68 C4 no 1st gear start unless manually shifted into 1st

Hi all, first post here. Just bought a 68 XR7 with a rebuilt 302 and an original C4 transmission. I’ve been playing around with the car and exploring how everything should work… The transmission wasn’t shifting as expected and I found that it usually won’t start rolling in 1st gear. If you put the selector in D, it actually starts in 2nd. If you put the shifter in 1st, it will start in 1st. It almost never has a 2-1 downshift on coasting also.

I’ve adjusted the kickdown linkage and I have a working 3-2 kickdown but no 2-1 kickdown.

I’ve got good vacuum signal to the vacuum modulator, and it doesn’t leak, and I’ve tried adjusting the screw which does change the 2-3 and 3-2 shift, but 2-1 is still missing. So I don’t suspect the vacuum modulator being the issue.

Next steps are to do a fluid and filter change, the fluid doesn’t look great. Trans also leaks a little. I may try putting in some AT205 when I change the fluid.

Is a 1st gear start and the 1-2 and 2-1 shift controlled by the valve body? Is that something I should take apart to look for blockages? I may be willing to freshen up the valve body but likely not up to rebuilding the entire transmission myself. If the valve body is gummed up, would fresh fluid unstick it or do I need to add some kind of additive for a few hundred miles and then change it again?

Only other thought I have is that maybe I’m not delivering enough vacuum at idle to force a 1st gear start if that is how the transmission knows to engage 1st. I know they have different color bands on vacuum modulators, but I haven’t been able to find out what those colors mean.

Thanks for any wisdom!

It’s possible an earlier “Green Dot” transmission was swapped into the car. The D position on a green dot only shifted 2-3. Try starting off with the selector in 2 and see if you get a 1-2-3 shift.

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Thanks Hemikiller - I was doing a test drive to see if your suggestion proved to be true and I figured out the problem. I don’t have a green dot transmission - moving the shifter to [2] locks out 3rd gear, but what I did find is that I have 2 positions in [D]rive. The first, immediately after shifting from [N]eutral to [D], you feel the car lurch and shift into [D]. The second position, just a fraction of an inch away, as you push against the [2]nd gear bar. And in this lower D position, 1st gear is locked out. Obviously I’m not properly in D in this lower spot.

I captured a quick video of the issue : https://www.youtube.com/shorts/rrz_HaZQdL4

Not sure how to firm that up… shifter linkage adjustment? What might be worn out?

Fixed the problem. The shifter linkage was out of adjustment by half an inch. Raised the vehicle up, disconnected the linkage. Put the floor shifter into D fully against the 2nd gear gate. Then found the correct transmission position for D and rejoined the linkage.

The transmission body shifter is P R N D 2 1 from the vehicle rear to the front. P is not a detent, but a sprung position kept in place by the hand shifter gate.