1979-1993 Fox Body Mustang Lower Seat Spring Install & Lower Frame Restoration

Today, we'll show how to replace the lower seat springs in a Fox Mustang and do a little bit of lower seat frame resto.

While removing the old upholstery and foam, we found that the passenger lower seat frame had some bad rust and needed some help to make it look better. Not to mention, the lower roll spring for the seat foam had rusted through and broke and needed to be replaced.

The roll spring and four helical springs are easy to remove and install, but they require a little disassembly. You will have to remove the seats from the car, remove the seat track assembly, separate the seat back from the seat bottom, and then remove the lower seat foam from the frame to expose the springs.

Most of you will be replacing the lower seat foam springs while you're installing new upholstery, but there may be those few times that you need to replace these components without installing new upholstery and foam. We already have a few articles that will help you with this process. Check out the seat removal and the upholstery removal article.

Tools Needed

• Socket and Wrench Set
• Power Ratchet or Hand Ratchet
• Flat Head & Phillips Screw Driver
• Wire Cutters
• Trim Removal Tool
• Pliers
• Paint
• Scuff Pad

1. With the foam removed from the seat frame, use a pair of pliers or another applicable tool that works for you to remove the four helical springs from the seat frame.




2. At the front of the frame, lift up on the four tabs with a small pry bay.



3. Remove the roll spring from the seat frame.

1. If you’re going to restore the frame, follow along for the next several steps. If not, feel free to skip ahead to installing the new roll spring and helical springs.



Disconnect the electrical connection and dislodge the harness push pins.





2. Carefully remove rubber lines from the air pump and remove this assembly from the frame.




3. Remove the (2) Phillips head screws securing the pump to the frame and remove the air pump.




4. Carefully remove the snap ring from the clevis pin that secures the pivot plate arm to the seat frame.



5. Drive out the pin and do the same for the other side.



6. Loosen and remove the bolts securing the bolster adjustment plates and remove plates.



7. Loosen and remove the screws securing the lumbar switch bracket to the frame and remove bracket.



8. Remove the roll pins from both sides of the driveshaft with a pair of pliers or a suitable punch and hammer.



9. Remove the driveshaft and the two washers.



10. Hold the adjustment block with one hand and turn the screw with the other to remove these components. There is one on each side.



11. Keep in mind that the adjustment blocks and screws are side specific, so make sure you make a mental note of which side is which.



12. At the front of the frame, loosen and remove the Phillips head screws securing the metal clips and plastic guides for the pullout knee bolster. The frame can now be prepped and painted.



13. I utilized our shop equipment and media blasted the frame, the lumber switch bracket, and the knee bolster clips. If you don’t have access to a media blaster, some good old-fashioned elbow grease will do the trick. Working in a well-lit and well-ventilated area, spray the frame and other components with a black e-coat. The SEM version we sell at LMR.com is our favorite. Allow plenty of cure time before reassembly.



14. We soaked the hinge plates and the other hardware in some naphtha and cleaned this stuff with a wire wheel on a bench grinder. If you don’t have this, wire brushes and scuff pads will work just fine.



15. At this time, you'll begin reassembling all of the components into the lower seat frame. Just reverse the removal steps.



16. When reinstalling, you may want to take the time to clean, degrease, and reapply grease to all previously removed compoenents.



17. IMPORTANT: To “zero” the adjustment screws, hold the plate with one hand while you turn the screw. Whenever you feel the screw begin to push against the plate, stop turning.

1. The next few steps for the roll spring will be shown on the driver side seat frame that didn’t need the restoration work. First, you’ll want to gently bend the (4) frontward tabs a little to make the installation easier with a small pry bar.



2. Position the roll spring into place.



3. Hook either side of the helical spring over the roll spring and then pull the helical spring into the seat frame with a tool that has a hook on it. Do this for all four of the springs.



4. If you have sport seats, you’ll notice that the roll spring is technically too wide. This is an easy fix to replicate the width of the factory roll spring.



5. On the outboard side of the spring, cut the wire in separate sections to remove it from the grouping rod.



6. Roll the ends of the wire off the metal reinforced rod at the front and rear of the spring. Trim the grouping rods to length, leaving a bit of material on the ends. Repeat these steps for the other side.



7. Tap the four tabs with a dead blow to even them out. Now you can reverse the removal steps to put everything back together.



8. After that, you’re good to go!

We hope this step-by-step article has provided a better understanding of removing and installing the lower seat spring and restoring the lower frame in your 1979-1993 Fox Body Mustang.