How do I adjust the third brush?

[ricosan]

Hey Guys,

 

I have read everything I can find on adjusting the output of of a Delco/Remy generator but I can't find anything describing  how the "adjustment" is performed.  I have taken the metal strap off that covers the access holes to the brushes.  This exposes 2 brushes on one side and something on the opposite side that I can't see very well but it looks like it may be the third brush however I don't see any way to adjust it.

Any help appreciated.

ricosan

[ply33]

On the Delco-Remy generator on my car there is a lock screw on the back plate of the generator that has to be loosened and then the third brush can be moved. On my generator the third brush holder has a little arm that I can use to move the assembly.

 

I don't know how much they changed the design for different customers (mine is a Chrysler product) or over different years of manufacture, so yours may be different.

[ricosan]

ply33

 

Here are some pictures of my Generator.  

Edited June 17, 2016 by ricosan
Photos (see edit history)

[Friartuck]

The third brush assembly moves in an "arc like" manner over the copper commutator. What you are actually doing is moving the 3rd brush in relationship to the ground brush (180 degrees opposite to the 3rd brush). Move it in small increments. A good adjustment value is to be about zero amps (fast idle) on the ammeter with the head lights on (generator produces enough current to operate the head lights and ignition). That should be about 7-8 amps with the lights off. The intent here is not to cook the battery during normal daylight driving.

[DavidMc]

As Friartuck says " The intent here is not to cook the battery...."    

Keeping to a maximum of around 8 amps also prevents cooking of the generator.  On my first project may years ago I set the third brush to give about  15 amps (maybe more it was a long time ago) and the generator eventually overheated and solder melted out around the commutator. . Once it was repaired and the set to about 8 amps it has never given a problem.  There is no cooling on those early.generators

[ricosan]

I see a lot of screws in the generator (see pics), but they don't appear to adjust anything.  Am I at the wrong end?  Do I adjust the third brush while the engine is running or do I stop it each time and adjust and restart the engine?

ricosan

[Guest]

The machine screw is on the "end" of the generator.  It holds the third brush holder tight to the end frame of the generator.

[Guest]

Attached are some pictures of an end plate removed from a Delco Remy generator for a 31 Cadillac. It should be similar to yours, although yours appears to have a cooling air tube installed on the end plate. This picture shows the applicable screw from the outside. I have a scribe pointed to the screw. This picture shows the same screw from the inside. Again, the scribe points to it. Note that the screw simply goes into a thin tab, and that there are only a couple of threads, so don't loosen it but about a turn. If it comes out of the tab, the tab will fall off inside the generator. The screw does not adjust anything, but simply causes the tab to be locked against the shiny ring that surrounds the bearing in the picture. The 3rd brush is attached to this ring and will rotate with it.

This picture shows the scribe pointing to the third brush. Note to the right of the scribe how the brush holder for the third brush is attached the shiny ring and will rotate with the ring when the tab is loosened.

This picture shows the scribe pointed to the ground brush. Note the pigtail wire running from the brush holder and grounded to the end plate via a screw connection.

This picture shows the third brush rotated to the maximum. Note that it is as far away from the grounding brush as it can go as mentioned by friartuck. So, the procedure is to loosen the applicable screw slightly, reach through the slot with your index finger and rotate the third brush, and then tighten the screw. Do this with the engine not running. Adjust brush, tighten screw, start engine and check results. Repeat as required. Do not over tighten the screw. If you strip the tab, that's bad.

 

Edited June 20, 2016 by Guest (see edit history)

[Friartuck]

I'm going to add my $.02 here. This picture of my 3rd brush assembly maybe easier to follow. The 3rd brush is the one on top. It should have a means to secure the entire arm against the case without shorting it out. In the below example, the third brush assembly is on a plate that pivots around the bearing.

 

 

Edited June 18, 2016 by Friartuck (see edit history)

[ricosan]

Thanks Guys,

 

Caddy, thanks for the great  pictures.  It's so true, "a picture is worth a thousand words!"  

You have exactly the same generator as mine. I was looking for the adjusting screw in the wrong area.  I found the screw on the end cap.   I was then able to move the third brush.  

BTW,  the tube attached to the end of my generator is a shaft connecting it to the water pump.

ricosan

[Owen_Dyneto]

I rarely drive at night so I adjust my 3rd brush differently than has been recommended.  I adjust for a maximum charge rate of about 5 amps at road speed for daytime driving.  If I'm going to drive more than a few blocks at night, I readjust to about 5 amps at road speed with the lights on, and return to the normal daytime setting when nighttime driving is finished.

[Rich Janouskovec]

I have a resistor wire? in my generator on my 31 OLds that burned out. Does anyone know where I can get one? Something like what is on the first generator pictured from ricosan.

It also looks like Friartuck's last picture may have one in it also.

Edited October 3, 2016 by Rich Janouskovec
additional information (see edit history)

[Friartuck]

31 Caddy reported on another thread success with Advanced Electrical Rebuilders in Michigan. Perhaps Jason will sell you the needed part. http://www.aerrebuild.com/

 

Be patient with Jason, apparently it takes him some time to return phone calls and emails.