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Old Apr 13, 2006 | 06:21 PM
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Poking around under my 79 today & was looking at the tranny, it didn't look right, no kick down cable. Got the numbers off the ID plate & lo and behold its a THM400 from a 81 454 Chevy 1/2 or 3/4 ton pickup.

Yahoo! Now I also found that the electric kickdown switch was never installed. Does someone have a picture of this switch & it's placement and the wiring diagram for it?
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Old Apr 13, 2006 | 06:27 PM
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Get a new tranny.
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Old Apr 13, 2006 | 06:38 PM
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Originally Posted by ratflinger
Poking around under my 79 today & was looking at the tranny, it didn't look right, no kick down cable. Got the numbers off the ID plate & lo and behold its a THM400 from a 81 454 Chevy 1/2 or 3/4 ton pickup.

Yahoo! Now I also found that the electric kickdown switch was never installed. Does someone have a picture of this switch & it's placement and the wiring diagram for it?
Are you sure it gets an electric kickdown switch. I have a 69 with the THM400 and the only electrical wires to the tranny are for the start up lockout switch.
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Old Apr 13, 2006 | 06:44 PM
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Am I crazy in thinking the 400 used a vacuum opperated downshift?
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Old Apr 13, 2006 | 07:52 PM
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Originally Posted by AGVI
Get a new tranny.

Why?
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Old Apr 13, 2006 | 07:58 PM
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the wire leads to the gas pedal inside the car .the switch is located on the throttle mechanism itself.
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Old Apr 13, 2006 | 08:25 PM
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I am watching this thread. I dont think my 75 kick down, or vacuum modulator, or what ever it is that is supposed to work is working either.

kdf
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Old Apr 13, 2006 | 09:40 PM
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Vacuum modulator it has (so the tranny knows that the engine is getting ready to produce more power) and there is a single wire terminal on the left side of the tranny, forward of the speedo cable connection, which I assume is the electric kickdown (maybe it is a converter lock-up, I need to know). Now the current setup worked when I drove the car home (400+ miles), then I parked it in the shop & gutted the interior, which I'm now reinstalling, as well as the hydroboost.

As far as a new tranny, I agree with Jughead. This car will never be a DD, weekend cruiser only & I'd never recoup the expense of a 4-speed auto.
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Old Apr 14, 2006 | 10:47 AM
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check out the BTO site, I think they have the info on there somewhere that you need
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Old Apr 14, 2006 | 01:13 PM
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'69 TH-400 definitely has an electrical switch for the "kickdown" or "detent". I think it's an orange wire, goes to the blade terminal on the driver's side of the tranny. The wires come through a grommet on the firewall, near the gas pedal. The switch mounts under the dash near the gas pedal arm. As the arm comes by, it moves the switch position.

There are also lockout switch wires, but they are inside the car, mounted on the shifter.

I've heard that the TH-400 is extemely durable. I hope to be firing mine 435 hp/CY automatic up very soon.

For the other poster: If your vette came with a TH400, it will be an electrical kickdown, I'm pretty sure if it's a TH350, its is a cable from the carb linkage to the passenger side of the tranny.

You don't need an operable "kickdown" to drive and enjoy a car, but it sure is a fun feature when working.

Steve
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Old Apr 14, 2006 | 02:09 PM
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How do I tell what trans is in my vette? I know the trans was replaced at one time but I don't know what's there now. Where are the numbers located?

Thanks.
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Old Apr 14, 2006 | 02:47 PM
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Here's a site: http://www.teufert.net/trans/tranny.htm

On my TH400 there was a metal tag riveted to the tranny on the passenger side, half way up & about 2/3 for the way back from the bellhousing. The tranny part number was on the RH side, cast into the bell house & the production stamping is on a pad above that. On the plate, on the lower left hand side was 81 - FP. You look this up on the website I referenced. Mine was installed on an 81 & the FP referenced the vechicle/engine type (454 Chevy 1/2 or 3/4 ton)
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Old Apr 14, 2006 | 02:49 PM
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Originally Posted by Jughead
Why?
A th400 is alot stronger.
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Old Apr 14, 2006 | 02:56 PM
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Originally Posted by ratflinger
Here's a site: http://www.teufert.net/trans/tranny.htm

On my TH400 there was a metal tag riveted to the tranny on the passenger side, half way up & about 2/3 for the way back from the bellhousing. The tranny part number was on the RH side, cast into the bell house & the production stamping is on a pad above that. On the plate, on the lower left hand side was 81 - FP. You look this up on the website I referenced. Mine was installed on an 81 & the FP referenced the vechicle/engine type (454 Chevy 1/2 or 3/4 ton)
Thanks. I'll have to crawl under the vette this weekend to see if I can find the numbers.
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