Pre-war (up to 1942) DIY Generator Rebuild

[J. Russo]

I wanted to share this experience in case there is anyone out there that is considering rebuilding their own generator.

I have a 1941 Cadillac Series 63 Sedan. It has a good used generator #1102693. I purchased another used generator with the same model number that I knew needed to be rebuilt.

Since I retired from the workforce, I'm always looking for things to do or try to keep myself busy. I decided to rebuild a generator.

DIY Cost: $267 without the armature. $390 with the armature. Includes shipping.

The most important thing to do first is take pictures of everything as you disassemble the generator. This will help you remember the order of everything to be re-assembled. The pictures also are a huge help when assembling the smaller parts and making the wire connections correctly. I also used several baggies and labeled them with all of the small parts. Don't lose the woodruff key for the pulley!!!!

The inside parts to the generator are pretty basic. Armature, 2 brushes, field coil set, felt washer, 2 gaskets, bearing, bushing, 2 terminal posts for the field and ammeter wiring and a felt oil wick at the bushing end of the generator.

I purchased the following parts from The Brillman Company: Field Coils, bearing, bushing and brushes.
I purchased other parts on Ebay: Armature (NOS), oil wick, nut and washer for the pulley, pole shoe screws, generator cover band.

This publication was a tremendous help to me. I was able to download it for free, but I can't find the link. It has detailed diagrams and parts lists for a lot of different Delco electrical products.

https://www.ebay.com/itm/284492607653

This link will help you determine if the armature needs replacement.

https://www.youtube.com/watch?v=qNV7TylIzSY

This link explains how to clean the commutator.

https://www.youtube.com/watch?v=oB-h-vZc6FY

This is a great video showing assembly. It also includes a starter:

https://www.youtube.com/watch?v=XIUpfmQ1LTw

The armature I purchased was a bit of overkill as the existing armature tested fine. However, I wanted everything new.

The following are the biggest lessons I learned from this.
- The 2 flathead pole shoe screws that hold the field coils in place are extremely tight. They show on
  the outside of the generator. I had to buy a socket with a wide flathead screw driver inserted and
  use a long ratchet to loosen them.
- When I tried to install the new field coils, the armature wouldn't fit between them. I compared the
  old coils to the new and they didn't match. I called Brillman, thinking I had the wrong field coils
  and they told me they use a machine to compress the coils and get them installed. I had to
  ship the generator housing, the new coils and the armature to Brillman and have them install the
  coils for me. They needed the armature to measure how much the new coils needed to be compressed. 
- The old bearing was the open type that required periodic lubrication through 1 of the oil ports at
  the front of the generator. The new bearing is the closed type that doesn't need lubrication.
  Therefore, the front oil port no longer needs oil.
- There are 2 gaskets on the generator. One on each end piece of the generator. They were not available
  anywhere, so I made my own. They say with the closed bearing a gasket isn't needed, but I installed
  one anyway.
- When installing the new brushes make sure they are installed the correct way. They are sloped at each
  end. 

Things to pay attention to during re-assembly.
- There are 2 wires from the field coil set that require connection. One is a bare wire that needs to
  be soldered to the generator Field post. The other wire should have a connector on the end of it.
  This wire gets connected with 2 other wires (brush wire and Ammeter post wire) with 1 screw near one
  of the brushes.
- Make sure the field and ammeter posts are installed before inserting the armature or they won't fit
  when you try to install them.
- The brushes need to be held back before inserting the armature. If they are not held back, they will
  block the armature from being fully inserted and could damage the brushes. I used paper clips to hold
  them back. The installation video above explains this.
- There are 2 sleeves that get installed on the front end of the generator over the armature shaft.
  Make sure you install them in the correct order. The small sleeve is installed before the larger
  sleeve. 
- When installing the fan and pulley, make sure the fan is installed correctly. The diagram shows this
  accurately in the document link I attached. Install the pulley with an impact wrench if one is
  available. Don't lose the woodruff key!!!!

After assembly was completed I took the generator to a local shop and had it tested with my voltage regulator. Everything tested out great. I will be installing the rebuilt generator in my Cadillac.

[Jay Friedman]

Great write up. I copied and saved it.  I usually take my generator and starter to a local auto electric shop for rebuilding, but it's useful to have your tips available just in case I ever had to do it myself. 

PS Brillman is a good company.  I've bought stuff from them several times.