Suspensions 05 and up: The game changed with the new Mustang
The 2005 Mustang was introduced wearing a brand new coat and surrounding an all-new skeleton. These upgrades caused heads to turn and changed the rules of the game for tuning and upgrading a Mustang’s suspension. Previous Mustang generations left the enthusiast several basic improvements on the table to add some hi-performance fun on the track as well as on the street. It’s true - the 2005 Mustang is an all new platform (aka skeleton) that fixed many of the “sins of the past” but there are still plenty of appropriate modifications available to tune your Mustang for your personal needs. If you want Street performance and occasional autocross or road racing handling, the stock structure of the 05+ Mustang is pretty stout right out of the shoot. As a result, there really is no need to tune your Mustang suspension by adding sub frame connectors or strut tower braces to stiffen the body....now most of us like the look and idea of strut tower braces, so if you like the look or feel better about having a strut tower brace, go ahead and add it. They will not make your street car handle any better than a Mustang without a strut tower brace, but they don’t cost much and are a great way to dress up the engine compartment. Let’s look at a key piece of the game that we can change for a tuned suspension.
Springs are available in two basic forms - linear rate and progressive rate. Linear rate springs compress a specific distance under a specific force, regardless whether the spring is at the beginning of the compression or at the end of its compression. Progressive rate springs have a variable degree of stiffness based on how far the spring has been compressed. The beginning portion of the spring travel is very soft, but as the spring continues to compress the force required to compress the spring increases. These springs tend to provide a better balance of ride comfort and performance. Linear rate springs tend to be a bit more abrupt but tend to be a bit more precise for performance handling. If you are looking to replace your 05+ Mustang stock springs with traditional springs, make sure you pick a spring construction that matches your use and desired outcome.
The 2005+ Mustang seems to respond quite well to Coil-Over Suspensions. The term Coil-Over is a reference to the location of the spring relative to the dampener (shock or strut). Traditionally, Mustangs built before 2005 had the front spring located between the lower control arm and the body structure. The strut was then attached between the spindle and “strut tower”. Converting this suspension system to a Coil-Over set up required a threaded collar and spring perch added to the outer portion of the strut, then a smaller spring specifically designed to slide over the strut replaced the traditional springs. Under this approach, the entire load was managed by the strut and the strut tower and provided several advantages: a reduction in weight, ride heights adjusted with ease and the ability to adjust the weight of the vehicle being carried by either side of the car (also referred to as setting the corner weights of the car).
The 05 Mustang was born with McPherson struts in the front and the spring perch and shock in the rear attach directly to the axle housing. Since the McPherson strut is technically a “Coil-Over” design, the body structure is already prepared for the load to be applied through the strut attachment. Installing an adjustable “Coil-Over” suspension on a 2005 requires a new strut with a threaded collar, adjustable perch and a specific spring for this application. For the rear suspension, we use a very cool adjustable spring perch to allow us to set the ride height and achieve the right corner balance. The benefit of this kind of adjustability is that you will have complete control over setting the ride height and stiffness of your suspension.
Now to finish this Mustang set up, we use the MRT rear suspension handling package which includes new lower control arms that add stiffness in the control arm and bushings and also aligns the control arms so they are not in bind to between the body and axle. Finally we add the MRT adjustable Pan Hard bar and relocate the bracket so that we do not get any deflection in the Pan Hard bar. This set up allows us to center the axle to the body and gain clearance to the differential for when we add the differential girdle. Bottom line: to make your 2005+ Mustang rule the road or track, add a Coil-Over suspension and a few minor rear suspension additions and get the performance you want!
- Scott Hoag
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