need help with C4 trans
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New User
Joined: Feb 2003
Posts: 6
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need help with C4 trans
I have a 1979 ford f100 with C4 trans. It wont shift from 1st to 2nd or 3rd automatically. I have to do it manually and it still wont go into 3rd. I put a new mod valve in it. Can someone please help me.
Elder User
Joined: Sep 2004
Posts: 500
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From: midwest
if it wont go into 3rd you may have deeper problems, but check your kick down linkage at the carb. if its not adjusted or not there due to a swap of some kind this can make the trans act suprisingly strange. also the modulator may have an adjustment in the end of the vacuum port. after you get it shifting this can change your shift points. also double check your fluid!!!!!!!!! let me know what ya find..
Laughing Gas
Joined: Jun 2003
Posts: 1,166
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From: Chino, California
remove the modulator and the push-stem. With the stem in the modulator, press the stem on a kitchen scale. It should click at 11 pounds. If it's more, turn the adjusting screw until it takes less pounds.
Make sure you are getting enough vacuum (or any at all) thru the vacuum line.
If it won't go into third manually, you have either a servo problem, or another problem. I doubt your mod is the culprit, it's there for auto shifting.
Make sure you are getting enough vacuum (or any at all) thru the vacuum line.
If it won't go into third manually, you have either a servo problem, or another problem. I doubt your mod is the culprit, it's there for auto shifting.
