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Mustang Rear Lower Control Arm Tech: MM Extreme Duty series control arms

Extreme Duty control arms

  • Direct replacement for the stock lower control arm.
  • Tubular steel construction is over three times stiffer than the stock control arm.
  • Large 2" diameter round steel tube provides maximum stiffness.
  • Engineered design prevents binding of suspension movement.
  • Large PTFE-lined spherical bearings at each end allows freedom of motion for both pivoting and angularity, preventing unwanted deflection while still allowing the angularity required for proper articulation.
  • Spherical bearings prevent damage to the torque-boxes by easily allowing the suspension to move as needed.
  • Greatly reduces axle wind-up.
  • Moderate change in NVH.
  • Swaybar mounting brackets are 3/16" thick steel, shaped to increase their strength, and are welded on both sides.
  • Powdercoated black
  • Spring perch location on non-adjustable arms does not change ride height.
  • Available with adjustable height spring perch

The MM Extreme Duty Rear Lower Control Arms should be used in any high horsepower application, or any form of racing. Large PTFE-lined spherical bearings at both ends of these control arms completely eliminate deflection, yet allow the articulation required to prevent torque-box damage. This reduces axle windup, and allows the car to react to throttle input more quickly. These are the only control arms available that have spherical bearings at both ends, and yet do not require a coil-over conversion kit. MM's Engineering Team solved the problem of keeping the control arm upright and aligned with the chassis, when the springs are left in the stock location, by designing urethane alignment bushings for the chassis-side spherical bearing.

Rear lower control arms with spherical bearings at each end:

  • Precisely locate the rear axle
  • Do not deflect fore-and-aft
  • Reduce axle wind-up
  • Reduce wheel hop
  • Do not cause suspension binding
  • Stop torque-box damage
  • Improve traction!

While some people may have concerns about the potential for increased NVH with spherical bearings at each end of the control arm, we have found the Extreme-Duty control arms to be suitable for street use. There is only a very slight increase in noise and vibration over a stock control arm. This minor change is usually only noticeable in a car that has the stock, quiet mufflers.

Muscle Mustangs and Fast Fords magazine tested the MM Extreme-Duty Rear Lower Control Arms in the January 2003 issue, as part of their test of the MM Street & Strip Box. They found the car's 60-foot times to be remarkably consistent, varying only .02 seconds over the course of 10 runs.

To adjust, or not to adjust...
Extreme Duty control arms are available in two styles: Ride height adjustable or non-adjustable.

Adjustable Extreme Duty control arms

  • Allows easy changes to ride height, both up and down.
  • Raise the rear ride height by up to 2 inches.
  • Lower the rear ride height by as much as 1 inch.
  • Adjust ride height without the need to jack the car off the ground.
  • Improve traction by fine-tuning the instant center location and anti-squat geometry by changing the ride height.
  • Aids with adjusting the corner-weights.
  • Available in both series: Heavy-Duty and Extreme-Duty.

Standing Starts and RLCA Bushings Urethane rear lower control arm bushings should not be used for any type of drag racing. The statement "any type of drag racing" includes any hard standing start launch, whether it is at the drag strip or a stoplight on the street. Hard launches, when the engine RPMs are increased significantly and the clutch is released abruptly, put an enormous sudden shock load on the control arm bushings. Urethane bushings will suffer a shortened lifespan from this type of use. The higher the power level, the stickier the tires, and the better everything else that helps a car launch more quickly is, the greater the stress on urethane bushings, and the shorter their lifespan. If hard launches are part of your lifestyle, then order MM Extreme-Duty Rear Lower Control Arms.

Specific tech about the MM Heavy Duty control arms

Specific tech about the MM Road Race control arms

General Tech about MM rear lower control arms

Mustang Rear Lower Control Arm FAQs