SM420 Transmission Problem?

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Oct 14, 2003
This is more of a general question and possibly less of a Cruiser question, but I though I would give this forum a try before going to the shop and spending a bunch of $$$! I have an FJ40 with a recent Chevy 350 and SM420 transmission conversion. I am having a problem at times shifting into or out of gears - mostly out. I push in my clutch and can not move the shifter out of gear without really pulling hard on it (and sometimes hearing and feeling a "clunk"). This does not happen all the time, but more so when I've been driving it around for awhile. Could this have something to do with the clutch master, slave cylinder or clutch rather than the transmission? Any advice or recommendations would be greatly appreciated!
PM pinhead, he is the SM420 guru. It sounds like your clutch is not fully engaging though. The sm420 is far from a smooth shifter, but you should not have to pull or push really hard to move through the gears. If it is the tranny, rebuild it yourself. It is a really basic tranny. I knew nothing about trannys when I got my sm420. I looked through the tech write ups here and just disassembled it, carefully laying the parts out in the order they were in the tranny. Getting it in and out of the 40 is the biggest hassel.

Ditto on the clutch. Check to see what pressure plate and slave cylinder were used. Stock slave is OK if you get a low cone diaphragm.
Both the pressure plate and slave cylinder came with the 350 motor which was pulled out of and older Chevy Blazer.
t.o. barring?
If it ends up being the trani give Gordie a call at Stick Only Transmissions in Sun Valley, California. (818)768-4747. He was a real big help when I did my install and had all sorts of questions.
The clutch is dragging if it makes a grinding noise going from 3rd to Low or reverse. I doubt that it is something wrong with the tranny. Run it until something more significant happens.

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