How To Replace Rear Seat Sound Deadener | 1984-93 Mustang

In this article, we’re going to be taking a closer look at this rear seat sound deadener piece designed for the backing plate in 1984 to 1993 hatchback Fox Mustangs. So the back story on how this section of sound deadener came to be is just like several other components that we've talked about on camera; it originated from LMR owner Shannon Guderian's full-on restoration of his Uncle Ted’s 1985 ASC McLaren. While assembling the interior, Shannon wanted as many new parts or like-new parts as he could get his hands on, but this particular piece of sound deadener was non-existent. So, we made one!

This section of sound deadener is sandwiched in between the rear seat backing plate and the floor on 84-93 hatchback Fox Bodys. Its intended purpose is to be a transition filler piece from the trunk area to the seat well and helps dampen sound/road noise from this area. These are commonly ripped, torn, or missing and can also be dirty from spilled drinks or general filth. So if we take a closer look at the 5.0 resto piece, you’ll notice that the material is a heavy-duty felt and that all of the cutouts and overall dimensions mimic the factory piece. The pre-cut design will help save you time and money!

In terms of the felt material, 5.0 Resto’s sound deadener is very similar to the factory part, but is slightly thicker and does not have the thin piece of jute backing. From the factory, this section of sound deadener was secured to the backing plate with staples. So in an effort to make the installation very straightforward, we had a thin strip of pressure-sensitive adhesive applied to the felt material so that it easily attaches to the hinge on the backing plate.

The adhesive will allow the backing plate and the sound deadener to be an inclusive piece which greatly helps with the reinstallation that way you’re not juggling two individual components and struggling with lining everything back up. Now for those of you considering other restoration items for your hatchback Fox Mustang, this sound deadener pairs well with the items like the hatch area carpet.

Application

So, as far as applications are concerned, 5.0 Resto’s rear seat backing plate sound deadener is designed to fit 1984 to 1993 hatchback Fox Mustangs. In the box will be a pre-cut piece of sound deadener and a hardware pack that includes all new hardware for the general area. Today we’ll be installing this piece into our 1993 LX Fox Body Mustang.

Fox Body Rear Sound Deadener Replacement Steps

1. Because of the positioning of this sound deadener, removal of the seat backs is not required. Although, for some additional working room, we would recommend that you remove the front seats and, of course, the rear seat bottom.


2. With the front seats and rear seat bottom out of the way; release each rear seat back and fold them down. To gain access to the (4) seat back to hinge bolts, you’ll need to roll back the hatch area carpet. This carpet is secured to the backing plate with trim screws.


3. Remove the (4) 7/16" seat back hinge bolts. There are (2) per side.


4. Locate the outward 7/16" bolts securing the backing plate to the floor, remove these from the plate.


5. Go ahead and remove the (5) Phillips head screws securing the backing plate to the car.


6. Bring the backing plate forward to clear the rear interior quarter panels and remove the plate from the car.


7. With the plate on a workbench, use a flat head screwdriver to lift up on the legs of the staples. Work your way across the plate until all of the legs on the staples have been released.


8. Flip the plate over and carefully dislodge each staple with the flat head screwdriver. Fully remove each staple with a pair of needle-nose pliers.


9. Discard the old sound deadener and use this time to inspect the plate. Our plate definitely had room for improvement so we used this opportunity to spruce it up a bit. First, we used a dead blow and flatten the hinge on level ground. If needed use a block of wood and hammer to dolly out any high spots from the staples.


10. Remove the (4) 7/16" bolts securing the seat back strikers and set these aside.


11. Next, we thoroughly cleaned the backing plate with a brush and all-purpose cleaner. Wipe up the residue with a microfiber towel. After that, we scuffed the entire plate with a green scuff pad, warm water, and dish soap as a lubricant. Wipe up the residue and use compressed air to blow out the nooks and crannies. Thoroughly wipe the plate with a clean microfiber towel and paint prep.


12. Working in a well-lit and well-ventilated area, paint the plate using black e-coat. I found this to be a very close match to the original OEM finish. Follow the directions on the can until the entire plate is painted.


13. Don’t forget about the seat back strikers. Scuff, prep, and paint these as well, and give everything time to dry.


14. With all of the parts dry, we’re ready for reassembly. Roll out the new sound deadener and dry-fit the plate first. The adhesive section will adhere to the underside of the hinge and the material will face towards the front of the car.


15. Make sure the hinge is centered on the new sound deadener, and then use a fresh razor blade to cut just the tape liner. Don’t cut all the way through.


16. Remove the liner from the tape and attach the hinge to the tape. Firmly press the tape to ensure that it properly bonds to the hinge.


17. At both ends of the hinge, cut the material alongside the plate. Remove the liner and then roll the material over and secure it to the top side of the hinge. Do this for both sides.


18. Align either one of the strikers with the existing marks on the backing plate and tighten the provided hardware. Do the same for the other side.


19. At this point, the backing plate is ready to be reinstalled into the car. Position the plate underneath both sides of the rear interior quarter panels.


20. Align the bolt and screw holes and first loosely install the (2) outward bolts.


21. Install the (5) of the provided self-tapping trim screws into the existing holes.


22. Go ahead and fully tighten the (2) outward bolts. By the way, these bolts don’t have to be crazy tight.


23. Lift up on the seat back and align the hinge with the holes. Install the provided bolts and tighten them down. Do the same for the other seat back.


24. Reposition the hatch area carpet and secure it to the backing plate. We do provide (4) new screws if you want to use them.


25. Lift up on the seat backs and reengage them into their respective latches.


26. Reinstall the rear seat bottom and front seat seats, and then you’re good to go.

Wrapping things up with 5.0 Resto’s hatchback backing plate sound deadener; this is definitely a must-have finish-out piece for your Fox Body project.