cant go into 4th gear

So i just put a motor in my 2010 speed 3 and before it blew up 4th gear would take some effort to get into. now i got my car all running and everything was good but still no 4th gear it just grinds ive tried adjusting the shifter cable and itll work for one or two shifts then it just goes right back to not fully engaging and grinding. anybody ever seen this before????? and can yall please help?????

 

So what I am hearing is that its not an issue until the transmission is warmed up a bit?

 

Correct so fuel injector seal was messed up so i pulled my intake and and fuel rail, i have new seals for the top of my injectors coming in tuesday then car will be good other than no fourth. ive only been able to drive it maybe 12 miles to work and home 3 times and two of three no fourth. by trade im a transmission specialist for ford. so rebuilding can be an option but im hoping car isnt down much longer its been almost a month since i blew it up so im trying to see what else it could be before i pull the unit and have to wait another month to rebuild the trans

 

Could be bent shift forks. Unfortunately that's pulling the transmission.

Check the top of the trans to see if there is something preventing the full movement of the shifter

 

i have and nothing is binding when i move the gear selector on top of the trans it goes into 4th just fine. if the car is warm and i try and go into 4th using the selector on the trans its hit or miss. sometimes its good other times it wont fully engage.

Im going to drain the fluid monday and put something fresh in it. what trans fluid should i use?

 

Trans fluid:
https://mazdaspeeds.org/index.php?threads/transmission-fluid.10324/

 

How were you able to adjust the mechanism before and it worked for a while then reverted? You left some marks to verify it had no reshifted back to a different (the bad) position?

 

The cable didn’t move after my adjustment after some more observations. It seems more like the cables are stretched. Or my shift fork is bent…

Also when down shifting from 3-2 once I’m at around 2k rpm and slowing. the shifter will slightly come out of second just enough for me to hear it grind.

 

Buddy of mine had an issue grtihis trans to shift after putting it in after an engine swap, needed the Shifter linkage re adjusted.

Sounds like that's not doing it which leads me to believe shift fork could be on its last legs, it wanting to pop out can be the shift fork on these trans or the good old synchro

 

Well if anyone has or knows of any good videos of people doing a trans tear down i would appreciate the link. Also what is the trans called (like for ford we have 10r80)