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#17290 07/22/2003 11:09 PM | Joined: Jul 2003 Posts: 4 Junior Member | | Junior Member Joined: Jul 2003 Posts: 4 | my neighbor recently purchased a '63 3/4 ton with a '57 vette 283 and a 350 trans. i read that some 350's have "3 1/2" gears due to a lock-up feature, creating overdrive. does anyone know a way of determining whether it's a standard 3spd or has overdrive from looking at it? (the truck can't be driven to test it due to brakes and tires right now). thanks! | | |
#17291 07/22/2003 11:50 PM | Joined: Feb 2001 Posts: 1,897 Member | | Member Joined: Feb 2001 Posts: 1,897 | If it has a lock-up torque convertor, there will be extra wires to the tranny. they should be a connector plug somewhere along the side of the case above the edge of the tranny pan an inch or so. I haven`t heard of a 3& 1/2 speed tranny before though 
There is enough good in the worst of us and enough bad in the best of us that it does not behoove any of us to criticize the rest of us.
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Be yourself. If you are ever lost, It will be much easier to find yourself if you know who you are!
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#17292 07/23/2003 1:17 AM | Joined: Oct 2002 Posts: 69 Wrench Fetcher | | Wrench Fetcher Joined: Oct 2002 Posts: 69 | th350-c is the lockup converter model th350, not any change to the three gears, C models are the same 2.52 1.51 1.00 gearsets, the converter and wiring is only difference from a non-C model th350, however there are three different bellhousings for GM production plus several for jeep and AMC and so forth. whole different main case casting*
ppl misunderstand the C model trannies all the time
it is not overdrive, overdrive auto trannies were the 700r4/4L60E/4L80E and 2004r and thats it
look for the wiring plug on driver side of tranny halfway back or so, almost next to the shift shaft, if it has none then its not a C model 350, the solenoid for lockup like to stick and not unlock and that causes dying at idle problems, i prefer non lockup models, they only made them for a few years in the early 80s and then did away with them after that
Randy the easter wabbit ! -here to help fellow enthusiasts as best as possible  parting some vehicles, 54 ford truck 57, chevy 210, 69 fairlane coupe HT and others, | | |
#17293 07/23/2003 7:54 AM | Joined: Jul 2003 Posts: 4 Junior Member | | Junior Member Joined: Jul 2003 Posts: 4 | if the c model's lockup gear isn't overdrive, what is it? | | |
#17294 07/23/2003 8:02 AM | Joined: Feb 2001 Posts: 1,897 Member | | Member Joined: Feb 2001 Posts: 1,897 | It basically locks the torque convertor so it is a direct drive to the input on the tranny.
There is enough good in the worst of us and enough bad in the best of us that it does not behoove any of us to criticize the rest of us.
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Be yourself. If you are ever lost, It will be much easier to find yourself if you know who you are!
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#17295 07/23/2003 2:30 PM | Joined: Jul 2000 Posts: 962 Shop Shark | | Shop Shark Joined: Jul 2000 Posts: 962 | Its not a gear in the tranny at all. The converter has a locking feature that prevents the slippage normal to most torque converters. Its a gas saving feature, and not a great one at that. RPM drop in minimal, maybe 50-150 RPM at cruising speeds. For performance applications, better to use a non-lockup tranny and converter. The lockup clutch in the converter can fry in high-HP aftermarket applications.
good luck
chip
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