How to Install Lowering Springs on Your S550 Mustang

How to Install Lowering Springs on Your S550 Mustang

Last Updated July 21, 2021 | Bill Tumas

2015-2018 Mustang Lowering Springs Installation

Here at CJ’s, we've shown you several different ways to lower your 2015 Mustang using lowering springs from well-known manufacturers such as Ford Racing, Steeda, and Eibach. The one thing all these springs have in common is they always lower the back more than the front to give the car a nice flat stance. Many have said that sometimes it actually looks like the rear sits lower than the front. The reason for that is because it’s an optical illusion.

If you look at a 2015 Mustang, the rear wheel wells actually sit closer to the ground than the front ones do from the factory. We've always felt that a more even look between the front and rear would make the S550 look a lot better. That can be done with a set of raked springs. By raked, we mean that the front is actually lowering the car a bit more than the rear for an aggressive, muscle-car stance.

We’ve teamed up with a well-known spring manufacturer to produce these CJ Pony Parts springs that are going to lower the front end of your Mustang GT 1.5" and lower the rear 1" and EcoBoost, 1” all around.

Today, we're going to show you how to install a set of these CJPP Springs along with a pair of Maximum Motorsports Caster Camber Plates using our 2015 Mustang GT.

CJ Installation Video

Step-By-Step Instructions

Tools Required:

  • Lift and Pole Jack or Jack and Jack Stands
  • 1/2” Ratchet
  • 13mm Socket
  • 18mm Socket
  • 3/4” Socket
  • 13/16” Socket
  • 15/16” Deep Socket
  • 21mm Socket
  • Short Extension
  • 15mm Wrench
  • 17mm Wrench
  • 1/2” Impact Gun
  • Panel Removal Tool
  • Hammer
  • Spring Compressor

Installation Time: ~2-3 hours

Difficulty: Moderate

Tools laid out on bench

  1. The first step of the installation will be to get your car up off the ground and remove all four wheels using a 21mm deep socket.Lifted Mustang without wheels or tires
  2. With your front wheel off, you can begin by disconnecting the sway bar from the front strut. In order to do that, you’ll need to grab a wrench and put on the back side to hold the sway bar while you remove the nut. Once the nut is off, just move the end link. Closeup of front strut and sway bar
  3. With the end link out of the way, it’s time to disconnect the caliper. On the back of the caliper, you’ll find two 15mm bolts holding the caliper to the spindle. Once you remove those bolts, you’ll be able to slide the caliper off the rotor and set it aside and out of the way. Be sure not to let the caliper hang by the brake hose! Bill removes the brake caliper
  4. Once the caliper is set aside, be sure to remove the two ABS line connections from the strut using the panel removal tool. You can then remove the rotor.

    Note: Removal of the rotor isn’t mandatory, but suggested. If you leave the rotor on the spindle, just put a lug nut back on so it doesn’t fall off the spindle after the strut is removed. Carefully removing the ABS line
  5. Next, you’re ready to remove the two bolts holding the spindle to the strut. When using your impact to remove these nuts, be sure to leave the nuts just to the end of the bolt. The reason for doing this is because you’re going to have to hammer these bolts out since they are splined and pressed into the spindle. Leaving the nut on the end allows for more surface area to hit so you don’t mushroom the end of the bolt. Bolt is mostly unscrewed, with nut still attached
  6. You’re now ready to hammer the bolts out. Be careful to make sure the nut is perfectly on the end of the bolt as you’re hammering. Once you’re past the splined portion of the bolt, you can remove the nut and should be able to pull the bolts out by hand.

    Tech Tip: If this is the first time these bolts have been removed, they can be stubborn. You may have to put some serious force to get them to budge, but they will eventually come out. The splined portion of a bolt
  7. Next, you’re ready to separate the strut from the spindle. Remove the nuts and jiggle the spindle to slide the two strut bolts out. You can then let the spindle hang. The wheels spindle hangs
  8. You can then move up to the engine bay. The strut is held to the strut tower by three nuts. Remove the first two and then when you’re ready to remove the last one, make sure you’re holding the strut from the bottom or it will fall off. closeup of strut tower bolt being removed shot from further away showing how to hold strut in place
  9. Move the strut assembly to a table or floor that you can work on – now it’s time to remove the spring from the strut. First, you’ll have to use a spring compressor to compress the spring and then you can remove the strut mount nut from the top.

    Safety Note: This is potentially the most dangerous part of this installation. When the spring is on the strut, it’s under hundreds of pounds of pressure. Be sure to get a high-quality spring compressor like the one we are using for our installation. The removed strut assembly
  10. You are now ready to compress the spring in order to remove the strut mount nut on the top. You will know that you compressed the spring enough when the rubber at the top begins to separate from the mount. A compressed spring
  11. Once the spring is fully compressed, the pressure is off the strut mount, meaning you can remove the nut on the top. While removing the strut mount nut, be sure to hold the mount so it doesn’t spin. Removing nut from top of strut mount
  12. Once the mount is off, you can pull the strut out from the spring. At this point, you will want to carefully decompress the factory spring. The decompressed spring
  13. Before putting the new CJ Pony Parts Spring on, there are a couple of changes that need to be made. You’re going to want to remove the dust boot and factory bump stop off the strut. The CJ Pony Parts Springs come with lower profile bump stops and a new dust boot to install in their place. dust boot is removed from the strut
  14. Slide the new supplied bump stop into the new dust boot and slide on the strut as shown. sliding new bump stop into place
  15. While we are installing these raked springs, we wanted to add Maximum Motorsports Caster Camber Plates on our GT as well. These caster camber plates will allow us to dial in our alignment to perfection after the springs settle. caster and camber plates to also be installed
  16. The Maximum Motorsports Caster Camber Plates are going to replace the top of the strut mount. You’ll want to separate the top of the factory strut mount and replace it with the new Caster Camber Plate. Orient the stud plates with the bearing plate assemblies as shown below. The horizontal notch in the stud plate should be parallel with the horizontal edge of the bearing plates. Caster camber plates being lined up with bearing plates
  17. You’ll then want to align the new Maximum Motorsports plate on top of the rubber insulator until they slide into place. The caster camber plate should be able to spin cleanly within the rubber insulator. New assembled strut mount
  18. You’re now ready to assemble the strut with the new CJ Pony Parts Lowering Spring and Maximum Motorsports Caster Camber Plate! You can start by putting the new spring into the compressor and compress the spring. You can then slide it into the strut assembly. Compressed lowering spring strut being inserted into sring
  19. After making sure the spring is seated properly in the bottom spring isolator, you can grab your new caster camber plate and mount and slide it over the top. Be sure that the rubber isolator on the mount is seated correctly around the top of the spring and begin to tighten it down.

    Tech Tip: You’ll know when the strut mount is completely tightened when the mount or strut spins as you’re tightening it. Grab the mount with a towel or cloth while you’re tightening the nut so it doesn’t jolt when you’re holding it. adding the caster camber plate mount
  20. Once the top nut is tightened, make sure one more time that the spring is seated properly in both rubber isolators. Then, you can decompress the spring to complete your new spring/strut assembly. The completed strut assembly
  21. Now, you’re ready to re-install the new assembly in your Mustang. Make sure the “ear” of your new Maximum Motorsports Caster Camber Plates are facing the outside of the car when sliding up the strut tower.

    Note: If you’re still using the factory strut mounts on your installation, there is no specific orientation the mount needs to go when it’s installed in the strut tower. Correct orientation for caster camber plates
  22. Next, slide the assembly from the bottom of the car into the three bolt holes in the strut tower. Grab the included Maximum Motorsports top plate, washers and nuts and hand tighten them into place. Connecting new strut to strut tower
  23. Next, you’ll want to connect the spindle back together with the bottom of the strut. Before doing this, make sure your ABS line is where it’s supposed to be. Slide each bolt through and put a nut on each end of the bolt. Remember, these are splined bolts so give them a tap with the hammer to start them off. Then, tightening the nuts will pull the bolts completely tight. Bolts in correct location and ready to be tigthened tightened bolts
  24. After the strut to spindle bolts/nuts are completely tightened, you can reinstall the rotor and caliper.

    Tech Tip: When you put the rotor back on, put one lug nut on to keep the rotor still while you reinstall the caliper. Brake rotor is reinstalled
  25. After that, make sure your ABS lines are all back into place correctly and then you’re ready to reconnect the sway bar end link. Remember, you’ll need a wrench and impact to tighten properly. sway bar end link
  26. Once the sway bar end link is tightened, move to the engine bay. Torque the three strut tower nuts to 46 ft/lbs. Three strut tower nuts being torqued to spec
  27. Next, repeat the entire process on the other side and then you can move to the rear suspension.Bill stands under the rear suspension of the Mustang
  28. On the rear end, the first thing you want to do is pop out the ABS line to give yourself some more room. Then, unbolt the brake line bracket. Popping out the rear ABS line
  29. Next, you’ll want to remove the two rear strut mount bolts. Using a drill to remove the rear strut mount bolts
  30. Next, pop the black cover off by rocking it back and forth. Then, you’ll want to remove the single strut nut on the top and remove the mount from the strut. The single strut nut Removing the mount from the strut
  31. You’ll then want to remove the rear dust boot and bump stop from the strut. Note that there is a little ridge at the top of the strut that will take some strength to get the bump stop over. Pulling the rear dust boot off of the strut
  32. Once you have it off, just separate the factory bump stop from the boot by pushing it down inside. Pushing the bump stop free from the boot
  33. Here, you can see the height difference between the factory bump stop and the CJ Pony Parts Lowering Spring Bump Stop. Side by side comparison of bump stops
  34. Slide the new bump stop into the dust boot from the bottom as shown below. Then, reinstall it on the rear shock with the bump stop at the top. Sliding the new bump stop into the boot The bump stop and boot back in location on rear strut
  35. Next, you’re ready to tackle the rear springs. Grab your pole jack and support the rear subframe. Pole jack is used to support the rear of the Mustang
  36. Next you’ll want to move to the bracket connecting the rear subframe to the body. Loosen these two bolts but leave them partially screwed in as the bracket does not need to be removed. Removing the bracket that connects the rear subframe
  37. Next, you’ll want to remove both subframe bolts on the side you’re working on. There’s one near the bracket and then another in the rear. subframe bolt is pulled clear Second subframe bolt is pulled clear
  38. Next, you’ll want to slowly lower the rear subframe until there is no more tension on the spring. Pole jack is used to lower subframe
  39. Pull down on the suspension and use your other hand to pull the spring out of the subframe. Hand pulls down on the suspension Other hand reaches around wheel to pull spring free
  40. Remove the insulator from the factory spring and transfer it over to the top of your new CJPP Spring. Be sure that the logo is facing upward as you install it back in the car. Insulator is placed on top of new spring
  41. Next, you’ll install the new spring the same way you removed your factory one. Make sure the end of the bottom coil matches up with the stop in the bottom of the bucket on your rear subframe. spring is reinserted
  42. Once the spring is in place, raise the rear subframe using the pole jack. Make sure the spring seats properly as you’re raising the subframe up. Pole jack is ued to raise the subframe
  43. Then, you want to put both subframe bolts back into place. Just make them hand-tight for now. Then, tighten the bracket back into place. Reinserted subframe bolt being tightened by hand Socket wrench tightens the subframe bracket into location
  44. Hit both subframe bolts with the impact to get them fully tightened. Impact drill is used on subframe bolt A view of the impact drill from further away
  45. With all the subframe bolts back in place and the spring installed, you can let down the pole jack and move to the rear shock. Reinstall the mount on the shock and then put the black cap back on. Mount is reinstalled on rear shock
  46. With the shock and mount back together, you can re-install it on the car. Slide the mount under the tabs on the body to hold it in place. Hand tighten the bolts to get them started, then fully tighten. Bolts on mount being tightened by hand Correctly positioned strut mount
  47. The last step is to re-install the ABS line and brake line bracket you removed originally. Reinstalling ABS Line
  48. Repeat the process for the rear suspension on the other side and your installation is finished! Lowered Black S550 Mustang GT

Please Note: Please keep in mind that this guide is a tool to help you install the parts on your vehicle. If you don’t feel confident in performing this installation properly on your own, have a professional install the parts for you.

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About the Author

Bill is our resident Mustang expert with over 25 years in the auto industry. He’s produced hundreds of videos as the host of the CJ Pony Parts YouTube channel. Read full bio →

How to Install Lowering Springs on Your S550 Mustang

We really dig the look of these CJ Pony Parts springs on our 2015 GT. The lowered look screams, “modern,” while the raked look screams “old school muscle car.” Best of all, with the Maximum Motorsport Caster Camber Plates installed, we’ll be able to get our alignment dialed in perfectly. Installation is a little more involved than those Mustang owners who may be used to doing lowering spring swaps on solid rear axle cars, but definitely do-able for the do-it-yourselfer.