Generator pulley interchange

B

bobscogin

Senior Member
I'm putting a '42 Mercury engine in my '28 RPU, and want to convert to a single belt for driving water pumps and fan mounted on generator. So, I'll need a gen pulley with the threaded bosses for the fan. What's the story on these? From what I've read, seems the '38-'39 pulley has the fan mounting holes and will fit the 2 brush generator. Is that correct? Further, I understand that the 3 brush generator pulley, of which all years have the mounting holes, don't fit the 2 brush generators. Is that correct? If so, can they be modified to fit? Thanks, --

Bob
 
bobscogin said:
I'm putting a '42 Mercury engine in my '28 RPU, and want to convert to a single belt for driving water pumps and fan mounted on generator. So, I'll need a gen pulley with the threaded bosses for the fan. What's the story on these? From what I've read, seems the '38-'39 pulley has the fan mounting holes and will fit the 2 brush generator. Is that correct? Further, I understand that the 3 brush generator pulley, of which all years have the mounting holes, don't fit the 2 brush generators. Is that correct? If so, can they be modified to fit? Thanks, --

Bob
Click to expand...

You are correct. You need a two Brush pully that has the provisions for a fan, which I believe were '38 and '39. The earlier three brush pullies will not fit the two brush generators and can not be reasonabily modified to work. Originals are getting hard to find BUT I think I saw a reproduction of the pully you need in Sacramento Ford's Catalog. May be other parts vendors also have them.

I hope this helps,

Chris
 
I also think the good folks at Antique Ford in Rosemeed, CA? was working on a US-made repop.

OR..... An even better option is to get in contact with Fordbarn's own Charlie S.

He'll either modify the pulley you have or you can buy one of his from his stash of cores.

Great, quick service at even better prices. Great guy and has been a Fordbarn regular since the the beginning.

Charlie Schwendler
5845 Cole Rd.
Orchard Park, NY 14127
716-662-9159

cac5845@yahoo.com

Good luck.
 
The 39 deluxe has a crankshaft fan. 39 truck and i'm not sure but think the 39 standard had the generator mounted fan. I don't know if the standard had the 2 brush generator or not. I saw a screw on fan mounted pulley on ebay in the past several days. It was aluminum and don't think I would like that. I had an after market cast aluminum pulley on my 39 deluxe last summer and it cracked and the front fell off. Lucky the engine was idling and I heard a slight clunk, looked and found the front of the pulley on the frame. The whole front came off right down to the hub. I was about 10 miles from home, the belt stayed on and I watched the digital volt meter I had on to see if the belt came off, I made it home and changed the pulley. The aluminum pulley got real hot compared to a cast iron one. The one on eBay is turned out of bar stock, billot is the new term. I think these will get hot but not crack like a cast one. G.M.
 
Thanks for the info. Before I seek out an original OEM pulley, I thought I might do a little research for an alternative.
I found some pulleys here, including one with provisions for a fan.
http://www.qualitypowerauto.com/catalog.php?item=69
They're made for alternators, so I don't know if the diameter/speed would be right for a generator. The bores are listed as 17mm. Anyone know the shaft diameter of the 2 brush generator?
Bob
 
Also, the split isn't actually between 3 and 2 brush generators...the '38-9 2 brush used the 78 pulley, left over from 1937 when they went to the big shaft size on three brush generators. Easiest parts breakdown to follow is the one in the '38-9 parts book, partially replicated in the '38-9 restoration book. You also need the '37 bracket/front plate, which is curved to fit into the curved fan blades on the pulley.
From there, I have not progressed, but I think case and armature length may be a problem...I have everything I need to figger this out but have had no time. I have a complete 2 brush fan gen, extra 78 hardware, and a truck COE setup which uses the 78 nose and a fan/gen pulley made for the 2 sheave truck pumps. Need to spread it all out and see what fits where.
You are not going to just slap a '37-39 pulley onto a '42 generator, though.
 
Bruce Lancaster said:
You are not going to just slap a '37-39 pulley onto a '42 generator, though.
Click to expand...

Nothing is ever as simple as it seems. Given the current popularity of the AV8, seems like someone would be making a hybrid pulley that fits the later generator and has a fan mount. Well, I've got a lathe, and I've got metal, so----

Bob
 
I've got a couple of pulleys that work, they're stock parts... problem is, I don't have a way to I.D. them.... Swap meet finds... My favorite is from a truck, it's large, this keeps the fan speed down... The generater seems to get spun fast enough... Karl
 
Bruce Lancaster said:
Post what you figgerout and make! I think that this area is still only dimly understood...research continues.
Click to expand...

I'm a ways from needing the generator; engine is still in the build stage. However, if I come up with a workable solution, I'll surely document it and post it here.

Bob
 
Bob, A few years ago I got some of my different Ford V8 fan mount pulleys together and attempted to do a little picture description of all these pulleys. I never totally finished getting PN's and ID descriptions together on this. Any who, here are the pictures of what I did get done. I found the '39 std pass. car and '39 PU truck both had the pulley that most people want. This pulley has an ID that will fit the two brush generator. I also found some smaller OD pulleys with the larger ID that will fit the two brush generator as well. I know I saw a reproduction of the '39 std pulley being offered by someone but CRS strikes again and I can't remember now where I saw this. I hope these pics help you or others in some way. Good luck! JM

FordFanMtGenPulleys-1-1.jpg


FordFanMtGenPulleys-2-1.jpg
 
On that...I believe the 1937 pulleys were the first with big shaft that will work for later armatures. The commonest carries the 78 prefix right on it, as does the matching front plate. Earlier all seem to have the small shaft and not a whole lot of metal for reshaping. From the parts listings for the '38-9 2 brush gens using the '37 type pulley and front, you will see that there are several variants of each of the parts with prefixes like 77 and 82 because there were a couple manifold stud heights and fanbelts, truck and V860 variant pulley sizes, etc. The differences would not matter a whole lot for a non-stock application.
Most pulleys I have found carry the cast-in prefix, and once you have that the parts books will tell you what vehicle the thing was for.
The cabover version I have carries the 1940 01-W or Y (forgot to look), uses the 78 front I think, and has two sheaves to match the double sheave truck pumps.
I need to get back to this project and find out which later cases and armatures are in play here.
 
That chart gives numbers for the bigger parts involved. There are also text charts fully listing out all the parts in the generator in the cumulated parts books. Once you identify the sevearl passenger, truck, and 60 versions of the two brush fan mounts you will have some options on pulley and front plate. Most pulleys and plates have the PN prefix cast in so you can get a clue on what the piece came from. The 78 pieces are the most common since they were used in full production on the '37 3 brush.
By the way, the full chart listings of generator pieces will likely drive you blind and crazy...
 
The 38 and 39 two brush fan mount generators have slide on pulleys. The 40 and later fan mount pulleys are screw on. The armature for the 38 and 39 generators is longer for the nut and washer that is required. Also, these generators (38 and 39)have the 78 front cover.

I found it interesting that the 38 and 39 two brush generators use the brushes from the three brush generator and you just throw away the third brush. I don't see any difference in the output from either generator.

I have a caution when removing the pulleys from either style generator. Make a fixture that will mount to the four fan screw holes. Make the fixture large enough so you can tap the fixture lightly to remove the pulley. Also, when removing the screw on style use the same fixture and mount it to a vice. Take the generator apart, wrap a fabric oil filter removing tool around the armature and unscrew the armature from the pulley.

I have been sucessful in locating both styles of generators is large Ford swap meets such as the Model T Swap Meet in Long Beach and the LA Roadster swap meet.

Good luck. Don
 
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I find that most of my later type armatures found in screw-on pulley generators are cut for keyways. The early 2 brush actually used most of the 3 brush gnerator, it looks like, but I have a fan mount that seems to be all '40-48 type stuff behind the 78 plate and pulley and will be figuring out how that one was done. Likewise the cabover one I have seems to be late type case.
 
I have a fairly large supply of Ford armatures from 38 thru 48 and they all have keyways but only the 38 and 39 armatures utilize the keyway for the pulley. Why do the later series have a keyway? I don't know, possibly there is another application for the armature that requires the keyway. I just looked at my supply with the screw on pulley, one has the G420 and the other is not marked, both of these use the 01A front cover. I think that both of those pulleys must have been after market because G420 is not Ford. The other 3 or 4 are the slide on pulley style and they have the 78 front plate.

There is a great picture of the 38/39 two brush generator on page 456 of the green bible. Actually I do see on page 458 where the 81T series is used on 38 thru 41 large truck with a double sheave pulley. On page 460 it shows that the armature 78 10005-C was used on both 3 brush and 2 brush generators.

The pictures of the pulleys is great. I think it is obvious that only the pulleys on the right side have the large hole as is required for the 2 brush or late 37 three brush.

Jim Gordon, Antique Ford in Rosemead Ca. was going to produce the pulleys but the last time I talked to Jim he said he was not going to do the project.

It would seem that there would be a need for a cast iron knock off of the screw on style pulley because there are so many more of that style generators around. I don't know if the cost could be recovered though. I don't think aluminum is the way to go.
 
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I think the market has been reduced by alternator setups.
You can see the multiplicity of odd application generators, lots of them by 1948, so I think the keyways may have hap applications on late cabovers or who-knows-what.
Now, if you look at the huge range of generators by 1948, some existed only in very small numbers, all of the HD police stuff and such, but even the ones used in general production models of passenger and truck vehicles are quite numerous. The need for many lengths and other variations of armature confuses interchange, and of course the heavy overlap of parts between early 2's and late 3's is something of a surprise to many. And--the book larnin' stops at the case, because Ford made that a NS part.
 
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