Whiteline S550 Ford Mustang – Introduction and Initial Testing

Whiteline S550 Ford Mustang – Introduction and Initial Testing

by Mike Kojima

Whiteline, just in case you didn’t know, is a leader in the aftermarket performance suspension industry. They offer well-engineered and high-quality sway bars, bushings, suspension geometry correcting kits and recently coil overs for a wide variety of cars. We really like how Whiteline’s parts fit and work, and thanks to their large applications list, Whiteline products find their way onto many of our builds.

As you’ll recall, we used Whiteline’s suspension parts extensively on our own Project S197 MustangWe installed their Watts link, third link, trailing arms, trailing arm relocation brackets, and sway bars with great results.

Recently, Whiteline obtained a late model S550 Mustang to not only function as a test mule for their S550 chassis parts development program, but to also act as a rolling showcase for their Mustang product line. The Mustang will also feature upgrades to the engine, braking system, and the cars’ cosmetics to make it an all around performer. We will be documenting the build and testing progress here on MotoIQ.

The S550 chassis has an unusual rear suspension design that will be somewhat tricky to modify, and we are very eager to see what Whiteline will come up with in the way of springs, bushings, sway bars and their latest offering – the new Max-G coilovers.

First, let us introduce the Whiteline Mustang as it was purchased.


Whiteline obtained their 2017 GT Fastback Base Model Ford Mustang from Galpin Ford in North Hills, CA. There was no reason to buy a heavily optioned, fully loaded car because their plan is to extensively modify it, and Galpin Ford had plenty of Mustangs on the lot to choose from.

Directly from the Ford Factory, the GT Mustang has a pretty impressive set of parts as standard equipment for a solid performance base to start with:

  • 3.31 limited-slip rear axle
  • 5.0L Ti-VCT Coyote V8
  • 6-speed manual transmission
  • Engine oil cooler
  • 13″ rear brake rotors with single-piston calipers
  • 14″ front brake rotors with 4-piston calipers
  • AdvanceTrac® with Electronic Stability Control (ESC)
  • Electronic Line-Lock
  • Independent rear suspension
  • Selectable-effort Electric Power-Assist Steering (EPAS)
  • Vented 4-wheel disc brakes
  • 18″ magnetic gloss painted machined-aluminum wheel
  • Air extractor hood vents
  • Launch control (requires manual transmission)
  • P235/50R18 tires

With such a solid base, the new S550 Mustang is a great choice to modify. We all know about the Mustang’s Coyote engine’s power potential. With its state of the art, 4 valves per cylinder, DOHC heads with variable valve timing and rock solid aluminum block with 6 bolt main bearing caps, the engine can take quite a bit of power, even forced induction.

The chassis is also state of the art. Ford finally ditched the solid axle rear suspension on the base model Mustang for a multi-link independent suspension. An innovation the rear suspension has is a vertical compliance link that helps keep the spindle from twisting under torque load, resisting wheel hop without resorting harder bushings that increase NVH. A welcomed win-win scenario, in a sea of never ending comprimise, when building performance cars for the masses.

The front suspension is McPherson strut with an interesting dual ball joint lower control arm. Dual ball joints are used to give the lower outer control arm pivot point a virtual center of rotation. This allows stuff like a camber curve that gives more negative camber and positive caster gain on the loaded outer tire in a turn. This design can also reduce the wheel tilt in the wrong direction on the less loaded inner tire that happens when you run increased negative camber and positive caster with conventional struts.


Whiteline wasted no time adding its livery to their newly acquired Mustang. Before enough miles were clocked for its first oil change, the Whiteline Mustang was sent to Galpin Auto Sports, aka GAS, for its first round of mods.


Before the modifications start, the GAS techs look at the hood’s mounting points and everything that will need to be removed from the stock hood in preperation for a lighter weight piece from Anderson Composites. Items like the hood latch, windshield washer plumbing, OE insulation and weather strips will need to be transferred to the new carbon hood.


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