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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.

The only two things I can think of that would cause a buzz would be the relay or solenoid. If the relay is not getting full current either because of high resistance in a connection or a bad switch, it might not have enough strength to fully pull in which would result in a buzz that would affect everything downstream. The relay contacts may also be burned and not providing full current to solenoid..

The solenoid has 2 coils--a heavy pull in coil and a lighter hold coil. The pull in coil is released by the internal contacts when the solenoid is fully engaged and the hold in coil is supposed to do it's job. If the hold in coil isn't holding, then the solenoid will vibrate or buzz and be fairly loud. A bad connection or poor ground would be suspect there. If the contacts are mis-adjusted or something is preventing the solenoid from fully extending and not allowing a complete quick opening of the contacts, that would cause the buzz and also burn the contacts. Is that what you meant by badly burned or was wrong with the first solenoid. If the pawl is gummed up or possibly burred, that might cause a slow engagement.

EDIT: You didn't mention any clunks or harshness but in the 47 service counselors, page 69 there are some mechanical things that might apply to your slow engagement--and there might be the ratcheting your mechanic refers to. In a later counselor, they mentioned a lot of corrosion and shorting problems being reported with the bakelite connector in the OD harness. Don't know if your 41 has that connector but might be worth a look.

I agree with the above if the "buzz" is electrical, but if it has a mechanical sound to it, check the travel of the OD case lever.

Sounds like a bad contact in your solenoid. You mite be able to fix it your self.
Greg

I'll take O_D's suggestion a bit further. My recently acquired Custom Super Clipper was making a buzzing sound when the OD knob under the dash was pushed in, but the OD would not engage unless the knob was held in. When pressure was released from holding in the knob, the noise would return. It turns out that the outside of the OD lockout cable had come loose from the knob-cable housing. There is also a switch on this housing. I secured the outside part of the cable to the housing using a clamp I devised, and this fixed the problem. The sound was definitely a mechanical sound not an electrical one. Wishing you an easy fix.

The noise I am experiencing is somewhat quiet, so it ends up being hard to distinguish between mechanical and electric.

The OD engages as soon as I let up on the accelerator, there is no pause or hesitation. But I hear the noise (if it happens to be there at all) until I let the OD engage (by backing off the gas). That is another reason I doubt it is mechanical. When the car reaches the speed for the Governor to shift into OD, the small dash light goes on and the buzzing starts. As soon as I let off the gas, the shift to OD is made, the light goes off and the buzzing stops, all at the same time. If it was the pawl not engaging, it seems to me the noise would be while the shift is being made. Maybe I am veiwing this wrong though. I think once the light goes on, that means the pawl has been pushed into position where it should be caught by the balk ring. Is there anything at this point in the operation (with the pawl pushing in, but not yet in the opening in the balk ring, so not yet able to engage in the slots in the sun gear) that would result in a ratcheting noise? It seems to me the noise would come later, when deceleration has allowed the pawl to go through the opening in the balk ring and try to engage the slot in the sun gear. I assume if it did not engage crisply, you could hear a ratcheting while the pawl would ride accross the slot in the sun gear.

Once the shift is made, which feels completely smooth, there is no unusual noises, whining, etc. When I come to a stop, I can hear the OD click out to disengage.

The solonoid that we removed from the car was essentially fried. I don't have it, but my recollection was there was a large winding with some terminal conectors at the end. The winding was no longer connected, with the wire completely burnt (a big section, not just a little) and the terminal looked quite burnt as well.

I am really feeling like I should work through the sequence of switches and connectors, energizing each and seeing if any causes the buzzing to occur. I am pretty sure that either the manual, or a previous thread on the forum, has a pretty good walk through sequence. But since I don't know what I am doing, I want to avoid shorting out anything, etc. If anyone has a thought as to which component to check, and how to check it, I would appreciate the knowledge.

The relay seems to have been eliminated with your last description so all that's left electrically is solenoid. When you are at speed, the relay closes between term 1 & 4, energizing pull in coil and light. When you let off gas, the solenoid is able to move so one set of contacts in solenoid opens pull in coil circuit and another the light circuit. The relay stays energized until you either kick down out of OD or go below speed so it must not be causing the noise.

What I'm concerned about is the burned solenoid. The only way I can see that much damage is if the wrong voltage was applied or if the pull in contacts are not opening allowing that coil to stay energized constantly--which it's not designed to do.

You could follow the procedure in econo drive manual to pull the solenoid, leave everything connected but ground the solenoid case (a heavy wire & tight connection or maybe a jumper cable) then energize everything by grounding the OD wire at governor. The plunger should snap out one time, and stay. Moving the gas pedal to kickdown position should drop everything out and if governor still grounded, releasing gas will cause it to snap out again. If no noise, all is well. Then put back in and repeat the governor ground. If noise, then something is binding or preventing travel. Then would be a good time to measure the actual current draw on pull in coil. If it still was drawing current when engaged, that would not be good. A few months ago another poster was having problems with his OD solenoid, and I believe he found a different shaft length on his replacement.

In addition, there are a couple of cautions in the OD manual regarding the solenoid spacer installed correctly and to make sure the gaskets proper thickness. If either of those were wrong, I could see it causing an issue.