Early Car Voltage Regulator Mystery

[BlueSideUp]

I am in the process of rebuilding the electrical in my 1970 911T. The alternator just came back from being rebuilt so I thought I'd install a new voltage regulator from Pelican. My car is equipped with a Bosch 55A alternator.

So I pulled out the old unit and found this....



On the left is the new VR from Pelican and on the right is the original unit I pulled out of the car. If it isn't the original one it has been in the car for a long time. Obviously the old one is much larger and has the extra "box" attached. The plugs are all the same.



Here is the current home for the regulator. I'm in the process of restoring the engine compartment so this view will drastically improve.

[304065]

That's the original VR. The old ones are electromechanical, meaning they actually have moving parts inside. The tape around the bottom should be white if it's not radio-supressed and yellow if it is, but the external box is a radio noise supressor.

From an operating standpoint I wouldn't be concerned, as the new Bosch probably has the same "set point" or target voltage output. Being transistorized it will probably hold the voltage better than an electromechanical type VR and last longer if it doesn't get too hot.

Caution: if you diassemble the electrical console, be sure you get all the wire routing noted, you don't want to have to guess when you put stuff back. The fuse box cover is NLA so be careful. Dupli-color "Satin Black" should be a good match for the paint. Pins and sockets for the 14-pin connector are available new from Pelican. Be careful not to use lacquer thinner or anything too strong on the wires, you can rub the tracer stripes off them.

[BlueSideUp]

John- Thanks for the reply. I plan to take plenty of pictures during any disassembly, my memory just isn't that good. I think the cardboard cover disappeared a long time ago unfortunately. Any tips on how the 14 pin connectors come apart? It looks like the ECU connectors used on newer Bosch Motronic cars. I'm thinking a little electrical contact cleaner would be good for the connections.

I think the tape was yellow. The external supressor looks to be about 1970 vintage. Will it make a difference if I don't use the external radio noise supressor?

[304065]

Fear not: the cover is available on Ebay from time to time offered by one to whom the sum of the parts is worth more than the whole.

The 14 pin connectors come apart with a little pressure and then they spring open and the wires fall out onto the floor leaving one holding the plastic shell and hoping that you can get them back in the right order, because otherwise you're going to have to engage reverse gear to get the battery to charge, and so on. So be gentle and be sure to take note of which color wire goes with which pin. If you look VERY carefully, maybe even get the neighbor kid to help you with his keen vision and a magnifying glass, you can actually SEE that the pins are numbered one through fourteen.

Contact cleaner is excellent as is a gentle ink eraser. You want to eliminate all funky green corrosion. The pins are silver plated, but there will probably be funky green stuff just behind them where the insulation was stripped.

I really don't think it will make a difference, and the external suppressors are a known failure point. I think the BMW 2002 used a similar regulator. To be honest I don't have a radio in either of my cars.

Good luck!