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HYDROMATIC GUYS...what do I have, Thanks!!

Forum: C3 Engines, Driveline and Handling

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HYDROMATIC GUYS...what do I have, Thanks!!

Posted: 6/21/08 6:07pmMessage 1 of 8
e
engineguy63
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Easthampton, MA - USA
Joined: 5/27/2007
Posts: 114
Vette(s): 1970 corvette conv, 350 auto.
Well Guy's...and Gal's, looks like my engine #'s match the VIN, but, The tranny is not the correct one. Runs great and seam's to shift nice and crisp, so , I realy cant complain...BUT....I realy what to know if it is even the correct type of transmission...and if the gearing would be diffrent than it is supposed to be. SO...looking to find out the following if possible, and I took some pictures that I hope will help.
1) is it in fact a THM400 like it is supposed to have, or something else
2) if it is...or is not a 400, is the gearing difrent and going to make issues for the drivetrain
3)the following #'s are on the tag...can anyone tell me what vehicle the tranny is from....and how it would be diffrent from the one that is supposed to be in there  75P480        75CP  40309   
 
    Thanks for your help...then I think I will stop searching out #'s and torchuring myself!!Confused
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HYDROMATIC GUYS...what do I have, Thanks!!

Posted: 6/21/08 6:11pmMessage 2 of 8
e
engineguy63
Former Member
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Easthampton, MA - USA
Joined: 5/27/2007
Posts: 114
Vette(s): 1970 corvette conv, 350 auto.
TRANNY PIC


(modified large image to link)Adams' Apple2008-06-21 18:40:41
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HYDROMATIC GUYS...what do I have, Thanks!!

Posted: 6/21/08 6:12pmMessage 3 of 8
e
engineguy63
Former Member
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Easthampton, MA - USA
Joined: 5/27/2007
Posts: 114
Vette(s): 1970 corvette conv, 350 auto.
Tranny




(modified large image to link)Adams' Apple2008-06-21 18:38:21
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HYDROMATIC GUYS...what do I have, Thanks!!

Posted: 6/21/08 6:21pmMessage 4 of 8
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kstyer
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CUYAHOGA FALLS, OH - USA
Joined: 12/2/2003
Posts: 6424
Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!
If you have a fairly square pan with a corner cut off, it's a THM350.  If it's a rectangle with notches in two corners, it's a THM400
 
The 400 uses a 2.5:1 first gear ratio
The 350 uses a 2.75:1 first gear
 
I don't have a book for the numbers.   Someone??
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HYDROMATIC GUYS...what do I have, Thanks!!

Posted: 6/21/08 6:23pmMessage 5 of 8
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kstyer
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CUYAHOGA FALLS, OH - USA
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Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!
THM400
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HYDROMATIC GUYS...what do I have, Thanks!!

Posted: 6/21/08 6:44pmMessage 6 of 8
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Adams' Apple
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 22720
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
I consolidated three threads into this one.
It is a 400 trans. Adams' Apple2008-06-21 18:44:31

Joel Adams
C3VR Lifetime Member #56    
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

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HYDROMATIC GUYS...what do I have, Thanks!!

Posted: 6/22/08 4:46amMessage 7 of 8
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engineguy63
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Easthampton, MA - USA
Joined: 5/27/2007
Posts: 114
Vette(s): 1970 corvette conv, 350 auto.
Thanks KSTYER, and Joel...sorry I made it a couple posts..........GLAD AT LEAST IT IS A THM400......little bit of seapage around gasket so I am gonna change the gasket and filter. The parts where ordered as for a 1970...will they fit if tranny is a '75    Shocked
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HYDROMATIC GUYS...what do I have, Thanks!!

Posted: 6/22/08 8:58amMessage 8 of 8
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Adams' Apple
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 22720
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
All 400s are the same...there are no differences in anything but the calibrations of the valve body, and a (very)few internal parts differences. As long as you order/request parts for a 400, they'll work just fine.

Joel Adams
C3VR Lifetime Member #56    
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

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