The Stovebolt Site Forums The Shop Area Driveline SM420 that has sat for a while

I am gearing up to swap in my SM420 to my '65 C20 Crusty Biscuit. The transmission has sat for a few years, a few, more like 16 under the eave of the house on the back patio (covered). It had a cover over the shift tower to keep dust and dirt and water from getting in there. I have read on here to pour kerosene or diesel fuel in there if a transmission has sat out in the open. Would it be beneficial to do that and turn the input shaft with a drill? Basically fill it, shift it into each gear and turn the input shaft a few minutes in each gear and repeat a few times, then drain out the fuel, and pour in the 90w mineral oil? Even if turning by hand, would this be a good idea before installing it?

Yes, that's a good idea. Just be sure not to damage the input shaft snout with the drill motor chuck. It might be a good idea to wrap a couple of layers of tape around the end of the shaft, or maybe cut a slice out of a soda can to protect the shaft. It's hardened steel, but being careful is better than having to fix unnecessary damage. Even spinning the box in neutral will splash the solvent around effectively- - - -there's no real reason to engage any forward or reverse gears. Maybe use 4th. gear to get the output shaft and the rear bearing spinning.
Jerry

I didn't think of that. Yeah that would be bad news as it wouldn't play well with the pilot bushing if it was marred by the chuck. It may be better to turn the yoke instead?

No problem with turning the input shaft- - - -just pad the snout with a piece of soft metal like aluminum or brass shim stock before you attach the drill motor. You're going to need a variable-speed drill motor with a pretty big chuck, as I believe the snout is around 5/8" or so.
Jerry

Thank you sir. I shall give this a go.

Take the top off and look inside you can then see if any moisture had rusted anything in the case .I had one that was given to me was told it was good and it looked good until I took the top off ,You will have to make note when you take the top off that it goes back on the same

Double Dingo You could take off your PTO cover and see how it looks,look for chipssee if synchronizer brass rings have space left to work.Cycle them by moving your stick.

If there's a bolt-on flange at the output shaft end, use an impact wrench and a socket to spin the output end with the shifter in high gear. That might be simpler than finding a drill with a chuck big enough to grab the pilot shaft.
Jerry