The Stovebolt Site Forums The Shop Area Driveline Removing sm420 Transmission

I am removing what looks to be an aftermarket sm420 from my 55.1 Chevy. There is still shift linkage on the steering column from an old trans which pointed to aftermarket.

I am removing the trans for service and cannot seem to break it free. I'm sure largely in part due to my ignorance. I have removed the top two bolts but I don't see any others that are holding it on. In a few of the pictures I have pointed out which bolts I have removed in blue, and what looks like there should be bolts in yellow, but there weren't any there.

Any help would be appreciated.

https://goo.gl/photos/AJ7ctgZWQpgvUzcz9

There are two bottom bolts.

Take off the pan that might be under the clutch housing (screws can be reached with a screwdriver through holes in the frame cross-member).

There are two transmission bolts from the lower inside of the clutch housing.

-----

Transmission Removal - steps 9-11

http://chevy.oldcarmanualproject.com/shop/1955truck2/55ctsm0751.htm

Thanks Tim!

I was reading the 54 manual which says basically the same thing, but your hint to go through the holes in the crossmember (that was caked with about 2 inches of junk) did the trick.

Step 11b should have been: Make sure you have a buddy to help lift it up and out of the truck. It's heavy.

:P

Thanks again!

Danthemanmj23,

I did not know/think about those holes until reading about them, here.

Regarding the need for a buddy: when I was much younger, I used to install remove the SM420 by myself from below ("by hand"). I do not now believe that I was able to do that.

Tim,
don't they call that young and foolish!

I had it easy with my SM420 removal and installation. I borrowed a tranny lift from a friend. It had pitch, yaw and roll adjustments which made it really, really nice for lining up on installation.

I call it: I wish I was young, again.

Actually, I get hernias - in the early 70s (my early 20s) I bought a cheapo K-Mart (pre-Harbor-Freight) floor jack for lifting air-cooled VW engines.

Heres tha way I took it out:
http://www.pbase.com/dennygraham/image/120660807/large
Heres the way I put it in:
http://www.pbase.com/dennygraham/image/137545906/large

Those day of pressing 135lbs are long gone at the Graham garage.
dg

Goodness sakes that is some engineering Denny! Awesome!

I can tell those days for me are coming faster and faster, and I'm only 27...

You ain't even come close to hitting your prime Dan, at 27 I was
still trying to figure out who I was and what direction I
wanted life to take me. Oh, and what you will learn in the next
fifty years will amaze you when you look back on it.

That SM420 swap was very popular back in the day. Your 3-speed
obviously was swapped out for the 4-speed. But that transmission
was also an option from the factory and there are many 3100
trucks which originally had an SM420 in them at delivery.
dg

I swapped my 3speed for the SM420 by myself too... after taking out the three speed I thought putting the SM420 by myself would be a piece of cake... not so much... I was sore for days! And I was only 23 at the time!!

You think it is hard at 23, you should try it at 75! I managed with a transmission jack. The hard part was trying to keep it from tipping on the jack since the sm420 doesn’t have a flat bottom. I got it with my second try. I am a bit sore today, a lot sore I should say.

Just to let you and others know, you posted on a thread that is eight years old!