Stock 52 On Ton Transmission Strength.

[ChevyBrad]

How strong do you think do you guys the stock transmission is in my 52 Chevy 1 ton? I'm assuming it was way over built for its duties especially if I'm not hauling much with it at all and not driving around dumping the clutch. What about like a pretty stock 350? Also, would a T10 or Muncie transmission shifter clear the bench seat? Thanks.

[studda]

One thing to remember about those old transmissions is that the factory motors were less than 100 horsepower so they weren't really built to last behind much power.

[OrrieG]

I have never heard of anyone blowing up the old SM465 4 speeds, they are tanks. Muncie or T-10 linkage ends up under the front of the set, I don't know if they still sell the "right" kits. I had an M-21 in my first 57 truck (in 1969) and added flat stock to move the handle forward and to make it higher, which added to the throw length too. You might look at Loker to see if they have a linkage the mount further forward.

[dwcsr]

A 1952 would have been a SM 420. Used up til 67 behind 6 cylinders. It may work well behind a stock 350 as long as you weren't towing or hauling heavy.

[mr48chev]

As DWcsr said above they work ok with a mild engine as long as they are in good shape to begin with. The rub is that they can be a bit noisy and it takes a bit of finesse to shift one smoothly. That doesn't usually take long to learn though. The next generation compound fourspeed is a smoother operating trans all the way around.

They do make a Hurst shifter handle that works well with a car four speed and Hurst shifter. I had one in the 48 and still have the shifter waiting to go in another project someday.

[Katrina/10]

The SM420 was used behind V8s and in trucks up to 2 ton, so it should hold up fine.

[whitedog76]

The SM420 4 speed is as tough as nails. They came in everything from 6 cylinder 1/2 ton to GMC diesel powered 2 tons. The "SM" stands for Synchro Mesh. Which means the gears are synchronized, no double clutching required. The only gears that aren't synchronized are 1st and reverse. With a 7:1 first gear, I don't think you'll be needing it much on the street.

The 4x4 guys love them because of their strenth and ultra low first gear.

I wouldn't hesitate to put a 350 in front of one. I wouldn't get crazy and throw nitrous and a blower at it. A 300 hp engine would do fine paired with it.

The transmission has a wide spread on the gears, so you're no going to be able to ram and jam like a Muncie, but they are practically bullet proof otherwise.

http://www.fourwheeler.com/how-to/tr...ons-and-cases/

http://www.advanceadapters.com/tech-vault/gm-sm420/

[ChevyBrad]

That's awesome guys thanks for all the responses! That is good news. I had the truck running as basically a daily driver last summer with a stock 230 Chevy straight 6 with 4:10 gears in dana 60 which was alright for local driving but I wanted to put some 3:55 rear gears and cruise with a lot less rpm's but the 230 could barely handle the hills around here as it was ha. My initial plan this winter was to stuff in a 383 stroker with a 4 speed to make it my shop truck but I decided that I did not want to drop that much cash right now so a nicer cruiser is all I'm looking for right now. Yes they are tricky to shift quickly haha if you hold the clutch in for a half second it will shift nice very time and if you grind a gear you'll feel in your opposite shoulder haha. Thanks for all the advice guys!