Ok so my friend picked up a cable y1 tranny with a 5th gear popout. I put another used 5th gear syncro,slider,hub that was in good shape. Now we have it in the car. Drives and shifts fine. But when the car is on flat ground it will go into 5th and reverse one time. After that it refuses to at all until u take off and drive it.but. will still go in t
o 1-4 fine. Now if its stoped on a slight grade/hill it will go into 5th/reverse as much as u want it to. But only on a hill...so I hope someone has info on this cause I'm stumped. Were gona pull it and take it apart this weekend I just wana know what could the problem be. When I assembled it it went through the gears fine which I always check thoroughly. An help would be so helpful

 

I know its odd but I thought somebody would have experienced something similar....

 

Remove and reinspect the transmission, correctly. Not judging or anything, but there is something wrong inside of it.

 

No offense taking. I would still consider myself s novice tho I have fixed a few exploded diffs and broken gear but mistakes are possible. I try and read and learn as much as possible. Looking for pointers where to start. I'm gona put another reverse holder and shift change assembly. Just in case. And inspect 5th and 1st and 2nd....I'm hoping for more experienced opinions and advice

 

Check the 5th/reverse guide plate. (That thing you should align before closing up the bellhousing)