FAQs & Tech Tips

MM News

New! MM Technical Services: MM’s Engineering Team will provide setup recommendations specifically tailored for your Mustang. Get help choosing options for a Maximum Grip Box, deciding on coil-over spring rates, selecting a brake master cylinder, and advice on converting your Fox to Hydroboost.

New! Swapping a Coyote into a Fox Mustang? MM's Hydroboost Conversion Kits allow easy installation of a 1996-2004 Mustang Hydroboost power brake assist unit into a 1979-1993 Mustang.

New! Swapping an IRS into your Fox Mustang? MM makes it easier with a brake line kit made just for this conversion. Bolts-in, with no cutting or flaring of brake lines. Designed to fit standard IRS brake hoses.

New! MM now offers a tool for the giant nut securing a Mustang Hydroboost. This MM socket fits the 1-7/8" nut holding the Hydroboost to the firewall mount. Required when changing a Hydroboost unit.

New! MM's billet aluminum Pedal Box Spacer for Fox Mustangs. Replace the breakage-prone OEM plastic spacer when converting to manual brakes or Hydroboost.

Canadians! Please read the latest about ordering from Canada/shipping to Canada.

We've posted the parts list and link to the video of MM's Mustang in /DRIVE Tuner car Shootout

MM Coil-over Spring, 175 lb/in, 11", 2-1/4" diameter
Actual product may differ from photo.


  • Item # 225.175.11
  • Manufacturer: Maximum Motorsports


MM-designed this barrel-shaped spring for rear coil-over conversions in 1979-2004 Mustangs.

Does NOT fit 1980-1988 Thunderbird because the barrel-shape of the spring interferes with the unique Thunderbird rear shock tower.

  • Unique barrel shape increases the radial clearance between the spring and the threads on the rear shock.
  • The additional radial clearance keeps the spring from rubbing on the threads, a common problem with standard coil-over springs.
  • More overall travel is provided by the barrel shape than by a conventional straight spring of the same rate and length. More travel is added insurance against the spring coil-binding, even when a low rate is installed in a heavy car.
  • Barrel-shaped Coil-over Spring
  • 175 lb/in spring rate
  • 11" free length
  • 2-1/4" inside diameter
  • Designed by Maximum Motorsports.
  • Manufactured in the USA.

1 spring