Hitman's Pontiac Trans Am Forum

Trans Am Photos => Restoration Projects => Topic started by: Hitman on July 02, 2008, 11:34:47 PM

Title: Revamped the Stereo System
Post by: Hitman on July 02, 2008, 11:34:47 PM: Well, I figured it was about time to revamp my stereo system in my car. I did my first one about 6 years ago with a normal shaft mount stereo in the original spot in the dash, 6 disc CD changer in the trunk going through an FM modulator with amp and sub. I have been meaning to change it over for a while and update it, but just never had the chanvce to. So, I go some ambition and got around to making a quick change. I tore apart the inside of my car to do the radio swap for something a little more up-to-date and more of what I wanted.

(http://www.78ta.com/fpics/5479ff70.jpg)

I removed all of the wiring from the old system and kept it intact to maybe sell or use in another car maybe someday.

(http://www.78ta.com/fpics/54975d80.jpg)

I put the original AM/FM 8-Track radio in its place in the dash where it was supposed to go and then used one of the map pocket adapters to install my new head unit.

(http://www.78ta.com/fpics/54b7fdf0.jpg)

I went with the total black out face of this JVC stereo so that it wasn't as noticeable in the console when it was mounted. Here is a link to the stereo head unit I purchased for my car: http://mobile.jvc.com/product.jsp?modelId=MODL028306&pathId=133&page=1 . It has all the bells and whistles to it like MP3 plugs, iPod plugs, inputs and outputs galore, Bluetooth, HD Radio, Satallite radio, Digital surrond for watching DVD Movies on it... blah, blah, blah. Anyway, the reason I bought that one is because of the blacked out face of the radio.... it hides so nicely right down in that map pocket.

(http://www.78ta.com/fpics/54d96f00.jpg)

All in all, I like it and it took me about 2 hours to do. I had some extra wiring I had to do, but it was a pretty simple install.
Title: Re: Revamped the Stereo System
Post by: dgtldesigner on July 02, 2008, 11:42:57 PM: pretty sweeet!

hey what happened to your other floor mats?
Title: Re: Revamped the Stereo System
Post by: Hitman on July 02, 2008, 11:44:40 PM: They are in the trunk... I only take them out for shows.
Title: Re: Revamped the Stereo System
Post by: dgtldesigner on July 02, 2008, 11:45:28 PM: oh. well aren't you mr fancy with your two sets of floor mats.
haha jk buddy! ;D
Title: Re: Revamped the Stereo System
Post by: Klatt87 on July 03, 2008, 07:40:22 AM: I like that a lot. I am getting ready to put in a CD player and speakers in my car, not looking forward to all that wiring crap though :(
Title: Re: Revamped the Stereo System
Post by: 78ta on July 03, 2008, 03:11:09 PM: Hey Brett,
Thanks for the heads up on the post. Looks great. Nice choice on the stereo. It does hide the fact that it's a stereo pretty well. I'm always concerned about leaving my car with the t-tops out because it's so easy to pop the flip down face of the stereo off. That one will cetainly draw less attention to itself.

Anything on the map pocket adapter I need to change or add? Did you even have to refer to the instruction sheet I sent with it? Just wondering if there are any errors or something that needs to be clarified.

I'm going to replace the aftermarket Poineer the previous owner had in my car with a factory am/fm/8 track. I notice you have your glove box out. Did you go through the glove box to install the factory stereo?

Just curious, did you hook up both stereos? I did that on my 70 442. I just "shared" the right rear speaker between the two systems by installing a hidden double pole/double throw toggle switch in the right rear speaker wire. When I play the cd player, it plays through the 4 new speakers. 2 under the dash and the 2 in the package tray. When I play the factory stereo
+ 8 track, I flip the toggle switch and it plays through the center dash speaker and the right rear speaker. I always make sure one is off before turning the other on. The only time I really even use the factory stuff is when people at shows ask if the 8 track really works?

FYI anyone considering doing this, be aware that you have to switch both the ground wire and the signal wire for that "shared" speaker. New stereos use a "return" that actually goes back to the stereo instead of just grounding to the chassis like the old stereos. If you just ground the speakers for a new stereo to the chassis, you will burn up your new stereo. So in one position(old stereo), one wire on that speaker will be connected to the old stereo and one wire to chassis ground. In the other position(new stereo), one wire on that speaker will be connected to the new stereo and the other will connect to the return line on the new stereo.
Title: Re: Revamped the Stereo System
Post by: Hitman on July 03, 2008, 08:12:14 PM: nope, I had no problems with the adapter what so ever. It was an easy install and a good fit. I was going to hook up my original 8-Track, but didn't want to deal with the wiring quite yet, so I will leave that for another day. Yes, I took the glovebox out for easy access to get the old radio out and put the original radio back in.
Title: Re: Revamped the Stereo System
Post by: norwood on July 03, 2008, 11:27:37 PM: Quote from: dgtldesigner on July 02, 2008, 11:45:28 PM
oh. well aren't you mr fancy with your two sets of floor mats.
haha jk buddy! ;D

I thought that everyone had two sets...
Title: Re: Revamped the Stereo System
Post by: dgtldesigner on July 04, 2008, 05:07:45 AM: Quote from: norwood on July 03, 2008, 11:27:37 PM

I thought that everyone had two sets...

pft.. not me. i've only got one set. and they are crappppy
Title: Re: Revamped the Stereo System
Post by: Hitman on July 04, 2008, 11:22:44 AM: Actually, I have three sets. I have the normal basic black set in the car for normal driving, the set of fancy "Trans Am" mats with the bird, and then another set of the fancy "Trans Am" mats with the bird brand new in my closet. I am also going to purchase the correct black "GM" rubber floor mats as well. So, I will have four sets then.
Title: Re: Revamped the Stereo System
Post by: Hitman on August 16, 2010, 10:14:24 PM: I put this as information on my website as well here: https://www.78ta.com/resto/stereo.php

Also, on the bottom of that page is a Stereo Install Guide from Crutchfield that will help you to figure out what stereo goes into what car. Helps with all makes and models of cars. Also, if you order your stereo components through there, you will get an extra discount off of your purchase because you used 78ta.com to get there. Every little bit helps.
Title: Re: Revamped the Stereo System
Post by: CT Bird Fan on August 17, 2010, 06:04:20 AM: That looks great Brett!!! I wouldn't even have noticed the new stereo in the map pocket if you didn't mention it!
Title: Re: Revamped the Stereo System
Post by: deadfish on August 17, 2010, 08:02:05 AM: Quote from: CT Bird Fan on August 17, 2010, 06:04:20 AM
That looks great Brett!!! I wouldn't even have noticed the new stereo in the map pocket if you didn't mention it!

X2...I kept looking around the photos for your new "head unit"....It really does disappear in the map pocket..nice touch!

Rick C.
Title: Re: Revamped the Stereo System
Post by: 80TArebuild on August 17, 2010, 11:38:38 AM: I have my head unit installed in the map tray as well, and it just screams "Steal me!!! Steal me!!!" I really like the head unit you installed, maybe my wife will like it enough to justify an update for mine. Ya know for security reasons..haha...nice work!
Title: Re: Revamped the Stereo System
Post by: rad400 on August 17, 2010, 03:30:47 PM: So how much was the fancy radio?
Title: Re: Revamped the Stereo System
Post by: HOT76TA on August 18, 2010, 11:32:39 AM: Hey Hitman... that is an awesome install; I was wondering were a guy can get that adapter for the map pocket location to install such a stereo? OK... I should have guessed and looked first before asking... you have them available in your store... DUH
Title: Re: Revamped the Stereo System
Post by: racereaper7 on October 29, 2010, 11:42:12 PM: how hard was the wiring for the new stereo? im trying to install one for my dad could use some advice
http://www.78ta.com/smf/index.php?topic=27010.0
Title: Re: Revamped the Stereo System
Post by: jtwoodro007 on April 07, 2014, 10:06:13 PM: Hitman, I realize this is an old post but its exactly what I was looking from so thought I might get some help here. Did you ever rewire your original stereo like 78ta said he had done?

I purchased the map pocket CD adapter and plan on doing my stereo system upgrade some time in the next month or so. I have the original AM stereo for my 74 and wanted to make it operational again along with the new stereo. 78ta indicated he had placed a switch on the speakers he used for both stereos.

I'm installing two 3.5" speakers in the center dash location and wanted run the AM stereo off both front speakers. I am concerned about the ohm rating for the new speakers vs. the original mono speaker.

If you completed this project I would appreciate any direction on things to do and things to avoid!

Thanks a lot!
Title: Re: Revamped the Stereo System
Post by: Hitman on April 08, 2014, 09:11:15 AM: Yeah, I never got around to hooking up my original radio so it sits dormant in my dash for now. I have an article somewhere about hooking up new speakers to old radios and the proper way to do it. I will Find it and post it here

Sent from my SM-P600 using Tapatalk
Title: Re: Revamped the Stereo System
Post by: jtwoodro007 on April 08, 2014, 07:21:31 PM: That would be great. Thank you!
Title: Re: Revamped the Stereo System
Post by: 78ta on April 08, 2014, 10:34:06 PM: Hopefully, this info won't conflict with the article Brett is going to post and create confusion but this is what I did.

As has been stated in the post on the forum, old stereos used 8-10 ohm speakers and new cd players/stereos use 4 ohm speakers. Not exactly sure when they switched to 4 ohm. If you use 4 ohm speakers with an old 8-10 ohm stereo, it will work and will actually be louder than if hooked to a new stereo(that uses 4 ohm speakers). This because the 4 ohm speakers have less resistance. That's what the ohms are, resistance. It will be louder because the 4 ohm speaker has less resistance but that means that the stereo is moving more current than it was designed to move. As a result, if used this way frequently, it could burn up the amps in the stereo. Probably only a risk at high volumes but the service manuals have warnings stating that you need to use the correct ohm speakers.

If you want to use both stereos frequently, you would need to make sure somehow that, when the old stereo is connected to the new 4 ohm speakers, there is an additional 4-6 ohms of resistance in the speaker line to make it appear(to the old stereo) to have 8-10 ohm speakers like the original speakers it was designed to run. Could be as simple as putting a 6 ohm resistor in line with the speaker between the toggle switch and old stereo.

If you are only going to use the old stereo occaisionally and for a few minutes at a time, you probably won't even have a problem running the 4 ohm speakers directly to the old stereo. Just don't turn the volume way up. That's when I think you would run the most risk of over driving the amps in the old stereo. I didn't bother with the added resistor in my 442 but, as I said, I hardly ever play it unless someone wants to hear it at a show/cruise etc.

I also have a 78 trans am and installed two toggle switches in it to share the speakers between the new cd player and the factory am/fm/8 track. It's been a while since I did it but I think, while the factory ta stereo still used 8-10 ohm speakers, it does have a "return" line/ground like the new stereos instead of the speaker just going directly to chassis ground right at the speaker as it does on my 70 442.

So you just need two switches that have one set of contacts (two pins) on one side that control two pairs of pins on the other side. I think they are called double pole/double throw switches. On one side, you have two contacts I'll call the main contacts(which go to the speakers). One the other side, you have two pairs of contacts which I will call the secondary contacts 1 and 2. One pair of contacts/pins(1) will go to the old stereo's speaker outputs and the other pair (2) will go to the new stereo's speaker outputs.

So when the switch is in one position, the secondary pair of contacts 1 go to the old stereo speaker output and ground/return connecting the old stereo to the speakers.

When the switch is in the other position, the secondary pair of contacts 2, go to the new stereo's speaker outputs and ground/return.

On the TA, I drilled a couple holes in the left hand side of my glove box insert and installed the toggle switches there.
You could accomplish the same result with one double pole quadruple pole switch but that may be hard to find.

And for the electronics guys out there, I know there is a difference between resistance and impedance which is what the ohms rating on the speakers refers to but I was trying to keep it simple.