It’s well known in the pony car world that the legendary Mustang was derived from the relatively pedestrian Falcon platform of the early ‘60s. As such, the powertrain choices in the Mustang mimicked those of the Falcon, which meant six-bangers and small V8s were the order of the day. Large V8s, such as the FE series engines, were a tight fit, and since the first generation Mustang was primarily intended as a sporty commuter vehicle with emphasis on style instead of outright performance, this wasn’t really a problem for Ford. After all, by 1966 Blue Oval dealers had pumped well over a million Mustangs onto America’s streets.

Fast-forward 37 years, and we’re struggling with our Project Mustang’s Falcon roots. For some reason, Ford engineers back in the ‘60s didn’t anticipate how wiiiiiiide Ford’s current OHC V8 would be. Can’t really blame them, of course, but that doesn’t change the fact that our ’03 Cobra motor simply wouldn’t fit in the ’66 Mustang’s engine compartment without copious amounts of metal surgery. The problem, you see, is the Mustang’s OEM strut-type front suspension, and it’s shock towers. They’re simply too close together to slide the Cammer V8 between them. Hmmmm.

We thought about staying with the OEM-style suspension and modifying the shock towers, much like Kar Kraft did with the ’69 and ’70 Boss 429 cars, but ultimately that seemed to be lot of work for little gain. The thing to do, we reasoned, was to explore the possibility of replacing the entire front suspension system with a more modern design – one that didn’t have to rely on the factory shock towers at all. The benefit of a newer front suspension and subframe would be increased engine room clearance and vastly improved handling. The downside, obviously, would be cost. Contrary to what many people may think, Year One project cars are built on a fairly strict budget, and just like every enthusiast out there building a car we have to weigh our desires against the available funds. (An example of this was our ’69 Camaro project . We chose to modify the OEM front subframe instead of replacing it with an aftermarket unit primarily for cost reasons.) Ultimately, though, we decided the benefits of a front subframe assembly for the Mustang were such that we should proceed in that direction.

Once the decision was made to go with the aftermarket front suspension and subframe, we immediately looked to Martz, a suspension and chassis manufacturer of good reputation. We’d used a Martz front subframe assembly on the Paul Walker ’67 Nova project last year, and were impressed with the fit, finish and function of the unit. Martz builds an assembly for early Mustangs that uses a modified Mustang II type front suspension and steering system, and this looked to fit our purposes nicely. Handling would improve, parts availability was good given the Mustang II roots, and most importantly we could lose the OEM shock towers – which made room for the huffed OHC engine.

Installing the Martz front end required removing the stock front subframe assembly and shock towers. This was cut out as a unit, and after some careful measuring and making sure everything was square, we welded the Martz frame rails and crossmembers onto the unibody. The modified Mustang II nature of the Martz front suspension uses tubular upper and lower (square tubing on the lower) control arms, tubular strut rods, and coilover shocks that bolt to a beefy mount on the main crossmember and to the lower control arm. The Martz setup includes a manual Mustang II steering rack, but being the sophisticated types that we are (not to mention gluttons for punishment) we wanted power steering on the car. After lots of measuring and parts hunting, we settled on an early SN95 Mustang power rack that worked with the Martz tie rod ends, and also allowed us to use the power steering pump on the ’03 Cobra engine. Springs and damping were handled with QA1 adjustable coilovers – these allowed fine-tuning the damping along with adjusting the front ride height.

With the front suspension sorted out, we looked to the rear. Our first idea was to use the IRS from the wrecked ’03 Cobra donor car. We were sort of looking to build an ‘03/’66 hybrid Cobra anyway, and the IRS is such an important part of the new car we thought it would be a great addition to the old one. Once again, though, the tape measure caused us some indigestion. We ran into two problems, really. First, the overall width of the IRS with the wheels installed was considerably more than we could get between the quarter panels of the ’66. This type of thing can sometimes be overcome by going to a wheel with a ton of backspacing, thereby moving the tire closer to the center of the car. Problem number two was the ’03 Cobra wheel already had a ton of backspacing – so no dice on that solution.

Nope, the only way to get the IRS under the ’66 was to flare the fenders a bunch, which we really didn’t want to do, or perform surgery on the axles and basically make our own rear control arms. Not good. Narrowing the IRS and building new control arms would mean completely re-engineering the rear suspension geometry – and that’s simply something we weren’t prepared to do on this car. We’re gluttons for punishment, but not completely insane. Suspension geometry is best left to engineers who do such things for a living, not a bunch of gearheads with torches in a shop.

At this point we began to think how nice a Moser 9” located by a four-link setup with coilovers would look under the car. Again we looked to Martz for the suspension components. The beauty of the four link/coilover arrangement lies in its adjustability – not only is ride height easily adjustable, but so is pinion angle, side-to-side position and control arm geometry. So, by going with the Martz four link instead of the IRS, we lost a bit of the Wow factor and perhaps a little in the handling department, but we gained a good amount of adjustability and were able to complete the suspension setup on the car without spending an inordinate amount of time re-engineering everything.

The four link was relatively simple to install, once we had the Moser rear axle assembly anyway. The Martz four-link kit included a stout crossmember for front four-link arm mounting, and all we did to it was cut some holes in it for the exhaust to run through. QA1 adjustable coilovers were used in the back to allow ride height adjustment and suspension fine-tuning. The only real issue we encountered was massaging the front of the trunk floor area to clear the upper coilover mounting bar. This was relatively simply, though, and once the floor area was finished it was hard to tell the area had been modified.

That about wraps up the suspension setup on our Mustang project. Check out the photos for a good look at the components, just click on each thumbnail for a larger view with a caption. Tune in next time for a closer look at the engine and transmission.