PDA

View Full Version : positive gound stereo install



JoeMad
09-16-2004, 01:08 PM
Hello Friendly TR enthusiasits!
I want to install a stereo in my 1965 TR which is positive ground. To avoid getting a converter, is it possible to connect the radio directly to my battery without the hassel of a converter...if so, will this install impact the electrical in anyway?
if not, to you have any suggestions on what type of converter to buy?

Thanks, this place is great!

Mickey Richaud
09-16-2004, 01:26 PM
Hi Joe -

Just be sure you isolate the chassis of the radio from the metal of the body. And don't forget the antenna and speaker connections - the antenna is normally mounted directly to the body, and the plug that goes into the radio makes contact with the body of the radio. The speakers may or may not make contact electrically with the body, so you'll have to be careful there, as well.

Mickey

Kurtis
09-16-2004, 02:17 PM
Joe,

I went through this a year or so ago when I decided to install a stereo in my (then) positive ground TR4. I finally decide to just convert the car to negative ground. I originally hesitated doing this because I'm quite the dunce when it comes to electricity; however, the procedure literally took me less than 10 minutes, and could be reversed in 10 minutes if I chose to do so.

Instructions:

https://www.vtr.org/maintain/negative-ground.html

I highly recommend that you do the conversion and forget about converters or isolating the stereo. One additional note... I have an electric fan on my car, and had to switch the leads around on it as well after the conversion to make it run in the right direction.

Paul W.
09-16-2004, 02:24 PM
It might be easier, cheaper and less trouble to switch to negative ground. It's a very simple procedure which you can change back whenever you wanted to. Funny thing is, I don't practice what I preach. My TR4 is positive ground and I like it that way. But if I ever add a radio....
Here are the instructions on switching to negative ground from the VTR.ORG website:

<font color="blue"> The reason to do this conversion is convenience, not reliability - it allows you to use modern electrical accesories, especially radios.

1. Remove the battery
2. If you have a radio, remove it.
3. Remove the central panel in dash and reverse the wires conected to the Ammeter. Replace panel.
4. If you have an electrical fuel pump (non-original on TR-4), and it's a late model SU with a diode across the points rather than a condensor, reverse the connections to the diode.
5. Connect the (-) post of the coil to the wire going to the distributor, the (+) post to the wire going to the ignition switch.
6. Replace the battery, with the terminals reversed. If you are using the car as a daily driver, I'd strongly reccomend that you replace both the ground strap and the positive lead going to the starter solenoid with new cables. It's cheap, and will give you a better connection, which means more reliable starting.
7. Disconnect the two leads to the generator. Temporarily connect one end of a length of wire to the positive terminal of the battery. Touch the other end of the wire to the F terminal on the generator (the one the smaller lead is connected to, wire is brown with green stripe) several times briefly. This repolarises the field windings so you get the proper output.
8. Reconnect the two leads to the generator.

That's it - all the electrical devices on the car will now work like normal. You can install a new negative-ground radio, or other electrical accesories.
</font>

Geo Hahn
09-16-2004, 03:13 PM
[ QUOTE ]
...easier, cheaper and less trouble to switch to negative ground. It's a very simple procedure...

[/ QUOTE ]

In fact, the PO of my TR4 'converted' it to negative ground by the very simple expedient of installing the battery backwards. Ran fine (but wouldn't have for long) and remarkably didn't even cook the + ground radio. Needless to say -- Paul's procedure is the right way.

FWIW -- I choose to keep my TR3A positive ground and isolated the radio chassis &amp; antenna. The radio is isolated by being mounted to a bit of plywood which in turn is mounted to the body (easy to do since a TR3 radio is not in-dash. The antenna is isolated by using a big washer cut from a plastic milk bottle &amp; fitted between the hinged grippers on the antenna and the underside of the fender. Not for everyone but has worked fine for me for 20+ years. Just be double-darn sure you've got it totally isolated before you connect it!

JoeMad
09-16-2004, 03:21 PM
thanks, but the following statement bothers me. ..

""""""The reason to do this conversion is convenience, not reliability - it allows you to use modern electrical accesories, especially radios."""""""

will do this affect reliablity in anyway what so ever. ...

also, """"""3. Remove the central panel in dash and reverse the wires conected to the Ammeter. Replace panel. """"

What panel is this, do they mean the wood dash?

martx-5
09-16-2004, 06:24 PM
[ QUOTE ]
""""""3. Remove the central panel in dash and reverse the wires conected to the Ammeter. Replace panel. """"

What panel is this, do they mean the wood dash?

[/ QUOTE ]

The TR3's, and early TR4's had a seperate panel for the four smaller gauges held on by four thumbscrews in the back. That was eliminated with the wood dashes. You should be able to reach behind the dash where the ammeter is and remove the two thumbscrews holding the ammeter in. Push it out of the front of the dash, and reverse the wires.

Geo Hahn
09-16-2004, 08:20 PM
[ QUOTE ]
...remove the two thumbscrews holding the ammeter in. Push it out of the front of the dash, and reverse the wires.

[/ QUOTE ]

Or leave it as is &amp; get in the habit of reading it backwards. I think my TR3 ammeter swings the opposite way from my TR4 -- I have to stop and think to make either of them make sense.

No Joe, this change has no affect on reliability -- the electrics will be unreliable either way (mostly kidding).

Kurtis
09-16-2004, 10:57 PM
[ QUOTE ]
thanks, but the following statement bothers me. ..

""""""The reason to do this conversion is convenience, not reliability - it allows you to use modern electrical accesories, especially radios."""""""

will do this affect reliablity in anyway what so ever. ...

also, """"""3. Remove the central panel in dash and reverse the wires conected to the Ammeter. Replace panel. """"

What panel is this, do they mean the wood dash?

[/ QUOTE ]

The ammeter does not have to come out (or mine didn't anyway). I simply laid down up under the dash and switched the wires. Of course, if you don't switch the wires on the ammeter, all it will do is read backwards.

As others have stated, it has no effect on reliability. That's the point they are trying to make in the instructions.

Mickey Richaud
09-17-2004, 01:04 AM
[ QUOTE ]
Of course, if you don't switch the wires on the ammeter, all it will do is read backwards.

[/ QUOTE ]

Weird - when I changed polarity, the ammeter wasn't affected. It still jumps into positive area when revving, and goes negative under drain. Maybe I switched the wires, but I don't remember changing anything in the dash.

Mickey

Bugeye58
09-17-2004, 06:13 AM
Mickey, maybe you swapped them at the other end!
Jeff /ubbthreads/images/graemlins/devilgrin.gif /ubbthreads/images/graemlins/grin.gif