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Generator field coil retaining bolts

Posted By jrw429 14 Years Ago
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jrw429
Posted 14 Years Ago
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OK, parts have arrived, and I'm rebuilding the generator after my adventure driving home from Oregon to purchase the wagon. See the attached image, a full rebuild is definitely needed. The problem I'm facing now is how to remove the bolts on the side of the generator that hold in the field coils? The Ford 1957 shop manual shows a setup involving a bench press and a custom tool to remove the bolt. Assuming that is no longer available, how do I get the bolts out?



I've tried a 1/4" socket drive directly into the bolt holes. It is close but too small and will round the bolt hole.



I bought some 1/4" steel stock. That fit fairly well, just a bit loose but the 5/16" was too large. With a socket and ratchet drive on the end of the stock I could try to turn it, but it just rounded the stock.



Any other thoughts? I've tried several hardware stores and auto parts stores, but no luck.







Jim - Erie Colorado, 1957 Country Sedan
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oldcarmark
Posted 14 Years Ago
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A rebuilder would possibly have the correct equipment to do it.No point in ruining them.

http://forums.y-blocksforever.com/Uploads/Images/a82cee8f-be33-4d66-b65d-fcd8.jpg  http://forums.y-blocksforever.com/uploads/images/339ed844-0bc3-4c73-8368-5dd3.jpg
marvh
Posted 14 Years Ago
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I have taken many apart with a hammer and a sharp centre punch. With the hammer tap the punch in a

counter-clockwise direction with the punch's point set in the edge of the screw head. It takes a fair hit to break the screw free. You will have to file the sharp edge of the screw afterwards so not to rip your hands when handling the generator.



I have also found a correct sized square Proto easy out will take the punishment required to remove these screws. The screws are very tight.



Your generator bracket it looks like you have 40 amp generator with a 25 or 30 amp bracket. The bracket should fit the generator frame tight.

marv
jrw429
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The more I look, the more daunting it seems. I see threads where people talk about reshaping the coils once they are installed to get 0.100" clearance from armature to coils. And generally needing a press to get the bolts out and back in. Ugh. Is it really this difficult?



I'm starting to consider using the existing field coils, and replacing the rest of the internals.

Jim - Erie Colorado, 1957 Country Sedan
marvh
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You can r-use your field coils if they have not been damaged by heat or that piece of commutator ripping the insulation of the coils windings when it flew out.



You need a new armature for sure, set of bearings and brushes. On the armature you will find some numbers stamped on one of the laminated bars on the fat part of the armature.

You will need that number to tell your supplier for ordering a correct replacement armature.



My personal opinion would be to replace the generator with an alternator as the cost will be nearing the same.

Someone on here uses an alternator from a 97 Ford escort, there was write up if you do a search. This is a small alternator with internal voltage regulation and lots of air holes for cooling while putting out 75-95 amps depending on the build.

marv
Oldmics
Posted 14 Years Ago
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Check the field coils first.

If they have continuity and are not shorted to the case-reuse them as is.

Dump the core in the tank and scrub out all the stuff,blow it out real good ,then RECHECK AFTER THE BATH.

As long as the fields are not grounded to the case they are keepers.Shorted fields can even be saved by rewrapping the shorted coil with surgical suture tape.

Obviously you need a new armature.And the new brushs will have to be seated in with a soapstone.

Give it a whirl.Hell ya got it home-that was the hard part BigGrin

If you really have to replace the coils,a blunt punch will suffice to unscrew those square screws.Or an impact driver.Personally I would rather use the punch method.If you "punch" make sure to grind down the punch knubs caused by the punch impact as they will cut you.

I just reread the post by marvh.I bet we worked in the same shop!

Oldmics

DualQuad312
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this e-mail is in reply to the gentleman who is having difficulty taking out the anchor screws securing the field coils.....If you have a "square" set of craftsman chisels or punches you may find the the shank of one of these tools may fit, you can always grind the sides down..... Use an adjustible wrench to turn the punch or chisel....Tapping on  the screws with a brass punch first would help to jarr the scews loose....

Jeff

jrw429
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I think the advice to switch to an alternator is wise. And I will do that, but I kinda would like to have success rebuilding the generator first. This is the first time I'm really "doing" a car instead of talking and dreaming, so I want to muck about with all of it. I hope you'll all bear with me as I take this journey.



And it turns out the brushes were kinda worn. Smile Copper braid was broken off both connectors. One brush was worn all the way down to where the copper was wearing through the carbon.





Jim - Erie Colorado, 1957 Country Sedan
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jrw429
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Oldmics (11/9/2011)
Check the field coils first.




The new coils have about 8 ohm resistance. 320 feet of 24 guage copper wire would have about 8 ohms resistance. This makes sense to me.



I've removed both the ground and field terminal from the generator housing. The resistance of the coil is about 0.75 mega-ohms. The resistance from the field terminal to the housing is about 3.5 mega-ohms. The resistance from the ground terminal (not touching housing) to the housing is about 2.3 mega-ohms. This doesn't make sense to me. But whatever is going on here, it isn't good. The old coil has to go.



(The Ford shop manual says to test the field coils by hooking the battery directly to the two ends of the coil with an ammeter in series. Hooking the battery to a long copper wire with no load seems like a bad idea to me. The shop manual says nothing about the expected resistance of the field coils.)

Jim - Erie Colorado, 1957 Country Sedan
Oldmics
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While there probably is some electrical engineering measurement of the coils-in all of the rebuild shops that I worked at no measurement of the field coils was ever preformed.

To test the field coils,a simple A.C. lite bulb was attached to two leads.Connecting the leads to each other illuminated the bulb.

One of the leads was placed on the generator frame the other on the dissassembled field line.As long as it did not illuminate the bulb or burn up (literally) the fields were decreeded as reusable.

The A.C. hi voltage application was a better test than a D.C. continuity meter.The A.C. hi voltage also burnt away any copper debree or deposits left behind from the commutator and brushs.

Sounds crazy today but thats how we did it in many of the rebuild shops I worked in.

Oldmics



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