Z1 series ~ Alternator Magnetic Rotor

I am having trouble with fitting the magnetic rotor to the tapered end of the crank-shaft of a Z1A.
I appreciate that this is really a mechanical problem relating to an electrical component.
Firstly, I have three rotors numbered 3A. 5A and 5D. I'm not sure the significants of these numbers stamped on the outside face of the rotor along with a directional arrow.

Anyway, the problem is two rotors are too loose and one looks as so it might just make it, if I lapp., it in and probably do a little machining.
Has anyone an easy solution for this common problem?

I find the loose rotors are bottoming on the large extraction thread at the "small end" of the rotor To make the loose rotors fit the taper, I was going to bore some of the thread out of the rotor small end, say about 3mm recessed 1 mm depth, so that the tapered shaft can go further onto the taper! Any comments?

RegardZ.

Ive had my share of broken woodruff keys over the years Id love to hear of an easy fix also,other than the usual game of Russian roulette swapping parts to find one that fits.
Whats the end of your crankshaft look at?
Lots of them have spun chewing up crank over the years

Wireman, I have looked at the taper on the Z1A crank that I am working on, it seems in good condition. Also, I have two other cranks that I also use to check against they also seem in good condition.

I have changed my thinking, to avoid this bottoming out of two of the rotors. The idea now is to put a small 2mm x 45 degrees chamfer, on the end of the crank taper, this should help get the rotor further onto the crank, without taking away from the effectiveness of the taper jointing surfaces.

Funnily, I can't see a define surface that the rotor bottoms on. I thought initially it was the where the threaded (extraction) screw thread begins at the bottom of the rotor taper. Now I'm not quite sure?

RegardZ

Have you thought about using lapping compound on the rotor and crankshaft fitting areas? I'd think this will make for a very tight fit, just make sure to clean both mating surfaces good, before installing the rotor.

Thanks for the reply.... I usually use fine grinding paste to lapp the surfaces in, however, in a couple of cases I have felt the bottom of the crank tapered section, thumping on, what I think is the start of the extraction screw thread in the rotor, or possibly a worn section causing a shoulder, again in the rotor.
Hence, the idea of removing a small section (by chamfering the end) of the crank. I am only talking about > 2mm.

RegardZ.

Job successfully completed....
I did take the above mentioned fast way out and just linished the end of the crank taper, making sure I did not take more than 1.5 mm in the chamfer, bearing in mind there was a small chamfer there already!

It did work and all rotors fitted after a brief lapping with fine valve grinding paste. I guess I will have to adjust the damper washer to suit the slightly different position.
Regardz