I have had this issue for a long time, but have the bottom of the transmission opened up this weekend, and thought I would try to finally fix this. When I stop and try to put the trans into Park it won't lock in - the shift lever just comes back a small amount and sits between Park and Reverse, allowing the car to roll. It will go into Park if I hold the shift lever in Park and allow the car to roll a couple on inches either forward or backward. When doing this it will lock into Park with a click and stop rolling. Does anyone know what generally causes this? I'm working on replacing some seals in the trans and have the pan and valve body removed. I can see and move what I think is the shaft that puts the car into Park - it is a rod going back from the shift shaft area with a spring around it. I can't see what it goes back to, but I can move it forward and back 1/2 an inch or so. Is there a common cause of this problem? Is this something I can address without much further teardown of the trans?
Is it the original trans? The early cars came with a "Green Dot" C4 (there's a green dot on the shift indicator beside DRIVE) that shifted slightly differently than the later ones. The original shifter doesn't exactly line up with the indicated marks when used with the later C4. If you adjust the shifter rod (it's a turnbuckle type assembly) so that PARK works everytime the you may not be able to reach 1st and can only downshift as far as 2nd when manually shifting. Conversely, if you adjust it to reach 1st, you will have problems reaching park. In my car I found a happy medium that allows PARK to work, but I still use the handbrake for security. If I slam it I can get to drop into 1st, but not every time. I have to order in the C4 ends for my B&M shifter and fix it for good.
Not sure if the trans is original. My shifter has a white dot next to drive, and a green dot on a white dot next to 2nd. The shifter seems to move all the way from 1st to Park, it just won't lock into Park without holding it all the way forward and rolling the car a couple of inches.
Yeah, you're right about the green dot location. I didn't walk outside to look. Shorten the rod and park will work fine. It sounds like you have the problem I was describing.