Packard Forum Index » Post-War (1946-54)

Had a mechanic replace the differential gasket due to substantial leakage. I didn't want to get involved with pulling the axles. Also, I'm not familiar with the crush seal.
After he replaced the gasket, the rear end is whining/humming pretty good in 3rd gear...
Also, the Super 8 has an electomatic clutch. When I press the dash switch in while in neutral, the idle changes. It seems to idle higher when apparently not engaged. The electromatic doesn't seem to be working. With all the issues I have had, I do not want to get involved with that right now. Just curious why the rpm difference. Is the electromatic clutch wired to the positive side of the coil? I know he disconnected a wire to the + coil. I wonder if that is why the idle difference. Not sure what that second wire is for right now.
Great car, if I can get by some of the issues. Sat for quite a few years. It's a love-hate relationship.
Any thoughts?
Thankfully,
Al

The "whining" of the rear axle indicates an incorrect engagement of the ring and pinion gears, and/or worn or incorrect adjustment of the pinion or carrier bearings. If you let it run too long like this you'll ruin the gears so without much delay I'd remove the differential and have it checked by someone who is really familiar with this work - this is a pretty specialized type of work. The "crush sleeve" was part of the method of getting the correct preload on the pinion bearings.

I'll leave the Electromatic question to others, I'm not that familiar with it.

If it hums while coasting but not while pulling, chances are the pinion nut needs to be tightened as they do have a tendency to back off. Check and see if the u-joint flange moves around at all if you shake it. The key is to tighten the nut til any play only just goes away. Use a dial indicator to check. Then give the nut a max of a half turn more and stake it. Sadly you can't use the factory method for tightening that nut while all is assembled and in the car. If it whines on a pull, then it need rebuilding as Owen noted.

Idle speeds up when you turn on the Electromatic because it is trying to operate and is sucking extra air into the manifold through some of the perished components. Just turn it off, and if you want to be really sure, somehow plug the very large tube that screws in behind the carb.

Put the wire back on the coil where it was. That enables the overdrive to kick down by shorting out the spark for a couple hits while the overdrive disengages.

On the postwar Elecromatic, when you turn on the switch it energizes a solenoid valve built into the control unit to allow vacuum to be applied to the internal components. Depending on several other conditions, the vacuum is held or passed on outside to the power unit to disengage the clutch. If there is a damaged or missing component or open tube to provide a vacuum leak anywhere after the solenoid valve, I suspect that would be what is causing the engine to run faster. If the system is connected and intact, a couple of likely leak spots are a rubber hose just above the power unit and the rubber diaphragm inside the power unit.

ALM, curious that if your mechanic only removed the bolt-on housing of the differential and only replaced the gasket between it and the axle housing that you would now get gear noise. Maybe, it is a Ross suggests, only the pinion gear nut has come loose in this process. I hope it is an easy fix as the alternative is not nice. Good luck.

(o{}o)

Thank you again fellas!
I'll check the pinion ring nut (It was not humming before the mechanic worked on it) and reconnect the wire back on to the coil.
Sometimes, I get confused with the Packard technicals/mechanics.
It is one heck of an education. This website is so helpful. I don't know what I would do without it. Huge thanks to "Big Kev"!
I put the grill and hood back on today... I'll post a photo asap.
Loving every minute of it.
Al Miller