Strange Overdrive Noise

Posted by Jim Kavanagh On 2008/10/7 10:38:55

I just got the overdrive on my '41 Sedan working and I notice an intermitant noise.

With the OD engaged, occassionally, when the car hits the speed for the OD to kick in (dash light goes on), I hear what really sounds like a buzzing that goes away as soon as I let off the gas and the OD kicks in.

My mechanic describes it as a ratcheting noise and thinks it has to do with the pawl riding against the Sun gear before the balk ring captures it. I can't really see how that would cause this noise, but he does know these cars very well. It sounds much more electrical to me. Once it shifts, everything is silent and smooth. And it does not happen every time. Only occasionally, mostly under very gentle acceleration as opposed to rapid acceleration.

To me, it sounds very much like the noise that a bad Ford starter solonoid makes when you turn the key (a very rapid buzzing), but quit a bit quieter. Is there an electric switch that would likely make this kind of noise at the point of OD engagement? We did have to replace solonoid switch on the side of the OD unit as the old one was badly burned.

Any thoughts or tests that I might run to narrow it down. Obviously, pulling the unit is way down the line in my quest to fix this. Somewhere south of simply not using the OD.

I am wondering if the Solonoid would make this noise and if so, why. The old one was badly burned and i wonder what might have caused that.

Any help is really appreciated.