1990 Comanche AX-15 issues, pops out of 1st & sticks in reverse

[MJKally]

Hello, I recently picked up a 1990 4.0 Comanche as a project, with an AX-15 5-speed transmission. It was sat for 20 years until someone bought it and did some work to get it back on the road, they got it running and put a new clutch, clutch master, and clutch slave cylinder on it and (apparently) bled it, then ran out of time and money to work on it so they sold it to me. How much they knew about the issues I'm about to describe is anyone's guess, but it's my problem now. 

 

 

The transmission pops out of first gear pretty easily. It doesn't click into place as nicely as the other gears seem to, and if you give it some gas, it makes a bang and pops out of gear. if you try to hold it in, it grinds and tries to kick the shifter out. Second gear works just fine, and I’ve been using it in place of first to move the truck around, since it seems to be able to set off from a dead stop just fine in second. 

 

I haven't driven it far enough to get to third or fourth gear yet, but they seem to shift okay.

 

The other issue is that it gets stuck in reverse quite a lot. I suspect this is a clutch issue and it maybe needs bleeding more, because it refuses to disengage unless you push the clutch pedal to the floor and into the carpet, that just seems excessive. I am aware that there's a technique for shifting into reverse on these boxes which I haven't quite learned yet, but it getting stuck in reverse seems to be more than just user error.

 

I know that I'm in for a rebuild, but what can i expect to be replacing? The rebuild kits for the AX-15 all come with the syncro rings, but I don't know if that'll be enough, or if i'm going to need to replace gears or the sleeves on the shift forks.

 

Thanks. 

 

 

 

[ghetdjc320]

I’d suspect you may need a new synchro hub/sleeve and it may be wise to replace firs gear and reverse. There is also an updated 5th gear kit. You have the option to just buy a new or rebuilt ax15 which may be the easier bet. The ax15 is a fun but tedious rebuild process

[Eagle_SX4]

First gear popping out of gear is probably due to a worn shift fork. I had the same problem on a used AX15 I picked up. The previous owner rebuilt it but didn't look at the shift forks. A worn shift fork doesn't let you put it fully into gear and it pops out. The AX15 doesn't have shift pads on the forks and they are a wear item that needs to be looked at closely when rebuilding.

[pizzaman09]

I would at least bleed the clutch and make sure you are getting it fully to fully disengage the clutch.  I could see where it is it struggling to get into the gear fully from a standstill in first.    I am not confident this will fix it but it is way easier than tearing into a transmission.

[87MJTIM]

MJKally, nice to see you found ComancheClub. I had responded to you on JF previously. (I couldn’t recommend you to CC or else JF would chastise me.)

 

You can find all the information I referenced on CC and more. The members here really knowledgeable and will help you with all things MJ. 
 

Post some of your other pictures on CC. Also register your MJ in registry section. 
 

Welcome to the addiction!