VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 distributor gear pin

The distributor gear pin on my 32 keep-s shearing off. This is the 3rd one in two weeks. The car runs for a bit makes a misfire sound and that's it. I took the distributor apart again and nothing is binding and it is getting lubrication. Is there a problem in the camshaft or valve train that is causing this or the oil pump? It is getting frustrating.

Hello rayfl, Have you checked to see if you have the thrust washer installed on the top of the oil pump , before you install the distributor back in the block. Have you checked the distributor shaft for straightness, maybe it is bent and jamming during rotation.

Hello rayfl,
Gunsmoke may have something to offer on this topic. I would like to know a little more about how the distributor gear stays on the shaft after the pin shears. Are you able to pull the distributor and gear even though the pin is sheared? What keeps the gear from falling into the engine when the distributor is pulled? Ok, the gear does double duty, drive the distributor and drive the oil pump. When you pull the distributor, does the distributor rotate smoothly? Can you rig up a shaft to test the oil pump rotation? If both turn smoothly, suspect a weak shear pin or pins. A research of the shear pin used originally may be in order.

The gear continues to move on the shaft but the shaft does not turn so the rotor does not move. The gear can't fall off as it is in a housing and the end of the shaft is slotted to drive the oil pump.

What type of gear pin are you using?

And, as asked above, is the oil pump thrust washer in place between the bottom of the distributor gear and the top of the oil pump? If the oil pump thrust washer is missing, the collar at the base of the weight plate and the weight plate will drop down and wear against the distributor body. The weight plate, which is attached to the distributor shaft, can bind inside of the distributor body. This, in turn, could seize the shaft thus shearing the distributor gear pin.

I agree, I would check for thrust washer. I have replaced the pin on both of my distributors, and for one of them when the shaft was allowed to sit down on the base of the distributor, it was difficult to turn, seemed to want to bind. This would be the situation if the thrust washer is not in place. As others say, the thrust washer eliminates end play, and ensures the weight plate spins clear of the dist' base. I'm keeping my fingers crossed that mine will not bind as I used a split pin in both, very hard to shear, but likely to cause other issue if anything ever binds up. BTW, my car had run for years without a thrust washer, and as a result the gear on the Dist shaft was worn quite a bit, likely from the resulting end play.

There is no thrust washer in place. I have the distributor apart again and I put the shaft in the hole and it will not move the oil pump drive. I am assuming that the shaft should turn the pump freely. Is it possible one of the sheared pieces could have gotten into the oil pump and stopped it. Now I guess it is take the pan down and check the pump. Can I just drop it down in the car from underneath without a lift?

The pump shaft should turn freely. If the pump shaft doesn't turn that could be your problem. However, do not reinstall the distributor without a oil pump thrust washer.

Yes, the oil pan can be dropped without a lift. Jackstands will work just fine.

Thanks a lot. Now I just need the time. Sure do miss driving around.