FM "J" Mag on FM Z, Style D engine

[TomFG]

I'm trying to get the rotor out of a FM "J" Magneto. I have the "points" end all disassymbled, and have trying tapping the rotor out, but it's not budging. I don't want to break something. I see nothing else visable that could be holding it in. Does the bearing slide out of it's bore, or is there something retaining it, and hanging up the rotor? Thanks for any tips. I don't see anything in the diagram. Am I missing something?
Tom

[KidDynamo]

Check this out:

http://www.smokstak.com/forum/showth...ht=seal+washer

The washer mentioned doesn't always have a "milled off" area, though.

[TomFG]

Thanks for the help!
I see I wasn't the only one with this delima.
I did notice the swedged-in washer with the
milled off area on it.......but thought to myself,
"surely not"...... glad I didn't keep pounding...
hope I didn't crack anything!
Thanks, Tom

[ssimntih]

if you dont end up getting along with that "j" ive got an "R" with the drive gear for a z style d

[Dempster]

All FM J & X mags have a outer seal washer, oil seal, then inner seal washer and there is snap ring on shaft under those against bearing on back side. Wouldn't be the first time someone didn't know and busted it out on other side inside the housing. Shaft is press fit in bearing but will press out after snap ring is removed. Then another snap ring inside housing holds bearing but some models like the radio shielded military models or other industrial mags had a retainer washer with a screw on inside instead of a big snap ring. If you busted the housing inside sometimes can use one of those retainer washers to still hold the bearing in or if not I probably have a NOS or good used FM J 1 housing.

[TomFG]

I did manage to get the outer washer pried out, and then the retainer clip, but the rotor still wont tap out. I don't have a press. I don't think I broke anything yet, so I decided to clean things up the best I can with the rotor in place.
If I did get the rotor out, then I suppose I'd have to figure out how to re-magnetize the rotor magnets...... have a charger, but don't have any blocks to fit the curvature of the rotor.... guess I'll have to make some one of these days. Did manage to charge the magnets in the RV-1 Mag though. Thanks for the tips!

[KidDynamo]

Sounds like the rotor is stuck in the bearing inner race. It probably would press out, if you had the tools handy.

Some time ago, I found out that pounding is not the way to go. I gave mine an increasing series of "taps" and the rotor stayed put but the magnets broke out of the rotor casting and then I had junk!

I thought, well I can just take a rotor from an old Type J for a Wisconsin engine (very common) and turn the end to match the "Z" rotor. The keyway and the magnets, etc, all appeared to be exactly the same alignment. Just the ends were different, the Wisconsin rotor using an impulse.

I milled off the rotor end, turned a thread to size but it did not work. I quit at that point, and now have two body bag mags! Oh well......lot of spare points, condensers, caps, etc. LOL

[Dempster]

Well if the magnet isn't rusted in housing or stuck and has good air gap clearance yet leave it alone. You can still get to the bearing now from the back side to regrease it. That's why I said press and no hammering is NOT a good idea a sharp blow will knock the bearing out the housing busting it where the inner snap ring is. Steady slow pressure from a press is needed soak the bearing some if needed before pressing and clean the shaft if rusty but they usually slide right out. Fairbanks Morse originally supplied a screw type press made of plates, rods and threaded shaft with special end pieces are what is shown in the FM J service literature. It may show some of those in the FM Fundamentals of Magnetos booklet you can now find online to view. You could also use a large vise and piece of pipe to press it out. If you need FM J service literature or drawings plans for charging blocks email or PM me I have FM bulletin of the FM blocks works for all the FM mags and many others. You can get a kit that has gaskets, rubber oil seal and outer metal seal washer that is staked back in place.

Fairbanks Morse Magneto Fundamentals

http://www.oldengine.org/members/die.../MagFmBook.htm

[Dempster]

Some rotors will change like that to cut off and rethread but most won't. Have to make sure the cam is the same and key slot in same place in relation to the magnet poles also taper shaft same length as you probably found out. Some of those FM mags for V4 Wisconsin have magnet rotors with 4 poles and 4 lobes on cam those will only work in that particular mag.