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Subframe connectors should be your first modification when upgrading your Mustang's suspension.

Stiffening your Mustang's chassis with MM Subframe Connectors will provide several benefits:

  • Improved handling.
  • Improved launching.
  • Improved ride quality.
  • Increased comfort.
  • Floorpan damage is prevented.
  • Vehicle longevity is increased.

Handling is improved because chassis flex is reduced. This helps keep suspension loads in the springs and dampers, rather than being absorbed by the flexing of the unibody. When the chassis flexes it acts as a fifth spring, a spring with no damper.

Launching at the drag strip is improved because chassis flex is reduced. When stepping on the throttle pedal, engine torque will be quickly transmitted on through to the rear axle, rather than being delayed by flexing the unibody first.

Ride quality and comfort are improved by the reduction in chassis flex. This helps keep the forces from road irregularities in the suspension, rather than being absorbed by the flexing of the unibody. The car is much more damped and controlled over rough roads, eliminating the shaking and shuddering that is characteristic of stock Mustangs. The front seats are securely braced to the subframe connector tube. Without connectors, the floorpan flexes, allowing the seat to rock side to side, and fore and aft. That amplifies the motion felt by the seat occupants. Less violent motion means more comfort.

Damage is prevented, increasing your Mustang's longevity, because there is much less chance of fatigue cracks from overstressing of the unibody sheet metal. Without subframe connectors: It is common for the floorpan to crack around the rear mounting bolts for the front seats. Drag race cars often crack the exterior sheet metal at the top of the A-pillars. Improper placement of a floor jack will distort the floorpan.

What are "subframe connectors", and where do they go?
Subframe connectors are steel tube reinforcements that are welded to the bottom of the car. They connect the stock front and rear subframes together. This strengthens the flexible floorpan between the two subframes, and greatly increases the rigidity of the Mustang's unibody chassis.

Full-length Subframe Connectors
Maximum Motorsports created the first "Full-length" subframe connectors many years ago. This is yet another MM product copied by other companies. Beware of the copycats-MM's are still the best quality.

We have improved on our original design over time. We increased the length and height of the connector tube, which made the latest XL Series connector much stiffer than any other under-car subframe connector. We refined the seat mounting braces to improve fitment with a Torque-arm, and to reduce welding during installation of the connector.

  • MM Full-Length Subframe Connectors stiffen the chassis far more than standard subframe connectors. The taller tubing of the XL Series creates a connector that is 95% stiffer than a standard connector. The XL connector tubing is 53% stiffer than our previous Full-length subframe connectors. Be wary of companies who lack the engineering expertise to design their own subframe connectors. Some have copied our previous design. The new MM XL Series connectors are 53% stiffer than those copies.
  • MM XL Series Full-length Subframe Connectors extend from the rear lower control arm attachment point on the rear subframe all the way up to the firewall. This provides substantially more weld area between the connector and the chassis than other connectors. At 65", the extra length, increased number of attachment points, and extra height in the tubing make this the stiffest subframe connector available.
  • No need for jacking rails with the XL Series connector. You can lift your Mustang by placing a jack anywhere along the length of the connector tube!
  • No reduction in ground clearance. MM subframe connectors were carefully designed to not hang any lower than the lowest part of your Mustang-the exhaust system. The connector tube is no closer to the ground than stock mufflers, and matches the minimum ground clearance of the OEM Ford connectors on the late model SN95 convertibles. At no point along their length do the XL Series connectors hang lower than the exhaust system.
  • MM XL Series Full-length Subframe Connectors are made of 1.5" x 2" x .083" wall thickness rectangular tubing. The thinner wall tubing is used to lessen the weight, while the taller dimension increases stiffness by 95% over standard connectors.
  • Reinforcing plates at each bend prevent flexing that would otherwise occur with the thinner wall tubing.
  • Welded end caps seal the tube to prevent moisture from getting inside the connector and rusting them from the inside out.
  • Seat braces are welded to the connector tube during installation. This customizes the fitment to match your Mustang.
  • Choose either black powder coated or bare steel finish.

1996-98 Mustang Cobra Installation Note
These three years of the Cobra model require modifications to the transmission crossmember mounting flanges. Look at our consumer instructions for more details about installing full-length subframe connectors on these Cobras.

Standard Subframe Connectors
These were our first generation of subframe connectors. When we designed them in 1992 they were the strongest subframe connectors available for the Mustang.

  • Made of 1" x 2" rectangular tubing 46 1/4" long with .120" wall thickness. This material size makes the MM subframe connectors over 40% stiffer than other well-known standard subframe connector brands.
  • Rectangular tubing is superior to round tubing because it provides more weld area, for better attachment to the chassis, as well as not reducing ground clearance, as do round-tube connectors.
  • Welded end caps seal the tube to prevent moisture from getting inside the connector and rusting them from the inside out.
  • Seat-braces to reinforce the crack-prone area of the Mustang floor pan where the front seats attach are pre-welded to the tubes.
  • Choose either black powder coated or bare steel finish.

1996-98 Mustang Cobra Installation Note
See the note immediately above the Standard Subframe Connectors section. Both Standard and XL Series Full Length Subframe Connectors have special requirements for these Cobras.