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th350 / th400

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Old Apr 28, 2019 | 06:53 AM
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From: Stephens city VA
Default th350 / th400

whats everybody using for kickdown linkage ? ive got a lm7 5.3 truck manifold cable im gonna use either a th350 or th400 .
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Old Apr 28, 2019 | 12:09 PM
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From: Nitro Alley
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Just in case you did not know; the THM400 transmissions do not use any linkage or cable for high-speed down-shifts.

A vehicle originally equipped with the THM400 transmission will have an electric switch on the accelerator pedal to close a circuit going into the transmission and operate a down-shift solenoid on the valve-body.

When swapping the THM400 into a vehicle; a micro-switch on the throttle-body or carburetor throttle-plate will serve the same purpose, instead of an electrical switch on the accelerator pedal. You can use the micro-switch that is commonly sold for nitrous-oxide use.

Now for the THM350, make sure to purchase a down-shift/ kick-down cable.

You do NOT have to purchase a throttle-valve cable, as for the THM700-R4/ THM200-4R transmissions.
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Old Apr 28, 2019 | 05:20 PM
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From: Stephens city VA
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Originally Posted by vorteciroc
just in case you did not know; the thm400 transmissions do not use any linkage or cable for high-speed down-shifts.

A vehicle originally equipped with the thm400 transmission will have an electric switch on the accelerator pedal to close a circuit going into the transmission and operate a down-shift solenoid on the valve-body.

When swapping the thm400 into a vehicle; a micro-switch on the throttle-body or carburetor throttle-plate will serve the same purpose, instead of an electrical switch on the accelerator pedal. You can use the micro-switch that is commonly sold for nitrous-oxide use.

Now for the thm350, make sure to purchase a down-shift/ kick-down cable.

You do not have to purchase a throttle-valve cable, as for the thm700-r4/ thm200-4r transmissions.
thanks i didnt know that about the th400 . Im prolly going with the th350 to start with because i can get one cheap . Is there a bracket for the lm7 throttle body ? If so do you have a link ?
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Old Apr 29, 2019 | 06:59 AM
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Just block the low-control valve inboard on the th350 and then you can manually downshift any time you want/need

The kickdown cable in a th350 is not needed (unlike the 700r4 where it's a necessity)
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Old Apr 29, 2019 | 08:41 AM
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This^^^^^ Don’t forget to remove the kick down rod/pin and plug the hole. ICT Billet makes a real nice o-ringed plug for that hole. You can pull the pin up and cut it off with with good wire cutters vs removing the pan.
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