Steeda S550 Mustang Coupe Rear IRS Subframe Support Braces (2015-2021)

59 Review(s)
$10.00 (3%)
Eliminate wheel hop and keep your S550 Mustang planted! The Steeda IRS braces stop your subframe from moving under your car to provide better handling and stop wheel hop. Nothing is permanent with installation and it can be done at home with basic shop tools. No noise, vibration, or harshness will be added to your Mustang.
Part Number: 555 5754
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Suggested Mods


With the release of the new 2015 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, we 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. One of the areas team Steeda wanted to focus on was the rear IRS subframe.

As you have seen with our IRS Subframe Bushing Support System, it limits the movement of the subframe by filling in the voids of the OE bushings. With Steeda's IRS Subframe Support Braces, we have taken the S550 rear suspension to another level!

Our Steeda S550 Mustang Rear IRS Subframe Braces for 2015+ Fastback coupe Mustang 5.0L GT, 5.2L GT350, 2.3L EcoBoost, and 3.7L V6 fastback coupe (non-convertible) is built in-house from 4130 chrome moly steel and powdercoated silver metal flake, this part isn't only strong - it also looks great under your new Mustang! What we did was tie together 3 very important points on the S550 chassis. We utilized existing threaded holes in the rocker panel (the strongest part of the body) 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.

Also, unlike competitors kits that have not been released yet and only replace the factory bracket, our Steeda kit supports that bracket while connecting to 2 additional locations, therefore providing twice the support! Best part about this kit is it uses all existing holes in the chassis so the car doesn''t have to be modified in any way and adds no NVH whatsoever.

PATENT NO.: US D784,211 S

See the IRS Support Braces in action in our Steeda Q500

Notice how composed our Q500 is throughout this turn at Palm beach International Raceway

Purchase your Steeda S550 Mustang Rear IRS Subframe Braces for your Fastback coupe 2015+ Mustang GT, GT350, EcoBoost, and V6 (non-convertible) at Steeda Autosports today!

Also fits the S550 GT500

Product Benefits
  • Better handling for more stable cornering
  • Limits IRS sub frame movement
  • No permanent modifications necessary
  • No added NVH
  • 50% more connecting points
  • Reduces wheel hop
  • Lifetime warranty
  • Installation does not require removal of cradle

CA Residents: Cancer and Reproductive Harm WARNING

Hi everybody Brian from Here today to speak to you about our Subframe Braces for the S550 Mustang. When Ford was developing the S550 Mustang they built it so that it could be competitive around the world and popular around the world. And this posed a challenge for them. The challenge was switching over to and independent rear suspension. They hadn't offered a Mustang with independent rear suspension since 2003-2004. So changing that over was quite the challenge for them. When they did this, they utilized a subframe that bolted to the chassis and that was held together by four bolts. Now at those four bolts are bushings and the reason I'm telling you this well they left some room for improvement! To build on that statement further the bushings are fairly soft from the factory, and the reason that Ford designed these bushing to be relatively soft was to absorb any sort of vibration that might be transmitted through the subframe and isolate that from the body. Now that's great for driving the car everyday but as soon as you throttle into it you get wheel hop! We have many solutions for you but today we're going to focus on the subframe braces. Now the way these work is they connect in three strategic places on the back of the car. They mount toward the front of the rear tire to the chassis, come back to the front mounting point of the subframe and then back out toward the lower control arm and tow arm to reinforce those points. Now it's just not a matter of reinforcing those points it's also a matter of triangulating those three points. This is going to eliminate any sort of deflection left or right as well as forward backward and you know that triangulating something is going to add rigidity. Now this is important for a couple of reasons. That rigidity will make the car communicate better with you the driver. In addition, it's going to help keep the subframe planted in place and help remove that defection in those soft bushings. whether it be side to side or forward backward. It's going to help reduce wheel hop coming out of corners as well as wheel hop you experience when you accelerate hard going straight. And to further legitimize the efforts we put into designing these, we utilize these on our #20 SARRC Championship S550 Mustang as well as our World Record setting Silver Bullet Mustang. And since we know that weight is the enemy of performance, we've constructed the Subframe Braces out of 4130 chromoly, which is light weight and extremely strong. In addition we've powder coated them for durability and if anybody seeks a peek underneath the car it's going to look great! Now these are also really easy to install. No modifications are needed to the car and we provide all the necessary hardware to mount them. These also carry our lifetime warranty. In addition they're Made in the U.S.A. at our Valdosta Georgia facility. Because Speed Matters! Subscribe to our Youtube Channel If you enjoyed this video, be sure to hit Like. Don't forget to follow us on Social Media. Have a great day!
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Fitment & Features


Manufacturer: Steeda Autosports
Made in USA: Yes

Installation Information:

Level of Difficulty: Easy
Install Time: About 45 Minutes
Tools Required: Basic Shop Tools
Print Instructions: Installation Instructions
Install Video:

Vehicle Fitment:

Fits Model Year: 2015, 2016, 2017, 2018, 2019, 2020, 2021

Customer Reviews

Rating Snapshot

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Average Customer Ratings


No more wheel hop!!
It fit great with provided hardware. Super easy install just be mindful of rear lift arm placement ( I had to lift mine twice lol) . Along with all my other IRS stiffeners this part took out the last little bit of wheel hop I had.
Did you find this helpful?  1 of 2 Found Helpful
Verified Buyer   from Greensboro NC on 5/28/2021
Excellent part
Worth the time, money, effort spent. Suppression is more positive, car rolls easier. The car is a PP2 was pretty good as it was, now crisper . Well done Steeda ...........!!!
Did you find this helpful?  3 of 3 Found Helpful
from woodstock on 2/28/2021
Awesome product
Is like night and day in stiffening up my 2015 Premium GT. I have the performance package and I thought I was good but not until I bought and put on this that I realized that I had room to improve.
Did you find this helpful?  3 of 3 Found Helpful
from Adelanto California on 12/5/2020
Quality, easy install !
You can instantly see the quality when opening the box . They were easy to install , but the bolts have changed from the install videos posted . Looks great as well . These were my last chassis stiffening parts before suspension work .
Did you find this helpful?  1 of 1 Found Helpful
from Dacono on 12/5/2020
A track ready upgrade indeed
I currently run an S550 GT PP1 on progressive lowering springs and I installed this along with the Steeda Subframe alignment kit and subframe bushing support. Prior to install the rear end felt loose in the corners and would swing out slightly when pushing it hard making it feel unstable. After installing all three items the car feels planted and drives like its on rails. A far smoother ride on lowering springs (almost better than stock). This is a must have if you love taking your ride to the limit on the street or the track. I can't say if it was specifically this item but the three together worked well beyond my expectations.
Did you find this helpful?  5 of 5 Found Helpful
Verified Buyer   from So Cal on 9/18/2020
Outstanding Product!
These are awesome! Shipping was fast. Installation instructions were concise and easy to follow. Everything lined up nice. The hardest part for me was getting that 18mm wrench in there on the rear plate to stop that nut from turning during torque. I worked on the garage floor with the vehicle on jack stands. I can definitely notice the difference now when driving! Great job Steeda.
Did you find this helpful?  1 of 1 Found Helpful
Verified Buyer   from Greenfield, WI on 9/15/2020
GT350 Install
Nice quality pieces that bolted on without issue. Kit came with good hardware and correct bolt lengths. Highly Recommend.
Did you find this helpful?  4 of 4 Found Helpful
from Texas on 7/16/2020
IRS subframe braces
so let's start with they look great. perform well. i can't tell yea from an individual part how they are because i installed a lot of parts at one time. but they have helped tie the rest together quite well...happy with the purchase
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from texas on 7/11/2020
No more wheel hop
Super easy install did mine on a lift took 20 min. No more wheel hop and harder acceleration makes cornering more smooth
Did you find this helpful?  2 of 2 Found Helpful
Verified Buyer   from New York on 5/30/2020
Great on Whipple 350
Everything is definitely stiffer around corners, yet still seems to feel stock going over uneven bumps. NVH hasn't changed much at all.Substantially helps get the power down on my 750whp GT350
Did you find this helpful?  4 of 4 Found Helpful
Verified Buyer   from Dallas on 5/19/2020
Product review
These braces really made a difference. The car feels much more planted, especially at higher speeds.
Did you find this helpful?  2 of 2 Found Helpful
Verified Buyer   from Maryland on 4/13/2020
Had these installed as well as the subframe alignment pins, differential bushings, lowering springs and sway bars. I feel the car squats less, tracks straighter and is more stable under acceleration. I haven't tracked the car yet. May not have an opportunity to do that until June or later this year. A definite improvement over stock.
Did you find this helpful?  1 of 2 Found Helpful
Verified Buyer   from Libertyville, IL on 4/9/2020
Great product
One of the easiest mods to bolt in. Well engineered and work great. I installed with steeda subframe alignment kit and very noticeable improvement. Rear end tracks much more predictable at speed. Taking my GT350 to the next level. Thank you steeda. Oh and super fast shipping as always even during this corona flu pandemic. Thanks Steeda. You guys are the best
Did you find this helpful?  3 of 3 Found Helpful
Verified Buyer   from Spring Hill on 3/26/2020
Fit and worked good
Did you find this helpful?  0 of 1 Found Helpful
Verified Buyer   from LEBANON , PA on 1/15/2020
Hoppy hoppy grasshopper!
This is a super easy to install, and very effective way to tame the wild bucking horse and get it feeling a lot more 'stable' in the turns and from off the line. Much better feel. Effectively turns your pony into more 'performance sports car' and less 'hopped up 0 to 60 drag racer'. Although it still remains fully capable of the latter, it does so with its hooves firmly planted. I combined these braces with the Subframe alignment kit and the bushing support kit. these combine to make the 'Stop the hop starter kit', and it lives up to its name. Couldnt be happier.
Did you find this helpful?  2 of 2 Found Helpful
Verified Buyer   from Western NY on 12/7/2019
Stop the hop
A huge improvement as far as wheel hope and strengthening the rear subframe. A must have for any s550 owner. Excellent mod! Thanks Steeda!
Did you find this helpful?  3 of 3 Found Helpful
Verified Buyer   from Stanton, tn on 12/2/2019
A true DIY job
I just recently installed these as the final piece of my 'stop-the-hop' parts list. I don't know a lift, so I used ramps. Jack stands would work too, but ramps keep the center cleared out under the car. Lay out the parts and fasteners before. I used a 15 mm socket and ratchet to remove the factory bolts and install the Steeda-provided hardware. The only tool I didn't own was a 10 mm allen socket. It would be great if Steeda sold those as a $5 option, but you can get one at your local parts store. Install takes about 45 minutes or so. I didn't hurry and started all bolts before tightening and torquing. Everything lined up the first time and I didn't need to loosen any factory sub-frame bolts. I have not yet driven the car since I installed them, but I am 100% certain they will perform the way Steeda designed them to. I don't know if there is another company making something similar, but I can say this: Steeda is worth the money. They do their own R&D, the parts are made in America, and they fit the first time, every time.
Did you find this helpful?  5 of 7 Found Helpful
Verified Buyer   from Georgia on 10/26/2019
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!
Did you find this helpful?  11 of 11 Found Helpful
Verified Buyer   from on 9/10/2019
2019 bullitt
Very good product
Did you find this helpful?  3 of 3 Found Helpful
Verified Buyer   from Canada on 8/1/2019
2019 Bullitt
A must have no mustang completed without steeda sub frame connectors..
Did you find this helpful?  5 of 5 Found Helpful
Verified Buyer   from Texas on 7/29/2019
great product
I am a old SCCA road racer and love modifying my street cars to handle the best the can if and when I ever it to the track for a HPDE day. I have several Steeda handling products on my 2018 GT PP1 and love them all. I am not a tire burner and didnt really know if this would help the unbalance feel I seam to notice in the rear of the car, but thought I would give it a try. Adding this subframe support brace really brought everything together. I highly recommend this for the curves that you want to master.
Did you find this helpful?  13 of 13 Found Helpful
Verified Buyer   from CA on 5/2/2019
Stop the hop
These are top notch products and highly recommend them! Very easy install .??
Did you find this helpful?  3 of 4 Found Helpful
Verified Buyer   from TN on 4/4/2019
Best thing to stop wheel hop
I bought mine before they had the stop the hop kit but the best thing I bought to get rid of wheel hop, and keep the tires planted down on the road or track. The stop the hop kit from steeda should be the second thing you buy for the mustang!!! (First being the jacking rails to make install of the kit easier)
Did you find this helpful?  14 of 15 Found Helpful
from Acworth on 6/12/2018
Fantastic Product
I installed the braces in about 1hr using the list of tools provided in the instructions and it went smoothly with only 1 very minor issue! When doing this job I suggest that you tap the unused factory threaded holes prior to starting the installation they had some corrosion that didn't allow the bolts to start properly. I took it out for a dirive after the installation and listened for any noises and drove easy . There were none . I then drove somewhat aggressively and the wheel hop was no longer there and the car felt much better as far as stiffness goes! This is a fantastic product and I highly recommend it to everyone!
Did you find this helpful?  22 of 22 Found Helpful
from Brooksville, FL on 11/26/2017
Like these Support Braces
Installed these support braces a couple days ago using the easy to follow written instructions after viewing an installation video on u-tube. The install (driveway on jack stands) was easy and straight forward taking about two hours from start to finish. During post install test drive, the car felt much more planted on hard acceleration and definitely tracked straighter without getting sideways when shifting into second and third. No change to normal ride characteristics (harshness etc.) or change to NVH. Really like the planted feeling of the cars rear end when punching it. Recommend this item to help keep car straight when accelerating hard and banging a gear. No cons.
Did you find this helpful?  13 of 13 Found Helpful
from Gloucester Courthouse on 11/25/2017
There are no reviews for this product!

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