MTFCA Forum

T Purists, I suggest you ignore this post.

A friend with a 12 volt electrical system and WOSP geared starter recently swapped his generator for a Mitsubishi alternator that was installed on another friend's Model T. The gear is attached by a roll pin and I seem to recall others reporting problems with this arrangement. From what I can see the holes in the gear are slightly worn and the gear can be wiggled ever so slightly.

It is what it is and we need to deal with it. Any suggestions as to the best fix for the problem would be appreciated.

You are correct in their high failure rate.
The pin is actually a "C" pin. They do commonly shear. A real roll pin wont.
Replace it with a solid pin like original. There should be no wiggle.
If need be, drill slightly oversize & fit an oversize pin.

Tim

if the gear can wiggle slightly on the shaft, it sounds like it is a shaft/gear fit issue and if that is the case, that gear is going to, or already has started to damage the timing gear due to wobble. In any event, the gear must be one with the shaft and any extraneous movement is a bad thing and a new pin is not the solution...a new gear with the proper fit to the shaft is...

the roll pin or whatever type pin it is may in fact not have been up to the task and allowed relative movement between the gear and shaft and that movement has worn things loose

regardless, be sure to consider all facets of this issue to be sure you're fixing what is really wrong.

I would suggest a hardened taper pin. Ream the hole thru the gear and alternator shaft and out the other side. Then pound the tapper pin through the tapered hole and it will fit very snuggly. and done correctly it should not come loose.

frontyboy

I'm a real fan of taper pins as they hold better than straight pins. how ever they will not make up for a loose fit in the long run. I'm thinking
if the gear is loose on the shaft some thing needs to be addressed to prevent issues down the road. Good luck.
Craig.

Be advised, I have one of these alternators on the shelf. I used it on my Mother-in-Law roadster for a short time. Had to recharge the battery on the car numerous times, then had the alternator checked out at a shop. Found out that the alternator worked fine but it has a cut in speed of 1500 rpm.
On a modern car with a belt and pulley, it charges a battery very well, but with the small gear the car needs to get up to about 22 mph before it starts to charge. If you only drive around town, you sometimes never get up to that speed. Just letting you know that you should keep an eye on your amp meter.

As Scott explains, a new pin will not fix a sloppy fit between the gear and the shaft. It will be temporary, at best. If you can get a new gear that fits tight, you're good to go. However, if the shaft is worn, that's another story.

The stock generator has a half moon key as well as the pin. Do the alternator conversions not use the key?