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How to Install a Moroso Sealed Polyethylene Battery Box on your 1979-2014 Mustang

Installation Time

3 hours

Tools Required
  • Drill
  • ¾ drill bit
  • 7/16 drill bit
  • 9/16 socket
  • Ratchet
  • 9/16 wrenches
  • Glue
  • Wrench for battery clamps
  • Marker
  • Vacuum
American Muscle
Shop Parts in this Guide


1. Use the hold down bracket to mark the bottom of the battery box where you will drill the holes for the hold down bolts. 

2. Use the hold down bracket again to mark the trunk floor where the bolts will go through the floor. Make sure there isn’t anything under the proposed holes that you don’t want nicked, cut, or drilled through. Drill the holes.    

3. Drill a ¾ inch hole through the trunk floor for the vent tube and install the grommet.

4. Thread the hex nuts onto the hold down bolts a bit more than an inch up the threads. Place the box in place and pass the bolts through the holes and through the trunk floor.

5. Depending on where you drilled you holes you may need to move some stuff out of the way to access the bottom of the bolts. In my case I had to lower the gas tank by loosening the bolts holding the straps under the tank about as far down as they would go and still hold the gas tank up. Use a jack to hold the tank up while loosening the bolts.

6. Thread the lock nuts onto the bottom of the bolts; make sure the bolts are at least a full thread past the nut.

7. Tighten the hex nut holding the battery box down.    

8. You can drill the holes for the cables and vent before installing the box. I chose to do it afterwards so that I was sure where I wanted the cables/vent to exit the box. Drill (2) 5/8 holes for the cable grommets and one ¾ hole for the vent grommet.

9. Install the grommets; I used some glue to make sure the grommets stay in place.

10. Tighten the hex nut holding the battery box down.    

11. Install the Swell Latches by putting the threads through the lid, then the 2 rubber bushings, and then the nut. Hand tighten the nuts until the rubber bushings start to bow just a little bit.    

12. Install the vent tube through the grommet in the box and through the trunk floor.

13. Install the battery and tighten the terminals onto the posts.

14. Slide the bracket down the bolts over the battery. I used regular hex nuts and lock washers instead of the lock nuts to secure the hold down bracket.    

15. Install the lid by putting the Swell Latches through the holes in the box, and push down the tabs to seal the box.    

16. Vacuum up all the shavings from any drilling. Not applicable in my installation was dealing with the carpet. However if you still have the trunk mat to deal with remove it before you drill the holes in the trunk floor for the bolts and vent. Before installing the box, replace the carpet, feel for the holes you drilled and use a razor knife to cut x’s for the bolts and vent tube.

Installation Instructions Written by AmericanMuscle Customer Stephen Vilcot 3/20/2013   

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