Board index Flathead Power-Technical Questions, Answers, and Suggestions Indians Magneto Gear

Magneto Gear

Post Sat Jul 29, 2006 9:43 pm

Posts: 641
Location: Wisconsin, USA
I was stoning off the burrs on a mag gear on a 47 Chief today and found the gear to be very soft. Easily cut with a file. Is this normal or did this gear by-pass the hardening process at the factory? Another thing that makes me wonder, the mag shaft has a slot for a woodruff key, and another that would accept a round pin. The gear has provision for the round key only. I disassembled the motor, and assume it ran when the bike was reduced to parts for resto in the sixties. I would appreciate any help from board members with some experience with this mag. Thanks, Kyle

Post Sun Jul 30, 2006 6:23 am

Posts: 3158
Location: Central Illinois, USA

I'm in the middle of the same mess with three different motors on the bench.

The gears for a 101 and a 331 have round keyways opposite of the timing mark, but my 334 has both the round keyway opposite the mark, and a woodruff keyway adjacent to the mark, 180 degrees off.

The confusions that I find are that none of the round keyways resolve with a round groove in a Splitdorf mag taper, as if they were each individually drilled and pinned, some other mags. Aarrgh!

And the woodruff keyway on my Edison-Splitdorf taper is 90 degrees off from one of its two round keyways, not 180 from either!

I hope at least the centers of the gears are soft, as the round holes will certainly need to be re-drilled for re-pinning, and the odds that the woodruff indexing on my E-D is correct seem mightly slim. I fear its shaft may have been copped from a Four unit?


Post Sun Jul 30, 2006 6:54 am

Posts: 199
Location: Cedar Springs Mi USA


I think your gear missed heat treat. I just checked a couple I have with a file, and it skates over it like it's glass.

The round "pin" style key IS what it's supposed to run on.....they all have it. Why on earth, the Indian factory couldn't use the square key that was provided by Edison-Splitdorf in the mag shaft, is beyond me.

My guess is that Indian already had a bunch of gears marked for the timing, and this was their "fix" for it.

Post Sun Jul 30, 2006 11:12 am

Posts: 641
Location: Wisconsin, USA
Thanks Cotten for making my problem seem slight, you obviously have three times the trouble. And thank you Tom for checking a couple of your gears, I was fairly certain my gear wasn't right. The mag drive idlers are hard and I couldn't imagine why the mag gear would be left soft. I will check with a local heat treater to see if he can get it right as the gear is in good condition.

Post Sun Jul 30, 2006 7:23 pm

Posts: 3158
Location: Central Illinois, USA
Today I checked the three gears and found the 331 and 334 gears to be very hard, whereas the 101 could be worked with a file. Still not soft by any means.

Both the 101's Splitdorf and the late Edison-Splitdorf have both round and woodruff keyways, or what is left of them. But the Split's woodruff keyway is a little more than 90 degrees advanced of the round pin groove, and the Edison's is slightly less than 90 retarded, with an extra shorter round groove in between.

When I mocked up the Edison on the 101 (using toothpicks for a key in its longest round groove) and pulled it through to where the front intake was closing, and then a touch further to where the camchest timing marks resolved, the points follower was on the small lobe of the advanced points cam as if ready to fire.

(I didn't expect that, as resolved camchest marks on a harley do not fall on the front advanced timing mark, they?)

All I can see of the flywheels through any of the inspection ports is ancient balancing holes. Time for a degree wheel.

I didn't try the 101's Splitdorf, as the keyways are extremely blemished, and I'm skeered to open it to see the points.
(Both mags were reworked for customers years ago by a local tractor wizard, and although homely, they have been tested to throw fire... If I open them I will have to fix them.)

The keyways in the gears are knarly as well, and the round ones are drilled at a weird angle that does not follow the taper.
It would be great to know what an original pin looked like, because the holes all look oval to me!

My 334 still had the woodruff key in the Edison's shaft that came with the basket. But it appears that using it would put timing between pointscam lobes.

So confused.


Post Sun Jul 30, 2006 8:44 pm

Posts: 641
Location: Wisconsin, USA
It is interesting that the shop manual call for the mechanic installing a new mag to determine the proper location and using the groove in the gear as a guide, drill into the mag shaft for locating pin installation. Which suggests to me that we could be dealing with a nonfactory pin slot and a sloppy job if done by a mechanic with questionable skills. I guess the location just needs to be close enough to properly time the motor within the range of the slots cut in the points plate.

Post Fri Aug 18, 2006 12:10 pm

Posts: 77
Location: Espoo, Finland
Cotten et all

I was once told that the pin groove was drilled at place when the motor was timed at factory line. ie they put everything in place, timed the motor, checked that all marks are lined up and drilled a new hole for a pin.
That's why marks don't line up, when using other mag than the REAL original one.

I used the woodruff keyway and made a new mark on my mag gear.


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