Best amp location and "firewall" pass through

gilach · gilach's Garage

hello all,

i'm installing a new stereo in my 78. what's the best location for the amp? in the trunk or under the passenger seat? Apparently the amp i got doesn't get super hot so i think it would be fine under the seat.
now my second question, regardless of amp location i need to bring the wires in from the interior to the trunk. what's the easiest location to pull the wires in? i'm assuming the passenger side, but i'm really not sure. any help would be appreciated.
would a wire snake make things that much easier?

javadog · 04-26-2006, 05:20 AM

I've successfully mounted a pair of amps under the passenger seat of an SC. I made some z-shaped brackets that were fitted between the seat and the seat rails. The amps were attached to these. I isolated the amps from ground using rubber grommets in the mounting holes. No drilling was needed. The car's long gone, so I don't have pictures.

Crawl under the dash and see if you can find an unused hole that is plugged with a plastic plug. Most of my cars have at least one or two. If you don't find any, drill one where you want it with a uni-bit. Just check carefully before doing so, to make sure the location is where you want it and nothing is in the line of fire, so to speak. Rust-proof the edges of the hole with primer and paint. Install a wire grommet to protect the wires.

JR

wcc · 04-26-2006, 05:40 AM

You can put the amp under the PS seat easily. I managed to fit a small one under the DS seat also. So that isn't a problem.

As for you wires:
Run them along the air duct on the passenger side. Remove the carpet in the trunk and over by the hood strut you should see the air duct. Run it along side of that. Also, you'll have to remove the PS foot board and on the right side the kick panel. Then I ran my wires to the back seat under the carpet along the tunnel. I wouldn't drill any holes....

Good Luck!

Kraftwerk · 04-26-2006, 06:47 AM

He is right There is at least one extra extra hole in the pass. fire wall...

gilach · gilach's Garage

Any feedback on how to get the wires into the door speakers...checked it out, but it seems very tight? Should i attach the new wires to the old ones and then pull them through...will this work?
great, thanks for the advice guys.

javadog · 04-26-2006, 07:04 AM

Yes, you can use the old wires to pull the new ones into the doors. Just make sure you connect them well.

JR

Mysterytrain · 04-26-2006, 11:54 AM

I think the amp in the trunk makes the most sense as far as the wiring goes. If the amp is under the seat you need to think about the wiring harness that will feed it. Speaker wires- 2 or 4 pair of heavy guage, left and right stereo inputs, power -12 guage or so, ground back to the battery, the sensing wire for turn on. Sounds like a lot to 'sweep' under the carpet. The trunk mount would have everything close by ie: battery power, battery ground fuse panel and a short run from the backend of the stereo. I've seen some intersting mounting arrangements that replace the fiberboard and allow the amp to be tucked away up behind the dash hidden by the carpet and the trunk still usable.

Kroggers · Kroggers's Garage

Not the best pic I know, but here is my amp installation.

Britain Smith · 04-26-2006, 12:23 PM

Here is an old picture of mine...

-Britain

MuffinMan · 04-26-2006, 12:59 PM

I just finished up my stereo installation, and I put it under the passenger seat. I like that location because it's easy to route the wires under the carpet to the head unit, and you only need to pass one wire (the power wire) through the firewall to the battery. This is a big momma amp, and it still fits with no issues. Here are some pics:

therotman · 04-26-2006, 01:28 PM

I have an antique amp installed by the dealer when the car was new in 1980 under the passenger seat. They seemed to think it was a good spot

gilach · gilach's Garage

i went with under the passenger seat...i'm almost done...will post pixs when completed. i wanted to be least intrusive as possible. Also, i found my way through the "firewall" as i call it-i mean between the interior and trunk, there was a perfectly capped hole about 2" round just by the left hood prop. Got the back deck out no problem....last push will be for the front speakers, tricky part will be the wires. I got 5.1/4" speakers, so i have to create a baffle mount. Thank you all for the suggestions.

best, paul.

blucille · 04-27-2006, 05:08 AM

what are you doing with the old radio? I'm looking for a 1978 factory radio.

-Lewis

911pcars · 04-27-2006, 10:20 AM

Here's mine under the pass. seat.

You can run cable along the door sill and also beside the tunnel. Use a sheath to prevent the wires from chafing. An interior mount requires routing only one source wire into the trunk. A trunk mount requires a routing path for the speaker wires as well as the audio patch cables. If you use Monster-type cables, a larger cable routing hole is required.

Sherwood

Mysterytrain · 04-28-2006, 06:37 AM

Maybe, its six of one half dozen of the other. Back when I had an amp in my car it was in the trunk. Powered and grounded directly from the battery. The crossovers were mounted behind the fiberboard. Left/right speaker wires where routed to each door via the cavities in the trunk near the hood shocks the same way the power window and power mirror wires are routed. The only wires that went thru the bulkhead where the left/right preamp outs and the sensing wire to turn the amp on. As I recall they were routed behind the glovebox and up a tube like opening on the right side of the glovebox and into the trunk.

gilach · gilach's Garage

Sherwood, did you fabricate those crossbars? i'm trying to figure on the best way to finalize my install under the seat, and those look very sturdy. Me seats just have the rails.

best, paul.

911pcars · 04-28-2006, 07:59 AM

"....did you fabricate those crossbars?"

Paul,
The bright aluminum ones? Yes. They're flat al. stock 1/8" x 1" and bent to fit (vise and mallet). They lift the amp a bit off the floor for more air circulation (not that the amp is that powerful).

Sherwood

gilach · gilach's Garage

ah, that's clever...i'll think i set it up that way...like the air-flow concept. but the black cross bars are stock right? mine doen't come w/those suckers....it's time to fabricate.

911pcars · 04-28-2006, 08:54 AM

"..but the black cross bars are stock right? mine doen't come w/those suckers....it's time to fabricate..."

The black bars are part of the seat mounting bracket (Recaro).

Sherwood

gilach · gilach's Garage

need some help here. i hooked up the rear speakers and got a very high pitch sound that appeared to come from the tweeter cones on the 4X6's. You can only hear it when the stereo is turned all the way down. i checked all the wires, ground and positive connections, basically everything. then i realized this sound was coming from the engine bay, ie non stereo related. this sound comes on when the ignition key is in the Accessories position ie last click before start. does anyone know if this is the sound of the electric fuel pump?

best, paul.