Cutting-Edge Foxbody SR Progressive Springs

When it comes to enhancing the performance and handling of your Foxbody Mustang, one of the most effective upgrades you can make is installing progressive springs. These suspension components are designed to improve the comfort and responsiveness of your ride, while also providing a more planted feel during cornering and high-speed maneuvers. However, cutting Foxbody SR progressive springs might seem like a daunting task, but with the right knowledge and tools, it can be achieved with ease. In this comprehensive guide, we'll discuss the benefits, process, and tips for cutting progressive springs on your Foxbody Mustang.

two pictures of the same car in different stages
two pictures of the same car in different stages

Before we dive into the details, it's crucial to understand what progressive springs are and how they work. Progressive springs are designed with varying spring rates, which means they provide a softer initial ride but firm up as the suspension compresses further. This design allows for excellent comfort and compliance during low-speed and everyday driving, while also offering increased support and stability at higher speeds and during spirited driving. By cutting your Foxbody SR progressive springs, you can fine-tune the spring rate to better suit your specific driving needs and preferences.

the history of fox body mustangs infographical poster by tom mcinney
the history of fox body mustangs infographical poster by tom mcinney

Why Cut Foxbody SR Progressive Springs?

The primary reason for cutting Foxbody SR progressive springs is to customize the spring rate to better match your driving style and the weight of your vehicle. By lowering the spring rate, you can achieve a more planted and responsive feel during cornering and aggressive driving. Additionally, cutting the springs can help improve the ride quality and comfort by providing a softer initial spring rate, especially useful for daily drivers or those who prioritize comfort over outright performance.

the back end of a car parked in a parking lot next to a building at night
the back end of a car parked in a parking lot next to a building at night

Another advantage of cutting your Foxbody SR progressive springs is the ability to tailor the suspension to specific tire sizes or stance preferences. By adjusting the spring rate, you can achieve a more balanced and appropriate ride height, ensuring your tires maintain optimal contact with the road and providing a more stable and controlled driving experience.

Determining the Desired Spring Rate

Widebody Ford Mustang Fox Bodies:
Widebody Ford Mustang Fox Bodies:

Before you grab your cutting tools and start chopping, it's essential to determine the desired spring rate for your Foxbody Mustang. This process involves calculating your vehicle's weight, accounting for any additional accessories or modifications, and determining the optimal spring rate based on your driving style and preferences. A good starting point is to aim for a spring rate between 200-300 lbs/in, depending on your vehicle's weight and intended use.

To calculate your vehicle's weight, use the following formula: (Curb Weight) + (Passenger Weight) + (Cargo Weight) = Total Vehicle Weight. Once you have your total weight, you can use an online spring rate calculator to determine the appropriate spring rate for your Foxbody Mustang. Keep in mind that this is a starting point, and you may need to make further adjustments based on your driving experience and feedback.

Gathering Tools and Materials

a silver car parked in front of a building
a silver car parked in front of a building

Before you begin, make sure you have all the necessary tools and materials to complete the job safely and efficiently. Here's a list of items you'll need:

  • A hacksaw or plasma cutter for cutting the springs
  • Spring compressors to safely compress the springs during installation
  • Thread locker to prevent the spring seats from loosening
  • New spring seats (if required) to match the cut spring length
  • Measuring tape or a spring compressor/measuring tool to ensure accurate cuts

Steps to Cut Foxbody SR Progressive Springs

a black car parked in front of a building
a black car parked in front of a building

Now that you've determined the desired spring rate and gathered your tools, it's time to dive into the actual cutting process. Follow these steps to cut your Foxbody SR progressive springs safely and accurately:

Step 1: Measure and Mark the Springs

1979-1993 Fox Body Mustang Parts - Restoration & Performance
1979-1993 Fox Body Mustang Parts - Restoration & Performance
a silver car parked in front of a red building
a silver car parked in front of a red building
two pictures side by side one shows the engine and the other shows the car
two pictures side by side one shows the engine and the other shows the car
Foxbody Wheel Picture Thread
Foxbody Wheel Picture Thread
a red car parked in front of a garage next to two other cars on gravel
a red car parked in front of a garage next to two other cars on gravel
a red car parked in front of a body of water with the sun setting behind it
a red car parked in front of a body of water with the sun setting behind it
the front wheel and tire of a white car with text reading article fox body, wheel & tire guide
the front wheel and tire of a white car with text reading article fox body, wheel & tire guide
a white and black car parked next to a red truck
a white and black car parked next to a red truck
Rides - Twin Turbo Coyote Swap Fox Body. 💪🏻💪🏻💪🏻 | Facebook
Rides - Twin Turbo Coyote Swap Fox Body. 💪🏻💪🏻💪🏻 | Facebook
a green car driving down a track at night
a green car driving down a track at night

Before making any cuts, measure and mark the springs to ensure you cut them to the correct length. Using a measuring tape or a spring compressor/measuring tool, determine the exact length you need to cut the springs. It's a good idea to mark the cut line with a permanent marker or paint to serve as a reference during the cutting process.

Step 2: Compress the Springs

Safety is crucial when working with springs, as they can cause serious injury if not handled properly. Using spring compressors, carefully compress the springs until they are level with the spring perches. This will allow you to cut the springs without the risk of injury or damaging the suspension components.

Step 3: Cut the Springs

Once the springs are compressed, use your chosen cutting tool (hacksaw or plasma cutter) to cut the springs along the marked line. Be sure to wear appropriate safety gear, such as gloves and eye protection, during this process. When using a hacksaw, apply steady and even pressure, ensuring you don't create any rough edges or burrs. If using a plasma cutter, ensure you maintain a consistent cutting depth to avoid damaging the coil's inner diameter.

Step 4: Deburr and Finish the Cuts

After cutting the springs, use a file or deburring tool to remove any sharp edges or burrs from the cut surfaces. This will help prevent any damage to suspension components and ensure a smoother ride. Additionally, you may want to paint the cut ends of the springs to prevent rust and improve their overall appearance.

Step 5: Install the Cut Springs

Before installing the cut springs, apply thread locker to the spring seats to prevent them from loosening over time. Next, carefully install the springs onto the lower control arms, ensuring they are properly seated and aligned. Finally, reinstall the upper spring perches and tighten them to the specified torque.

As you begin to enjoy the enhanced performance and handling of your Foxbody Mustang with your newly cut progressive springs, it's essential to monitor the ride quality and make any necessary adjustments. Keep in mind that suspension setup is a highly personalized process, and what works for one driver may not be suitable for another. By staying informed and making informed adjustments, you'll be able to fine-tune your foxbody's suspension to meet your specific driving needs and preferences.