So im working with a new rebuilder shop to rebuild a 38 three brush generator to 12 volts. He assures me that with new 12 volt field coils it will charge fine with using a stock type cutout switch or a diode type replacement one. Has anyone ever done this? The reason I ask is the last shop that did the same conversion had it set up to use and external mechanical regulator. THANKS
Not sure why you would want to use a cut out and wonder why you might not want to take the opportunity to switch to a voltage regulator while you are making the changes. Not trying to tell you what to do, just curious myself. Pete
Why? Henry knew, in 1938, that the three brush was out and the two brush with firewall mounted regulator was in. Some 38's (mine included) came with two brush and regulator. Simple change from where you are at.
There was a guy selling on eBay using the diode instead of a cut-out from what I understand the cut-out sticking was the weak link of that system
The big disadvantage to converting a 3 brush generator to 12 volt is going to be the lack of amperage variation as you increase the loads(ie: lights, heater,radio etc).In 1936, Ford actually had a large case 2 brush generator with seperate regulator for this reason as the radio produced a large load, larger than the 10-12 amps that the 3 brush generators were normally set at. I built a 2 brush generator for my son's 27 roadster project by using the larger delco remy coils and shoes, as they will take a larger coil, but it only produces 25 amps. We did it this way, as the car is being built pre-war, and we felt it would look more period correct.
Lack of regulation, as with cut-out only, is a very weak spot of early systems that you don't want to continue on your conversion. Amp output is set by moving the thisrd brush, and that's it. Charge rate is the same regardless of draw... once battery is recharged from the start, if you are driving around in daylight with almost no current draw your battery is still being charged by whatever is set...meaning it is being fried, if amperage is enough to run lights for night driving. If amps are set low for daytime, you don't have enough on tap to run lights...not good. You CAN get modifed cutouts containing electronic regulation in 12 V, and there's also a guy who builds a regulator into the cover band. If you keep cutout, find a decent original and clean up its contact points. The repros are very flimsy electrically.
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