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| | | Joined: Jul 2020 Posts: 148 'Bolter | | 'Bolter Joined: Jul 2020 Posts: 148 | I have a couple of spare SM420s that I'm putting into storage. Both got a little water in them at some point. I just drained what was in them and refilled with a GL4 140wt oil, but for long term storage is there something better? I tried searching for "pickling" and "storing" transmissions, but didn't find much. Lots written about storing engines, but not transmissions. | | | | | Joined: May 2015 Posts: 11,039 Housekeeping (Moderator) Making a Stovebolt Bed & Paint and Body Shop Forums | | Housekeeping (Moderator) Making a Stovebolt Bed & Paint and Body Shop Forums Joined: May 2015 Posts: 11,039 | If you got all the water out, that gear oil should be just fine. No real difference between storage and use, although with use, it might warm up enough to evaporate a small amount of moisture.
Kevin 1951 Chevy 3100 work truckFollow this saga in Project JournalPhotos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together. | | | | | Joined: Jul 2014 Posts: 1,289 Moderator for Tons o' Fun , Co-Moderator Driveline Forum | | Moderator for Tons o' Fun , Co-Moderator Driveline Forum Joined: Jul 2014 Posts: 1,289 | You've probably already done so, but I'd recommend you rotate the input shaft , in each gear, to get all the gears covered in oil.
Ron - - Dusty53 1954 Chevy 3604In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell."
"They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel." | | | | | Joined: Jan 2002 Posts: 2,839 'Bolter | | 'Bolter Joined: Jan 2002 Posts: 2,839 | Ron,
That's a good idea for I have a spare SM420 out in my garage which has been sitting under my garage stairs for quite a few years. Time to pull it out and rotate the gears.
Craig My '50 Chevy 3100 5 window, '62-235cu, 3:55 rear My truck ....... Respect The Rust If I'm not working on my truck, '65 m00stang or VW camper, I'm fishing with the wife or smoking Salmon.
| | | | | Joined: Jul 2000 Posts: 2,191 Insomniac | | Insomniac Joined: Jul 2000 Posts: 2,191 | You might try taking the top cover off and spraying fogging oil in to protect the gears. Should last indefinitely.
Gord 🇨🇦
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1954 1/2 ton 235 4 speed
| | | | | Joined: Jan 2002 Posts: 2,839 'Bolter | | 'Bolter Joined: Jan 2002 Posts: 2,839 | Gord,
Thanks for the idea. Something I should consider.
Craig My '50 Chevy 3100 5 window, '62-235cu, 3:55 rear My truck ....... Respect The Rust If I'm not working on my truck, '65 m00stang or VW camper, I'm fishing with the wife or smoking Salmon.
| | | | | Joined: Mar 2004 Posts: 6,214 'Bolter | | 'Bolter Joined: Mar 2004 Posts: 6,214 | I you over fill it as far as you can there will be less air inside to produce condensation and all of the gears will be submerged in oil, no need to rotate. Mike B  | | | | | Joined: Sep 2009 Posts: 5,823 Gearhead, Stovebolt Tech and Parts Tracker, Mod for Swap Meet and GTT | | Gearhead, Stovebolt Tech and Parts Tracker, Mod for Swap Meet and GTT Joined: Sep 2009 Posts: 5,823 | Mike B - If you overfill it, won't there possibly be leakage, at least from the input shaft end? Not sure what you mean by "as far as you can"??? Many/most of the SM420s didn't have full seals on the input shaft, just the "slinger" set up which is going to at least allow seepage until the oil level falls below the bottom of the input shaft. Another suggestion for long term storage is to seal the shift tower. I've actually packed the shifter ball top and tower opening with grease and then covered with plastic wrap and rubber bands. Leaving this open to the air, even in an enclosed storage, still allows for moist air to get inside the top of the transmission and eventual condensation and rust forming. It can significantly affect the shift tower components over time. This is for really long term storage or if there's potential for leaks in your storage space from rain and what not. 
~ Dan 1951 Chevy 3 window 3100Follow this story in the DITY Gallery"My Grandpa Carl's Truck and How it Became Mine"1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
| | | | | Joined: Mar 2004 Posts: 6,214 'Bolter | | 'Bolter Joined: Mar 2004 Posts: 6,214 | Mike B - If you overfill it, won't there possibly be leakage, at least from the input shaft end? Not sure what you mean by "as far as you can"??? Many/most of the SM420s didn't have full seals on the input shaft, just the "slinger" set up which is going to at least allow seepage until the oil level falls below the bottom of the input shaft You'd have to get creative and seal the input shaft with some Plumbers Putty or electricians Duct Seal to try and keep the lube in the trans...note, I've never done this, but it seems doable to me Or, you could sink it in a 55 gallon drum full of used motor oil...set the trans on a brick in the bottom so any water that gets in is down below the trans... Mike B | | | | | Joined: Feb 2011 Posts: 1,362 'Bolter | | 'Bolter Joined: Feb 2011 Posts: 1,362 | [quote=Gdads51] Or, you could sink it in a 55 gallon drum full of used motor oil...set the trans on a brick in the bottom so any water that gets in is down below the trans... Mike B I'm not a fan of using used motor oil for preventing rust, there can be acids and such in it. As a kid I used it for awhile as chain lube in a chainsaw and it corroded the oil tank.
Kicking self for selling off my Taskforce trucks.
Still looking for an LCF or conventional big bolt in decent shape.
As of 10-26-2022, A 55.2 Taskforce long bed now the work begins
| | | | | Joined: Jul 2020 Posts: 148 'Bolter | | 'Bolter Joined: Jul 2020 Posts: 148 | I did spin the input shaft but did not run it through the gears, but good suggestion to do so.
The other downside to deliberately overfilling with transmission oil is that is the most persistently stinky fluid ever invented! ;-P Even a tiny drip somewhere will follow you around forever. I'll take my chances with rust instead! :-D | | |
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