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-JRi Shocks Suspension Kit, 2005-2014 Mustang
Actual product may differ from photo.
  • MM-JRi Shocks Suspension Kit, 2005-2014 Mustang

click on thumbnail to zoom


  • Item # JRiMM-1
  • Manufacturer: Maximum Motorsports

Select Option(s):

Rear shock lower mount

Front Spring Rate

Rear Spring Rate



Ultra high performance suspension kit for 2005-2014 Mustangs. Suitable for competitive road racing as well as driving on the street. MM teamed with the top-level designers at JRi Shocks to create this bolt-on package for the S197 Mustang.

  • JRi Shocks monotube strut and shock design has separate adjustments for compression and rebound valving.
  • Available with your choice of front and rear spring rates.
  • Wide range of damping adjustment allows choosing softer springs for street duty, or high-rate springs for road racing.
  • Threaded-body steel coil-over strut allows easy front ride height adjustment.
  • Aluminum strut-to-spindle mounts have incremental camber adjustment to extend the range of adjustability.
  • Rear ride height adjustment is performed with an adjustable lower spring perch on the rear axle housing.
  • Includes MM caster/camber plates unique to this package.
  • Billet aluminum shocks with choice of either spherical bearing lower mount for racing, or urethane bushing for street use.
  • Helper springs maintain spring tension at full suspension droop.

When ordering, select from the options above:

  • Rear shock mounting style: Spherical bearing for track use, or urethane for least NVH in street use
  • Front spring rate
  • Rear spring rate

Contact an MM Tech Associate for help choosing spring rates.

2014 - The brand new MM-JRi dampers were driven to 2 wins in NASA American Iron races at Virginia International Raceway, both wins by Beau Dunnivant in his S197 Mustang.

2015 - Beau Dunnivant scored 2 poles and 2 more wins running on MM-JRi dampers in American Iron.

PowerGrid high performance front swaybar end links.

The collaboration of JRi and MM resulted in a suspension package that provides superior performance for the discriminating Mustang driver. The JRi design team has years of experience at the very top levels of motorsports, and the MM team applied our Mustang-specific design talent to bringing the JRi advantage to the world of Mustangs.

The result?

  • More grip
  • Better performance from improved response
  • Lower lap times
  • Easy bolt-on installation
  • Ride quality suitable for daily driving when lower spring rates are selected

The JRi Advantage
JRi has focused their engineering talents on improving the most important damper design factors.

  • Reducing breakaway seal friction (stiction)
  • Reducing internal gas spring rate and rod force
  • Reducing friction during running and side-loaded conditions
  • Reducing hysteresis
  • Increasing dynamic response at higher frequencies
  • Increasing the adjustability range
  • Stability and repeatability during temperature fluctuations

With JRi dampers on your Mustang, you will experience:

  • Improved grip on bumpy surfaces
  • Improved turn-in response
  • Reduced wheel hop
  • Consistent performance regardless of ambient temperature
  • Good ride quality with street-appropriate spring rates

Better by Design
MM focused on applying the JRi advantage to the S197 Mustang platform by bringing our wealth of Mustang knowledge, our engineering and design expertise, and our manufacturing abilities to this project.

  • We applied our usual high standards of design, manufacturing, and performance to fit the JRi struts and shocks to the Mustang.
  • Our engineers designed unique proprietary components for this project.
  • Our Lead Test Driver piloted our shop car during extensive track and street testing as we developed the valving to best suit the S197 Mustang.
  • Our high manufacturing standards perfectly suited this project.
  • American Iron multi-time Regional Champion Beau Dunnivant's favorite design feature: The ability to easily tune the handling by changing both rear springs in the pits in under three minutes.

If your needs change, these JRi dampers can be reconfigured to suit. Beyond the tuning made possible by separate rebound and compression adjustments, JRi dampers can be rebuilt with custom changes to the valves, shim stack, and bleeds. If you like testing and fine tuning everything possible, with JRi there is no need to buy new dampers; these can be serviced and customized by JRi or other competent shock rebuilder.

  • Monotube damper design, front and rear
  • Both compression and rebound adjustments are located at the top of the damper, making it very easy to make adjustments.
  • Large diameter shafts give high bending stiffness and low dynamic friction.
  • Front ride height adjusted by lower perch on threaded-body coil-over strut.
  • Steel strut body
  • Billet aluminum mounting bracket with an ingenious clamp design connects the strut housing to the spindle, while also stiffening the spindle.
  • Strut mounting ears provide additional camber adjustment in finite increments.
  • Strut ears can be mounted to strut housing at different heights, allowing adjustment of bump/droop travel without making any internal changes to the strut.
  • Front spring couplers (between the helper spring and the standard spring) have a Teflon guide to prevent wear of the strut body threads.
  • New strut-to-spindle hardware (Ford lists this hardware as one-time use)
  • Bolt-on swaybar end-link mounting brackets securely clamp to the strut housing.
  • Lightweight aluminum shock body
  • Rear ride height can be changed by aluminum adjuster mechanism on top of the axle.
  • Lower rear shock mount available in choice of spherical bearing or high-grade urethane.
  • Your choice of spring rates
  • Top-quality 2.5" springs, front and rear
  • Low-rate helper springs ensure tension on the main springs at full droop, preventing the springs from coming off the spring perches.
  • Thrust bearings on front upper spring perch prevent any effect on steering effort.
  • MM Caster Camber Plates


  • 2011-2014 spindle
  • 2005-2014 chassis

Does NOT fit

  • 2005-2010 spindle. This spindle has a narrower strut mounting ear than the 2011-2014 spindle. The 2005-2010 spindle also only fits the undesirable smaller diameter 2005-2010 ball joint. Swapping your front control arms and spindles for the much-improved 2011-2014 versions is an upgrade you won't regret!

This MM-JRi suspension system uses standard 2.5" coil-over springs, front and rear. When ordering you may select your desired spring rates from the listed offerings above.

Need help deciding?
Contact us for advice.

Why are there no remote reservoirs, like other high-end dampers have?

The primary reason to have external reservoirs is to keep the damper oil cool. The MM-JRi dampers already have excellent cooling because they are a monotube design. The absence of external reservoirs significantly reduces installation time, and reduces fitment issues.

Why not rear coil-over shocks?

The MM Engineering Team chose a non-coil-over design for several reasons:

  • The OEM shock bracket on the axle housing was not designed for bump or spring loads. We prefer to not rely on the long term durability of a welded bracket that was never intended to support the spring load.
  • Keeping the springs directly on top of the axle tube, where Ford put them, provides for a much stiffer lower mount for the spring than the OEM shock bracket on the axle housing. Deflection of a spring mount under load would degrade handling and ride quality.
  • Locating a rear spring on the shock would increase friction in the shock due to increased side loads in the shock shaft and piston. Keeping the spring directly on top of the axle nearly eliminates this friction in the shock.
  • Rear springs can be changed in very quickly when the spring is mounted on top of the axle tube rather than over the shock.
  • There are fewer potential tire clearance issues when the springs are mounted on top of the axle tube.
  • Locating the springs on top of the axle tube places them in a location further inboard than springs located on the shocks. This inboard position provides a ratio of wheel rate to roll stiffness that is better for handling.

How do I choose spring rates?

Why is the warranty only one year?
The warranty is not against parts wearing out. The warranty covers defects in materials and workmanship in the manufacturing of the damper kits. If there was a problem in manufacturing it will become apparent within one year.

Maximum Motorsports provides a limited warranty to the original purchaser of this MM-JRi damper package for a period of one year from the date of purchase. If any of the covered items fail in use, we will replace that component. This is not a warranty against items wearing out from use, but is a warranty for the failure of any of the specific components listed. This warranty applies only to the original retail purchaser of this MM-JRi suspension package.


  • Loss of gas pressure
  • Significant fluid leakage
  • Gland bushing failure
  • Camber plate spherical bearing failure: Defined as the inner spherical bearing ball having axial movement of 0.005" or more, relative to the outer race
  • Camber plate spherical bearing failure: If the inner bearing ball cannot be moved relative to the outer race, when using the strut for leverage to cause angular and rotational movement.
  • Camber plate spherical bearing installation failure: If the outer bearing race moves relative to the steel cup the bearing was pressed into
  • Camber plate main plate bending or breaking
  • Camber plate bearing plate bending or breaking
  • Rear ride height adjuster breakage
  • Spring sagging
  • Shock eyelet urethane failure

Not covered

  • Any damage caused during a vehicle crash
  • Any failure when the strut or shock shaft is bent, as that indicates improper installation or crash damage
  • Spherical bearing inner ball that cannot be moved (rotated or angularity changed) by hand. It is normal that leverage from the strut is required to make the inner ball to move.
  • Any spherical bearing failure if lubrication had ever been applied to it
  • Any spherical bearing failure if a bumpstop was not properly installed
  • Any main plate failure (bending or breakage) if a bumpstop was not properly installed
  • Any bearing plate failure (bending or breakage) if a bumpstop was not properly installed
  • Crossthreading, breakage, or stripping of any threaded fasteners
  • Degradation of plating or the powdercoat finish due to age, or the application of fluids such as brake fluid or cleaners.
  • Any failure when the part has been modified
  • Any consequent damage resulting from any failure of the caster camber plate

Warranty Claims

  1. Contact Maximum Motorsports.
  2. We will assist you in evaluating the problem to determine if it is a candidate for possible warranty coverage. We may ask you to send us photos.
  3. If warranty coverage is likely, you will be given an RGA number to return the item to us. Items sent to us with no RGA number will be returned to the sender.
  4. You will then ship the damaged item to us (to the address on the Contact Us page), prepaid.
  5. Upon receipt we will evaluate the item.
  6. If your warranty claim is approved, we will ship the replacement component to you at no charge.