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| | | | Joined: Mar 2017 Posts: 326 'Bolter | | 'Bolter Joined: Mar 2017 Posts: 326 | Hello,
I have what I believe is an SM 318 in my 56 with a 235 engine, and it has started to show a little leakage out of the rear seal. I changed the fluid when I first got the truck almost 10 years ago now and have not needed to add any fluid since. To my knowledge, the transmission has never been overhauled since new; so my question is should I just replace the rear seal, or go ahead and do a overhaul. What would be the best source for kits and information for the work? I have done this once before on a 3 speed on an old Mustang, but that is the limit on my transmission experience.
The transmission does seem to be working fine, so other than a small leak, there appears to be no other problems with it.
Thanks for your thoughts,
Lee
1956 Chevy 3200, 235 w/3 speed
| | | | | Joined: Sep 2009 Posts: 5,994 Gearhead, Stovebolt Tech and Parts Tracker, Mod for Swap Meet and GTT | | Gearhead, Stovebolt Tech and Parts Tracker, Mod for Swap Meet and GTT Joined: Sep 2009 Posts: 5,994 | Lee - As long as it's doing its job with only the minor seal leak, I'd just replace that rear seal. Can be easily done in the truck and not disturbing a functional unit IMHO. Back on the road pretty quick to boot. 
~ Dan 1951 Chevy 3 window 3100Follow this story in the DITY Gallery"My Grandpa Carl's Truck and How it Became Mine"1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
| | | | | Joined: Apr 2005 Posts: 2,102 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 2,102 | P/N 9613S Output shaft seal available at Auto Zone for about $5.
Fred
1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine
| | | | | Joined: Mar 2017 Posts: 326 'Bolter | | 'Bolter Joined: Mar 2017 Posts: 326 | Thanks; I will pick one up.
1956 Chevy 3200, 235 w/3 speed
| | | | | Joined: Mar 2007 Posts: 3,440 Crusty Old Sarge | | Crusty Old Sarge Joined: Mar 2007 Posts: 3,440 | As long as you're at it , do a good flush and replace your fluid. Just good insurance.
~ Craig 1958 Viking 4400"The Book of Thor"Read the story in the DITY1960 Chevrolet C10"A Family Heirloom"Follow the story in the DITY Gallery'59 Apache 31, 327 V8 (0.030 over), Muncie M20 4 Speed, GM 10 Bolt Rear... long term project (30 years and counting) If you don't like driving yourTruck, you won't drive yourTruck..| Living life in the SLOW lane | | | | | Joined: Mar 2017 Posts: 326 'Bolter | | 'Bolter Joined: Mar 2017 Posts: 326 | I ordered a small kit from TPD that also has the gaskets for the side cover; so I can open it up and have a look inside to see what it looks like. Make sure the teeth all look okay and look for metal in the bottom, etc.
1956 Chevy 3200, 235 w/3 speed
| | | | | Joined: Jul 2019 Posts: 559 'Bolter | | 'Bolter Joined: Jul 2019 Posts: 559 | If its not giving you any problems then just replace the seal. Even if its missing teeth or whatever and its not acting up just run it. Normally the original New Departure bearings are better than any bearing that come in a rebuild “kit”. I have done a few Saginaw's, Muncie's and my newer T56 and usually the old sloppy transmissions really don't care about much as long as the parts in it are spinning and exist. If its not popping out of high gear then its probably all good. | | |
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