T86aa Transmission Problems

My T86AA transmission won't stay in first gear.I recently rebuilt with a kit from novak. It so apparently I did something wrong. It's a 1986 cj5, v6. I can hold it in gear, but if I let go of the stick it will pop out. Any help would be appreciated.

 

Jumping out of gear can result from a number of sources, usually worn parts. A common one is the individual roller bearings between the mainshaft and input shaft. If either or both of the bearing surfaces of these shafts have any appreciable wear, new roller bearings won't "fix" the issue. The same goes for the bushings on the gears that ride on the mainshaft. If there is any excessive play, it will jump out of gear. Also, endfloat of both the countershaft and input/mainshaft must be within specification.
I always dryfit parts to each other and the case before final assembly to see what the individual tolerences are.
-Donny

 

Did it pop out of gear before you rebuilt it?

Did you replace any gears?

First gear on a T-86 is s sliding gear (IIRC), without a synchromesh hub. FIrst, I would put it in first, and take the top off to see if the sliding gear is completely engaged with the gear on the countershaft.

 

Don't remember if it used to pop out. I didn't drive it very much before I rebuilt it. I will look at it with the top off.

 

Mine did the same and had other problems. I was not a fan of that transmission. I replaced it with a T14 and never looked back. Other option is to replace guts with T90

 

I opened up the top being careful nothing dropped into the box. I had it in first gear when I pulled the cover. I noticed that the sliding first and reverse gear was not all the way forward. In the first picture the sliding gear is not all the way forward. The second picture shows the gear after I pushed it all the way forward. It's hard to see, but u can tell the difference by looking at the helical teeth on the shaft.

When I looked at the bottom of the cover the forks seemed to be straight with very little wear and the detents were in the correct position.

Should a quality shifter boot tear as the picture shows.This one does not have that much usage on it.

 

The "modern" shift boots are mostly garbage. They often split apart in as little as a few months. One of these was a contributing factor to losing an otherwise good T90/D18. I had installed a "new" boot and parked the Jeep for a couple months with only a bikini top. Well, the boot split apart and nearly filled the trans with rain water. It floated all the gear oil out as it filled up with water. Who knew that much water could dribble down the cane shifter!
Now I only buy vintage boots, either NOS or even used. I have an original that must be at least 40 years old and it is still supple and no cracks. I also use M151 boots because they are usually about 20 years newer stock.
-Donny

 

Thanks good info.

 

Problem solved, yee haw!!! Sliding gear was .081 inches from being all the way forward. I checked the fork to see if it was square with case. It was not so I made it square to case. That fixed it. Thanks

 

Ah. Bent fork.

Never seen that before.

 

Yup,whoda thunk it. When I started I could put it in first and take the cover off and sliding gear would be .081 inches shy of being all the way forward. After I squared the fork and took the cover off it would be all the way forward. At that point I was hopeful, but still skeptical being only .081 inches.Test drive proved positive!!!!
I was concerned. Didn't want to drop trans and tc and rebuild again. Options would of been entire t90 parts package in my case or a rebuilt trans from Novak.