I'm installing some subs in the trunk of my '04 WRX, and was wondering where the best grounding point for my amp should be. In looking under the carpet in the trunk, I noticed on the left side of the trunk, near the jack, an open spot in the material about 3"x3" and was considering this spot for the grounding point. If anyone has any suggestions, they would be much appreciated. Pix of wrx trunk installs that show the ground attachment would help a lot too. Thanks.

 

1. find an inconspicious metal spot near the amp. (under the rug etc.)

2. get a flathead screwdriver.

3. rub the spot until you see bare metal. (only about 1/4" in diameter)

4. negative amp wire + fork/round connector + self-tapping screw = good ground.

 

Thanks, this helps. One concern that I have is that I'm worried about drilling the pilot hole for my screw in the wrong place. I would hate to drill into an important component under the trunk. This is why I mentioned this 3" square opening in the material that lines the trunk, under the rug. I'm just hoping it's okay to screw something in at this spot.

 

nevermind, nothing under the point at which I want to put the ground. I guess I should have just felt around a little more. And to anyone interested, the 3" square is a pretty good spot to put a ground.

 

he-he, forgot to mention to look for important parts.

i used to install systems back in the day and a "friend" wanted to come in and work on his mustang himself using our tools. it was pretty slow so we let him. a few hours into it i go and check how he is doing and i smell gas. he had drilled six holes in his trunk leading directly to his gas tank! i damn near died laughing. so yeah, always check b4 you drill.

 

Sounds like that mustang project turned into more than your friend bargained for! I was more worried about drilling into the muffler, but I would say that there is at least 4" between the bottom of the trunk and the top of the muffler @ this point.

Is there any problems with using a bolt and nut instead of a self tapping screw to connect the ground? I'm able to reach both sides of the trunk floor pretty easily to do so. I was thinking of doing this with a 1/2" bolt and using RTV sealant for the nut connection under the trunk (for waterproofing? there is a small chance for water and grime to get to the spot above the muffler)

 

a nut/bolt would do, as long as the size of the hole is as tight as the threading on the bolt. with a tight fit its really unlikely for enough water to do any kind of damage from that angle. i imagine gravity would take care the majority of the moisture that might even get to that spot, which really shouldn't be that much. your car would have to be submerged in water up to that point for a good period of time, in which case you would have more to worry about than a bad ground. sealant would work, as would a rubber washer.

i actually mounted my first amp upsidedown on the back panel just underneath the 3rd brakelight and grounded it there as well. it was small enough to fit just right and was about as stealth as it gets. i just zip tied the wiring along the trunk rails leading to the amp and made sure to leave some slack for the wires not to catch anywhere. however, i am in the process of adding a subwoofer. which means another amp, which means i will soon be looking for another good ground spot as well.