I pulled a SM420 from a 1961 GM delivery van today on half-price day at the pick-n-pull in Wilmington. $40 plus $10 core charge. There was 50,000 miles on the clock, but it could be 150,000 or 250,000. There was some metal powder on the magnet at the bottom, but no identifiable chunks of metal. I pulled it apart when I got home to check everything and it looks real nice except for wear on the 3-4 clutch gear hub. The wear in the center of the splines on the hub is .010, as shown in the picture below.

Is this wear excessive or normal?

<img src="http://members.home.net/cglabe1/photos/SM420hub.jpg">

From the ones I've pulled apart that looks pretty normal. I'd just slap the thing back together and run it. I've never bought one yet that couldn't just have the oil changed and be thrown in and run. They're damn near impossible to kill.

they do make rebuild kits still, think NAPA can get get em.
Or Gearman here for sure.
Not sure what you get but there close to 300 bucks for the kit.
That wear is no big whoop, run the mofo!!

what vehicle had the sm420 in it originally? so I will know what to look for in the junkyard. and how else can I identify one? what does one usually cost?


:beer: :usa:

Originally posted by Donald Butcher
what vehicle had the sm420 in it originally? so I will know what to look for in the junkyard. and how else can I identify one? what does one usually cost?


:beer: :usa:

Virtually any GM truck from 1/2 ton to 2.5 ton from 1947-1967 will have them if they have a 4 speed. The identifying feature is the large round hump on the passenger side and PTO cover on the driver's side. The transmission case is 10.5 inches long across the machined surfaces. There are plenty of pictures of them on this site. People tend to overlook the big trucks and delivery wagons but it is the same transmission. The ones on big trucks have a parking brake drum on the back of the tranny.

Pin,

If you need help or parts ... there is a company in SLC that has been rebuilding 420s for 55 years. He has everything you need (parts) and will take the time on the phone to assist you.
I can get you the info if interested. They have Had the UPS account for tranny rebuilds here in the west since day one. I saw about 30 sm 465s on the floor the other day going out to UPS.I hate to deal with tranny shops but not this one... these guys will take the time and have fair prices.

bennett

Originally posted by bennett
Pin,

If you need help or parts ... there is a company in SLC that has been rebuilding 420s for 55 years. He has everything you need (parts) and will take the time on the phone to assist you.
I can get you the info if interested.
bennett

Thanks Bennett. Everything else looks so good that I'm just going to put it back together and run it. All I need is a gasket set and a PTO cover plate.

Originally posted by Pin Head


Thanks Bennett. Everything else looks so good that I'm just going to put it back together and run it. All I need is a gasket set and a PTO cover plate.

Looks good to me. Run the fawker......What else can you expect for a $50?? :D:D:D

I got my tranny from pic n pul on half price day too. Truck had 70k on the clock and after pulling the cover off, I think that it was really 70k. Looked brand new inside, shifts like a dream. :D:D

Originally posted by bennett

If you need help or parts ... there is a company in SLC that has been rebuilding 420s for 55 years. He has everything you need (parts) and will take the time on the phone to assist you.
I can get you the info if interested.

bennett

Could you post the number? I need a 4th gear sycro and the clutch pins. :(
Thanks, Mike