Board index Flathead Power-Technical Questions, Answers, and Suggestions Big Twin Flatties 32E charging system

32E charging system

Post Sat Aug 15, 2009 9:21 am

Posts: 15
A close friend of mine has a fairly original 1937 UL, I've been having an ongoing problem with his 32E generator.

At a fast idle with the lights off the system is outputting just over 7 volts at the battery which I feel is about right.

With the lights on and with the third brush turned all the way clockwise it is only putting out 3.4 volts, thus unsufficient lights.

Also, with the lights off I can race the motor and the lights will faintly come on when they shouldn't which is puzzling.

I've never ran a three brush system and any suggestions will be greatly appreciated.

-Texas Wildman

Post Sat Aug 15, 2009 11:19 am

Posts: 2688
Location: Los Angeles, CA
There is a crossed wire someplace on that machine.

Post Sat Aug 15, 2009 2:42 pm

Posts: 1676
Location: Interlaken, NY USA

TW, Did it start doing this after working fine for some period of time, or has it always worked this way?
If the latter, I suspect the generator is not wired properly. It sounds like the Field coil hooked to the switch terminal is incorrectly hooked up. One lead is probably hooked to the "switch terminal, but the other is hooked to the "relay terminal". Hooked up this way, it would give the symptoms you describe. This field coil hooks from "switch" to ground.
Check it out and see what you find.

Post Sat Aug 15, 2009 5:07 pm

Posts: 15

In the two years that I got this bike running for Greg Hale who owns MC Creations in Houston it has always been that way! He has a couple of 32E generators that I'm going to try next week, the one that is supposedly a good one has 5/16-24 mounting holes and it would be a sin to drill his cases so I'm going to get on my little Rivett lathe and make two 5/16-24 by 1/4-24 sleeves.

So it sounds like an internal problem with the generator and not external wiring. Also, when I had his original generator off today to swap out the drive gear I noticed it had an excessive amount of end play.

My thing is machinist but Big Greg always presses me (reluctantly) into electrical work. I've made those "heli-sleeves" before, somebody said it can't be done but I've done it.

-Texas Wildman, aka 'lil stan

Post Sat Aug 15, 2009 5:50 pm

Posts: 349
Location: Champaign-Urbana, IL

Your answer to Frankenstein's response doesn't make sense ... He asked if it had always been that way, and if that was the case it was probably an external wiring problem ... Then you responded by saying yes, it's alway been this way, so it must be an internal problem ... HUH!?


Post Sat Aug 15, 2009 6:13 pm

Posts: 121
No internal genny problem will cause lights partially working! As Frankenstein says it will be in your switching circuit.

Post Sat Aug 15, 2009 7:58 pm

Posts: 15
OK everybody, I will look as to how I wired the generator leads to the relay and up to the switch. Like I said, my thing is machinist but I'm the only one at that shop that has enough reluctant patience and knowledge to wire bikes completely from scratch. My problem is, this is the only 6volt three brush that I've ever encountered. I've run 6 volt two brush systems but when I built up my panhead over twenty years ago I made the wise move (in my opinion) to a 65A 12 volt system. One can no longer find 6 volt bulbs these days when your a long way from home.

I'm the one that put Greg's '37 UL together as everybody else at his shop only knew about Evo's and maybe Shovelheads along with Sportsters. Show the rest of his crew a Linkert carburetor and they have this "deer in the headlights" look along with things like mechanical brakes, four speed transmissions and springer front ends. I've owned two Panheads, a 1951 Indian 80 and a 1966 Servicar - I'm the only "old school" guy that Greg knows. I'm trying to fix his electrical system the best that I know how. I may be ignorant but I'm not stupid.

Like I said in my first post, when the lights are off the battery is showing just over seven volts at a fast idle but when I turn the lights on the voltage at the battery voltage drops to about three and the lights "bleed thru".

Thank you,
-'lil stan

Post Sat Aug 15, 2009 8:29 pm

Posts: 2688
Location: Los Angeles, CA
I hope this may help.

Post Sun Aug 16, 2009 11:16 am

Posts: 15

Thanks for the wiring schematic, I've studied it in the manuals that Greg has and I guess I have to study more.

In my last post I didn't mean to belittle anybody at Greg's shop, I have the same "deer in the headlight" look when faced with things like fuel injection systems and later carburetors. Greg's mechanics are mostly younger than me and have never owned bikes that had generators, Linkerts and so on. MC Creations is actually a very good shop that can handle a wide variety of HD's - old and new plus Greg has lots of old parts that are hard to find. I work there part time / as needed mostly on older scooters plus machine work.

Thanks again,
-Texas Wildman

Post Sun Aug 16, 2009 6:10 pm

Posts: 1676
Location: Interlaken, NY USA

TW, In the first post, you say the headlight comes on weakly, (not weekly?), :lol: when ignition switch is in the "on", position.
Here's what I think is happening IF this is so: INside the generator are 2 field windings. one connects from the relay terminal internally, to the third brush. Sounds like that one is hooked up o.k. The other field winding should be hooked internally from the "switch" terminal, through the winding, to the ground brush terminal, again, inside the generator. However, on this generator, I believe the second field is hooked from the "switch" terminal internally, to the "relay" terminal internally. Hooked this way, with the ignition switch in the "on" position, current from the positive brush in the generator runs through the switched field through this wrong connection, and then out the switch terminal. From there it goes up to the Ign/lighting switch, connecting on the Lights terminal on the switch. The wire to the headlight also connects to this terminal. So the current then flows back through the headlight wire to the headlight. Then through the headlight bulb, and on to ground. Because the current is going through the field coil and then to the headlight, the voltage to the headlight is lowered by the resistance of the field coil, and the bulb lights weakly.
I really think all you're going to have to do is reconnect the switched field coil so that one wire is on the switch terminal, and the other is on the ground brush. Polarity will need to be correct on the connections, but I'd start by assuming that the wire on the switch terminal is correct, and the other lead only needs to be moved to the ground brush. Give it a try.
HOWEVER, if I misread about when the light lights weekly, this is all hogwash, and pay no heed. Except, it does explain how it IS possible for an internal genny connection to make the headlight light weekly, er weakly, Whatever. :mrgreen:

Post Mon Aug 17, 2009 12:14 pm

Posts: 202
Location: Middle England UK
I think DD is on the money and the glow with lights switched off is backfeed.I would expect the lights to be normal brightness with engine stopped.
If you have a known good late model generator you can fit two 1/4-24 Helicoil inserts straight in and use original screws and leave cases untouched.
You would of course have to reshim the new generator.
I'm not happy about the third brush being at full adjustment,I can't think of any need for this,but of course,I ready to learn. :wink:

Post Mon Aug 17, 2009 4:27 pm

Posts: 15

When I race the motor up with the ignition switch turned to the first click (ignition only - no lights) the headlight and spot lights faintly come on. When I turn the ignition switch to the second click (ignition and lights) the voltage at the batter drops dramatically.

Greg has another 32E generator that I'm going to try this Saturday, he doesn't have any 1/4-24 helicoils so I'm going to make "heli-sleeves) which I've done before.

My problem is time is getting short for my yearly Dyna Glide trip to Davenport, will you be there? If so I'd like to meet you!

-'lil stan

Post Thu Aug 20, 2009 6:10 am

Posts: 1676
Location: Interlaken, NY USA

TW, That drop to 3.7V, AT THE BAttery, has me concerned. I can't figure how to explain it except for a weak battery, which I'm sure isn't the case, 'cause you must have checked that along the way.
I won't be at Davenport, sorry to say. I don't usually get that far West. Haven't crossed the Mississippi in 30 yrs on a bike.

Post Sat Aug 22, 2009 12:04 pm

Posts: 15

This morning I installed my home made threaded sleeves into a 32E generator that was "known to be good" and Big Greg's '37UL now seems to be working correctly. Lights no longer "bleed thru" with the switch off, checking with a voltmeter at the battery showed about 7.4 volts with the lights off and about 6.4 with the lights on. Lights dim slightly at an idle but brighten up when the throttle is opened.

The original generator was supposedly sent to a starter shop for rebuilding and apparently they had a wire wrong as per your original speculation. Time permitting I'm going to take it apart and compare the wiring to your instructions and a Harley manual.

Thank you for suggesting an internal problem with the generator!

One week from now I'm hoping to be getting close to Oklahoma on my '97 Dyna and then to Davenport for the swapmeet.

-'lil stan
aka The Texas Wildman

Post Sun Aug 23, 2009 11:50 am

Posts: 1676
Location: Interlaken, NY USA

TW, glad to hear the good news! Enjoy Davenport, Maybe someday....

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