Need Transmission lockup help
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2nd Gear
Joined: Mar 2021
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Need Transmission lockup help
I recently rebuilt the 350 engine in my 1981 corvette. 030 engine now 355. This obviously did away with the computer. I installed a 2200 - 2500 stall LockUp converter but my th350 is still not locking up. The ECM use to control lock up but with the upgrades the ECM is bypassed. What can I do to get my LockUp to work. If this is too complicated, I am also considering swapping the th350 for a 200-4r. Any thoughts about the complications of the swap out would also be Greatly Appreciated!
Living the Vette life....
Joined: Mar 2018
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There are kits to do the lock up. Here is a link. The 81 did have an electronic speed sensor on the back of the speedometer that was connected to the factory ECM but i am not sure how or if it would work with the one kit for an electronic speedometer sensor. It would be worth a call to one of the manufacturers to see if it would work with the one for the electronic sensor. Others have just wired in a toggle switch and use it to lock up the converter while on the highway. Only downside to it, is you must remember to turn it off from coming to a stop or lower speeds. It can cause the engine to lug and stall at idle from my understanding. I was going to go this route with my 81 but ended up changing over from the T350 to a 4L60e transmission.
https://www.summitracing.com/search/...-type%3Ath350c
https://www.summitracing.com/search/...-type%3Ath350c
Last edited by MattoonVette; Mar 16, 2021 at 11:28 AM.
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From: New Or-leens Loo-z-anna
You can install a sealed relay in the engine compartment that will "turn off" the Lockup function when the brake pedal is pressed. There are Youtube videos that explain how to wire the relay correctly.
You MAY already have an electric switch on the brake pedal arm under the dash which can be rewired to bypass the ECM wiring that controls Lockup.
As Matoon Vette said.........Just be sure you buy the correct aftermarket kit if you go that route.
You MAY already have an electric switch on the brake pedal arm under the dash which can be rewired to bypass the ECM wiring that controls Lockup.
As Matoon Vette said.........Just be sure you buy the correct aftermarket kit if you go that route.
Drifting
Joined: Aug 2019
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Wire it like a 1980 . Use the cruise control/brake light switch to power up a the Vacuum switch that’s connected to ported vacuum. When the brake is off and vacuum between 2.5 to 7.0 inches of vacuum the TCC is applied . I use the same on my 1980 now with 700R4
Last edited by Eric P; Mar 17, 2021 at 01:21 PM.
Racer
Joined: Jan 2017
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From: San Francisco Bay Area
I recently rebuilt the 350 engine in my 1981 corvette. 030 engine now 355. This obviously did away with the computer. I installed a 2200 - 2500 stall LockUp converter but my th350 is still not locking up. The ECM use to control lock up but with the upgrades the ECM is bypassed. What can I do to get my LockUp to work. If this is too complicated, I am also considering swapping the th350 for a 200-4r. Any thoughts about the complications of the swap out would also be Greatly Appreciated!
Thread Starter
2nd Gear
Joined: Mar 2021
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I truly appreciate all the responses. You each have provided me with very insightful information. I will reach out to my local transmission shop to see if they can put this in motion. My head has me trying to get this th350 lockup to work but my heart is strongly leaning towards a swap out for the 200-4r transmission. Thanks for all of the input!
