TH 400 won't shift into 3rd gear..

[wariochavez]

Hopefully nobody has beat me to the punch. I just got my 350 turned into a 383 stroker so when i went out to take it for a ride i find out that tranny doesn't shift to 3rd gear. I have the TH 400 any ideas or remedies on what might be causing it. Thanks..

 

[Bassic1967]

the GM Turbo 400 uses an electric switch under the accelerator to kick the Transmission into passing gear, if this switch is shorting out or stuck it will result in the Transmission not shifting into second until 5000 rpm and not shifting into third at all

 

[wariochavez]

I'll give it a shot see if it works. Thanks

 

[Niedhogg]

the GM Turbo 400 uses an electric switch under the accelerator to kick the Transmission into passing gear, if this switch is shorting out or stuck it will result in the Transmission not shifting into second until 5000 rpm and not shifting into third at all

Seriously??? A switch under the accelerator? I thought I knew a lot about things like this, but I have never heard of a switch under the pedal...

 

[CJ]

~~~ I have never heard of a switch under the pedal...

Any 400 I have ever swapped into a vehicle did not have this.

 

[wariochavez]

If that's not it what do you guys recommend I do??

 

[jeepboy45]

you need to also check the vacuum line from the engine to the vacuum modulator on the Transmission housing...

I've had that pop off (twice) and oops....no upshifting for me.

Actually if i remember correctly, it would upshift , but I'd really have to wind up the R's to get it to dump gear.

 

[jeepboy45]

Any 400 I have ever swapped into a vehicle did not have this.

Its actually a kickdown switch..
You can reach up under the dash,,,above the pedal and move it with your hand and it will shift the Transmission DOWN a gear

 

[jeepboy45]

If that's not it what do you guys recommend I do??

personally i think it might be the vacuum line i mentioned...

but i have to ask....have you overheated your engine recently?

if so, CHANGE YOUR FLUID IMMEDIATELY..
When the Transmission fluid overheats (and it will if your radiator is overheating and you have the Transmission fluid running through it) its lubricating properties break down quickly. When that happens, your Transmission life is in question if you keep driving it.

my two cents from experience

 

[Niedhogg]

Its actually a kickdown switch..
You can reach up under the dash,,,above the pedal and move it with your hand and it will shift the Transmission DOWN a gear

Oh ya, I do remember this switch now! And I think I have it in my box of parts, so I'll have to remember to put it in! Boy am I glad this thread came up..

 

[Niedhogg]

Any 400 I have ever swapped into a vehicle did not have this.

I'll have to look at my 400 now, I remember seeing a pair of wires running back along the tranny towards the Transfer Case , but I just assumed it was for an indicator light for the 4 wheel drive, I never traced it down. I've seen these switches under the dash, kind of a slider style switch, but I didn't know they were kickdown switches, always thought it was a vacuum thing myself.

 

[CJ]

Ahh - the kick down switch. The reason I have never used one under the pedal is if (hardly ever do anyways) I ever hook it up it is always mounted on the carb, or I use a cable kit. -->> Lokar TH-400 Electric Kickdown Cable Kit - JEGS

The kick down switch will not keep the Transmission from shifting, it only works to down shift. As was previously stated, sounds like a bad modulator or a vacuum leak, low on fluid or even could be a stuck governor (though I doubt that).. This is a great thread that shows the switch and discusses many details of your problem. -->> T 400 kick down switch missing? - Chevelle Tech

 

[wariochavez]

Well happy to inform you guys that I changed the oil and filter on the tranny and it works great, i found some metal shavings in the oil pan but i'll get the overhaul done once it breaks down. Finally got my CJ5 running with the 383 stroker installed. Works great thanks for all of your input..

 

[JR74CJ5]

with a 383 stroker, that things got to be a bad, mamba jamba!



JR