Lost generator pulley while driving

[Robert Dip]

There are about 20 different pieces I changed to get the ’39 Coupe running right, and I am trying to make sure everything works fine. Surprise….thud, clung, clang…..something happened…maybe I forgot a wrench in the engine bay and it went flying. Checked the gauges immediately…oil pressure good, temp gauge slowly starting rising…oh, oh….fan belt ?? Luckily I was a few minutes away from my shop. To my surprise, the generator pulley was no longer there and the belt was tucked down, but not chewed away from the crank mounted fan.
This is a 12V rebuilt gen that I got from a guy on e-Pay that re-builds and sells them. Since it was a few years ago, I’d have to track back the source. I installed it recently, doing a few hundred miles without a problem, but, I do not want to have this happen a hundred miles away from home on a Sunday. I have another one from a project to replace, but I want to find out about this problem….a potential problem for everyone. The ‘other’ one I have has a locking snap ring, so I feel more confident.
Question: Since I still have the pulley, it fell tucked away between the rad and frame, How do I re-screw this pulley back onto the armature shaft, and how do I prevent it from coming off again?

Thanks…Robert

[Vic Piano]

I had the same thing happen to me with our '39 CS. I reinstalled the pulley and put a small weld on the nut and stud to insure that the pulley would not come off again. It has been on for almost six years with not problems.

[Kurt in NJ]

I used to have a homemade strapwrench using a piece of belt, also have put a belt around pulley and clamped in vice, then used strap wrench on armature ---the snap reing is a safety, the pulley needs to be tight to begin with, also if the bearing wasn't seated fulley the pulley can work loose.
the armature can be clamped gently in soft jaws in a vice

[G.M.]

The best way is to take the case off and hold the armerature in a big vice and tighten the pulley and lock nut. Put some lock tight on if that will make you feel better. A generator shop usually has an impact wrench with a special tool the grabs the pulley to tighten, with this you don't have to take it apart. G.M.

[19Fordy]

Impact wrench plus blue loctite. Plus you could "dimple" the threads with a center punch.

[Henry/Kokomo]

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19Fordy X 2

[Robert Dip]

I checked from photos just taken last week, to see the pulley mounted on the generator. Not much thread sticking out, to see if a jam nut could be placed. I checked from my stash of parts, including about 7 or 8 generators, and only one other had a lock ring. There is one that has a groove for the ring, but none was used. I was looking for one with a thin lock nut...seems to come to mind that I saw this. These are all old used generators, so I assume the pulley stayed in place.
Lock tite, weld tab, punched shaft are all to be considered. I also have a good 6V generator with a mounted pulley...I believe that the armature would be the same for 6 and 12V application. I have this crazy idea to have a spare gen on my trip next week, and taking an existing armature & pulley assembly and placing it into the field coil housing as my 12V back-up. For curiosity, will this work?

[nostalgia59]

Same thing happened to me a couple of days ago. I loctite it back on and dimpled the last thread with a center punch. I think what happens is when the engine stops the generator armature wants to keep spinning (inertia) and loosens the pulley....

[FlatheadTed]

I think the Fields only are changed when converting to 12 volt ,so I t should work , Some pulleys have a key way and and nut ,some screw on with then the snap ring ,You Will need to do what GM suggested .The lock tight is good but will not come of easy in the futcher

[Robert Dip]

Well, I bit the bullet. I used lock-tite, took a punch and indented the thread edge of the shaft. I still had reservations...paranoid as I am at the moment....and tig welded a small bead where the punched area was. I wanted to make sure that the bearing did not arc as trying to be a ground, so I bridged steel pieces between the threaded shaft that extends past the pulley a bit and my steel welding table. I like the tig because of having a smooth and clean weld. If this goes.....I would give up the hobby. Robert

[Henry/Kokomo]

Ah! The belt and suspenders theory. I like it!!