A while back I thoroughly molested a Triumph Spitfire, stuffed a rotary in it and reworked the stock suspension to the point that the body shell was really the only thing Triumph left from the poor thing and is why it got named the Abomination.
I have to thank the GRM gang for steering me in that direction, the RoSpit is what gave me the impetus to build mine. They built the first atom bomb, so to speak; I followed in their footsteps. My good fortune was that when I built my car the Miata had been out long enough for them to land in the junkyards, making my swap much simpler.
Surprisingly I get a fair number of Emails asking for clarification of what was done. Since I really didn't document it very well, I have no real way to pass on what I did.
Recently a good friend bought a 1970 GT6+ which was in pieces, it's a restoration that had been started but got stalled. Rather than put it back stock, my bud has asked me to do that Triumph molestation thing again. This time I plan to document the suspension mods better; maybe this will spark a few more cars! This car is not being built to any specific rule set, but in SCCA Solo 2 it's going to land smack in Modified. It could conceiveably run XP, except the firewall will be cut and that moves it to Modified.
Keep something in mind: all Spitfires and GT6's 1962-1980 have the same front track width etc. On the rear, the early cars (1962-1970) are narrower and that's what we are working with here. 1971-1980 are wider.
Here's pics of the rolling chassis in stock form. The first picture shows a Triumph anomaly which is really irritating when pretending to be a race car driver. Notice that the right tire is turning sharper than the left? That's backwards. Ackerman effect is where the inside turns more than the outside. It's due to the tie rod angle, in the pic you can see how they point toward the rear of the car. With fat grippy tires this will yank the steering wheel out of your hands! The fix is to move the steering rack rearwards. But as with anything, it sounds easy but the reality...
Next up, check out the rear suspension. This is a Rotoflex car, that's what those big goofy rubber rings are and it was Triumph's version of IRS. It was a pretty good start, but what is wrong with this picture? Check out the camber; it's positive. That's because Triumph used the transverse spring as the upper control arm. For proper camber gain, the upper arm should be shorter than the lower and since the spring flexes near the differential the upper arm is a helluva lot longer than the lower. The toe link at the bottom of the pic shows how they decided to control the toe, problem is that since the end of that link describes an arc as it moves it changes the rear toe as the body rolls in a turn. So here's a double whammy: positive camber combined with not very well thought out dynamic rear toe.
Spitfires and swing axle GT6's have a camber curve which adds negative camber as the suspension compresses, but they still have dynamic toe change and the 'jacking' effect that caused Ralph Nader to go ballistic on swing axle VW's and Corvairs and countless sporty car types to soil their undies.
The stock diff is also only good to about 100 HP, any more than that means driving very gingerly and that simply will not do. 
Next up: the front suspension. Again we have positive camber. The upper control arm is shorter than the lower meaning the wheel gains negative camber as it rises, but not enough. Then there's the bump steer issue. Notice how much shorter the tie rods are than the lower control arm? That causes the wheels to toe in as the suspension extends and compresses, more of that dynamic toe thing. The fix is to have the tie rod as close to the length of the lower control arm as possible and to have it parallel. (It's actually a bit more complicated than that.) So this means that along with the rack moving rearwards, it has to be narrowed and must be raised to level out the tie rods. This is nearly impossible with the Spit motor in the stock position, since it already is between the oil pan and the front pulley.
The idea here is to straighten out the front suspension and steering's awful geometry then make the new powerplant fit the chassis.
The Spit uses a 3 3/4" bolt circle, there's not a huge wheel selection for that pattern. Since part of this project is a big power upgrade 
more rubber is essential. We'll be using 15x7 wheels with 205-50-15 tires, they are almost exactly the same OD as the stock 155SR13 tires. These wheels will be a 4x100 bolt circle and used on Miata hubs. Those hubs will be on Miata uprights all the way around. This also opens the door for a whole bunch of nice inexpensive brake upgrades.
More as I dig into this further.
) so there's a lot of noice odds and ends to sell, such as a full set of SPAX 14 way adjustable shocks which have never seen road use. The engine will be for sale, as will the 4 speed tranny (no O/D, sorry) the stock rear suspension and axles etc.
The bolt hole for the ball joint is in the same place as the GT6 trunnion bolt. But the control arm is actually longer. How is this, you ask? The Miata ball joint pivots 1" from the bolt hole, the Triumph pivots at the bolt hole. So the modified arm is actually longer even though the hole's in the same place. This is very important, because it affects scrub radius and the motion ratio which affects the wheel spring rate and also the wheel travel. 
