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| | | | Joined: Apr 2019 Posts: 51 'Bolter | | 'Bolter Joined: Apr 2019 Posts: 51 | Can anyone tell me how to check my transmission oil? Is there an upper plug somewhere?
Bisongno niente. Voglio Tutto.
| | | | | Joined: Jul 2014 Posts: 1,291 Moderator for Tons o' Fun , Co-Moderator Driveline Forum | | Moderator for Tons o' Fun , Co-Moderator Driveline Forum Joined: Jul 2014 Posts: 1,291 | Please provide the year, model , and type of transmission (three speed or four speed transmission).
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: Apr 2019 Posts: 51 'Bolter | | 'Bolter Joined: Apr 2019 Posts: 51 | Good point, sorry. 1956 3100 4 speed.
Bisongno niente. Voglio Tutto.
| | | | | Joined: Jan 2022 Posts: 2,469 'Bolter | | 'Bolter Joined: Jan 2022 Posts: 2,469 | The plug you are looking for is on the passenger's side of the transmission. It has a square head. Remove the plug, The proper level is at or just below the level of the plug. Don't use GL-5 lube. It is not safe for brass, which is used in the transmission's synchros.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
| | | | | Joined: Jan 2014 Posts: 3,689 'Bolter | | 'Bolter Joined: Jan 2014 Posts: 3,689 | Tractor Supply sells the proper “Fjord Tractor” sae 90 for these gearboxes.
Someone more qualified can speak to this, but I am beginning to suspect that some level below the plug is preferable. My Sm420 likes to find its own level out of the input shaft area. I don’t totally understand, but the early SM420s had some sort of non-sealing seal at the front….by design.
1951 3100
| | | | | Joined: Oct 2021 Posts: 6,846 'Bolter | | 'Bolter Joined: Oct 2021 Posts: 6,846 |
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
| | | | | Joined: Apr 2019 Posts: 51 'Bolter | | 'Bolter Joined: Apr 2019 Posts: 51 | Great, thanks all. Thought so, my VW has the same plug. I've got the oily eyeglasses to prove it. I have a leak somewhere towards the transmission so I need to check that first. If it is just "sweating" I'm prob still low. Good on the Tractor tip. Would not have known that.
Bisongno niente. Voglio Tutto.
| | | | | Joined: Feb 2004 Posts: 29,825 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,825 | Early SM-420's don't have a front seal- - - -they just have a reverse spiral groove that pushes gear lube back toward the transmission case as the shaft turns, and an oil slinger that spins ahead of the input shaft bearing. If the case is too full and the vehicle is parked in a steep nose down position, lube will leak into the bell housing and contaminate the clutch lining. If you can reach the lube level with a fingertip through the fill hole, there's enough there to keep the gears and bearings happy.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Jan 2002 Posts: 2,841 'Bolter | | 'Bolter Joined: Jan 2002 Posts: 2,841 | Exactly! I put just enough oil in the gearbox so when I stick my index finger in the top fill plug hole I bend my finger downward to just touch the oil level. This is about 1/2” below the fill hole.
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.
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