Vehicle Fitment

The BMR SP012R rear lowering springs fit:

Ford Mustang S550

• Ford Mustang GT 2015-2020
• Ford Mustang EcoBoost 2015-2020
• Ford Mustang V6 2015-2017

These springs are designed to work with:

• Factory spring perches
• OEM mounts
• Camber plates that reuse factory-style perches

Important Fitment Notes

BMR notes that some aftermarket perches may not fit properly and can increase:

• Noise
• Vibration
• Harshness (NVH)

For supercharged or turbocharged V8 Mustangs with additional front-end weight, BMR recommends specific front spring combinations designed for boosted applications.

All BMR springs are manufactured from chrome silicon high-tensile spring wire, and are cold wound on a CNC coiling machine. The CNC coiling head can adjust the spring diameter in real time to make sure that Every spring is exactly the same.

Key Features

1.5-Inch Rear Drop

The SP012R lowering springs provide approximately:

• 1.5 inches of rear lowering

Benefits include:

• Reduced wheel gap
• More aggressive stance
• Improved weight transfer control
• Enhanced appearance

The S550 already has excellent proportions, but lowering the rear helps eliminate the factory “4×4 gap” that many Mustang owners immediately notice.

This guarantees that your right spring matches your left spring. Every BMR spring is compressed solid on the factory, not once, but twice.

Designed for Performance

While appearance is often the initial motivation for lowering a Mustang, BMR designed these springs with performance in mind.

Advantages include:

Reduced Body Roll

The lower center of gravity helps reduce chassis movement during aggressive cornering.

Improved Stability

Drivers often report improved confidence during:

• Highway driving
• Lane changes
• Corner entry
• High-speed cruising

Better Weight Transfer

Lowering the rear suspension can improve overall chassis balance, particularly during acceleration and spirited driving.

Premium Chrome Silicon Spring Steel

One area where BMR separates itself from many competitors is manufacturing quality.

The SP012R springs are constructed using:

Chrome Silicon High-Tensile Spring Wire

Benefits include:

• Superior fatigue resistance
• Increased strength
• Long-term durability
• Consistent spring rates

Chrome silicon steel is widely used in professional motorsports and high-performance suspension applications because of its ability to withstand repeated compression cycles.

Precision CNC Manufacturing

BMR utilizes CNC-controlled spring winding equipment to ensure consistency.

The manufacturing process allows:

• Real-time spring diameter adjustments
• Precise spring rate control
• Consistent production quality

This helps ensure that both left and right springs perform identically.

In suspension tuning, consistency matters just as much as spring rate.

Lowers the rear of your S197 Mustang 1.5-inches
Computer tested for accurate height and spring rate

Double Compression Set Process

Unlike many budget spring manufacturers, BMR compresses each spring solid twice during production.

Benefits include:

• Permanent spring set
• Elimination of settling issues
• Resistance to spring sag
• Consistent ride height over time

This process helps prevent the frustrating situation where a vehicle continues to lower itself weeks or months after installation.

Stress Relieved at 750 Degrees Fahrenheit

Each spring undergoes a stress-relieving process at approximately 750°F.

This helps:

• Remove manufacturing stresses
• Improve durability
• Increase fatigue resistance
• Extend service life

The result is a spring that maintains its intended performance characteristics over years of use.

Shot-Peened for Maximum Durability

BMR also incorporates shot-peening into the manufacturing process.

Shot-peening helps:

• Reduce residual surface stresses
• Improve fatigue resistance
• Strengthen the spring surface
• Enhance longevity

Many lower-cost spring manufacturers omit this step entirely.

Improves handling and ride quality
Lifetime warranty against spring sag

Individually Tested Springs

Perhaps the most impressive aspect of the BMR manufacturing process is that every spring is individually tested.

Rather than sampling batches, BMR:

• Compresses each spring
• Measures spring force
• Verifies spring rate
• Confirms quality standards

This level of quality control is uncommon in the aftermarket suspension industry.

Lifetime Warranty Against Sagging

Because of its extensive manufacturing process, BMR offers:

Lifetime Warranty Against Spring Sag

Coverage includes:

• Premature settling
• Manufacturing defects
• Material defects

For Mustang owners planning long-term ownership, this warranty provides valuable peace of mind.

Ride Quality Expectations

Despite the performance-oriented design, the SP012R springs are engineered to maintain street-friendly comfort.

Drivers can generally expect:

• Slightly firmer ride
• Improved body control
• Better road feel
• Reduced suspension movement

The Mustang remains comfortable enough for daily driving while benefiting from improved handling characteristics.

Why Lower an S550 Mustang?

The S550 platform already delivers excellent performance, but lowering springs can unlock additional potential.

Improved Appearance

The reduced wheel gap dramatically changes the Mustang’s profile.

Better Cornering Performance

A lower center of gravity helps the chassis remain composed during aggressive driving.

Enhanced Wheel Fitment

Aftermarket wheels typically look much better with a lowered stance.

Increased Driver Confidence

The vehicle feels more planted and responsive.

Lowering Springs vs Coilovers

Many Mustang owners compare lowering springs and coilovers before upgrading.

BMR Lowering Springs

Pros:

• Lower cost
• Excellent reliability
• Comfortable ride quality
• Minimal maintenance

Cons:

• Fixed ride height
• Limited adjustability

Coilovers

Pros:

• Adjustable ride height
• Suspension tuning flexibility
• Track-oriented setups

Cons:

• Higher cost
• Increased maintenance
• More complex installation

For many street-driven Mustangs, lowering springs provide the best balance of performance, appearance, and value.

Final Thoughts

The BMR Suspension SP012R Rear Lowering Springs are an excellent suspension upgrade for 2015-2020 Ford Mustang S550 owners looking to improve stance and handling without sacrificing reliability. Featuring a 1.5-inch rear drop, premium chrome silicon steel construction, advanced manufacturing processes, and a lifetime warranty against sagging, these springs offer the quality and performance that BMR has become known for throughout the Mustang community.

If you’re looking to eliminate wheel gap, improve chassis control, and give your Mustang the aggressive stance it deserves, the SP012R springs deliver both form and function in one well-engineered package.