So i have a 55-2nd series truck, and im going to put a 400 small block and a TH400 in it. Im not too up on a swap like this, so i have a few questions. The truck came with an automatic and i want to keep the original steering setup, but i see a bunch of wires on the TH400 and no idea what needs to be done to adapt it to work on the 55. Im sure i can adapt the shifting, but the wires have me stumped as to what they even do. I have no idea what year the trans even is. does anyone sell a kit for this kind of swap?
I am sure some will answer with the exact answer but the wires on my th400 go to a micro switch on the carburetor linkage so when you go wide open throttle it kicks the trans down. Dave
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"Wires"????? Like more than one? If you're referring to several wires that attach to the case near the shift linkage, that's the neutral safety switch and backup light wires. The single wire connector that goes inside the case is the kickdown solenoid circuit that is wired to a micro switch on the carburetor linkage. If the case connector has two terminals instead of one you have an extremely rare variant of the transmission called the "Super Turbine 400" with a variable pitch stator in the torque converter. That one requires some pretty special wiring that monitors things like throttle quadrant position and intake manifold vacuum. It was used mostly in big Buicks in the early 1970's, I believe. 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!
The switch pitch that Jerry is talking about requires a switch on the throttle or the dash to switch the converter veins from a low stall to a stall speed, I ran one in my race car for years with a simple push button. The second wire is the kick down switch, again from a throttle activated switch. If the transmission has more wires then this, It's not a T400. The 400 is a simple to install unit, no electronics required, they will run with out any inputs, it just won't shift as hard or as high in the rpm range, but it will live just fine. The 400 also has no cable to attach to the carburetor.
What does the shape of the pan look like? A 400 has an odd-looking kidney-shaped pan with a bulge about 2" wide on the passenger's side. Other GM transmissions like the TH 350 and 700R4 have rectangular pans. The 350 has one corner of the pan lopped off at about a 45 degree angle. 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!
Some TH400 had two wires that entered the case. One was to the kickdown solenoid. Some had another pressure switch inside that would cut off the a/c compressor while the transmission was in "passing gear"
That looks to be a T400, the only wire that is used is the yellow one in the last picture coming out of the black connector. The others are just a harness off of something else.
Ditto- - - - -that's a regular old 400 with a Chevrolet bellhousing shape. The rest of the wiring is part of an engine bay harness from whatever vehicle it was in. How long was it submerged? 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!
Ditto- - - - -that's a regular old 400 with a Chevrolet bellhousing shape. The rest of the wiring is part of an engine bay harness from whatever vehicle it was in. How long was it submerged? Jerry
The trans looks like it's been buried in a mudhole for a long time! LOL! 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!
The trans looks like it's been buried in a mudhole for a long time! LOL! Jerry
I wish it was mud. It looked like it was behind a motor that had valve cover leaks for 100,000 miles. Even the pressure washer wouldnt get that hard crap off. i used 2 different degreasers and they wouldnt touch it. Next is a wire brush..
