Thread: help with transmissions

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i pulled a sbc with a th350 trans and i discovered a wire plug in the trans on the drivers side. i did some research and figured out the it is for a "lock up trans" and it locks the torque converter and highway speeds...im puting the motor and trans in a 80 grand prix with a 3.8 and a th350. i hope that when i pull the motor and trans from that car that it has the same type of plug and the i can just plug it in.

my question is what if the trans in the car is a non lock up th350 can i still use the lock up th350 with nothing connected to the plug?

You can, but its a lot easier to use the lock up. Just run a 12vlt feed to the plug, and run it through a toggle switch. it helps with cooling and gas mileage.

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another

any other thoughts on the plug?

can someone tell me if this is a th250c or a th350c

Looks like a 350 to me. I like the glove on the tail shaft, it's a nice tough. If a standard converter fits, use that and cut those wire off or pull them out and fill the hole with epoxy or something. I didn't realize a 350 came with a lockup, I thought those were only necessary in overdrive transmissions.

Nah, the 350 lockup drops the rpms by about 3-500 rpms and saves 2-3mpg. its a pretty cool feature to have actually.

Alright well I know this isn't my thread to ask my questions but I am here to learn and have a question.... What is that plug for, what does it do, etc? Thanks in advance.

the plug is connected to a solinoid in the trans that locks the engine and trans imput shaft together by locking the torque converter...i discover my daily driver 81 impala coupe has the same trans...it shifts at about 35 into 3rd gear then kick down at 45 (must be the lock kicking in) i found that you can control this type with a brake switch and 2 vacuum switches...heres how the diagram works

12v hot when engine running....goes into a brake switch (normally close..circuit broke when brake is applied)....to a low vac switch(normally open circuit broke) the swtich closes at cruising speed and sends 12v to the high vac switch (normally closed) when u mash on the gas (highvac) is opens and kills the lockup....then to the 12v noid on the tranny

confused yet? no all i need to do is find those 2 vac switches..... anyone have part #?

The non lock and lockup convertors are different. Don't try to interchange them It won't work!

Originally posted by the lowrider
my question is what if the trans in the car is a non lock up th350 can i still use the lock up th350 with nothing connected to the plug?

Yes!!