MM News

Coil-over springs
There's a wide range of possible coil-over spring rates for a 1979-2004 Mustang. Make sure you choose one that will provide the handling characteristics and ride quality you want. Start by selecting a front spring rate that's appropriate for your Mustang's intended use. Then pick the rear rate to match, taking into account the rear suspension type (4-link, torque-arm, etc.).

How do I choose a front coil-over spring rate?
Decide on your performance and ride quality goals. See the list below for further explanation, and the table below for a quick reference guide.

Soft front springs improve rear traction when launching a solid-axle Mustang, and should only be used with stock-location rear springs instead of rear coil-overs. Front rates range from 150 lb/in to 225 lb/in.

Street driving
Good handling on the street while maintaining excellent ride quality requires mild rates, ranging from 250 lb/in to 325 lb/in.

High-performance driving
Autocrossing, open-tracking, and high-performance street use require front rates between 350 lb/in to 400 lb/in to provide excellent handling with a minimal compromise in ride quality.

Serious open-tracking
For no more than very limited street driving, stiffer front rates of 400 lb/in to 425 lb/in are best.

Competitive road racing
Requires stiff rates ranging from 450 lb/in to 525 lb/in.

How does my Mustang's weight affect spring choice?
From the lightest to heaviest 1979 through 2004 Mustangs, overall weight varies by over 30%. If your car is on the heavy side, bias your spring selection toward the stiffer end of the range listed in the table below. If your car is on the lighter side, bias your selection toward the softer end of the range listed.

Choosing the front spring rate
Use the table below to select the front spring rate and corresponding strut series that matches most closely how you use your Mustang.

I chose my front coil-over spring rate. Which struts do I need?
Use the same table below. Each MM strut series matches with spring rates within a particular range, so the optimum strut series for your chosen spring rate can also be found in the table below.

Front Struts
Typical Use Rate Description Coil-Over Spring Rates (lb/in) Strut Series
Street/strip Soft 150 - 225 Street
Street Mild 250 - 325 Street
Street & Track Moderate 350 - 400 Sport
Track Firm 400 - 425 Race MM2
Competition Stiffest 450 - 525 Race MM3


How do I choose a rear spring rate?
After deciding on a front spring rate, use our MM Rule of Thumb to select the rear spring rate that provides the best match to the front spring rate, while taking into account the rear suspension type (4-link, torque-arm, etc.). This involves subtracting the appropriate number from the front coil-over spring rate to determine the matching rear coil-over spring rate. The number to subtract depends on your Mustang's rear suspension type and your driving style. Use the information in the appropriate table below.

4-link (stock-style) rear suspension
Type of driving Number to subtract from front coil-over spring rate to arrive at rear coil-over spring rate (lb/in)
Street driving 150
Performance driving, autocrossing, and open-tracking 125


Torque-arm rear suspension
Type of driving Number to subtract from front coil-over spring rate to arrive at rear coil-over spring rate (lb/in)
Street driving 125
Performance driving, autocrossing, and open-tracking 100


The minimum rear coil-over spring rate is 175lb/in. If the above calculation results in a rear coil-over spring rate of less than 175lb/in, there are two options.

  • Increase the front coil-over spring rate and repeat the calculation, until the rear coil-over rate is at least 175lb/in.
  • Use a rear spring located in the stock location on the rear lower control arm. Contact MM and we will calculate which stock location rear spring will best match with your chosen front coil-over spring rate.

These recommendations work very well for most solid-axle equipped Mustangs. However, many factors may lead to changing the rear spring rate after you drive your Mustang with its new coil-over suspension. Just a few of those variables include your driving style, swaybar sizes, tire grip, car weight, rear control arm bushing types, lateral location devices, and so on.

I chose my rear springs. Which shocks do I need?
Use the same MM damper series for the rear shocks that you chose for your front struts.

If you still need assistance choosing coil-over spring rates for your Mustang:

  • As a service for our customers purchasing springs and coil-over kits directly from Maximum Motorsports, we'll make a recommendation specific to your particular Mustang and its usage: go to our Tech Services page.
  • If you don't buy direct from MM, ask for tech support from wherever you buy your MM parts.