Mustang Corkscrew Package

69 Fastback Defazio 10


How many classic Mustangs have you seen with the coilovers in the trunk? Yeah, it looks badass but honestly the looks were an afterthought. We put the coilovers in trunk for a reason: shock length.

You see shock length is ultimately what’s responsible for the ride quality and capability of the shock. Most rear systems are designed to do one thing well. Maybe they’re okay on a track, but they’ll break your back on the way home. Maybe they’re cushy on the street, but they toss you around on the track. And no amount of dialing up or dialing down the valving seems to help.

That’s why we designed our MOD 2 rear to incorporate a full sized shock. The only problem was we couldn’t fit it under the rear floor of the Mustang without giving it an SUV ride height. So we adopted technology more commonly seen on formula 1 cars than in Detroit, a cantilever system. By putting a pivot point between a pushrod tied to the rear end housing and the shock itself, we could lay the shocks down horizontally, giving us all the room we needed (and a bonus point of adjustment).

It looks cool, it works great, and you can lay it all out on the autocross then drive over railroad tracks with a cup of coffee in your hand on your way home.

What’s in the Corkscrew Package

Front Suspension

Up front we call in our MOD 1 Front Suspension Kit, a complete kit that replaces the stock upper and lower control arms, strut rods, shocks, sway bar, and bushings but doesn’t reengineer it. Look, Ford was on the right track with the original design, but it’s been 50 years and we’ve learned a lot.

For instance, caster. Caster is essentially the alignment angle of the upper and lower balljoint (it’s more complicated than that, but let’s keep things simple). In the 60s no one thought it was that important, so they set up a degree or two. Today, we know that the sweet spot is 6-7 degrees to minimize darting on the highway and improve high speed stability. That’s why we’ve engineered our upper arms to be offset, increasing base caster to fit in with our modern demands.

On the camber front, we offer a redesigned lower control arm with an adjustable heim joint. This allows you to easily dial in your preferred camber while also giving us a new way to attached our solid mount strut rods (which are also adjustable).

Are you sensing a trend here? The goal with our MOD 1 Front Suspension is to not only improve everything about the front of the car, but also to give you a level of adjustability that the old suspension simply could not offer. Combine this with an alignment from a shop that actually knows what they’re doing and you’ll feel a tighter, more responsive front end that’s point and shoot.

Rear Suspension

Originally designed to cruise on the street then destroy at the track, this suspension has seen years of refinement and development. Comprised of several components, this kit most notably moves the coilover from under the body up into the trunk using a cantilever-type setup more typically found on Formula 1 cars. Not only is this generally badass, but it allows us to run a full size coilover without worrying about packaging it under the car.

We’ve also designed this package to be minimally invasive, requiring only a small amount of cutting (a couple inches) to your trunk floor and the boxing of about an inch of your rear frame rails on either side. Try that with any of those other kits on the market.

In short, this kit offers classic Mustang owners an incredibly balanced, strong, tune-able system that’s as comfortable on the street as it is on the track. We’ve installed this kit in countless cars and made several refinements over the years and it continues to be a defining suspension for us at MMI.

Power Steering

If you’ve ever tried parking one of these cars without power steering, you know just how essential it is. But finding the right combination of pieces is a daunting task. Our focus started with the proper steering geometry, a bunch of math that helps tell us engineers how natural the steering is going to feel. After all, it shouldn’t take 13 turns of the wheel to turn a corner, nor should it take half a turn to make a u-turn.

So we start by replacing the steering box with a high quality KBS unit with a 14:1 ratio. We back that up with a KRC Power Steering pump, the likes of which can be found on everything from street rods to race cars. From there we source quality replacement components: center link, tie rod adjusters, and inner and outer tie rods. Again, focusing on the best stock replacements we can find, not the ones from the discount bin.

So why not go with a typical rack-and-pinion type setup so common these days? It all has to do with steering geometry, or the math behind why your car feels twitchy and unpredictable instead of solid and confidence inspiring. Unfortunately, feel often takes a backseat to packaging constraints (and consumers who say “I want that” without really being sure why). What everyone seems to be missing is that most rack and pinion systems actually make the original steering geometry worse.


For brakes we call in our MOD 1 Complete Brake Kit. Up front you’ll get a pair of 6 piston Wilwood Superlite 6 calipers over massive rotors (18″ wheels highly suggested). Of course we’ll want to mount those wheels on a set of our big pin spindles for improved strength and so that we can include a set of DRP Bearing Spacers.

In the back we’ll want a set of Wilwood D154 calipers and rotors, specced out with the BP20 brake pads all around. For the master cylinder and proportioning valve, we’ll run with the Mustang Specific Kit.

This package does not include a rear diff as standard, but it is an option. We’d recommend the N-Series from GearFX.


Front Suspension

Rear Suspension