MTFCA Forum

The previous owner had set the gen. in my '23 roadster to put out 10 amps at half throttle and above. So in an attempt to adjust the 3rd brush and following Royce Pettersons directions to lower the amperage output I discovered the 3rd brush was not accesable and in a different location than in the article example. So I removed the gen. and discovered it was positioned closest to the engine block. So I went to the bench and tore the gen. apart, checked and cleaned the brush plate, commutator and repaced all 3 brush leads and resoldered each. Reassembled but moved the brush plate 1/4 turn CW from the front. Replaced the gen. and started the engine. Now I get no reading at all at the guage and the cutout (purchased in the early 90s) does not work. Rotating the brush plate or the 3rd brush makes no difference. So I pulled the gen. back out. If I apply 6v to the terminal it will motor as it should. If I apply 6v to the terminal side of the cutout the points will make and will release when power is removed. Ive worked on alot of 3rd brush gens. on tractors but the brush plate is stationary and only the 3rd brush moves to change output. Did relocating the brush plate cause this problem? Is the brush plate location criticle to voltage output? What am I overlooking here?

Preston,

I just finished the rebuild of a generator.

Here is the way I put in the field coils , the brush plate and the terminal wire .

The other photos are from the test of the armature and the set up of the generator out put.

Maybe this will help.

Good luck
Andre
Belgium

Make a control of the way the field coils are sitting in the generator body. The brush plate must be set on a way corresponding the way the field coils are set in the body.
Most of the generators have the field wires crossed for the connections. Some of them are not crossing. With the experience I have it are mostly the Canadian generators that have the wires not crossing but I have small experience and I can't walk on water.


Good luck
Andre
Belgium

"The brush plate must be set on a way corresponding the way the field coils are set in the body."

That is just what I needed to know. Thanks Andre.

There is more to it: The brushplate must be set to correct null position. I will not elaborate, since it can be found here, with less typing...http://www.mtfca.com/discus/messages/50 ... 1433113127

or this one;
http://www.mtfca.com/discus/messages/50 ... 1446051073

There is a Tinkering T tips video by Mike Bender and Nick Nicholas that shows all of the steps to rebuild a Model T generator.

https://youtu.be/C7Psk4hK3gU

Thanks for the replies. Dan thanks for the video link. That explains everything very well. I went ahead and pulled the armature and went to the growler. Checked out good and the 3rd brush insulator is good as well. So Eklers sent a rebuild kit and I should be back together tomorrow. Mainly to replace the original field windings and a new set of brushes. Question is....I set the brush holder to the null position with 3rd brush removed. Apply 3rd brush and adjust at moderate engine RPM to desired amperage. Correct?

Preston

if you do not turn, undercut, and polish the commutator, you will wish you had. Find someone to do this for you or you will simply be buying time with the kit, and should not expect lasting success.

Armature was turned, polished and undercut.

Yes Scott, when I rebuilt mine I spent alot of time on the commutator doing just that and now it charges too good. I have to do that final adjustment of the 3rd brush on the car

Pretty good day today. Got the gen. back together, set the brush plate to null position with the gen. motoring. Installed and fired the engine. 3rd brush set full clockwise (from front) it will kick out 20 amps but set it down to about 6 at cruising speed. However at this setting Im getting about 8 amps discharge when lights are turned on at same speed. Is this a brush plate adjustment and then reset the 3rd brush again?

Preston,

I think your setting is just right. 6Amp is just ok.

Here is how I doo it.
If you watch my photo of the brush bridge, set the third brush all the way anti clock wise. Make the engine run at a brisk idle. Lose the four small screws and turn the brush bridge till you have about 1Amp charge. Tight the four screw and set the third brush till you have 5 to 6 amp charge.

Check the charge with the lights on and speed up the engine. charge should be 1 or 2 amp.
An old man told me to do so.

Job done

Andre
Belgium

That will be tomorrows agenda. Thanks.

What Andre said is the valid way to set null and charge rate with the generator in the car (not by motoring on the bench). Following his valid advice will likely result in the same exact setting you have now. I doubt that you'll hurt or help anything, but will learn a few things on the way...

With a mild charge rate like you have, you will recover the power discharged from the battery during starting, in less than about 30 minutes. Remember what your Ahr rating of your battery is and you will see that you could drive for hours on end with the lights on, and still have OOMPH in the battery to start the car. Few of us and probably you, will ever drive for hours on end in the dark, much less long enough to discharge the battery.

The issue is, if you charge enough to run lights with "0" discharge, you will be charging constantly at 12+A with them off. That is a recipe toward a new generator in short order, as well as a new battery as you will boil the electrolyte mercilessly. We drive our cars far faster and for far longer than Henry or Delco ever planned on, so we tend to set the charge rate far lower than they did, out of respect for the contents of our wallets.

While they are seemingly hard to come by these days, a modest investment in a voltage regulator to replace the old style cut out is a wonderful thing, and batteries love them. It is one of the few acknowledgements to technology that I allow on my starter cars.

I have a new VR from Fun Projects on the way.

Excellent. Follow the VR instructions to the letter regarding setting charge rate, and you'll be fine.

Preston, are they finally making the VRs again???

I just went on thier website and it says they are still backordered, so how were you able to get one?

Well Doug...I say one is coming. I placed an order about 2 weeks ago and recieved a paypal invoice. I went ahead and made the payment soooooo. I guess we'll wait and see how long it takes to process. I'll keep you up to date.

You can build your cut out your self with a diode available at most of the dealers.
In the photos my build 5 years ago and still standing. I works also great on a 12V system.

Good luck
Andre
Belgium

Called Fun Projects this morning. After some checking my payment was processed and the VR was mailed out last thursday. So I'm guessing they have some available.

Regulator arrived Sat afternoon. Got Peaches out and installed as instructed. Have max amp setting about 10 amps but she settles right down to around 4-5 amps at cruising speed. I think I dodged the bullet as I thought I was looking at replacing the gen. when all this started. Instead Im getting out with a rebuild kit and a new VR. I want to thank all that provided helpful information. Such a valuble website.
"Down in Florida soaking up 100+ % humidity and afternoon rainshowers."

Thank You Preston! after you told me about the VRs I emailed Fun Projects and they said they had a few left so got right on the phone and ordered one