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IRS differential mounts, aluminum, pinion angle adjustable, 1999-04 Cobra
Actual product may differ from photo.
  • IRS differential mounts, aluminum, pinion angle adjustable, 1999-04 Cobra
  • IRS differential mount, front mount side view
  • IRS differential mount, front mount adjustment
  • IRS differential mount, rear mount

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  • Item # MMIRSB-40.2
  • Manufacturer: Maximum Motorsports


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  • Aluminum differential bushings keep the IRS center section from moving, helping to prevent cover damage during wheel hop
  • Allows adjusting the pinion angle to reduce driveline vibration
  • Ideal for the hard launches of drag racing

Wheel Hop Breaks Parts

  • Wheel hop causes violent movement of the IRS center section, which can overload and break the differential cover where it attaches to the rear mount.
  • Overly compliant stock rubber differential mounting bushings allow that violent movement. Stiffer bushings, whether aluminum or urethane, prevent the flopping around that breaks the differential cover.

The unique MM design has specially machined spherical bushing sets that compensate for the changed angle of the differential housing when you adjust the pinion angle. Other companies' solid bushings lack this feature, causing increased stress on the attachment bolts, the differential mounting ears, and the IRS subframe.


  • Solidly mounts differential center section to the IRS cradle, preventing damage from excessive movement during wheel hop
  • Adjustable to set pinion angle, which can reduce driveline vibrations. Range of adjustment is over 4 degrees!
  • Includes aluminum mounts for all three bushing sets: The two front sets and the critical rear mount
  • Fits with the MM-modified FRPP differential cover
  • CNC-machined aluminum
  • Anodized for corrosion protection
  • MM-designed spherical front bushing sets

Fits 1999-2004 Mustang Cobra IRS

Unlike many others who offer only the front differential bushings, Maximum Motorsports took the time and effort to analyze the IRS system. The MM Engineering Team determined that all of the differential bushings must be replaced as a complete set. The complete set includes the two front bushings and the essential single rear bushing.

If you only replace the front bushings and leave the original rubber rear bushing in place, you'll create a mismatch in the stiffness of the bushing materials. In other words, the more rigid front bushings will deflect less, while the remaining rubber rear bushing will still deflect as much as ever. Damage from wheel hop will still be possible because the rubber rear bushing will deflect and allow the differential to flop around.

The mismatch in bushing stiffness will increase stress on the aluminum front mounting ears of the differential housing, which can lead to fatigue and stress cracking of the housing.

You can read Maximum Motorsports' highly detailed MMIRSB-40.2 IRS Differential Mounts installation instructions before purchase.