[East]

The TH 400 in my 1969 Firebird lost its ability to shift into low/1st. From a stop, in Drive, it starts in 2nd and shifts to 3rd. It will not shift to low manually.

It was a used transmission when I acquired it many years ago.

I just want to put in a transmission that will shift correctly and doesn't leak.

The car originally had a TH 350 and I don't have the kick-down switch. Which switch is supposed to be installed: carburetor or gas pedal?

Where can the switch be purchased?

[Dragncar]

Your T400 should be a easy fix. I have rebuilt several with the Ron Sessions book. If you are handy at all you can do it.

[grivera]

Not sure where you’re located but Jim Hostler in Delaware is as good as it gets and reasonably priced.

[East]

I bought Cliff's book but my confidence and track record doesn't convince me that fixing it would be a better option than buying one fresh.

[East]

I am in Las Vegas- not so close to Delaware
So I suppose the ones on Summit or the like are not a wise choice or money well spent?

[78w72]

Originally Posted by East

I am in Las Vegas- not so close to Delaware
So I suppose the ones on Summit or the like are not a wise choice or money well spent?

best bet is to call a local trans shop & have yours rebuilt, should be very reasonable if you pull the trans & bring it in to them. i just had a th350 rebuilt locally for less than $500 & that included the name brand rebuild kit. would be a good time to buy a new converter too if you want to get a little more performance out of it. or check craigslist or FB marketplace for another used one for a few hundred bucks but thats a gamble as you found on your current used one.

as for the new ones from jegs or summit, they are usually good units too & will have a warranty of some kind, but a new one from b&M or TCI will be a quality rebuilt trans, i have a TCI street fighter TH400 behind a 500+hp stroker engine that has been doing great & shifts very firm, supposed to handle ~700hp. they are a little more pricey at $1000+ but that includes the trans with no core charge. theres a few other companies that sell them new/rebuilt too.

[track73]

The kick own switch on my 67 Catalina was on the gas pedal linkage on the floor board.

[Carousel72TRed]

Just to verify: My GTO when in Drive shifts through all 3 gears starting from a standstill but when I manually shift down to Low from Drive or 2nd it will NOT shift into Low which indicates a linkage or shift lever problem and nothing wrong internally with the transmission.

Carousel72TRed

[78w72]

Originally Posted by Carousel72TRed

Just to verify: My GTO when in Drive shifts through all 3 gears starting from a standstill but when I manually shift down to Low from Drive or 2nd it will NOT shift into Low which indicates a linkage or shift lever problem and nothing wrong internally with the transmission.

Carousel72TRed

what speeds are you doing the downshift to 1st at?

just as an FYI: i used to have a stock th400 in a 78 t/a that didnt downshift to 1st manually while moving unless it was at a certain speed/rpm, you could be doing ~30-35mph & pull the shifter down to 1st & it wouldnt go into first until the car got to a certain speed/rpm, usually about 20mph, then it would drop in. pretty sure this is the case with most stock auto transmissions, they wont downshift unless at a certain speed/rpm. for mine at least, it was not a linkage or shift lever issue, its in the programming of the valve body or governor.

i currently have a TCI th400 with a manual valve body & it will drop into 1st or 2nd regardless of the speed or rpm... to a point im sure, but i can be doing 35-40 mph & pull the shifter to 1st & it will bang into 1st, totally different than the stock th400 i described above.

maybe some others with more knowledge of how the downshifting works can explain this more?

[grivera]

I have no experience with Summit or Jegs transmissions so can’t offer advice there.

[67Fbird]

alot of racers there in Vegas. When looking for stuff..I always recommend the local drag strip....walk and talk to folks. Local is always a good source on big items. Yes buying one in a box works 95% of the time....guess what YOU would be the 1% failure then trying to coordinate shipping ...blah blah blah. Sine you are only building a mild 400 that should be candy to most any tranny builder. FWIW it should NOT cost you $2000 either! (provided you R&R it)
Kickdown switch should go on carb,,,provided you have a Q-jet. BUT any snap switch will do...pedal or carb.

https://www.ebay.com/itm/350482022728

[Carousel72TRed]

78w72,

Thank you for replying. A few (more than a few) I used to be able to get it to downshift manually to low but I had to hold the console shift lever down for it to stay there in low. After the restoration when the motor and transmission were put back in it would not shift down into low manually from 2nd or Drive. From a standstill holding the console shift lever down in low it would shift from 1rst to 2nd like it normally would do in Drive. When I try to shift to low from 2nd or Drive I am going at a very low speed less than 20 mph. My kickdown switch I believe works because when it just shifts into 2nd at a very low speed it will kick down into 1rst. when I get on it. That's why from all the correspondence I have received so far it leads me to believe it is an adjustment problem because my shift cable is stretched or the cable needs to be adjusted properly to the selector lever. Hope I explained it all to you.

Carousel72TRed

[78w72]

Originally Posted by Carousel72TRed

78w72,

Thank you for replying. A few (more than a few) I used to be able to get it to downshift manually to low but I had to hold the console shift lever down for it to stay there in low. After the restoration when the motor and transmission were put back in it would not shift down into low manually from 2nd or Drive. From a standstill holding the console shift lever down in low it would shift from 1rst to 2nd like it normally would do in Drive. When I try to shift to low from 2nd or Drive I am going at a very low speed less than 20 mph. My kickdown switch I believe works because when it just shifts into 2nd at a very low speed it will kick down into 1rst. when I get on it. That's why from all the correspondence I have received so far it leads me to believe it is an adjustment problem because my shift cable is stretched or the cable needs to be adjusted properly to the selector lever. Hope I explained it all to you.

Carousel72TRed

yes that explanation makes sense... i just wanted to mention my experience with stock TH autos & since the speed/rpm wasnt mentioned in the above posts i wasnt sure if maybe that was the issue with yours.

if it downshifted right before the rebuild & nothing else changed then it sounds like it could be a shifter/linkage issue. hope you can figure it out.

[Schurkey]

Originally Posted by Carousel72TRed

I used to be able to get it to downshift manually to low but I had to hold the console shift lever down for it to stay there in low... ... From a standstill holding the console shift lever down in low it would shift from 1rst to 2nd like it normally would do in Drive. When I try to shift to low from 2nd or Drive I am going at a very low speed less than 20 mph. My kickdown switch I believe works because when it just shifts into 2nd at a very low speed it will kick down into 1rst. when I get on it. That's why from all the correspondence I have received so far it leads me to believe it is an adjustment problem because my shift cable is stretched or the cable needs to be adjusted properly to the selector lever. Hope I explained it all to you.

Sounds like a mis-adjusted or defective cable, coupled to the Idiot Proof nature of the stock valve body, which prevents being in first gear if the RPM would be too high. Even with the shifter in "1", the trans will upshift if the speed is high enough. And it won't downshift into "1" if the speed is too high.

Adjust the shifter/cable, see what happens.

Note that your issue is entirely different from that of the original poster.

[track73]

https://www.ebay.com/itm/18446817079...oAAOSw8GFfcs8Z

[Schurkey]

Originally Posted by track73

https://www.ebay.com/itm/18446817079...oAAOSw8GFfcs8Z

Holy crap is that over-priced! Somebody must be "trolling for idiots".

Far as I know, there's two versions of that switch--with the change happening around '69--70. The later switch is by far the most common.

The Treasure Yards are full of 'em.

EVERY ONE needs to be opened-up for cleaning and re-lubing; and then to have the ratchet-slider re-set. The switch is "self-adjusting" but only if the ratchet is moved to the beginning position. Too many folks wind up putting rubber hose over the switch contact arm, where it touches the gas pedal linkage--they don't know how to re-set the switch. Once the initial position is set, adjustment happens when you tromp the gas pedal--you'll hear the switch ratchet to proper position.

[RocktimusPryme]

I would probably just call a local transmission shop. TH400s should be on the menu everywhere. Call two or three, tell them you want a performance build and go with who you like best.

FWIW I also swapped in a th400 into my first gen, never bothered with the kickdown switch. It really just never comes into play. If I ever need to I just manually shift to second and hit the gas. More fun that way anyway. Even then, I think Ive needed to do that maybe 10 times ever. I think the kickdown comes into play more if you have an OD transmission.

[Half-Inch Stud]

I still build the TH400s, local only. Plenty of hard parts. Resto/Street/Strip, no boosted/nitrous/lineLocks.

[Carousel72TRed]

My 69 GTO will not shift into low manually but when it's in drive it goes through all the gears. As far as your car not shifting into low it could be your shift cable is stretched and you may be able to adjust it or buy a new one . On page 7G3 in the 69 Pontiac Service Manual is the procedure for adjustments with the transmission in the car. Also you may be able to adjust the selector lever position.

Carousel72TRed

[Schurkey]

Originally Posted by East

it starts in 2nd and shifts to 3rd.

Originally Posted by Carousel72TRed

My 69 GTO will not shift into low manually but when it's in drive it goes through all the gears.

Starting in 2nd gear is totally different from not being able to cram the shifter into Manual Low.