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MM K-member, Mustang, 2005-2014
Actual product may differ from photo.
  • MM K-member, Mustang, 2005-2014

click on thumbnail to zoom


  • Item # Mm5KM-7
  • Manufacturer: Maximum Motorsports

Select Option(s):

Swap for Mm5KB2-21 (Scoop brace)

Add Bumpsteer kit
Add Engine Support Brace?


MM K-member for 2005-2014 Mustangs. This new MM design achieved not only our primary design goal of improved handling performance for a lowered Mustang, but it also met all of our secondary goals.

Design Goals Achieved

  • Optimized roll center height for a Mustang lowered to the limit of the American Iron rules.
  • Stronger and stiffer than stock k-member, to allow less deflection under cornering and braking loads.
  • Fits stock motor mounts, for least change in NVH
  • Fits stock front control arms, with stock or aftermarket bushings
  • Fits both electric and hydraulic steering racks
  • Allows easy oil pan removal without requiring additional engine support
  • Upgradable to SLA suspension


  • Bumpsteer kit. If you do not already have a suitable bumpsteer kit, the Mm5TR-2 is discounted to only $120 when purchased at the same time as this MM k-member.
  • Some means to support the engine during installation. MM's engine support MMT-11 is discounted to only $39.97 when purchased at the same time as this MM k-member.

Not compatible with extended-length ball joints.

Related Parts

  • Improved cornering ability due to raised roll center height.
  • Improved turn-in response and more precise control due to increased rigidity. This MM k-member has 30% less lateral deflection than a stock k-member has at the same cornering load.
  • No need to buy new front control arms; the robust stock control arms are used.
  • No change in NVH (noise, vibration, harshness) when stock motor mounts are used.
  • No change in NVH when stock front control arm bushings are used.
  • Increased rigidity improves front end stability and predictability.
  • Allows oil pan removal without the need for hanging the engine from a support beam.
  • Has provision for mounting upper control arms, for a future upgrade to an SLA suspension.
  • Control arm pivot standard location is 5/8" higher than stock, with second set of holes 1-3/8" higher than stock.
  • DOM steel tube construction
  • Includes 2-point brace to stabilize rearward control arm mounts
  • Weight: 42.5 lbs.
  • Compatible with aftermarket front control arm bushings
  • Works with both S197 steering rack types, hydraulic and electric
  • Has mounting brackets for MM radiator core support brace that also serves as an adjustable mount for the front swaybar.
  • Compatible with stock 2011-2014 radiator core support brace (minor modification to the OEM brace required).
  • Durable black powdercoat finish
  • Mounting points for future addition of an SLA upper control arm


  • 2005-2014 Mustang
  • Stock motor mounts
  • Urethane replacement motor mounts
  • Stock front control arms, 2005-2014
  • Stock front control arm bushings
  • Aftermarket replacement control arm bushings, urethane and Delrin
  • 2005-2010 hydraulic steering rack
  • 2011-2014 electric steering rack

Does NOT fit:

  • Extended-length ball joints because the bumpsteer spacers required with an extended-length ball joint cause the tie-rod to exceed its angularity range.

Design Goals

When it comes to the k-member, we feel that improved geometry and strength/stiffness are head and shoulders above all other considerations. For the S197 k-member we put not increasing NVH at the secondary level. Reducing weight comes last because it is nearly impossible to reduce weight without also reducing strength and stiffness. Since the k-member supports the entire front suspension while also holding up the engine, we feel that simply in the interest of safety we need to maintain a particular level of strength. If one is serious about weight reduction, we feel it should be done by reducing the weight of something that is not a mission-critical part, as the k-member is. Fiberglass or carbon fiber body panels are our first choice. This does not mean that we ignore weight-saving, as one can readily see from the lightening holes in the k-member. We do what we can, as long as we are maintaining our desired strength and stiffness.

This k-member is not aimed at drag racers who want to save weight at any cost. We know the majority of our customers are using their vehicle on the street, with occasional track events. Durability and low NVH are their primary concerns. Most of our Fox/SN95 parts were designed for street driving, and then tested and proven on racecars. We followed the same path when we designed this k-member.


With the S197 strut suspension design, most of the cornering loads are fed into the forward control arm pivots on the k-member. The highest loads at the rearward control arm pivot mounts of the k-member are during heavy braking. We focused on making the section forward of the rear pivots stiffer than the stock k-member. We also concentrated on feeding those loads primarily into the upper frame rails.

We built two fixtures to load test the k-members. The MM k-member deflected 30% less than the stock k-member during a simulated cornering load. So far we have tested one aftermarket k-member, which deflected 40% more than the stock k-member did in the same test scenario.


NVH is increased by using non-stock motor mounts. Many people complain of excessive vibration, especially at ide, when using urethane motor mounts. Some NVH comes from non-stock Front Control Arm bushings. These cause more of an increase in impact harshness than vibration. NVH is certainly subjective. What one person finds acceptable for daily driving another considers intolerable. In our opinion, the S197 is less tolerant of changes that affect NVH than the previous generation. Bushing changes that cause unnoticeable or minor increases in NVH on a Fox/SN95 chassis may cause noticeable NVH increases with the S197 chassis.

Motor Mounts

Over the past several years we heard many complaints from people about increased NVH, primarily caused by the proprietary urethane motor mounts used in their aftermarket S197 k-member, regardless of the manufacturer. We also heard from our dealers, and other installers, who disliked having their customers complain about increased NVH after installing a k-member.

Through the building of several iterations of our first design, one of which is on the yellow Vortech SEMA car, we encountered many design issues trying to route tubes around the stock motor mounts while also offering two control arm mounting heights. The machined aluminum blocks lower the top mounting flanges of the k-member, eliminating all of those difficulties.

As a bonus, by mounting the motor mounts to the aluminum blocks, the engine could stay in its stock location even when the rest of the k-member was removed. That greatly improves access for maintenance and header installation.

Aluminum Blocks

  • Each aluminum block is aligned to the frame rail with a close-fitting pin that fits into the same hole in the frame rail that Ford used for alignment on the assembly line.
  • The k-member mounting flange has over-sized holes to allow shifting it relative to the blocks, allowing precise squaring because it can move more than the stock k-member can. In the event that even more movement is needed, the pins can be easily removed from the aluminum blocks to allow shifting the blocks on the frame rails.
  • The blocks were designed to place the top of the k-member below the pinch weld on the underside of the frame rails. This lower position allows the k-member to be adjusted without running into the pinch welds.
  • Yet another bonus: The blocks were designed to provide an accurate mounting point for the upper control arm of an SLA suspension. We are still in the testing stages of our design and have no planned release date.

Front Control Arm Height

For extreme lowering, when moving the FCAs to the upper set of holes would be beneficial, several things are required.

  • Spacers are needed to move the rearmost FCA mount upwards to match the front mount. Not yet available.
  • The stock rearward FCA bushing must be replaced because its large diameter would interfere with the frame rail; smaller diameter aftermarket bushings of either Delrin or urethane are required. MM has urethane front control arm bushings.
  • Bumpsteer must be addressed by installing a bolt-through bumpsteer kit. The stronger bolt-through style is required instead of the tapered stud to prevent breakage from the increased load from the extra leverage of the greater length required to properly locate the outer tie-rod end to match the FCA in the upper set of holes. Not yet available.


We did not alter the angle of the FCA pivot axis because we did not want to significantly change the stock anti-dive percentage. The act of lowering an S197 will cause an increase in anti-dive. With the stock k-member, lowering the car one inch increases anti-dive from approximately 15% to approximately 20%. With this MM k-member, lowering one inch with the FCAs in the lower set of holes also increases anti-dive to about 20%.

We learned 15 years ago through testing that significantly increasing the anti-dive of the Mustang strut suspension caused a bad effect that far outweighed any beneficial effects: Encountering even small bumps during heavy braking would easily cause front wheel lock up.

There are two main reasons why increased anti-dive worsens braking on an S197 chassis. First, and this applies to all cars, as anti-dive is increased the resulting suspension geometry causes the tire to move more forward with bump travel. This makes the slope of the bump steeper, increasing the vertical acceleration of the tire, bouncing it off of the ground. Second, the geometry required for increased anti-dive increases the bending load on the strut. This increases friction in the strut, causing poor compliance of the tire to the road. This second problem is missing from an SLA front suspension because it does not have a strut.


A bumpsteer kit is required with the MM k-member. The stock front suspension has the usual Ford design of a small amount of bumpsteer (toe-out under compression) to promote understeer. Raising the inner FCA pivot points requires changing either the inner or outer tie-rod pivot points to match, just to maintain the stock bumpsteer (toe-change). The easiest way to do this is to use a bumpsteer kit at the outer tie-rod end.

Front Control Arms

We are not in a hurry to make our own. The 2010-14 Ford arms, with the larger ball joints, are very robust. A lighter weight arm would likely not be as strong and stiff.

Floorpan Distortion

Do NOT lift up the car by placing a jack or lift arms underneath the rearward k-member mounting points. Doing so can distort the bottom of the double-wall floorpan, moving the bottom steel upwards.

Steering Vibrations

The advent of the electric rack in 2011 brought both good and bad. The stock EPAS anti-nibble programming was based on the stiffness of the stock rubber front control arm bushings. Replacing those bushings with stiffer urethane or Delrin causes the feedback loop in the anti-nibble programming to become unstable, causing the system to oscillate. These oscillations are felt in the steering wheel as vibrations. By allowing the use of the stock control arm bushings, we are able to minimize any EPAS steering related issues until a solution cheaper than upgrading to the FRPP rack can be found.


All tubes are mild steel DOM tubing. The main tubes, on the lower plane, are 1.75" diameter with a 0.095" wall thickness.

The Envelope

We maintained the same ground plane as the stock k-member. The other tubes are located to provide more clearance towards the engine, exhaust, etc., than does the stock k-member.


Yes, it is heavier than a stock k-member; 42.54 lb vs. 40.52 lb. We tried, but upon meeting our design goals, this is where it is. Handling is improved. Stability and predictability are improved; the front end feels much more… Planted is the best word for it. There is less front-end drama when cornering. Maintenance and header installation is greatly improved. Someday an easy SLA upgrade will be possible.

Radiator Core Support

It is a fair bit lighter than the stock core support. Provision for a stock-location swaybar mount is an option, as well as mounting points for a splitter.

Forward Braces

These connect the MM core support to the MM k-member. They add stiffness to the front end. The swaybar mounts are located on the braces. The braces include a provision for shifting the swaybar pivots fore/aft to better align the end links on adjustable front swaybars.

Engine Support Beam

We designed an inexpensive tool to greatly aid in the installation of the k-member (MMT-11). When using an engine hoist to support the engine during k-member removal, the legs block access to the underside of the vehicle. Our engine support beam spans the strut towers and uses ratchet straps to temporarily suspend the engine while the k-member is swapped.

You can read Maximum Motorsports' detailed Mm5KM-7 K-Member installation instructions before purchase.