My '73 doesn't seem to downshift
03-29-2004, 12:35 PM
#1
Race Director
Thread Starter
My '73 doesn't seem to downshift
When I punch it, it just bogs...like the Q-jets are famous for I guess.
Is the downshift controlled by a cable? Or vacuum? What should I look for the diagnose this?
Thanks.
Is the downshift controlled by a cable? Or vacuum? What should I look for the diagnose this?
Thanks.
03-29-2004, 02:04 PM
#2
Re: My '73 doesn't seem to downshift (vvv90)
I replied to your other post.
So, you do have a problem with the kick-down. Hmmmm.....I'm sure there's a paper somewhere, but I'll write what I can from memory.
There's a single-wire connection near the tail end of the transmission on the driver side. This goes to the solenoid inside the transmission that controls the kick-down. This wire is fired by the switch up by the gas pedal. When you turn the key on before starting the car, you should be able to floor the gas pedal and hear the flap door in your cowl induction open up (I confirm this each time I start the car). The same switch that powers the flap door controls the trans kick-down.
If you don't hear the flap door, then follow the gas pedal lever up under the dash to where the switch is. It's a simple spring-loaded depress switch that's actuated mechanically by the gas pedal lever. On my car, there seems to be a sleeve around the sleeve pin - giving it some additional leverage. It slips off occasionally, and no-more kick-down. You could also consider a slight bend in the gas pedal level linkage to adjust.
So, if the flap door is working, then let's confirm whether the trans kick-down is working. Disconnect the light brown wire connection near the headlights - the wire going up the hood is for the flap door. Then do the pedal-to-the-metal test again with the ignition on but the car not started. You should be able to hear an ever-so-slight click coming from under the car. If you don't, there's no connection to the solenoid in the transmission, or the solenoid is busted.
All hope is not lost. On my car, there's two possible connections on the wire going to the transmission, but only one wire in the connector. I just pulled it out and repositioned the connector to use the other one, and viola' we have kick-down!
I'm no help if you have to dig down into the transmission. Good luck. GM
So, you do have a problem with the kick-down. Hmmmm.....I'm sure there's a paper somewhere, but I'll write what I can from memory.
There's a single-wire connection near the tail end of the transmission on the driver side. This goes to the solenoid inside the transmission that controls the kick-down. This wire is fired by the switch up by the gas pedal. When you turn the key on before starting the car, you should be able to floor the gas pedal and hear the flap door in your cowl induction open up (I confirm this each time I start the car). The same switch that powers the flap door controls the trans kick-down.
If you don't hear the flap door, then follow the gas pedal lever up under the dash to where the switch is. It's a simple spring-loaded depress switch that's actuated mechanically by the gas pedal lever. On my car, there seems to be a sleeve around the sleeve pin - giving it some additional leverage. It slips off occasionally, and no-more kick-down. You could also consider a slight bend in the gas pedal level linkage to adjust.
So, if the flap door is working, then let's confirm whether the trans kick-down is working. Disconnect the light brown wire connection near the headlights - the wire going up the hood is for the flap door. Then do the pedal-to-the-metal test again with the ignition on but the car not started. You should be able to hear an ever-so-slight click coming from under the car. If you don't, there's no connection to the solenoid in the transmission, or the solenoid is busted.
All hope is not lost. On my car, there's two possible connections on the wire going to the transmission, but only one wire in the connector. I just pulled it out and repositioned the connector to use the other one, and viola' we have kick-down!
I'm no help if you have to dig down into the transmission. Good luck. GM
03-29-2004, 02:09 PM
#3
Race Director
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Re: My '73 doesn't seem to downshift (vvv90)
Check this thread out, might give you the extra umph you are looking for:
http://forums.corvetteforum.com/zerothread?id=583416
http://forums.corvetteforum.com/zerothread?id=583416
03-29-2004, 02:48 PM
#4
Burning Brakes
Re: My '73 doesn't seem to downshift (vvv90)
Hello, My 72 has the same problem. As did my 67 GTO (same tranny and gas pedal switch) The issue once we confirmed that voltage was getting to switch and switch was sending voltage to tranny when activated was that the pedal was not activating the switch. Since their is no adjustment on the switch that I can figure out, we taped a small piece of 3/8 fuel line to the switch lever to make it fatter so the pedal would hit the lever and thus go far enough to activate it. Changing the thickness of the lever allows you to determine how far you have to hit the pedal to get the downshift. I like the downshift to happen sooner than the factory setting which requires you to floor it. It like it to happen around 3/4 throttle.