I understand the logic, but no modern suspension is likely to fit in the rear without cutting out the trunk floor, the floor behind the seats, or both. Triumph's swing axle and transverse leaf suspension design is obsolete, but brilliantly compact, occupying only a narrow tunnel across the car, plus some space very low ahead of the axle for trailing rods.If I had to do it again I would look real hard at grafting on the whole rear ( or front ) suspension/motor setup from a modern car. Especially after two great builds, Baratong and Moltonmetal, report the sane week link. The REAR END.
The custom Miata NA/NB-based suspension shown earlier doesn't look like it fits the floor: the floor's drop into the trunk would likely interfere with the upper control arms, unless they have an unreasonably narrow base.
The front is comparatively easy, as there's nothing but a pair of frame rails to work around.
Those are track widths (rather than body widths), and one source shows rear track up to 50" depending on vintage; yes, that's a problem. The first-generation Miata (common chassis for kits and conversions) has about 55" track width as well, which would be one reason that the custom Spitfire rear suspension shown earlier using NA/NB Miata bits has custom control arms.The real problem is Spitfires are 48" wide. The Tesla 66 wide the Prius is 60 and the Fiat is 55
I'm guess I'm just not enough of a fan of the Spitfire body to want to build a whole new custom car - powertrain, suspension, structure, and floor - and fit half-century-old bodywork to it.
I don't think Spitfires with original engines (or even modified engines) blow up rear ends very frequently. Maybe the solution is just to manage the motor's torque output?