About damn time I dredged the the swamp for an update to ‘Making a Faster Horse’; my never-ending story of modifying a 2000's era Mustang to make good on the marketing machismo checks it was writing all over town.
Part 1: Making a Faster Horse [An Introduction]
Part 2: Making a Faster Horse [Step 1, skip to Step 3]
Part 3: Making a Faster Horse [Overnight parts from Michigan]
Part 4: Making a Faster Horse [In Trouble With Management]
Part 5: Making a Faster Horse [An aside, numero uno]
I also snuck in some work on a rainy day to install new dampers, but it was not among the 'official' stories told thus far, so I'll also detail those activities below.
Last we left off I was banned from car purchases until our move concluded, I had just dropped off the Mach1 with my friend at VMP Performance to have subframe connectors installed, and while he had my car, I'd spend what would become the better part of a month gaining an appreciation for a GT500, with an accompanied absurd 730whp.
Good news, we've moved! I've got not one but two garages (2 car + 1 car) and a whole new list of honey-dos that are getting in the way of spending money and time on this car, but inches over time become feet, and feet over time become miles, so let's inch along.
I've really enjoyed the GT500 and would be lying if I didn't say I attempted to procure long-term ownership of it -- but with the move and other efforts already underway, and a need for a more practical car if we add to the fleet again -- it was not meant to be, at least not right now. For antithetical reasons to why I'm building the Mach1 (track), the GT500 would be an amazing car for me -- it is heavier, larger, and brutally fast, but composed and complaint, has more advanced controls while still being an analog experience, with more interior space than the Mach1 for passengers. It couldn't replace the Mach's purpose but for a 2+2 GT car to be used on the street? It is everything I could hope for from such a vehicle.
So what exactly is the deal with subframe connectors anyways?
Well that requires a bit of history on how the SN95/New Edge Mustang chassis came to be, but feel free to skip down to the / if you're already apprised or just don't care.
Ford History Lesson
Being based on a platform from 1978, cars were not particularly safe, not stiff, and the targets were to float between destinations more than carve your way to them one apex at a time. Most cars see heavy improvements or more often wholly new chassis over the course of three decades, but not the Mustang.
In the 80's Ford was riding high on the success of the Ford Taurus sedan and saw efficient FWD platforms and creative sharing as a great way to save time and money. Ford worked closely with Mazda, as Ford held a 25% stake in Mazda at the time, to develop a new Ford Mustang, sharing a FWD platform with the Mazda 626/MX-6. Planned for an 89' release, news broke in 87' and the loyal fanbase of Mustang faithful's were outraged at the notion of a Japanese, FWD Mustang. Salvaging the FWD Mustang program and rebranding it as Probe; Ford initiated an 11th hour redesign of the Mustang and resigned to a mere facelift to carry the Mustang through the end of 1993. After some initial consideration to shorten the Thunderbird's elaborate MN12 chassis, price targets for the entry-level Mustang forced the program to instead once again re-use the FOX platform, significantly updating it into what would be called FOX4, or later SN95. The platform saw significant improvements over previous FOX platforms, particularly fore and aft of the axle centerlines, and even some in-between which resulted in a near 100% increase in rigidity from the previous generation. Even with these improvements it was still 75% that original FOX platform from 1978; for a performance application, the chassis still flexes a lot. Convertible cars required factory-installed bolt-in subframe connectors to tie the front and rear subframes together due to the stiffness lost with the soft top. Performance models such as the Cobra, Bullitt and Mach1 coupes each included the convertible subframe connectors to improve handling over the standard cars.
/Ford History Lesson
These rails helped, but they are thin, only bolted in-place, and don't extend very far into each subframe, so through leverage and force, the car still flexes a TON, even with light or static loads. This can be seen most-easily by driving the car up ramps or lifting one-side with a jack. The doors will become resistant to opening due to friction between body panels from the flex. Driving, you can sometimes visually see an oscillation between the hood and cowl/A-pillars. Turn-in can feel vague as a result, bumps you'd think would at least be softened by the marshmellowy chassis instead stay with you for far too long as the force bounces around the car, winding and unwinding the chassis. The entire car was acting as a giant spring, without a damper to tame it.
Below you can see the hollow square-tube factory rails, running outboard of the exhaust.
This image shows a stock bolt-in SFC against a Maximum Motorsport weld-in SFC. Most basic weld-in SFC's match the MM design.
I originally intended to go with Maximum Motorsports subframe connectors, but they were on an 8 week backorder due to COVID-related manufacturing delays. The HP-wielding madman in charge suggested Stifflers instead and indicated he could have them in days. I researched a little bit about the company and found them to be founded by an engineer with a background in IndyCAR, a love for Mustangs, and for making them handle far better than they should. Their kit starts with the full-length weld-in rails, which may also be used as a jackpoint once installed, and optionally may be upgraded with an additional pinch-weld rail, doubling the beam stiffness, and cross-braces to tie them all together.
The entire 'system' on another Mustang
We opted for the base arrangement for now, with potential to add the rest of the system should it be necessary in the future.
The full-length SFC's get bolted to the front seat mounts and then welded to each subframe to assure they are fully tied together.
A bittersweet exchange as I return to the Mach1:
When I picked up the car it felt very much the same, sounded very much the same too, but upon crossing the first bump in the road I could feel immediately that the car was more rigid, no longer wobbling for a second after the bump had passed. At speed the car felt more cohesive, I couldn't fully appreciate the Koni dampers before the subframe connector installation. Later at home when I went to investigate an underhood concern, I drove the car up on ramps I found the shock and shudder normally present in the process absent, and that once the car was lifted, the door opened as effortlessly as it had on flat earth, closed as easily too.
While technically already done before I sent the car away for subframe connectors, I also had dampers to install, from Koni.
The stock Mach1 suspension is an upgrade from the standard V6 or even V8 cars, equipped with Tokico dampers stock -- they were quite good in their day but 145k miles and almost two decades have not been kind to them. All of the original dampers had either failed entirely or were on their way to failing.
The Konis made a huge difference, but also highlighted how flexy the chassis still was before the SFC's went in, as the wallow I initially blamed worn dampers for was as much or more so due to the floppy car as a whole. It also took me awhile to figure out the best settings for the dampers, as they can get rather stiff when cranked up, but set near full-soft and I found road conditions often found the bumpstops. I've settled at 3/4 turn away from full-firm (adjuster range is approx. 1.75 turns). Accessing the underhood adjusters is easy as they are on top of the dampers, plainly visible at the top of the strut towers.
The rears however are typically covered by the trunk carpet panels, which required some minor hole saw surgery to make accessible going forward.
I'm pleased with the handling for now, as it handles how I feel a stock car of the era should. Not to say there isn’t loads more still to do, but it is a good plateu on which to rest until until the more extreme changes I have planned are ready to go. There are still some age and wear issues to address, including a rear suspension squeak that may be sway bar bushings, and failing outer tie-rods up front leading to noises there too. There is also that pesky underhood concern that is at the very-least an A/C system leak, though coolant may be finding its way out too, more to come there.
I have several parts on order to resolve the A/C leak and the suspension noises, hopefully to arrive in the next 7-14 days. Once I'm certain there are no engine issues to worry about, we'll schedule some garage time to execute the transmission swap.