Best Control Arms for the 2015-2020 Ford Mustang (S550)

The best control arms for the 2015–2020 Ford Mustang (S550) fix the one problem every lowered or track-driven S550 runs into: rear alignment that will not hold. The S550 was the first Mustang with a fully independent rear suspension (IRS), and while that transformed how these cars handle, it also made them sensitive to ride-height and load changes. Drop the car an inch on lowering springs or coilovers and the rear camber goes negative, the toe wanders, and the inside edges of your tires start cupping. At NLP Performance in Tampa, FL, the rear toe and camber arms are some of the most common suspension parts we ship for GT, EcoBoost, and GT350 owners — and they are also some of the cheapest horsepower-per-dollar handling upgrades on the car. Below we compare five control arms from SPC Performance, Whiteline, and SPL Parts, covering the rear toe, rear lower, and front lower positions, with prices from about $140 to $720.

Why the 2015–2020 Mustang (S550) Needs Upgraded Control Arms

Control arms are the links that locate each wheel and set the suspension geometry — camber, caster, and toe. On the S550's independent rear suspension, the factory uses stamped-steel lower arms, a vertical link, and a toe link with a small eccentric bolt for adjustment. That setup is fine at stock ride height, but it was never designed for the aftermarket. The moment you lower the car, the geometry shifts in ways the OEM parts cannot correct.

Two things happen. First, rear camber goes negative — often past –2.0° on a car dropped an inch — because Ford's non-adjustable (or barely adjustable) upper arms simply cannot dial it back. Second, rear toe changes, and the factory eccentric bolts that set toe tend to slip under hard cornering loads, so the alignment you paid for walks out of spec on track or on a spirited canyon run. The visible symptoms are tucked rear wheels, twitchy behavior on throttle, and tires that wear out on the inside edge within a few thousand miles. Upgraded, adjustable control arms restore the range the factory left out and lock the setting in place.

You do not need to replace everything at once. For most street-driven 2015–2020 GT and EcoBoost cars, an adjustable rear toe arm is the single most valuable part, followed by a rear camber (upper) arm. Dedicated track cars benefit from front lower arms with spherical bearings that sharpen turn-in and remove bushing deflection. We break down each position below.

The 5 Best Control Arms for the 2015–2020 Mustang (S550)

Every arm below is in stock at NLP Performance and confirmed to fit the S550 platform (2015–2020, including GT, EcoBoost, and GT350 unless noted). We have grouped them by position so you can match the part to the problem you are solving.

1. SPC Performance 72380 Rear Toe Control Arm — Best Overall

The SPC 72380 is a forged-aluminum rear toe arm with a turnbuckle-style adjuster that lets you set rear toe across a plus or minus 3° range — far more than the factory eccentric bolt allows — and then lock it so it does not move under load. On a lowered 2015–2020 GT, this single arm takes the car from darty and inside-edge-chewing to planted and predictable, which is why it is our most-recommended S550 suspension part. Install runs about three hours in the driveway and is rated moderate difficulty; plan on a professional alignment afterward. At around $256 it is the highest-value handling fix on the car.

2. Whiteline KTA228 Adjustable Rear Toe Arm — Best Street Alternative

Whiteline's KTA228 is a heavy-duty adjustable rear toe arm that rides on synthetic-elastomer bushings instead of a spherical joint, so it holds alignment under load while keeping street manners quiet — no extra noise, vibration, or harshness through the floorpan. It is the arm we recommend for daily-driven GT and GT350 owners who want the toe correction of the SPC unit with a more compliant, OE-like feel. At $299.95 (marked down from $421.88) it is a strong value, and because it is sold as an adjustable-length arm, it covers both street-lowered and mild track setups.

3. Whiteline KTA416 Front Tension Link Lower Control Arm — Best for Traction

The KTA416 is a front lower control arm (the tension link that locates the front wheel fore-and-aft) built with a firmer bushing than the OE rubber. Its job is traction and grip under power: it reduces the arm deflection that lets the front wheels move around on hard launches and corner exit, so steering stays precise and the nose tracks where you point it. For anyone who has added power to a GT or EcoBoost and feels the front end get vague under throttle, this is an inexpensive fix at around $201 (down from $282.88). It is a bolt-in replacement and does not change your alignment settings on its own.

4. SPC Performance 12050 Forged Rear Lower Control Arm — Best Budget Pick

At about $140, the SPC 12050 is the lowest-cost way to upgrade an S550 rear corner. It is a forged T6 aluminum replacement for the factory stamped-steel rear lower arm — stronger, lighter, and far more resistant to bending if you catch a curb or load the rear hard at the strip. It is not an alignment-adjustment part; think of it as a strength-and-weight upgrade and a sensible insurance policy on a high-horsepower drag or autocross car. Pair it with the SPC 72380 toe arm above and you have covered the two rear-lower positions that take the most abuse, still for under $400 combined.

5. SPL Parts Front Lower Control Arms — Best for Track Builds

SPL Parts is the brand serious road-course and time-attack S550 owners reach for, and the front lower control arms show why. They run spherical bearings in place of rubber or poly bushings, which removes virtually all deflection — steering response and front-end feel sharpen noticeably — and they are built from heavy-wall steel to survive curbing and high-g loads. At $719.10 (down from $799.00, plus an extra 5% off right now) they are the most expensive arms here, and the trade-off is more noise and maintenance than a street bushing. If your Mustang sees real track time, they are worth every dollar; for a street car, the Whiteline KTA416 is the smarter buy.

Control Arm Comparison: SPC vs Whiteline vs SPL

Here is how the five arms stack up side by side. Match the position to the symptom you are fixing: rear toe for a lowered car, rear lower for strength, front lower for traction or track precision. Prices shown were accurate at publish time and update live on each product page.

Front vs Rear Control Arms: What Should You Upgrade First?

Upgrade the rear first. On the 2015–2020 Mustang, the independent rear suspension is where lowering causes the most alignment trouble, so an adjustable rear toe arm delivers the biggest, most immediately noticeable improvement for the money. Start with the SPC 72380 (or the quieter Whiteline KTA228), then add a rear camber-correction arm if your rear camber is still beyond the range you want after the toe is set.

Move to the front only after the rear is sorted, or if your specific complaint is front-end vagueness under power. The Whiteline KTA416 tension link is the budget answer for street cars chasing better traction; the SPL Parts front lower arms are the track answer, trading some comfort for spherical-bearing precision. For a dedicated road-course GT or GT350, a full set — adjustable rear toe and camber arms plus SPL front lowers — is the end game, and still lands well under the cost of a coilover kit.

Installation & Alignment Notes

Rear control arms on the S550 are a bolt-in job with hand tools and a jack. Plan on roughly three hours per pair for a first-timer; the toe and lower arms share the same subframe-mounted hardware, so if you are installing more than one it is efficient to do them together. Set adjustable arms to the factory length as a starting point before the car goes back on the ground.

Always finish with a professional four-wheel alignment. Adjustable toe and camber arms exist so an alignment shop can actually bring a lowered S550 back into spec — without them, the tech is stuck with whatever limited range the factory left. For a street-lowered car, a common target is roughly –1.5° to –2.0° rear camber with a small amount of rear toe-in for stability; your shop will fine-tune to your tires and driving style. Torque all hardware to Ford's factory specs, and re-check fasteners after the first few hundred miles.

Still deciding on your suspension plan? Browse the full S550 suspension collection or start with our top-pick SPC rear toe arm — our Tampa team can confirm fitment for your exact year and trim.