Need help with Ford 3000 generator rebuild

[dbritt]

Hello, I'm a newbie to this forum. I hate to resort to asking for help, since I usually figure things out on my own. Eventually. But, this one has be stumped. I am restoring my old 3000 diesel that sat in an enclosed shop for the last 16 years without moving or being started. Everything has gone by the book until I got into the generator. I tore it down and had to clean out an unimaginable amount of dirt dauber nests and brown recluse spider skeletons. The generator worked the last time the tractor was running, but the bearings were making noise and the brushes are about half worn down, so I wanted to fix it up right while I am at it. I did a complete cleanup on all the parts, repainted the housing, end plates, fan, pulley, etc, and it all looked like new. But, when I reassembled it, I noticed that the commutator runs so close to the brush fixed brackets that it looks like it could actually be rubbing against them. If not, there's not a paper's width of clearance. Note that I can NOT say that it wasn't this way before I tore it down. It may have been, but I had no reason to check the clearance before disassembly began. I have a hard time believing it could have been that close without having issues.

I pulled up the generator exploded view in Ford's service manual and everything is there, and in the right place, but the armature seems to be sitting an 8th or 16th of an inch too far to the rear. I could find no reason for it to be running that close. As it happens, I had an old generator that I had to replace with this current one several years ago, so I got it out and looked in the back end and could see at least an 8th of an inch clearance between the end of the commutator and the brush fixed mounting brackets. After tearing the bad one down and comparing everything, there are a couple of minor differences. The bad one is dated coded 6-66 while the new one is coded 8-67, so both are replacements of the original, but close in production dates. The differences are in the spacer on the front of the armature that goes between the armature windings and the front bearing. It's a different type and is spaced a 16th of an inch farther forward on the shaft from the windings than the one I'm rebuilding. The second difference, and what does not appear to be contributing to the problem is an O-ring in the bad one that isn't in the new one. However, it's not in the exploded parts drawing. It is a very thin O-ring in a groove about halfway down in the bore for the rear bearing in the end plate. There is a groove in the one I'm rebuilding, too, but no O-ring, and there's not an O-ring shown in the drawing or in the parts list. I don't know what that groove is for, and I find no mention of it in any service info, but one would think if they machined a groove in the bore, SOMETHING should go in it, a snap ring would have been my first thought. No snap ring in the parts drawing either. I'm wondering now if someone had this same problem that I'm having and put that O-ring in there to keep the rear bearing from bottoming out in the bore and letting the commutator run so close to the brush brackets.

Has anyone seen this before? Does anyone have a 3000 with the 22-amp generator of about the same vintage, who would be willing to look in the openings of the back plate and see just how close their commutator is to the brush brackets? I don't know how to post pictures yet, or if it's allowed, but if someone needs to see a picture of what I'm talking about, send me a PM and I'll e-mail you some pictures. I've spent 2 days trying to figure this out and am about ready to either place an order for a new generator, or an alternator and conversion kit.

Thanks in advance for any help you can provide.

David B.

 

[dbritt]

Update: I've been looking through various documents online this evening, and sure enough, I found one that lists an O-ring and refers to it as:

O-ring, 1.125" ID x .070" THK, Bearing, Start Year: 01/01/65 with a Part# of 87026S94. Messick's lists that part number with a picture of the O-ring, and it's the one that's in the "bad" generator. So, I guess it's supposed to be there.

However, even though it's listed in the parts list, there is no reference number to it for the exploded view drawing of the generator, and it is not shown anywhere on the exploded view. Therefore, I have come to the conclusion that it is intended for the bearing to slide past that O-ring so that it rests on the outer race of the bearing and prevents it from turning in the bore. It is not a press fit in the bore, so I guess this O-ring is what keeps it from turning in the bore.

Now, since that appears to be the case, I am back to the issue of why the lack of clearance between the commutator and the brush holder's fixed bracket. I went ahead and reassembled the good generator, and nothing actually touches or rubs on the commutator, but it is dang close. I spun the generator by hand after reassembly and it produced between 4 and 10 volts, depending on how fast I could spin it. So, it appears to be working, but I'm sure uneasy about that tiny clearance. I guess I'll put it back on the tractor when the project gets to the point that it's ready for it, and then I guess we'll see if the lack of clearance going to be a problem. Unfortunately, now I have to disassemble both generators again so I can steal the O-ring out of the "bad" one and install it in the "good" one.

DB