TH400 kick down switch , help!
Thread Starter
Instructor
Joined: Dec 2007
Posts: 245
Likes: 2
From: Jersey shore NJ
TH400 kick down switch , help!
I think I have two issues.
The trans does not kick down all the time . I've checked the switch and can hear it click when I puch on the pedal. when I stomp on it the trans only downshifts sometimes.
when it does kick down it shifts back up really quick.
I did change the modulator to see if that would help. no change.
Any thoughts?
The trans does not kick down all the time . I've checked the switch and can hear it click when I puch on the pedal. when I stomp on it the trans only downshifts sometimes.
when it does kick down it shifts back up really quick.
I did change the modulator to see if that would help. no change.
Any thoughts?
Racer
Joined: Aug 2007
Posts: 323
Likes: 0
From: CA
I think I have two issues.
The trans does not kick down all the time . I've checked the switch and can hear it click when I puch on the pedal. when I stomp on it the trans only downshifts sometimes.
when it does kick down it shifts back up really quick.
I did change the modulator to see if that would help. no change.
Any thoughts?
The trans does not kick down all the time . I've checked the switch and can hear it click when I puch on the pedal. when I stomp on it the trans only downshifts sometimes.
when it does kick down it shifts back up really quick.
I did change the modulator to see if that would help. no change.
Any thoughts?
On my 74, it will not kick down after 45-50 MPH.
glassman74
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
If the governor pressure level in your tranny is above a specific value when you try to "kick it down", the shift can't be made. That feature is a 'safety' protocol to prevent the tranny and engine from over-revving. It wasn't a very precise setting...determined by spring pressures in the valve body control circuit...so some cars wouldn't downshift when it was still 'safe' for them to do so. To test your downshift system, just set your speed at about 35 mph in "Drive"; then go to WOT. A downshift should occur in less than a second. If it does not, the downshift circuit is 'kaput' and the kickdown switch/linkage and/or the [internal] solenoid is defective. If it does downshift, the kickdown circuit is working as intended. {but maybe not just like you'd like it]
Thread Starter
Instructor
Joined: Dec 2007
Posts: 245
Likes: 2
From: Jersey shore NJ
Thanks for the replys, This is the first time i've ever heard that it will not kick down over 45-50 mph. That stinks! I will try it today and see if that is the case, but i'm pretty sure most of the times i've been trying to get it to kick down i'm about 45 mph.
What about the fact that when it does kick down it usually wants to goes back to 3rd?
What about the fact that when it does kick down it usually wants to goes back to 3rd?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
Actually, I believe that the Chevrolet Chassis Service Manual has a chart in it which gives the shift points [tolerances, anyway] and downshift points for your car in MPH. This could help you diagnose if you have a problem or not.
Your tranny will kickdown into 1nd gear, but only if the engine can handle that downshift speed. (i.e., try kicking it down when you are going 20 mph at steady speed and has only shifted into 2nd.)
Your tranny will kickdown into 1nd gear, but only if the engine can handle that downshift speed. (i.e., try kicking it down when you are going 20 mph at steady speed and has only shifted into 2nd.)
Last edited by 7T1vette; Feb 8, 2009 at 12:47 PM.
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