TH350 Downshift

[ACK]

For those with a TH350 tranny and 3.73 rear ... Love the transmission, with the exception of the kickdown. Above 35mph it will not down shift when given WOT. I have full kickdown cable pull at WOT, so I'm left scratching my head. I'm curious if this is the norm for a truck with a 3.73 rear and can it be increased to kickdown at a higher speed by changing the governor weights.

[ACK]

Anyone with a TH350, would you share the max speed for a kickdown from 3rd into 2nd and your trucks rear end gearing.

[joedoh]

make sure your pedal is opening the carb to WOT, setting the kickdown to WOT only works if your pedal opens the carb that far, and aftermarket carbs with factory linkage seldom work together perfectly in this respect.

If you need to, adjust the stop on the kickdown cable on the carb side a little. this will allow the kickdown to operate at full pedal instead of WOT on the carb.

[ACK]

The kickdown is hooked up to a Rochester B. The kickdown cable is set to fully extend when the pedal is on the floor, at which point the linkage is fully forward on the Rochester and I believe is also WOT.

[MikeB]

Originally Posted by ACK

Above 35mph it will not down shift when given WOT. I have full kickdown cable pull at WOT.

Is that true for 3rd to 2nd, and 2nd to 1st?

The governor controls full throttle up-shifts. When do those occur?

[ACK]

The trans will downshift from 3rd to 2nd at 35mph or below.

Under normal acceleration, 2nd upshifts to 3rd at 35mph, when gunning it, 2nd to 3rd upshift has been as high as 55mph.

I've read the TH350 is designed to kickdown from 3rd to 2nd, but not 2nd to 1st. 1st gear upshifts to 2nd around 15mph – at that speed, no need for a kickdown . As a side, the tranny shifts smoothly, no noises, and I changed the transmission fluid & filter about 2 years ago and didn't find any metal in the pan. Also, vacuum is good.

[octanejunkie]

I don't remember too much hassle with setting it up when I had a TH350 but that was a while ago...
I do remember downshifts from 3rd to 1st under certain conditions though.
I was running a Lokar type cable, vs OE, but the theory is the same.

Try this link http://www.chevelles.com/forums/showthread.php?t=95549

[mechanicalman]

Originally Posted by ACK

The trans will downshift from 3rd to 2nd at 35mph or below.

Under normal acceleration, 2nd upshifts to 3rd at 35mph, when gunning it, 2nd to 3rd upshift has been as high as 55mph.

I've read the TH350 is designed to kickdown from 3rd to 2nd, but not 2nd to 1st. 1st gear upshifts to 2nd around 15mph – at that speed, no need for a kickdown . As a side, the tranny shifts smoothly, no noises, and I changed the transmission fluid & filter about 2 years ago and didn't find any metal in the pan. Also, vacuum is good.

My 72 used to have a T350, 3.08:1 rear gear. It would wind to 75 or more before shifting to 3rd gear WOT.

Have you installed a "shift kit"? Did this involve governor springs and advertise better fuel economy? Sound like you are shifting too early all the time and maybe fighting a governor issue.

[Lee H]

I don't know what max speed is but mine will kick down from 50-60 at least. And mine will also kick down from 2nd to 1st.

[donut]

Sounds like either it's way out of adjustment or not connected in the transmission. Just my thought. Maybe someone "in the know" will be along.
Mine would kick down around 50 or so (don't remember) and this was with 4.10's

[Lee H]

If memory serves me correctly, (probably not), stock THM350 WOT shift is 4,500 RPM.

[cadillac_al]

You should play with that cable some more. Make sure it pulls smoothly and springs back with no binding. It should downshift when you floor it at a speed below your 2nd gear top speed. Mine goes almost 70 in 2nd and it will easily kick down to 2nd if I floor it at 55 mph. Yours may not be working at all. I think without the cable the governor will downshift from 3rd at 35 mph, like yours is doing.

[mechanicalman]

Originally Posted by cadillac_al

You should play with that cable some more. Make sure it pulls smoothly and springs back with no binding. It should downshift when you floor it at a speed below your 2nd gear top speed. Mine goes almost 70 in 2nd and it will easily kick down to 2nd if I floor it at 55 mph. Yours may not be working at all. I think without the cable the governor will downshift from 3rd at 35 mph, like yours is doing.

I think you are right. Maybe the valve is stuck in the valve body?