Steeda Autosports has once again taken the S550 Mustang to the next level of performance and comfort with our exclusive Adjustable Urethane Differential Mount Bushing Insert System for all 2015-2021 Mustangs! When our engineers sat down to design this kit, we had to come up with a way to increase performance without sacrificing too much drivability and preserving the cars street manners per the driver's preference.
Unlike our competitors' kits that take 3-4 hours to install and force you to permanently modify the rear IRS suspension with a Sawzall, Steeda's does not! Steeda's kit installs in under 1 hour, is adjustable and can be easily removed - it simply doesn't get any better than this!
Minimize pinion angle changes, increase traction, eliminate wheel hop and differential deflection with Steeda's new kit. Made from high-strength urethane to Steeda's exact specifications and durometers, our kit comes with 2 different bushing options - our red 'street' 80 durometer bushings and our black 'performance' 90 durometer bushings. Both bushing options will increase performance while the red bushings offer the least increase in NVH as compared to the black. Like all kits on the market, our kit can add noticeable NVH due to increased transfer of gear whine noise problematic to some Super 8.8 IRS differentials.
Steeda's kit adds the strength and support the OEM bushings need to perform the way our customers intended. Once again, this is not a permanent modification - there is no drilling, cutting or pressing required. Simply loosen and remove a couple bolts and this kit installs in less than 1 hour. Bushings are included for both the front and rear differential mounting locations. Grade 10.9 hardware is included with zinc-plated washers.
Note: For hardcore enthusiasts that want ZERO pinion deflection, try our 555 4440 kit. This kit features aluminum bushing inserts. For race-use only as it will increase NVH and gear noise.
Note: Does not fit GT350 or Mach 1.
Note: This product may increase noise, vibration, and harshness (NVH) after installation. NVH may increase slightly with red/street bushing inserts, but more aggressively with black/performance bushing inserts. This product itself does not generate any additional NVH, rather it transmits existing rear differential noise into the cabin by firming up the OE bushings.
Product Benefits- Limits IRS differential movement while increasing traction and eliminating wheel hop
- Adjustable stiffness with red or black bushings
- Easily removable, not a permanent modification
- 100% designed, manufactured, and made in the USA
- Installs in 1 hour or less
- Also fits the 2020 S550 GT500
Note: Due to changes in the OE subframe bushings, the bushing inserts will not fit 2021 GT500's or 2022 Mustang's
Today we will be installing the Steeda S550 Differential Bushing Insert System. Lift and support the car by the chassis on a vehicle lift or jack stands. Place a jack underneath the front of the subframe to support it independently from the car. To install the rear IRS differential bushing, you must loosen the 2 rear 21mm bolts that hold the subframe in place. You can only remove these 2 21mm subframe bolts, if the front subframe brackets and bolts are securely fastened. Doing 1 side at a time, remove the differential 18mm bolt.
Once the bolt is removed, install the urethane bushing with the provided large washer. First, insert the short billet aluminum spacer into the rear urethane bushing, and then install the bushing into place where the factory 18mm bolt was removed. Repeat the steps on the other side. Torque the 110mm long bolts to 129ft.lbs.
To install the front bushings, locate the main subframe bolts. 2 blue ones that are 21mm hex headed bolts. Remove the 2 front bolts and the 4 13mm hex head bolts (2 per side) securing the front subframe support bracket to the chassis, allowing the subframe to droop down in the front. With the IRS drooped down, you can now remove the front differential bolt. Remove only 1 at a time. You are removing 1 factory bolt and replacing it with 2 new bolts. Then install the 7/8 headed 14mmx65mm long bolt and the 7/8 washer with blue loctite. From the rearward towards the front, in the same manner the stock bolt was. Torque to 129ft.lbs.
Take the longer billet aluminum spacer and insert it in the front urethane bushing. Fit the bushing into place from the front side where the original factory bushing. Grease is included for ease of installation and is not required for operation. Bolt the front bushing into place with the provided 7/8 headed 14mmx35mm long bolt and washer with loctite. Torque to only 35ft.lbs.
Repeat the steps for the other front differential bolt. Once both front IRS differential bushings are installed, tighten back up the subframe support bracket and subframe bolts. Torque the 21mm subframe bolts to 129ft.lbs and the 13mm bolts to 41ft.lbs.
Thank you for choosing Steeda, where Speed Matters!
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