I rebuilt the 1965 mustang C4 automatic transmission in my car and put the rebuilt transmission back into my car. This is the first transmission I have ever built. It will go into reverse, park, neutral and Drive just fine, but when I drive the car it doesn't up shift. It feels like it is staying in first and I can only drive it up to 25mph at the most, then the engine starts to Rev up. The petal is not to the floor at 25mph but if I try to push it harder and go faster, it sometimes feels like it is slowing down. I don't know why it doesn't go faster, I am positive that I put the Trans back together correctly, I followed all instructions. Any help would be greatly appreciated! Thanks!
Doesn't shift!
DynastyGreen65
21 - 26 of 26 Posts
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28 Posts
Checked valve behind the modulator and it was in correctly, as well as pin. I will check kickdown.
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28 Posts
Ok so here the update:
Car runs great now. Has good power. Exhaust smells clean. Starts right up and drives right away (no stalling). Still has transmission issues. It has no problem with it bogging down when I step on the gas harder anymore. Transmission has one issue and that is that it still won't shift. I have checked modulator, valve behind it, pin, Vacuum and kickdown. I assume I have some sort of issue with the valve body or governor, maybe a stuck valve. I am going to pull the valve body out and check, and I'll check the governor.
Car runs great now. Has good power. Exhaust smells clean. Starts right up and drives right away (no stalling). Still has transmission issues. It has no problem with it bogging down when I step on the gas harder anymore. Transmission has one issue and that is that it still won't shift. I have checked modulator, valve behind it, pin, Vacuum and kickdown. I assume I have some sort of issue with the valve body or governor, maybe a stuck valve. I am going to pull the valve body out and check, and I'll check the governor.
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28 Posts
UPDATE!
The car shifts! It upshifts and downshifts well. After I got the motor running well, I took her for a drive, and it upshifts at about 13mph then again at about 25mph. Drove her 60mph the other day. Thanks for all your help.
The car shifts! It upshifts and downshifts well. After I got the motor running well, I took her for a drive, and it upshifts at about 13mph then again at about 25mph. Drove her 60mph the other day. Thanks for all your help.
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7,715 Posts
so what was the problem and congratulations on your first tranny fix. youre a lot braver them me. ida shelled out the $1800 to a shop 
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28 Posts
My problem was a few things, the modulator was part of the issue and so was the fact that the engine wasn't running well. Thank you.
21 - 26 of 26 Posts
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