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| | | | Joined: Feb 2008 Posts: 47 Wrench Fetcher | | Wrench Fetcher Joined: Feb 2008 Posts: 47 | Hi all,
I have a '58 2 ton with a 4 speed that I assume is a SM-420 that is jumping out of 4th gear. Is there an easy fix for this? Or is it in need of a rebuild? Can they be rebuilt? Or would it be better to look for another tranny?
| | | | | Joined: Sep 2006 Posts: 1,997 Big Bolt Forum Co-moderator | | Big Bolt Forum Co-moderator Joined: Sep 2006 Posts: 1,997 | I was hoping to find a transmission manual on line at the old chevy manual project site, but could only find 3 and 5 speed along with automatics.
I am sure someone will chime in on the subject. But just wanted to relate a story about my 1952 Willys transmission. My brass syncro rings went out one time and I took the transmission out with the help of my manual. It wasn't hard to take it apart. Once I replaced the syncro rings and put the transmission back in and reinstalled it would pop out of gear. So I took it apart and the only thing I could find was there was a thrust washer on the back end of the cluster gear shaft that was a few thousands out. Got a new one and installed it, and that was the problem.
I would try to rebuild first if the gears are in good shape. If the gears are bad I am sure it would be cheaper to find another one. Good luck.
A day without laughter is a day wasted- Charlie Chaplin
When wrestling a grizzly bear, you have to keep at it until the bear gets tired, not when you get tired. 1948 Chevy 2-Ton | | | | | Joined: Feb 2002 Posts: 12,029 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Feb 2002 Posts: 12,029 | | | | | | Joined: Sep 2006 Posts: 1,997 Big Bolt Forum Co-moderator | | Big Bolt Forum Co-moderator Joined: Sep 2006 Posts: 1,997 | Bill,
Thanks for that link. I may have to use it sometime.
A day without laughter is a day wasted- Charlie Chaplin
When wrestling a grizzly bear, you have to keep at it until the bear gets tired, not when you get tired. 1948 Chevy 2-Ton | | | | | Joined: Jan 2008 Posts: 4,960 'Bolter | | 'Bolter Joined: Jan 2008 Posts: 4,960 | Before you tear into your transmission, check to make sure you have a pilot bearing and check your clutch housing for being off center. This will cause a transmission to jump out of high gear. Of course your transmission may have a lot of wear and need a rebuild, but I always like to check the easy things first. | | | | | Joined: Feb 2008 Posts: 47 Wrench Fetcher | | Wrench Fetcher Joined: Feb 2008 Posts: 47 | Thanks for the info guys, and Red58 thanks for the link I'm sure it will help. | | | | | Joined: Nov 1995 Posts: 5,714 Bond Villain | | Bond Villain Joined: Nov 1995 Posts: 5,714 | Harry -- Google "SM-420 Rebuild" and you should get a lot of info (and pictures  ) -- especially from the 4x4/rockcrawler sites. A few years ago, I rebuilt my 420 using info I got from several of these sites -- including a manual I downloaded from a Toyota landcruiser site (can't remember it now). The rebuild is pretty easy and fun -- Heck, *I* did it. I got the kit from Stick Only in California, but the Novak kit looks great. The trick is to work slowly/methodically on a big, clean, well-lighted bench and keep all the parts in order (don't mix up gears or synchros -- or forget which is which  ) Have fun!
~ John A kid raised on Hotwheels, Matchbox and Tonka cannot be reasonably expected to own only one vehicle as an adult. 1949 Chevrolet 3804In the Legacy Gallery | In the Gallery Forum1973 IH 1310 Dump1963 Kaiser M38A12001 International/AmTran RE3000 "Skoolie"2014 Ford E-350 4x4 (Quigley) | | |
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