MM News

Mustang Rear Coil-Over Tech

Unlike other companies' rear coil-over kits, the MM kit does not cause a reduction in bump travel from stock. This is critical for lowered vehicles to prevent excessive bottoming of the suspension and reduced ride quality.

We designed our rear coil-over kits for 2.25" diameter springs, rather than the more widely used 2.5" diameter springs. The smaller diameter spring provides more clearance for wide tires, more space between the spring and the chassis to reduce the possibility of interference, and lower weight than a 2.5" diameter spring.

Unique to the MM rear coil-over kit is the proprietary Delrin/aluminum upper shock mount. This ball and socket design allows the angularity of the shock to change, as is required for the suspension to move freely. The non-compressible MM Delrin/aluminum upper shock mount replaces the shock's original rubber upper mount under the shock tower, which would severely deform under the car's weight. The MM kits also include urethane replacements for the original rubber lower shock eye bushings, for the same reason.

Included with the kit is a new lower shock-mounting bracket that attaches to the axle with two bolts, and is constructed of heavy gauge steel. The OEM stock lower shock-mounting bracket was designed with one attachment bolt, and is inadequate to carry the weight of the car. Our Panhard Bar axle mount provides a very sturdy mount on the driver's side of the car. If you do not have a MM Panhard Bar, you will need an additional lower shock mount, part number MMSM-2.

Note: See here for MM's Racing Upper Shock Mounts.

Coil-overs for Bilstein

The rear coil-over kit for Bilstein shocks requires that a groove be machined into the shock body. If you are purchasing your Bilstein shocks at the same time as your coil-over kit, note in your order that you need them pre-grooved to accept your new coil-over kit. Adding the prefix "G" to the standard shock part number denotes grooved shocks. Our MM Sport and MM Race valved shocks are only sold grooved. If you already have the appropriate Bilstein shocks, MM can machine the groove. Please call our Tech/Customer Service Line for details.

Note: MM's Bilstein coil-over kits (part numbers MMCO-3 and COP-3) should only be installed on the Bilstein shocks designed for use on the 1994-04 solid axle cars, even for 1979-93 cars. The later model shocks have a lower shock eye that is more securely attached to the shock body than the early model shock eye is attached. This improved attachment of the shock eye is required because the shock body carries more of the vehicle weight when a coil-over kit is installed. There are several additional advantages to using the later model shock: Increased bump travel, decreased droop travel, and a cellular foam bumpstop that comes installed on the shock, allowing removal of the stock hard rubber bumpstop.

Note: Installing an MMCO-4 kit onto 2003-04 Cobra OEM Bilstein IRS shocks requires installation kit MMSM-10. Additional details below.

Coil-overs for Koni

The Maximum Motorsports rear coil-over kit for Koni shocks can be fitted to Sport ("Yellow") Single or Double Adjustable shocks. 1994-04 Koni Sport shocks for solid axle vehicles can be used with the Koni coil-over kit without modification. Koni Sport shocks designed for 1979-93 solid axle cars, and those designed for IRS equipped vehicles, require removal of the metal dust boot to be compatible with our coil-over kits. If you intend to install this MM Rear coil-over kit on a Koni shock other than the Sport Single Adjustable or Sport Double Adjustable shocks listed above, note that the MM threaded sleeves are designed for a Koni shock housing diameter of no larger than 1.630". Other models of Koni shocks may have a different housing diameter.

MM removes the metal dust covers and performs the other modifications necessary for installation of our Koni rear coil-over kits. Pre-modified shocks are available from MM, or we can modify your shocks. There is no extra charge for the modifications. Please call our Tech/Customer Service Line for details.

MM recommends that the Koni shocks for 1994-04 solid axle cars be used on 1979-93 solid axle cars to avoid modification requirements. These late model shocks have several advantages over the earlier versions. They allow the removal of the factory frame-rail bumpstops because they come with Koni's high quality foam bumpstops already installed on the shocks. The late model shocks also have an advantage in providing more bump travel, and less droop travel, than the early shocks.

Note: Installation of a rear coil-over kit may require the removal of the quad shocks because of minor interference. If you are using MM Rear Lower Control Arms, you will not need the quad shocks. The MM control arms do a better job of controlling wheel hop than the quad shocks, because the MM arms eliminate the bushing deflection that causes wheel hop.

NOTE: The MMCO-6 kit for the Koni 30 series racing shock requires the MMSM-3 Racing Upper Shock Mount for installation.

2003-04 Cobra Rear Coil-over Installation Kit

The 2003-04 IRS Cobras were fitted at the factory with OEM Ford Cobra Bilstein struts and shocks. These same OEM Cobra Bilstein shocks have been a popular upgrade for owners of earlier IRS Cobras. Whether originally fitted to the car, or installed at a later date, the OEM Cobra Bilstein shocks come with a different upper rubber isolator assembly than do the aftermarket Bilstein IRS shocks. Do not reuse the OEM Cobra Bilstein upper rubber isolator when installing a MM Rear Coil-over Kit. An aftermarket Bilstein upper rubber isolator must be installed.

The OEM Cobra Bilstein upper rubber isolator is shorter and softer than the isolator that comes with an aftermarket Bilstein shock. Because it is shorter and softer, the OEM Cobra Bilstein upper rubber isolator cannot be correctly preloaded when a MM rear coil-over kit is installed.

Not having enough preload on the upper rubber isolator may cause a clunking sound from the rear shock tower area. It also can cause damage to the upper aluminum socket of the MM coil-over kit, and damage to the shock's retaining circlip. Not all vehicles may exhibit these symptoms. However, if the above combination of components is being used, Maximum Motorsports strongly recommends replacing the OEM Cobra Bilstein upper rubber isolator with the MMSM-10 installation kit. This will keep noise to a minimum and increase the longevity of components.

Aftermarket Bilstein shocks (including 2000 Cobra R OEM Bilstein shocks not purchased from Ford) come with the correct upper rubber isolator, and do not require this installation kit. When installing a MM Rear Coil-over Kit with OEM Cobra Bilstein shocks, regardless of what year chassis the shocks are installed on, order an MMSM-10 installation kit. This kit includes the correct upper rubber isolators, thrust washers, and locking nuts.