81 SC Alternator Update

[czeitler386]

Hi All,

I'm currently in the process of updating the external VR style alternator on my 81 SC to the newer, internal style. My question is regarding the charge indicator lamp: according to the technical service bulletin for this update there is a resistor needed to account for the lower lamp wattage (according to the bulletin the lamp may not go out without this). I haven't been able to find this resistor (appears to be discontinued)...Just curious how those of you who have done this update have dealt with this.

A bit of background as to why I am doing the update, for those of you who are interested:

Earlier this year had some charging system issues which ended up being related to worn brushes, which I replaced and the problem went away. Now I am dealing with all interior/exterior lamps pulsing (intensity) with engine RPM - I am almost certain this is the diode bridge going bad. That itself is an easy fix...On top of that, I have a suspected bad connection in the external VR/noise suppressor circuit that will cause an intermittent "no-charge" situation (yes I have replaced the VR). I am pretty sure said bad connection is in the noise suppressor itself (see white arrow in image). I can wiggle the connections and cause the battery lamp to turn on/off. Given that I am having issues with the external VR/noise suppressor circuit that I can't figure out, I want to replace the whole thing with the internal setup.



Cheers!
Chris

[Targalid]

I disconnected the three prong plug you show in the photo. At the alternator the blue wire goes at 12 o'clock. The black wire with the spade connector at the alternator from the external voltage regulator is not used. I simply folded it back on itself and taped it to keep it out of the way. No resistor was required to have the alternator lamp work normally. The air deflector needs to have a small portion cut out to accommodate the bulge from the internal voltage regulator. I used a small saw and a file to accomplish this minor modification.

[pete3799]

Originally Posted by Targalid

I disconnected the three prong plug you show in the photo. At the alternator the blue wire goes at 12 o'clock. The black wire with the spade connector at the alternator from the external voltage regulator is not used. I simply folded it back on itself and taped it to keep it out of the way. No resistor was required to have the alternator lamp work normally. The air deflector needs to have a small portion cut out to accommodate the bulge from the internal voltage regulator. I used a small saw and a file to accomplish this minor modification.

This is what i did as well. No resistor required.
I seem to recall that either a different nut , or washer or spacer was required for the new alt. also.

[Trackrash]

I recently rebuilt my alternator and replaced my regulator with one like you have.

I eliminated the noise suppressors on my car with no ill effects. My '71 has different looking noise suppressors than yours, if that matters. My take is, that the noise suppressors were for the old fashion mechanical points style regulator and not needed for the modern solid state regulator.

[Bob Kontak]

Originally Posted by Targalid

The air deflector needs to have a small portion cut out to accommodate the bulge from the internal voltage regulator. I used a small saw and a file to accomplish this minor modification.

+1 Good catch.

If you have the desire to sniff around for a used one that fits the later regulator they are out there. Guessing they would be in the $100+ range now? They were $75 ten years ago. I did not pull the trigger. Just used a dremel with one of the better cut off wheels.

Off topic. Signs of an aging man.... I looked at OP's picture kind of glancing and saw the black regulator. I saw the German "generator" on it and thought it was car battery sized. Here's the scary part. I thought the Permatune was a roller tool box with a stack of drawers.

[czeitler386]

First of all, thank you all for the replies! Some new developments this evening...

Originally Posted by Trackrash

I recently rebuilt my alternator and replaced my regulator with one like you have.

I eliminated the noise suppressors on my car with no ill effects. My '71 has different looking noise suppressors than yours, if that matters. My take is, that the noise suppressors were for the old fashion mechanical points style regulator and not needed for the modern solid state regulator.

Funny you should mention that...I was interested in bypassing the suppressor to see what would happen (before tearing into the alt. replacement), so tonight I did just that..

I bypassed the noise suppressor (went directly to VR) and sure enough, my lights no longer pulse with RPM and the charge lamp goes on/off when it is supposed to. Now I am debating on whether or not to do the update at all.

After removing the suppressor, I measured charging voltage at 1500 RPM (13.5 volts) and with headlights on it drops to 13.3 volts. I recall that being similar, perhaps nominally higher, before removal. I basically live with the multi-meter in the car, so I'll keep an eye on it.

Does anybody else have experience with bypassing the noise suppressor on this type of setup?

[timmy2]

Tossed my noise suppression module 5 years ago for the same reasons.
Been fine ever since. Modern radio has built in noise suppressiion.
Also Installed solid state VR