My 1950 Willys Trail Rig

[OWEN]

Well my Stak is still being built I guess but I want to have the transmission ready for when the transfer case arrives.

The transmisson is a SM420 from a 1950 GMC pickup. The only thing I am doing is changing the mainshaft and rear adapter housing to a Novak 23spline output dana 300 adapter.

I followed Novaks instructions for removing the main shaft, it was pretty easy.
Next I cleaned up the case with some simple green, wire wheeled it, and then cleaned with paint thinner


I have been liking this paint a lot lately and I had some kicking around


I bought the setup used, cheap. The previous owner had beat the shaft a little at the input end to remove it, which mushroomed it over a little. I spun it on the latthe at work, had to use sandpaper. The material of the shaft is very hard, it broke the cutter as soon as it touched!

I test fit the mainshaft with the input, and everything is all good now.

Next step is to swap everything over to the Novak main shaft and install... probably tomorrow.

[clean4drxj]

Looks good Owen, I happen to like that hammered paint myself, it's great for things that dont have a perfect surface.

[ninetysix-ex-jay]

Damn Owen, I have never broke a tool steel bit before. Go American made parts

[OWEN]

Damn Owen, I have never broke a tool steel bit before. Go American made parts

Yea, I know it has to be fairly hard to hold up to the surrounding metals. I should know more about metallurgy but Novak says they are "case hardened" Perhaps I will try to find out more about what that means.

Assembled my mainshaft tonight.
Started by dissassembling everything off of the old main shaft. I didn't take a picture but you just let the 1st gear assembly rest on the arbor plate and press the pilot of the shaft down. The gears and components are then left in a pile.
Cleaning and inspecting... Everything looked amazing considering this transmission is 60 years old.


Assembly.
The only two things that need to be pressed on are the 3rd gear bushing and the 4th gear clutch hub. The arbor press is a kick ass tool.


Done


Next, I have to put it in the trans. I also have to decide what to do with my front output. In the first gen SM420's there is no input seal just a spiral the propels gear oil into the case as the shaft spins. Good idea but if parked on a hill, the thing is gonna leak. There is a hole in the retainer (you can see it in the pic below) so any gear oil that gets by in theorgy just drains into the bellhousing, and not onto the clutch disc. I think I would rather have a seal. The easiest solution I am guessing is to swap a newer (1954 or newer) input shaft and retainer in, or Novak has an upgrade.

[OWEN]

Oooooo more pictures of parts


Can't get over how stout this thing is!

[clean4drxj]

thats a nice new addition!

[Customjob]

Oooooo more pictures of parts


Can't get over how stout this thing is!

Wow, thats beefy. I wanna know how you like the full hydro when you're done. I'm still leaning towards it.

[OWEN]

Wow, thats beefy. I wanna know how you like the full hydro when you're done. I'm still leaning towards it.

Well I couldn't find any testimonies of poeple on forums going back to another steering setup from the full hydro, it seems like it is the be all and end all steering solution for pretty much any wheeling rig. I have hihg expections and hoepfully it will work well but I will let you know for sure.

Well I finished my transmission. I was able to pick up a 1966 SM420 for my input swap...free! It was from a C60 or something like that, it had a big badass shifter (that I will probably put in my towrig)


Installed a new seal!


I found the front bearing oiling ports were a little different between the two
1950

1966


on the 1966 trans you can see the "5th hole" where the input goes, it is for the oil to flow out of the retainer... where the 1950 has the machined out spot (in a different spot. The hole/notch lines up with a dimple on the input to allow the oil to flow So i determined I would have to duplicate the 5th hole.

I set up the case in my drill press, leveled it and setup a magnet to grab the chips




Once that was complete I installed the input and gave it a good once over and installed everything else... ready to go



My Stak will hopefully be in any day, it will be 6 weeks from when I placed my order this wednesday, good thing I am not in a rush.

[Ruepart Hoaxley]

Good idea on the magnet!

Looking forward to seeing the Stak on this rig.

[Zullock Holmes]

sweeeeeeettttt

looks good man you're gonna love full hydro. I never realized how awesome it could be until i drove adam's buggy. That setup turns 39's on a spooled axle with less effort than any steering wheel i ever turned before. when they say one finger, they are not kidding around. lol.

[clean4drxj]

I like the progress, I'll have to check this out next time I'm over.

[Lawn Guyland]

awesome, owen

[OWEN]

Thanks guys, I hope to have it in the garage this weekend or next week sometime... and hopefully the Stak will be in any day now, tomorrow will be 6 weeks since I ordered. My birthday is this weekend, it would be nice to have it by then

[OWEN]

Called last Friday, Stak said my case is about 2 weeks from shipping.

Ballistic ends and tube inserts for the front came in this yesterday... a lot less time then last time I ordered!

oh and...

[HeavyMetal]

Nice decision.