T-86 Slides OUT OF 1st Gear

My CJ-5, V-6, T-86 trans actually "slides" out of 1st gear when trail riding and on and off the throttle.
The cluster gear, 1st/Rev gear, and all the bearings/small parts have been replaced.
Even with slight pressure on the shifter I can feel the gears trying to slide into neutral.
The shifter, detents and rails all seem OK.
Any suggestions?
Thanks, BRAD

 

1st and reverse slider facing the proper way with shift groove towards the front ? ( I don't know if it's even possible to install the wrong way, it probably wouldn't shift; but they do point this out, so maybe it is?)
bent fork
movement of the mainshaft, snap ring missing, incorrect endplay, bad front or rear bearing
all I can think of

 

Mine does the same thing...pulling it out soon...maybe I will have some diagnosis for you in the near future!

 

I had the same issue after I rebuilt the tranny. I couldn't figure it out. I pulled the tranny back out and took a look to see if my rebuild job was messed up. Couldn't find anything wrong so a gave up and sent the whole thing in to a transmission shop who had experience with the T86. They said it was nothing that I did wrong, but was in the shift fork adjustment. They made the adjustment and everything worked smoothly after that. Apparently it was not fully engaging into gear and the helical cut gears caused it to walk under load.

 

If the tranny has first gear synchros in it, it sounds like they have bit the dust. Or are getting ready to.

 

I am seeing the same issue and this post has me thinking about pulling the access plate and the shift tower to check this on mine. What kind of adjustment needed to be made top the shift forks? I am thinking I didn't put the shift tower back on correctly when I reinstalled the transmission after it was rebuilt.

 

I wish I could tell you what adjustment the transmission shop made, but I wasn't present at the time they did the work.

I would recommend putting the shift tower on the tranny, shifting it into first, and then slightly raise the tower up to see if you can see if first gear is far enough forward to fully engage with the cluster gear below. If it looks as if it isn't, I would move the shift fork forward on its rail.

 

Mine was doing the same thing, took it out and put in a muncie 4 speed, nice lower gears. The 86 is very weak and too high geared.