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Technical early flathead Ford V/8 generator 2 brush vs 3 brush

Discussion in 'The Hokey Ass Message Board' started by dwollam, Sep 10, 2020.

  1. dwollam
    Joined: Oct 22, 2012
    Posts: 2,320

    dwollam
    Member

    @rusty valley, I understand!

    Love the roadsters. On top of all my other projects, I'm gathering parts for my 3rd '27 T roadster pickup on Model A chassis. This one is actually a touring front half with Model A bed. The 1st 2 were actual roadster pickups. Just a place to put leftover pieces and move on to someone else to complete.

    Dave
     
  2. dwollam
    Joined: Oct 22, 2012
    Posts: 2,320

    dwollam
    Member

    I got this 3 brush generator brought to me yesterday. Fields look crappy and should be replaced along with the wires. Can I replace them with 2 brush fields and use just 2 brushes and /or replace the end plate with a 2 brush plate? This one has vent holes in front plate and the rear.

    Dave

    20201031_113825.jpg 20201031_113834.jpg 20201031_113957.jpg
     
  3. dwollam
    Joined: Oct 22, 2012
    Posts: 2,320

    dwollam
    Member

    And....Just a few minutes ago I was putting things inside the shop and I picked this up in a box, thinking I had left the previous one sitting outside. Then realized it was another one entirely! Probably came from the same friend. It looks like a combination of parts that had been used on a '28 Model A pickup but has a ruined V/8 front mount and was either for a Model A or a N series Ford tractor! It also has a larger diameter pulley.

    Dave 20201031_151231.jpg 20201031_151238.jpg 20201031_151252.jpg
     
  4. dwollam
    Joined: Oct 22, 2012
    Posts: 2,320

    dwollam
    Member

    As I thought, my friend called me this evening and said he dropped this one off too!
    @rusty valley

    Dave
     
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  5. rusty valley
    Joined: Oct 25, 2014
    Posts: 3,883

    rusty valley
    Member

    i have not studied the internal wiring to see if one could convert a 3b to a 2b. i do know the case is slightly bigger on the 2bs, so output would possibly be lower with a smaller armature. food for thought
     
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  6. Deuce Lover
    Joined: Feb 15, 2009
    Posts: 1,047

    Deuce Lover
    Member

    Last edited: Nov 1, 2020
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  7. continentaljohn
    Joined: Jul 24, 2002
    Posts: 5,504

    continentaljohn
    Member

    I have found that the 2 brush has small slots on the back vent with the ones in my collection . I haven’t found one that doesn’t and as. @Deuce Lover noted the pullies have both curved and straight cooling fins I have found the pullies are smaller in diameter . Great conversation going on this subject on the fordbarn right now.
     
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  8. dwollam
    Joined: Oct 22, 2012
    Posts: 2,320

    dwollam
    Member

    I bought a used double pulley 2 brush generator off you know where from Canada. It is the large diameter pulley and has the fan mount. I'm thinking it was for a large cab over truck. Number cast in the front mount starts with O1A-***** so it is at least 1940? It does motor so it may be usable. Double pulley is ok as my fan is shorter than I would like. Wouldn't mind finding a longer fan. I'll post pics of the gen later.

    Dave
     
  9. Gregm1
    Joined: Dec 16, 2020
    Posts: 22

    Gregm1

    GOOD LUCK DAVE !

    GREG
     
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  10. LSGUN
    Joined: May 26, 2007
    Posts: 1,358

    LSGUN
    Member
    from TX

    So does anyone have an actual picture of a ‘39 2 brush fan mount generator? How is the pulley attached, nut and washer with key? Are the screw on fan pulleys with a snap ring aftermarket for later gens? The more I research the more confused I get. What’s the correct diameter pulley?
     
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  11. rusty valley
    Joined: Oct 25, 2014
    Posts: 3,883

    rusty valley
    Member

    cant help with a picture, but there is really no "correct" pulley size. pulley size determines fan speed, and therefore charge rate. you may want a higher fan speed on something like a city bus that seldom see's highway speeds, or you may want a slower fan speed , less wind noise, on a highway driven car. smaller pulley, faster speed, bigger pulley, slower speed. the same generator could have come with any size pulley from ford
     
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  12. LSGUN
    Joined: May 26, 2007
    Posts: 1,358

    LSGUN
    Member
    from TX

    I guess I should of clarified between the 85hp and V860, I’ve seen a chart that shows the V860 pulley being smaller in diameter. What about the pulley mounting, is this an aftermarket pulley?

    6C157B16-A1B3-4B7C-8CD0-80C6474B7A58.png
     
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  13. rusty valley
    Joined: Oct 25, 2014
    Posts: 3,883

    rusty valley
    Member

    that looks like the small ford pulley to me. they cant get smaller, no more room for the fan bolts ! i've seen many different types of these pulleys. if there is a part number, i have the green book to look it up
     
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  14. LSGUN
    Joined: May 26, 2007
    Posts: 1,358

    LSGUN
    Member
    from TX

    I appreciate the insight, it was on a gen I was offered to purchase. But note the mounting, it looks like an aftermarket pulley for the later gen, screws on with a snap ring end instead of a nut.
     
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  15. rusty valley
    Joined: Oct 25, 2014
    Posts: 3,883

    rusty valley
    Member

    some are like that. the snap ring is confusing, folks have been known to assume its on a keyed shaft and proceed to break the pulley because its threaded on. the generator chart in the parts book will make you're head spin...there are so many variations
     
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  16. I believe the pulley in the picture posted by @ LSGUN is an aftermarket pulley used to convert '40 to '48 generators to mount a fan. The pulley appears to be the type which screws directly on to the armature shaft and is retained by the snap ring. Ford started using this arrangement in 1940. I do not believe that Ford ever made a single sheave fan mount pulley for the '40 to '48 generators. But, who knows, there may have been some truck, bus, or military version.
    I have attached a photo of a '46 to '48 generator. It shows the snap ring on the end of the shaft to keep the pulley from unscrewing. The pulley is the normal passenger pulley of 3.18 inch outside diameter. The first photo is of a '39 Standard generator. It has the old keyway type mounting to keep the pulley on the armature shaft. There is a lock nut on the end to keep the pulley on. This is a two brush generator and was used on 1939 Standards only. Several parts are unique to this generator. The one shown has a pulley outside diameter of 3.68 inch. It is for a 60 HP, the 85 HP used a slightly larger pulley.

    !_39 Gen.JPG !_46 to 48 Gen.JPG
     
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  17. continentaljohn
    Joined: Jul 24, 2002
    Posts: 5,504

    continentaljohn
    Member

    Anyone convert a 3 brush to 2 brush to 12v neg ground info
     
  18. dwollam
    Joined: Oct 22, 2012
    Posts: 2,320

    dwollam
    Member

    Greg, when are you going to be gone so I can come get that '39 Standard Generator??

    Dave
     
  19. Wardog
    Joined: Jan 12, 2010
    Posts: 2,437

    Wardog
    Member

    F8664063-03A7-4D37-AFFC-3E605CAE5305.jpeg DE929F94-F295-4364-8B8E-FB4D27BB759F.jpeg 64C42D93-18F4-445F-A2B7-0521CDD8C863.jpeg
    I’ve just put my coupe on the road. I’m running a 3 brush generator converted to 12 volt with a fun projects cut out with a diode installed. I need to find the balance between charging and not over charging. I have very limited electrical knowledge but from what I’ve read the cut out basically just protects the generator from the battery running back in to it when the engine is not running. So could I set the generator to maximum output and run a regulator from a later model? As you can see, I’d really like to use this generator.
     
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  20. Truck64
    Joined: Oct 18, 2015
    Posts: 5,325

    Truck64
    Member
    from Ioway

    A diode changes the charge voltage the battery will see slightly, it has a voltage drop of about 1/2 volt compared with a mechanical cutout relay. That doesn't sound like much, but in terms of a 12 volt battery, on a percentage basis it is a lot. Remember, 12.6 volts is "fully charged" and 12.0 is almost "dead". There's practically only a 1/2 volt total from "empty" to full if you think about it.

    I thought about bypassing the cutout with a diode on a later style VR, just to avoid the possibility of battery backfeed and looked into using a diode. I don't know enough about the system you are describing, but the principle is the same, you need to compensate by about 0.7 volts due to forward voltage drop.
     
  21. WB69
    Joined: Dec 7, 2008
    Posts: 1,958

    WB69
    Member
    from Kansas

    Awesome thread. Learned a lot from it. Amazing the knowledge on this site.
     
  22. Wardog
    Joined: Jan 12, 2010
    Posts: 2,437

    Wardog
    Member

    @Truck64 thanks for the reply.
    I took the generator into my local auto electrician today.
    I had the cut out wired wrong...
    He set the third brush to 5 amps output on his test bench and had it putting out as much as 16 volts at a higher speed than this engine will ever spin it. The only thing to do now is drive it both at day and night and check battery voltage.
     
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  23. F-head
    Joined: Oct 20, 2007
    Posts: 1,171

    F-head
    Member

    Here’s a couple of 81-A generators chromed and converted to 12 volt by my pal Gary Duff
    The top one has the rare v8 60 pulleyand NOS field coil screws These are for my projects these have had ground poles added 81E90583-2FAE-468A-BEB3-4EEC98CB214D.png DE555DE2-4481-4820-BC23-EBBE99852E36.png
     
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  24. dwollam
    Joined: Oct 22, 2012
    Posts: 2,320

    dwollam
    Member

    I'm still on the hunt!

    Dave
     
  25. V8-m
    Joined: Jun 11, 2020
    Posts: 195

    V8-m
    Member
    from Alaska

    I'm also thinking about converting my generator to 12v but I have completely different idea. I found very small alternator. Two outputs are available-40Amps and 60Amps. Internals off this alternator are very small and from my research it could fit inside the generator housing. So... generally I want put alternator in generator housing not changing look of it.
    Do you guys think 40A will be enough? I don't have anything more than lights to be powered so 40A x 12V = 480W should be more than enough.. I must check stator diameter if its the same between 40 and 60 A I take 60.....if not it will be 40A
     

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    Last edited: Feb 24, 2023
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  26. Frank Carey
    Joined: Oct 15, 2009
    Posts: 574

    Frank Carey
    Member

    In Bill Toboldt's 1952 book "Fix Your Ford" he says:
    If the generator and regulator and electrical system are in good condition but it is impossible to keep the battery fully charged because of considerable low speed operation, a smaller pulley may be installed. This will drive the generator at a faster speed and keep the battery charged. This smaller pulley is Ford part number 8BA-10130-C and has an overall diameter of 2.76 in. However, the life of the driving belt will be reduced because of the sharper bend as the belt passes over the pulley.
     
  27. Tall Coil
    Joined: Apr 20, 2023
    Posts: 1

    Tall Coil
    Member

    hi Dwollam,
    This is my first time to reply on this site so please be patient with me. when this discussion started Rusty Valley mentioned that he had a three brush generator converted to a 40 amp alternator by E.J. Whitney Co.. That's me !
    One of the photos I saw was a front mounting bracket with no air holes and a pulley with no cooling fan on the back of the pulley. These were used on 32 and 33. and with only 12.5 amp output, they could get away without cooling.
    So in your case you want a two brush generator with a pulley carrying a radiator fan. I will start by saying that the easy way to identify a 2 brush is by the narrow air slots at the rear of the field housing. The combination of 2 brush with a radiator fan pulley was never done by Ford. The only way it was done was with an Aftermarket pulley that has threads to screw it onto the 2 brush armature. Those pulleys are almost as rare as hens teeth. ( personally I horde them) There was also some discussion about bearings with this setup being overworked. The front mounting bracket on the 3 brush models have a snout that extended the bearing out to be inside the the pulley which puts the belt load right over the bearing. Two brush doesn't do that but the shaft and bearing diameters are larger and I believe are sufficient for the task. I would use modern sealed bearings. You may need a shim where the generator mounts to the intake manifold in order to align the pulleys.
    Everyone keep in mind that the wide belts and pulleys Ford used up until the 50s have more friction area and don't need to be very tight. The tighter they are the harder the bearings have to work.
    At this time I have converted 512 Ford generators to alternators, 6 or 12 volt while using many of the original outside parts to keep them looking correct. Most of them have been the three brush type.
    I have many photos of the different pulley options Ford used if someone is interested.
    Tom
     
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  28. dwollam
    Joined: Oct 22, 2012
    Posts: 2,320

    dwollam
    Member

    @Tall Coil , thanks for the reply. I do have to disagree with you on no 2 brush gens with fan mount as "39 Standard cars and pickups did indeed use 2 brush with fan mount. '39 Deluxe went to crank mounted fans. I have a friend with a stock '39 Standard and it has gen mounted fan. I have since bought three 2 brush gens with factory fan mounts and one with a double pulley from a cab over truck. I will be mounting one on an 8ba engine with truck pumps and 8ba gen mount so it can be slid forward to line up pulleys.

    Dave
     
  29. ndnchf
    Joined: May 22, 2012
    Posts: 2

    ndnchf
    Member
    from virginia

    Ressurecting an old discussion because it is pertinent to my questions. I'm still a bit confused

    I'm trying to identify these two generators and their applications. On the left is a 3 brush with T2 date code (Feb 1939). It has 4-3/8" diameter fan mount pulley, keyed with nut. On the right is a 2 brush, no date code found yet. It has a single terminal post on the side and one on the back. A 3-1/8" diameter screw on non-fan pulley with clip. The pulley is sheet metal, not cast. Perhaps aftermarket?

    My intent is to rebuild and offer them for sale, but want to be sure of their application.
    Thanks,
    Steve 20231015_071918_copy_1008x567.jpg
     
  30. BJR
    Joined: Mar 11, 2005
    Posts: 9,814

    BJR
    Member

    It would be interesting to find out what it takes to put a voltage regulator on a generator that originally had a cutout on it. Does anyone know, and can explain it to us?
     
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