Replacing generator field windings

[MVal]

My 30-31 generator recently overheated (250+ deg) and the field pole insulation is scorched and mostly missing so am considering replacing both field poles and anything else to put it back into usable condition. But before I spend money on the field windings etc. and get involved in the project wanted to know if anyone has some experience in removing the screws holding the poles in place as they look pretty securely in place. Have considered using a rachet with a screwdriver attachment in a drill press but thought maybe someone had a better idea and more experience.

[Y-Blockhead]

I recently replaced the field coils on two starters (converted them to 12v) and had to drill out the screws (same screws as generator) and install new screws. The bevel on the screw is at a different angle than the bevel in the starter or generator case (~1°) so they are basically an interference fit and just about impossible to remove without destroying the screw anyway. Once you drill the head off you can remove the threaded part by hand.

I broke two Snap-On bits using an Impact Driver with no joy. Much cheaper to replace the screws.

[Synchro909]

Try a little heat on the head of the screws. Heat them till red hot with an oxy torch, allow to cool and undo. If they are still tight, I'd use an impact driver to move them. A drop of penetrating oil will help.

[montanafordman]

I ended up using my wire welder on a couple generators I'm rebuilding. I welded along the slot in the screw and built it up above the screw along the slot high enough to grab with a pair of vice grips and turn them out. The heat, plus the leverage gained from grabbing the built up weld bead made breaking the screws loose much easier. Then I replaced the screws.

Of the two generators I'm working on - I assembled one with good original parts. It motors beautifully but I have not yet tested it on a car. The other I have a new armature and field coils for and I can't seem to get the pole shoes tight enough not to interfere with the armature. Even tightening the pole shoes with bolts wont seem to cut it. I may have to take it to a generator shop to see if they have any better method of tightening the pole shoes and forming the field coils around the shoes and contouring to the inside of the generator case.

[tbirdtbird]

do a search i have described a very easy method for removing these. it is similar to the OP's ideas of a bit in a drill press.
they are supposed to be in there tight; the pole shoes want to be tight to the case

[Herb Concord Ca]

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Y=blockhead has the rigth idea, that how I do both generators and starters. what is left in the pole piece you can remove with you fingers!

For Montanafordman, new field coils need to be formed to both the case and the pole piece for them to fit correctly for armature clearance. I also use C-clamps to hold them in place while it tighten the screws.

[RonC]

Bring it to a local starter/generator rebuilder with the new field coils and ask him to replace them. There is a clearance spec to the armature but I don't know what it is

[steamgas]

a good machinist should have them both out in less then 15 minets.

[ndnchf]

I'll tell you up front, it is very difficult without the correct tools. The screws are extremely tight - and they need to be. There is only about .010" clearance between the pole shoes and spinning armature. New field coils need to be formed to fit around the shoes. this is done as the screw is tightened. I made the tools to use a 3 ton arbor press to remove and install the screws. You can get a tailpipe expander at Harbor Freight that will really help in seating the pole shoes/fields. Any generator/starter shop can do this for you for a few dollars.

[nkaminar]

Take two large C clamps and clamp one pole to the generator housing close to the screw on both sides, fore and aft. Use the impulse screw driver that you hit with a hammer. Clamp the poles to the housing again when you re install them. Same idea as the tail pipe expander that ndnchf talked about.

[Fhane]

I use a small punch to loosen the screws by placing the punch on the end of the screw slot a taping it counter clock wise. Replace with new screw if you want to. To set the shoe and coil I use a 3/8 by 16 bolt (I think) and tighten the shoe and coil. Remove the bolt and replace it with the proper screw. Might need a few taps with the punch and hammer.

[Benson]

In post #1 you say generator overheated.

The battery is what regulates the voltage that the generator puts out.

If battery connection becomes loose while generator is charging the voltage can exceed 40 volts and generator will smoke.

This can happen if the battery connections (inside or outside of generator) or the wiring from the battery to the generator has a loose connection.

If you do not find and fix this loose connection then the rebuilt generator will burn up also.

[BRENT in 10-uh-C]

Originally Posted by steamgas

a good machinist should have them both out in less then 15 minets.

Geez, I am wondering why the need to offer advice on this post 6 years after the fact??

Originally Posted by Benson

In post #1 you say generator overheated.

If you do not find and fix this loose connection then the rebuilt generator will burn up also.

Again, this post is over 6 years old!! Since MVal has posted many times since then but has not mentioned any ongoing problems with his generator rebuild work, maybe we could/should assume he has likely found his problem by now?? Just a thought!!

[DJ S]

Originally Posted by BRENT in 10-uh-C

Geez, I am wondering why the need to offer advice on this post 6 years after the fact??





Again, this post is over 6 years old!! Since MVal has posted many times since then but has not mentioned any ongoing problems with his generator rebuild work, maybe we could/should assume he has likely found his problem by now?? Just a thought!!

Perhaps it's good to add additional info to this thread for a future resource to others... Just a thought...

No need to put others down when they're trying to help others.

[Benson]

Originally Posted by DJ S

Perhaps it's good to add additional info to this thread for a future resource to others... Just a thought...

No need to put others down when they're trying to help others.

Exactly DJ S I agree with you:

I will not post the details of what I really think here.

But this kind of comments is the reason that I do not comment on this website very often anymore.

I guess my 60 years ...

[BRENT in 10-uh-C]

Originally Posted by Benson

Exactly DJ S I agree with you:

I will not post the details of what I really think here.

But this kind of comments is the reason that I do not comment on this website very often anymore.

I guess my 60 years ...

Agree with what? You posted your thoughts on a 6 y.o. post. I posted a question why everyone decided to answer something 6 years after MVal actually needed the help. I even put a smiley face when I asked my question as it was not belittling anyone. No need for either of you to get your feathers ruffled. I apologize if that's all it took for me to offend either of you Geesh