TRZ Motorsports Solid Axle Conversion Crossmember (2015 - 2023 Mustang S550) - S550-204
Convert Your S550 IRS to a Fox Body - Style Triangulated 4-Link
The TRZ Motorsports Solid Axle Conversion Crossmember (Part #S550-204) enables 2015 - 2023 Mustang S550 owners to replace the factory IRS with a proven Fox Body - style triangulated 4-link setup. Built for high-horsepower drag cars and serious chassis builders, this conversion creates the correct upper and lower control arm geometry needed for solid-axle performance.
The kit includes the crossmember itself plus upper and lower control arm hardware and inserts for existing 3/4? rod ends. While the crossmember bolts to the S550's factory frame locations for alignment, it requires welding into the vehicle's cage and surrounding structure. Both the upper and lower torque box areas must be welded and reinforced, and TRZ specifies that this conversion requires a 25.5 MINIMUM chassis.
The design features multi-hole UCA/LCA mounts for geometry tuning and supports both 9? and 8.8 housings, whether centered or using stock pinion offset. Housing-side lower control arm brackets must be moved inboard and installed at 32.5? - 34? on center. You will need Fox Body - length upper and lower control arms.
TRZ recommends:
- 8.8 Housing: TRZ Bolt-In Double Adjustable Rear Upper Control Arms
- 9? or 8.8 Housing: TRZ Bolt-In Dual Rod-End Rear Lower Control Arms
Performance Features
- Converts S550 IRS to Fox Body - style triangulated 4-link
- Includes crossmember, UCA/LCA hardware, and 3/4? rod-end inserts
- Bolts to factory frame for locating - welding required for proper integration
- Requires a 25.5-minimum chassis for safe installation
- Adjustable multi-hole upper and lower control arm mounts
- Works with 9? and 8.8 solid axle housings
- Accepts centered or OEM pinion offset setups
- Housing-side LCA brackets must be relocated to 32.5? - 34? on center
- Requires Fox Body - length upper and lower control arms
- Compatible with TRZ adjustable UCAs and LCAs
Quick Specs
- Vehicle: 2015 - 2023 Mustang S550
- Conversion Type: IRS ? Fox Body triangulated 4-link
- Chassis Requirement: 25.5 minimum
- Included: Crossmember, hardware, rod-end inserts
- Housing Compatibility: 9? and 8.8
- Pinion Options: Centered or stock offset
- LCA Bracket Spacing: 32.5? - 34? on center (relocated)
- Control Arms Required: Fox Body - length UCAs and LCAs
- Part Number: S550-204
Fitment
- 2015 Ford Mustang
- 2016 Ford Mustang
- 2017 Ford Mustang
- 2018 Ford Mustang
- 2019 Ford Mustang
- 2020 Ford Mustang
- 2021 Ford Mustang
- 2022 Ford Mustang
- 2023 Ford Mustang
Frequently Asked Questions
Does this crossmember directly bolt in?
No. It bolts in for positioning only - proper installation requires welding to the cage and chassis structure, including torque box reinforcement.
What control arms do I need for this conversion?
This setup requires Fox Body - length control arms. TRZ offers compatible adjustable upper and lower arms for 9? and 8.8 housings.
Why Buy from Beefcake Racing?
Beefcake Racing is your trusted source for TRZ Motorsports chassis components with fast shipping and expert tech support. For help choosing control arms or planning an S550 solid axle swap, email sales@beefcakeracing.com or call 1-855-827-7223.
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