Auto shifting problems
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New User
Joined: Jul 2003
Posts: 8
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From: Florida
Auto shifting problems
I have a 94' F-150 that has been upgraded to a 7.5 big block 460. The transmission is a C-6 I believe (an auto 3-speed) Any way the transmission has a bar that connects it to the kickdown control on the Holley 750 carb. It is held on with a clip and I believe there was a spring for tension. I picked the truck in nashville and drove it to florida. When I arrived home here in florida I noticed the transmission was slipping or not shifting the way it was. I found the bar came disconnected from the carb and put it back on, I couldnt find any spring so I placed a spring i had on it. But no luck, It still wont shift right. The transmission wont shift out of first until I let off the gas. Once it shifts I can step on the gas again as long as I dont let it shift back into first. If it hits first the RPM's keep rising and the tranny wont shift again till i let off the gas. Its a big headache!!!! SOME ONE PLEASE HELP!!!!! THank you. MATT
If its easier you can email me at mattmatt77@lycos.com
If its easier you can email me at mattmatt77@lycos.com
Posting Guru
Joined: May 2003
Posts: 1,525
Likes: 3
Auto shifting problems
The linkage from the carb is only for kickdown. Shifting is controlled by the vacumn modulator. You should have manifold vacumn at the modulator. If the vacumn line is off you will have difficulty with upshifts (late and hard).
Posting Guru
Joined: May 2003
Posts: 1,525
Likes: 3
Auto shifting problems
It is possible that you have a sticky governor or sticky throttle pressure valve. The throttle pressure valve is behind the vacumn modulator and the governor is on the output shaft inside the extension housing. If one or both of these valves are getting sticky I would be suspicious of some kind of failure inside the transmission. If you pull the modulator to check the valve in the transmission case be careful not to lose the pin in the modulator.
