Steeda Rear Subframe Support Braces IRS Fastback 2015-2020

Steeda Rear Subframe Support Braces IRS Fastback 2015-2019 is rated 4.8 out of 5 by 32.
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  • Limits Irs Sub-Frame Movement
  • No Permanent Modifications
  • 50% More Connection Points
  • Improves Handling
MSRP $279.95
You save 13%

Steeda Rear IRS Subframe Support Braces for all 2015, 2016, 2017, 2018, 2019 and 2020 Fastback Mustangs.

As you may have seen, Steeda's IRS Subframe Bushing Support System solved many problems with a quick and easy solution that limits the movement of the subframe by filling in the voids of the OE bushings. Now with Steeda’s IRS Subframe Support Braces, they have taken the S550 rear suspension to another level!

The Steeda S550 Mustang Rear IRS Subframe Braces for 2015-2020 Fastback Mustang V6, EcoBoost or GT are built in-house from 4130 chrome moly steel and powdercoated silver metal flake, this part isn’t only strong, it will look great under your new Mustang! What they did was tie together 3 very important points on the S550 chassis. Steeda utilized existing threaded holes in the rocker panel and connected that to the front mounting location of the IRS subframe and the rear mount of the lower control arm and toe link. Connecting these 3 points together not only adds rigidity that was lacking in the rear, but also more control of the whole car.

Features and Benefits:
- Better Handling for More Stable Cornering
- Limits IRS Sub-Frame Movement
- No Permanent Modifications Necessary
- No Added NVH (Noise, Vibration and Harshness)
- 50% More Connecting Points
- Reduces Wheel Hop
- Made In The USA

*Will NOT work with Convertible 2015-2019 Mustang Models.

With the release of the new S550 Mustang, Steeda knew that addressing the IRS system would be a top priority. Being the first production Mustang with an IRS since the 03/04 Cobra’s, they knew there would be a great opportunity to capitalize on Ford’s new piece by giving it the Steeda advantage. As with any suspension system, deflection is an issue if it’s present. Anytime a piece is moving, twisting or vibrating when it should be stationary is a major problem. And Steeda came up with a simple and inexpensive solution to a big problem.

Installation Difficulty


Novice skill is required for this installation.

Installation Videos

Vehicle Fitment

This product will fit the following Mustang years:

Rated 5 out of 5 by from Great deflection reduction starting point. Very well constructed and finished. Strong material for confident deflection control. Immediate change in the entire drive line oscillation forward and backward. And yes, immediate wheel hop reduction. Doesn't do everything to resolve hop, but helps signisignificantly. Diff bushings and subframe bushing lockouts are highly recommended with the S550 IRS. I'm installing those this weekend. I'm running 9.5 psi of boost, so these braces were a great start on deflection control. [Ya, I know I should have done the suspension first... I had the good sense to wait for the 675 hp, but not the ability.] Thnx Steeda and CJPP. Patrick
Date published: 2017-07-26
Rated 5 out of 5 by from Unbelievable difference I installed these supports in conjunction with the G-trac brace. Wow, the effects are more pronounced than I expected in tightening up the Mustang's chassis! First, it eliminates the rear end 'rubber band' effect when aggressively turning that everyone complains about. Wheel hop is greatly diminished. Also, it limits the rear subframe movement in a way to prevent the dreaded vibrations/harmonics in the driveline that I was getting in between 40-55 mph. This is one of those parts the factory should have included stock. For install, I had to finagle the passenger side a bit but I was fortunate it fit with out shifting the subframe. Certainly, these braces are worth the price and installation effort. Put this down as a must-do item.
Date published: 2016-02-07
Rated 4 out of 5 by from Great addition to the new IRS Installed these along with the rear cradle bushing inserts and supports. That way I only needed the alignment re-set once. These braces look great and are quality made. Install was fairly easy with the car on jack stands. Would have been much easier on a lift. The reason for only 4 stars is the bolt supplied in the kit to attach to the front cradle brace was the wrong thread pitch for my 2015 GT PP and I have to make a run to the local hardware store for the right bolt. They also could have made this so that the front cradle bolts are still accessible after install which they are not. My car does feel more solid in the rear now. No negative affect on NVH.
Date published: 2018-02-21
Rated 5 out of 5 by from Make the Rear Hook So, a little backstory on these braces. The reason they don't work with the convertible is that the convertible already has a rear subframe-to-body brace installed. These Steeda braces use some of those same mounting points for fastback cars that are otherwise left unoccupied. This is why they bolt up without any modifications and why they can't be used with convertibles. With that being said, these make a huge improvement. It feels like the rear wheels are practically bolted into the back of your seat rails. Before, the rear had a very vague feel that made it hard to tell if the rear was going to break loose, even in just casual driving. Now, the rear feels much more dialed in and tracks with the front wheels much better. I have a lot more confidence in how the car drives. Installation is relatively easy, just finger tighten all the bolts first and align the braces and then torque it down.
Date published: 2017-09-17
Rated 5 out of 5 by from Massively improved handling I have only had these on for two days but I instantly saw massive improvements in turning and heavy acceleration. I have made a number of sharp turns in 1st gear and they have been super smooth with no sign of giving out like it would before. I have also gotten a few clear freeway onramps to really let her go and there was zero sway unlike before, the car stayed straight as an arrow. This one piece has greatly increased my confidence in the car and I no longer feel on the verge of losing control at times. I would highly recommend this as a first or even only suspension upgrade. The results were impressive, the install was easy, and the price is cheap compared to coilovers or other expensive suspension mods. If you don't feel confident in your car at times, get these now!
Date published: 2019-09-10
Rated 4 out of 5 by from Great Product Performance Horrible Packaging Not sure who's to blame, but I give this 4, instead of 5 stars, for the hassle and let down. Received these IRS braces in a Steeda box, which was undamaged, but looked like it had been previously opened or returned. When opened for install, ALL the hardware was loose and washers were missing. No bags for the hardware, just thrown in the box. The braces were in good repair. After a trip to the hardware store, the installation was relatively easy, since my subframe was close in alignment. Approximately 1 hour for install on jack stands. As far as the Steeda braces and customer service...AWESOME! I emailed Mike and he assured me this was highly unusual. For my troubles, they emailed me a discount code, which I used promptly on more Steeda parts. I have an AirLift 3P suspension. Coupled with the G-Trac K brace, this is by far the best chassis stiffening mod I've done. Adding one component at a time, for comparison, these IRS braces make the rear end feel planted and unified. Stiff but not harsh for daily driving. Again not sure if packaging was CJPP's fault or Steeda's, but I HIGHLY recommend the braces for improving handling performance.
Date published: 2017-02-11
Rated 5 out of 5 by from Like night and day! Took my Mustang out the other day. First time it's moved since before Christmas. And I noticed the difference immediately. I did a lot of work to this car over the winter. Headers and a 3" exhaust, were the big things. So I really can't get on it til I get it tuned next month. But I was able to feel the difference the first time I pulled out of the driveway. Installation was a breeze. I didn't experience any of the problems that some people have talked about. For me, everything lined up, and went together just fine. Highly recommended!!!!!!!!!!
Date published: 2016-03-14
Rated 4 out of 5 by from Solid product! Installed on my s550 after CJ Pony Parts lowering springs. Definitely tightened up the rear end.
Date published: 2015-07-14
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Hi Will this work with the Steeda extreme G trackK member ? Thaks for your answer

Asked by: Piot
Yes it will.
Answered by: rk cjpp
Date published: 2019-11-20

Do the rear wheels need to have weight on them to properly install this or can a floor jack be used with wheels off the ground ?

Asked by: Russell
The wheels can be off the ground.
Answered by: rk cjpp
Date published: 2019-06-17

Do you need the bushings kit along with the support braces or not?

Asked by: Ponyexpress18
Its not required to use them together.
Answered by: rk cjpp
Date published: 2019-05-05

Will it work with Steeda jacking rails installed? As far as bolt location in the front. Also, i have a BMR cradle lockout kit installed, will that cause any installation issues?

Asked by: Steve Dailey
These will work with the jacking rails, not sure about the BMR cradle lockout kit.
Answered by: rk cjpp
Date published: 2018-02-22

Will this work with the side exit exhaust mid pipe

Asked by: Tonyxmkh
We have not fitted this part with a side exhaust kit.
Answered by: rk cjpp
Date published: 2018-01-25

I have already purchased these for a 2017 GT fastback 5.0 Can I also install a Cradle Bushing Lockout Kit?

Asked by: BOMBA1
These will not work with the Lockout brackets, but will work if you are just installing the Lockout bushings
Answered by: Daxy
Date published: 2018-01-10

Do I have to remove the exhaust in order to install them?

Asked by: grandsammy
The exhaust does not need to be removed for installation.
Answered by: rk cjpp
Date published: 2017-01-10

You've answered that the Steeda Jacking Rails can be used together with this brace. I'm assuming that the Jacking Rails should be installed first and then the brace? Is this correct? TIA.

Asked by: tencrore
It could go either way, but personally I would install the braces first.
Answered by: CJPP Dave
Date published: 2017-01-28
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