Folks:

Please bear with me - and have some patience.....

I posted this on another site, but got very limited response, so I'm doing it here, as I believe the drivetrain in my 1969 Camaro is the same as a comparable 1969 Corvette.

I recently bought this Camaro, and the Kick-down does not work at wide open throttle. I followed some instructions on adjusting the cable at the carb linkage end, so that the last 1/4" or so travel of the carb linkage, pulled the Kick-down cable, at a point where there was resistance on the cable.

Since this did not give me the Kick-down action, what do I need to check to diagnose this problem further?

BTW - I do have a 69 Tri-Power with M21, so am a big Vette fan, just don't have much experience with the t350's.

Thanks in advance for the help!

Rob

 

Check Modulator on the side of trans

 

Nope. Modulator doesn't affect downshift operation. Depending on the model of THM-350, it has either an electric downshift switch (activated off of throttle action) or a kickdown cable. The kickdown cable movement translates to movement of a valve in the valve body. The electric downshift switch type trans can have several possible sources of fault with that system: bad switch, bad switch wiring, no power to switch, bad connection to transmission, failed solenoid switch on valve body, solenoid switch orifice plugged so that it can not dump pressure, bad connections/wire inside the trans [connector on case to solenoid switch].

Use a voltmeter to see if 12vdc is reaching the kickdown switch, and then being passed by the switch when activated. Also, put 12vdc to the trans solenoid switch connector on the transmission case and listen for the action of the switch inside (clicks when energized). If no 'click' when powered, either the internal wiring or the solenoid switch is faulty. The switch is easily replaceable (drop sump pan) and not that expensive; and you can do a trans oil/filter change while you are fixing it.

If your kickdown cable system is inoperative, I would recommend that you take the car to a local trans repair shop and get an estimate for the repair. It may be more expensive to fix than you feel justified for the loss of the kickdown feature. You can always manually downshift the transmission.

 

Pull the cable out of the trans end.......it has one bolt. See if the little wire inside is still hooked to the cable......this wire has a hook on it that grabs the TV cable.

Jebby

 

add more resistance to your kick down cable adjustment , you almost have to have the kick down valve bottomed out to work , there's a strong spring in the valve body on the kick down system so don't be afraid to add more tension , then cruise a steady 25 mph then kick it down and see if it down shifts to first

 

Still don't know whether the OP has a kickdown cable or an electrical kickdown switch......

 

from the original post

 

It doesn't sound like you are adjusting the cable correctly. You need to pop the adjuster release tab on the cable at the carb bracket "up." When the tab is released and "popped up," you put the carb at wide open throttle. In this position, you then press the lock tab back down. Before you do this, have someone in the car push the gas pedal to the floor and verify that you are actually achieving wide open throttle. It is very common for these cars to not get to WOT due to the throttle cable not being installed in the correct throttle position, or due to misadjustments of the pedal & linkage. If it's not going to WOT, it won't downshift, in spite of the correct adjustment as outlined above.

Lars

 

TH 350 has cable, TH400 has switch.

 

Did the THM-350 always have a kickdown cable? (initial design?)

 

Yes.

 

Thanks.

 

It is very common for these cars to not get to WOT due to the throttle cable not being installed in the correct throttle position, or due to misadjustments of the pedal & linkage. If it's not going to WOT, it won't downshift, in spite of the correct adjustment as outlined above.

Lars

Added in -- if the carpet is too high from a change or adding insulation, it will never go to WOT. Check mechanics of carpet, cable and throttle going to WOT before you get messy.