Stock and swapped into a light weight 1st gen RX7 it'll spin thw tires at highway speeds

Ofcourse theres the rotaries.  Lots and lots of potential but the demand a serious learning curve to preserve apex seals,  but even blown they are just as fast lol.  

Thank you so much for the help i really appreciate it.
From what you have told me i will probably try to redesign the sub-frame, because it sounds a little simpler and probably less costly as well.

I do plan on swapping in the miata drive train as well, which should provide enough power considering how light the Metro is.