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| | | | Joined: Jan 2013 Posts: 1,518 'Bolter | | 'Bolter Joined: Jan 2013 Posts: 1,518 | Thinking about a trans change for my 53 3100. Currently it has a 3 on the tree. I like the idea of the sm 420 because of the sycho'd 2nd gear.
Does anyone know about the availability of hard and soft parts for rebuilding these trans? Imagine bearings are still available. Also, I would need the style with an enclosed ujoint. Are these trans still plentiful or am I going to have a chore finding one that is ready to go or at least rebuildable?
Thanks,
Steve
1953 Chevrolet 3100261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done In the DITY GalleryVideo of the 261 running1964 GMC 1000305 Big Block V6, sm420, the next cab off restoration
| | | | | Joined: Feb 2004 Posts: 29,777 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,777 | There are still plenty of transmissions available, and a fair amount of repair parts, seals, and gaskets. You might want to invest in a good Louisville Slugger bat to fight your way through a horde of rock crawlers who love those transmissions and try to buy up every one that's available!
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Jan 2000 Posts: 734 'Bolter | | 'Bolter Joined: Jan 2000 Posts: 734 | Novak has the info and parts you'll need.
Matthew 6:33 1952 Chevy 1/2-ton 3100 Late '55 235/SM420/torque tube 3.55 Dalton Highway survivor (using original 216) www.truckwithaheart.com | | | | | Joined: Sep 2012 Posts: 306 'Bolter | | 'Bolter Joined: Sep 2012 Posts: 306 | ** I recently purchased a complete SM420 rebuild kit from Novak's and was told it would be short one synchro because they are no longer made. I got lucky all of the synchros were in great shape at time of rebuild. | | | | | Joined: Dec 2015 Posts: 2,063 Big Bolt Forum Moderator | | Big Bolt Forum Moderator Joined: Dec 2015 Posts: 2,063 | there is a rebuilt one on Seattle Craigslist (Maple Valley) but it is for an open driveline. He wants 250 and has been trying to sell it for a while. | | | | | Joined: Nov 2005 Posts: 324 'Bolter | | 'Bolter Joined: Nov 2005 Posts: 324 | I have one that I pulled from a '48 panel awhile back. I was told it worked, but the engine was missing some parts so I never ran it. It does turn freely by hand and shifts to all gears. It sat out for awhile and rain got in it, I dumped it out, but I don't know the internal condition, it might be fine. Years ago I found one in a junk yard and had it rebuilt. The mechanic told me to get an sm460 instead due to parts availability. I went with the 420, it works, but will fall out of 3rd, I just hold it when I'm in 3rd. | | | | | Joined: Apr 2010 Posts: 436 'Bolter | | 'Bolter Joined: Apr 2010 Posts: 436 | Still have an SM420 in my '62 C10. It was originally a 3 on the tree truck, but a PO cut up the floorboard and dropped the 4 speed in. I was able to find the correct floorboard sheet metal and column and it all looks factory now. I've had no trouble with it.
When I first got the truck in 2005, I took it to a local tranny shop and had them give it a fluid change and once over. They said it was in great shape.
From what I was told, these things are nearly bulletproof. They were put in everything from 1/2T to 2 1/2T trucks. My C10 has an L30 spec (275hp) 327 in it and the SM420 handles it with ease. | | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | I have one that I pulled from a '48 panel awhile back. I was told it worked, but the engine was missing some parts so I never ran it. It does turn freely by hand and shifts to all gears. It sat out for awhile and rain got in it, I dumped it out, but I don't know the internal condition, it might be fine. Years ago I found one in a junk yard and had it rebuilt. The mechanic told me to get an sm460 instead due to parts availability. I went with the 420, it works, but will fall out of 3rd, I just hold it when I'm in 3rd. Walter, that should be 'SM-465' Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
| | | | | Joined: Jan 2005 Posts: 310 Shop Shark | | Shop Shark Joined: Jan 2005 Posts: 310 | there is a rebuilt one on Seattle Craigslist (Maple Valley) but it is for an open driveline. He wants 250 and has been trying to sell it for a while. The transmission is exactly the same between a torque tube and an open driveline. The only difference is the rear bearing retainer, which also makes up the front portion of the u-joint ball area. The bearing retainer can be replaced, thereby converting the transmission to a torque tube.
-Tim
'51 Chevy 3104 w/'56 235, 848 Head, HEI Dizzy, Corvette Cam, Split Manifold and Dual Carter YF's
| | | | | Joined: Sep 2016 Posts: 6 New Guy | | New Guy Joined: Sep 2016 Posts: 6 | I have a 58 Chevy Viking COE 1.5T truck that has a SM420 in it. I was driving it back from work (everything was fine) parked it... went out a week later and found that it would no longer go into 3rd gear. Craziest thing ever. I called Novak to see about getting a rebuild kit for it and they don’t have the synchro’s for mine either? I guess once these Transmission crap out they can be used as boat anchors...
The Transmission may not need rebuilt but if I am going to pull it out I’m not going to put it back without knowing it is going to last... | | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | If the housing for the shift rails gets full of oil, one cannot shift it.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
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