Re: Strange Overdrive Noise

Posted by Jim Kavanagh On 2008/10/7 17:54:48

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.