I just finished installing a 4 guage amp wire from the battery to the trunk, and I thought I'd give a little detail on how I did it without drilling holes or too much cussing

I ran the wire through the rubber grommet in the firewall, so no drilling was necessary, much like how this install was done:

https://www.rx8club.com/showpost.php...45&postcount=6

Now that looks fine, but easier said than done! But its not really that bad, if you do it like I did.

For the wiring kit, I used this one (although any 4 guage kit should work similarly):

http://www.cardomain.com/item/ROCCP4POR

First thing first, getting the wire through the firewall. Since this amp kit has a fuse block attached to one end of the power wire, I decided to run the entire wire from under the hood into the car, and back into the trunk.

Looking at the photo of the installation from above, you will see that the wire was poked through the grommet on the lower right side. This is exactly what I did too. First, I took a large screwdriver and poked a hole in the grommet from inside the car. The screwdriver easily went on through into the engine compartment.

Next, I got a short length of 16 guage wire (about 2 feet) and duck taped it to the power wire (the end that will be fed into the firewall), and duct taped the other end to the screwdriver (the part sticking into the engine compartment.) Make sure you get a good hold, wrap the tape around once, the whole width of the duct tape. Once you have that in place, you should be able to pull on the screwdriver handle, pulling the power wire through the grommet into the car. Pull slowly, and maybe have someone guide the 4 guage wire into the grommet opening. From there it should come right through the grommet (it will make the hole bigger, but it will come through.)

That was the hard part. Remove the screwdriver, but leave the 16 guage wire attached to the power wire! You will use this to guide you the rest of the way. Feed that 16 guage wire through where you want to go (around the fuse panel, under the wire cover along the drivers door.)

Now the next part, getting it to the trunk. Take a new piece of 16 guage wire (about 3 feet long) and start in the trunk. Pull back the flooring on the drivers side so you can feed the wire down into the corner behind the back seat. Feed this as far as you can, at least a foot. After that, go inside the car and lift up the front part of the back seat behind the driver. The front of the seat is held by a couple of snaps, it should pull right up. From there, you should have enough room to reach your hand under the seat and feel around for the wire you fed in from the trunk. Once you have that, tie it to the wire attached to your power wire (twist it tight), then go to the trunk and pull it through. Again, you might want help to guide it up. Be careful that your power wire is UNDER the seat belt!

Power wire has been run! For the ground wire, I attached it to the spare tire mount, located behind the side panel on the drivers side of the trunk. Be careful pulling away the carpeted covering, that snap breaks easily. I tested this bolt with a multimeter and had zero ohm resistance, so it was a good ground. I had to dremel the hole on the ground clamp a tad bigger so the bolt would fit through it.

Thats it, I hope this helps take some frustration away for someone

Just another quick note, the way I did the ground test: I took a multimeter from Radio Shack, set it on RX100, and shorted the +/- terminals. It should read exactly zero. If not, tune it in with the adjustment ****. Once that is done, get yourself a length of 16 guage wire, about 15 ft (enough to reach from the battery into the trunk.) First, test this wire. Put your multimeter terminals on each end of the wire, be sure you still get zero ohm reading. Next, run the wire from the battery negative (-) terminal into the trunk of the car (outside the car ). Touch one multimeter terminal to this wire, and the other terminal to a ground location in the trunk. Find a spot that reads as close to zero as you can. Anything more than 1/2 ohm resistance is not good! My location on the spare tire mount read zero.

 

great, you should move this to the DIY section.

 

not to throw a wet blanket on this cause he did a great job but entering through that grommit is very risky there are hundreds of exposed wires there plus if the wires heat up you may have a mess on your hands.

the good old, remove the wash fluid tank,,,drill a hole through the firewall at the center of the circle is much safer

good luck guys...I'm glad you did it without wrecking havok (it appears)

 

The wire came through the grommet with plenty of room to spare. ie, it didn't push the existing wires around whatsoever. As for heat, I'm running a 400W amp on 4 guage wire (the amp calls for 8 guage), so I would hope heat would not be an issue. I'll keep on eye on that though.

 

you sound like you know what you are doing...I'm not worried I'm worried about some people if you know what I mean (Tim Taylor home improvement type guys )

 

Yeah I see the concern, if you damage these wires it could be a mess However, the existing wires are in their own taped up bundle, and the risk of hitting them is pretty low if you are careful.

 

Do all the RX8's have the spare tire mount? If they do, where is it exactly located? Can you give a more specific location with detail on where this exactly is?

Thanks

 

It is on the trunk wall on the drivers side (mine is left-hand drive) close to the back seat, just pull the carpeted covering toward you, there is one plastic snap in the middle of it (that is snapped into the tire mount itself)

I would assume all RX8s have this, but I only have mine to go by. I have no spare tire, just a tire kit. I'm actually guessing this is a spare tire mount, but it looks like one to me.