If you’re familiar with Project 5-Liter Eater, you’ll know that our 2015 EcoBoost Mustang has a variety of tasteful modifications installed on it. Recently, we addressed only a portion of the suspension by installing sway bars. One of the next pieces to the puzzle was to address our Mustang’s stance. And, because the new S550 platform uses an independent rear suspension (IRS), changing the rear springs on the ’15 Mustang is an all-new game.
To get our stance right and improve our spring rates as we continue to maximize the potential of our Mustang’s new IRS setup, we reached out to our friends at Vogtland North America located Temecula, California. The kit we’ve installed is Vogtland’s Sport Lowering Spring Kit, PN 387016 available for order. Project 5-Liter Eater is primarily serving daily driver duties, but the car is also our weekend autocross machine. Striking the perfect balance between all-out performance and daily comfort is why we went with the more balanced Sport Lowering Kit.
The Engineering Behind A Vogtland Lowering Spring
In most cases, lowering springs are designed to lower a vehicle and improve handling and performance. The manufacturing process starts in Vogtland’s facility in Germany, where springs begin as a concept for a vehicle. Leila Vizzari, president of Vogtland North America comments, “The material we choose for our springs is very crucial. Lower-grade material springs will lose their height over time due to the high-impact usage.” The springs are manufactured using a special oil-tempered steel and a mix of alloy materials known as high-tensile strength chrome-silicon (CrSi) and chrome-silicon-vanadium (CrSiV).
“The spring kits are tuned to function with the factory dampers. However, you can use our high-performance dampers that are available with the sport lowering springs as a suspension kit.” – Leila Vizzari, Vogtland North America
The material also effectively reduces unsprung weight on the vehicle, which ultimately translates into greater handling characteristics. Vogtland takes the process a step further after the presetting phase and seals the springs. The springs are phosphated and then powder-coated, which provides a long-lasting corrosion barrier from water and rust for years of service.
Vogtland Sport Lowering Springs
Vogtland Mustang Sport Spring Lowering Kit
- Designed to give the Mustang a racecar “raked” stance
- Lowers center of gravity and improves overall handling
- Progressive spring rate: racecar handling when you want it
- Powder-coat finish for optimal life
- Lowering: one-inch front / one-inch rear
- Compatible with all Mustangs including convertibles and coupes
- Compatible on all Mustang OEM wheel and tire options
The springs provide two different “spring settings” for a balance between performance and comfort. Vizzari comments that these springs are made specifically for all ’15 Mustang models, both coupe and convertible. They’re also engineered to be compatible with all factory optional Mustang tire and wheel options. Rest assured, there won’t be any clearance or rubbing issues with these springs.
Vizzari also explains that these springs can be used with or without the factory shocks and struts, stating, “The spring kits are tuned to function with the factory dampers. However, you can use our high-performance dampers (recommended) that are available with the sport lowering springs as a suspension kit. That will ensure the end-user gets the most optimum handling and performance.”
Let The Installation Begin
The installation is fairly simple and straight forward. The springs are a direct replacement, which means there are no modifications required for installation. Since our ’15 EcoBoost has such low mileage, we chose to use the original shocks and struts. Keep in mind, whenever a car is being lowered, the entire suspension geometry is changed, including the steering angles. It is highly recommended to perform an alignment after installation.
Once you have a jack, and jack stands handy (or a lift), you’ll need the following wrenches and sockets: 1/2-inch ratchet, 13mm, 15mm, 18mm, 21mm, 22mm, 24mm, 17mm wrench as a panel removal tool; a hammer or mallet; and a spring compressor. Note that a 1/2-inch impact gun or breaker bar is necessary when removing the front strut from the strut plate.
Loosen the two bolts holding the front strut assembly into the spindle. Note that those two bolts are splined, so you’re going to need a hammer now to loosen them. Now that the bottom of the strut is free from the knuckle, remove the nuts at the top of the strut assembly while holding the bottom of it so it won’t drop freely.
To begin the rear suspension, start by removing the rear brake caliper, then disconnect the ABS sensor. Next, remove the rear sway bar end-link, then the bracket holding the rear brake line. Remove the top rear shock mount bolts. Support the rear lower control arm, then remove the two bolts cradling the rear subframe. Slowly release the subframe, using the weight of the subframe itself to decompress the spring in the lower control arm.
Have a friend assist you with a pry bar and pry in a downward motion on the lower controller arm. This allows you to slowly decompress the spring, removing it with ease. Before you install the new springs, transfer the factory isolates over and ensure the spring is seated properly. Lastly, use the control arm to compress the spring and bolt it back into place. As we mentioned, this process is identical for both sides, and fairly easy to complete.
These springs are made specifically for all ’15 Mustang models, both coupe and convertible. They’re also engineered to be compatible with all factory optional Mustang tire and wheel options. – Leila Vizzari, Vogtland North America
On the autocross, steering characteristics also feel much tighter than before during turn-in. Because the car sits slightly lower now, our center of gravity has been decreased respectively. The rates are such that the rear-end isn’t too stiff, which could cause the rear-end of the car to rotate and feel non-linear. In the slalom, or in a hard sweeper, the higher spring rate was made present as the suspension compressed.
Aesthetically, we eliminated the factory truck-like stance. The car looks fantastic, and the ride-height is perfect. Not so low that we can’t navigate parking lots, driveways, and speed bumps.
Thanks to the lowering springs, Project 5-Liter Eater now has a more aggressive raked stance, improving the muscle-car look we think it needed. Keep in mind, our ’15 EcoBoost came from the factory with a slight rake. Since Vogtland springs are designed from the style of the OE spring, the lowering springs retained that rake. The springs really are a superb design, allowing for the car to be lowered the correct way.