M5OD-R1 usually pops out of 5th

[TheAbstracted]

So I bought a rebuilt M5OD-R1 for my '88 2.3, and it's a lot better than my old one - except that it refuses to stay in 5th, at least most of the time. Sometimes it will stay on the first try, but usually it'll pop out 3, 4, 5 times or more before it stays. I've been trying to research why it would do this, but every answer I've seen pop up seems to relate to it never staying versus usually not. I think maybe I might have messed up the shifter mechanism because it was really difficult to get the stick onto it and I was really banging on that sucker, but I really wouldn't know if that would have anything to do with it, transmissions are not my forte. I did see one answer saying the shift fork for 5th can be adjusted by a star nut on the outside of the transmission, but even though my old one has that and I could see what it was doing while I turned it, my new one just tightens and loosens that same nut instead of it adjusting anything. Don't know, I do have a warranty on this if all else fails but I'm really hoping this is something I can fix myself without too much trouble, as it was a royal PITA to get my old one out and this one in by myself, which is what would be happening again if I need to do that.

 

[SenorNoob]

Can you get pics with the shifter out? Might give somebody something to work with. IDK?

 

[Shran]

Popping out of gear means that gear is not fully engaged or something is worn so bad (bearings, etc) that it's causing other things to move around.

Did your new transmission come with a shifter stub installed already? Is that the part you were hammering on or are you talking about the longer/upper part of the shifter?

IMO you are probably looking at a 95% chance that it was assembled incorrectly or assembled with worn out parts. There is a small chance that the adjustment eccentric star nut will do the trick. I don't remember ever needing to mess with that when I worked on one of these. I do remember finding worn out 5th/reverse shift forks and it's possible that the 5th/rev slider ring got installed backwards. It's possible that the top cover is bunged up somehow. I think I would suggest taking advantage of the warranty right now rather than trying to fix it.