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SR Performance Polyurethane Spring Isolators; Rear (79-04 All, Excluding 99-04 Cobra)

Item 56055
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      Review & Installation Video

      Product Information

      Features, Description, Reviews, Q&A, Specs & Installation


      • Made of Graphite Impregnated Urethane for Long Life
      • Improves Handling and Steering Response
      • Fits: 1979-2004 Mustangs


      Performance Upgrade. If you are installing a new set of lowering springs it is a good time to replace your old worn out rubber Spring Isolators with a new set of SR Performance Polyurethane Spring Isolators available from AmericanMuscle.

      Superior Materials. These SR Performance Polyurethane Spring Isolators are made from polyurethane that has been impregnated with graphite so they will not dry out and crack like the stock rubber pieces.

      Application. Designed to replace the stock Rear rubber units found on the 1979-2004 Mustangs these SR Performance Spring Isolators will greatly improve the handling of your lowered pony. Not for use on SVT Cobra's with Independent Rear Suspension (IRS).

      SR Performance

      Fitment: 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Details

      MPN# 56055

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (100+)

      Write a Review

      Ratings Summary

      4.9 out of 5 overall rating from 100+ customers

      Installation Time: Afternoon

      Installation Cost: $250-$500

      • March 14, 2020

        5 1990 GT - scubbasteve76 Installation Time: Afternoon

        Mods for my mustang

        Great deal just what I needed. Perfect fit not to bad to install

        Helpful (0)
      • February 26, 2020

        5 1994 GT - Robert Installation Time: Afternoon

        Work like they should!

        Went from no isolators, ride height too low, and extremely rough ride. Raised it up just enough as well as smoothed the ride out. No complaints here

        Helpful (0)
      • February 18, 2020

        5 2000 GT - BrandonR Installation Time: Less than 1 Hour

        Spring isolators

        Fit perfect no more noise from the rear just a smooth ride

        Helpful (0)
      • January 29, 2020

        5 1997 GT - WillyBilly Installation Time: Afternoon

        Much better than the OE’s

        Condition of OE isolators were terrible when installing new rear springs in my 1997 GT convertible. New immediately they could not be used again. Ordered the polyurethane isolators and installed them. Besides the new springs improving the rear height of the car, I feel the new isolators helped contributed to the improved ride height as well. Headlights now are properly aimed.

        Helpful (0)
      • September 24, 2019

        3 1997 Cobra - RobertF Installation Time: Shop Install Installation Cost: $500-$1000

        Lowering Springs

        I started by replacing struts, lower front control arm bushings and ball joints, all rear end bushings (upper control arms) including the upper rear bushings in the axle itself and all shocks. And I installed alignment plates and strut braces. The car drove really well at this point. Then I added lowering springs, bump steers and spring isolators. The car still drives well but looks a whole lot better: the car originally sat very high on its springs and looked odd at best. The most significant improvement in handling was when the bushing in the upper rear axle housing were replaced. The rear axle had been moving around and the car was dangerous accelerating in a turn. And it did not track very well, requiring continues steering input. I am still considering installing a panhard rod to lock down the rear even more. However at this point the car is a delight to drive and it looks great.

        Helpful (0)
      • September 05, 2019

        4 1997 Cobra - jasonp

        fits as advertised

        seems good thus far. I have not had a chance to run the car yet

        Helpful (0)
      • August 22, 2019

        5 1997 Cobra - DominickF Installation Time: Less than 1 Hour

        Sr isolators

        fit good easy install with rented tool from my local shop

        Helpful (0)
      • August 14, 2019

        5 1988 GT - Will Installation Time: Less than 1 Hour

        Perfect fit

        I purchased a set of adjustable springs for my 1988 mustang GT and the spring bushings were in bad shape. I ordered a set of these for the rear and it was a perfect fit. Snug and tight.

        Helpful (0)
      • July 30, 2019

        5 1997 V6 - Brandt Installation Time: Afternoon

        Nice Fit

        Fit was like new, made a difference in the ride.!!

        Helpful (0)
      • July 15, 2019

        5 1991 GT - WilliamP Installation Time: Afternoon

        Excellent quality

        These isolater to me are of good quality and seem to made of durable material. I also bought the front set from American Muscle!!! Even though my wife works at Mustangs Unlimited. Sorry hun....

        Helpful (0)

      Questions & Answers (9 answers)

      5 Top Rated Questions

      I put lowering springs all around. Now when I hit a bump it jars me out of the seat. Will these fix that?

      • They may help settle the springs on the seats but, shocks are responsible for the ride quality I would recommend changing the shocks.

      Helpful (1)

      will these affect my ride height at all if i change out the stock isos to these? i havent lowered the car but getting new shock absorbers

      • No, it won't effect ride height . Change them out.

      Helpful (1)


      • We recommend reaching out to a MUstang forum for detailed instructions on replacing spring isolators without removing the lower control arms. 

      Helpful (0)

      do these work on the stock springs?

      • The SR Performance Polyurethane Spring Isolators can be used with stock and aftermarket springs.

      Helpful (0)

      Are these spring isolators universal? Im purchasing godspeed Traction-S Sport Springs and am not sure whatsoever if it matters what size or diameter the isolators are. Thanks

      • These isolators will work with any 79-04 Mustang, with the exception of 99-04 Cobras. This will also work with different springs.

      Helpful (0)
      Post Your Question
      4 More Questions
      Will this lower the car at all? 1 answer
      Hi, Will these isolators squeak like polyurethane bushing would? I don't want to have to install things 2 times to re-grease them down the road. Do you require or suggest special grease to avoid that, or they will stay quiet for the life of the part like rubber would. Thanks. 1 answer
      When installing lowering springs, I reused the old isolators. Eventually, I began hearing a loud clunking noise whenever I hit a bump. If I replace my isolators, will the noise go away? 1 answer
      What's the inside and outside diameter for these. I want to use to fit for an adjustable coil over set. 1 answer

      Installation & What's in the Box

      Installation Info

      What's in the Box

      Hardware included:
      • None required

      Tech Specs

      Will It Fit My Mustang

      • Bullitt - 01
      • Cobra - 93, 94, 95, 96, 97, 98
      • Cobra R - 95
      • GT - 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 00, 01, 02, 03, 04
      • LX - 87, 88, 89, 90, 91, 92, 93
      • Mach 1 - 03, 04
      • Other - 79, 80, 81, 82, 83, 84, 85, 86
      • V6 - 94, 95, 96, 97, 98, 99, 00, 01, 02, 03, 04

      Does not fit 1999-2004 SVT Cobra's with Independent Rear Suspension (IRS)

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