Question for you folks who may know: I have a 46 half ton with a 235 engine in it. Currently it has the original transmission in it. My question is this, will a Muncie SM420 work in this truck? I know it will bolt up to the engine but will it work? I’m assuming the bell housing is the same as for the original 216. I want to use it if the 4th gear is taller than the 3rd gear in my current tranny. I have yet to research those gear ratios.
Thanks for any help. Below is the transmission I’m considering.
1946 Chevy 1/2 ton "patina" pickup with a 1953 235 engine, otherwise all stock and unmolested!
The SM420 isn't going to get you going any faster than your current tranny. The 4th gear in it is a granny or stump puller LOW gear. It's the type of tranny that's generally used as a 3-speed unless you need a lower gear to start a big load moving. Both it and your 46 3-speed have a 1:1 high gear ratio. You are probably wanting an overdrive tranny - T5 or similar. Those will require you to go to an open driveline to the rear axle.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 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.
The SM420 isn't going to get you going any faster than your current tranny. The 4th gear in it is a granny or stump puller LOW gear. It's the type of tranny that's generally used as a 3-speed unless you need a lower gear to start a big load moving. Both it and your 46 3-speed have a 1:1 high gear ratio. You are probably wanting an overdrive tranny - T5 or similar. Those will require you to go to an open driveline to the rear axle.
Hmmm, you mean 1st gear is the stump puller gear not the 4th right? Anyway this does help. I wondered what the ratio might be. I won’t do a T5 due to all that is involved. I wish it were easier. What I did find is a ring and pinion set on the filling station.com web site for about $400 so that’s likely what I will do. The SM420 was offered to me and so I wanted to look into it. Thank you. Bob
1946 Chevy 1/2 ton "patina" pickup with a 1953 235 engine, otherwise all stock and unmolested!
Assuming you have a column shift 3spd gearbox, I'd keep it for it is a great theft deterrent helper. My '50 has a SM420 and honestly, I don't pull tree stumps too often.
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.
One advantage to the SM 420, besides being tougher than woodpecker lips, is that 2nd. gear is synchronized. You can shift to 2nd. while rolling up to a stop sign without grinding gears. 1st. only gets used when a really heavy load is involved, or starting on a very steep hill. A SM 420 and a 4.10 final drive is a good combination. If you can find a Dana 60 axle and a 3.73 gear like I've got in my 59 Suburban with a 420 trans it's even better. 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!
That sm420 has a 7 digit casting number. That means it's a later model; it has the neoprene front seal and you can still get syncro rings for it if you want to rebuild it. No backup light switch so it's not a '67.
