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I think I'm over the ax-15

2K views 21 replies 5 participants last post by  c5wagner 
#1 ·
So last sunday I went up to my local trails in big bear, but on my way up I had to upshift but it would not go into gear. I had to pull over, and it would not go into any gear and then it finally went into reverse, and after shifting into reverse, it was easy to shift into any gear again. This happened many times but it exited gears easily but wouldn't shift into a gear again without trying all the gears until it worked again. This has been intermittent all this week and I have no clue what is wrong. I just rebuilt it (correctly as I'm pretty savy with these thing), changed the clutch parts while doing it, shimmed it right when mounting again. This started after the drive up the mountain when before it worked amazing. I have a few transmissions I can replace it with that are all rebuilt and I have in the garage: 1988 700r4, 2 turbo 350s, and unfortunately I just sold my nv4500. So it's either fix the ax-15 or put in an automatic. I have priced the adapters, and the adapters would be cheaper than another ax-15, and I can't find a core in my area to rebuild either.
 
#2 ·
It almost sounds like one of the little balls that keeps the shift forks from sliding into gear while another gear is engage is worn down. I know if two of them try to engage at the same time it will stop you from being able to shift, but if you try to shift into a gear that is used by the shift fork that is not in the correct position it will put it back into place and let you shift into other gears. Hard to explain, but since you said your savy I think you followed that.

I know if one of those is out of place just a hair it can stop you from being able to shift into any gear except the one that is out of place which realigns it and corrects the problem until it vibrates out of place again.
 
#3 ·
I was suspecting that, but those didn't come in the master rebuild kit. Know where I could find them? I actually tried when rebuilding the POS but didn't have luck...
 
#6 ·
I worked as a rebuilder in a transmission for for years before my job i have now. I helped out a lot of guys like overkill. Ha, i wouldnt use the 700r4 or the th350 behind the inline 6. They take a lot more power to turn than the ax15. It probably is a worn or sticking detent in your rail system. One thing you could try is a company called "lube gaurd" makes an additive for manual trannys. Its in a yellow bottle by the gear oil at most parts stores. dump some in and drive it for a bit while you round up anther ax15 to build. I would build another one and swap it out.

heres a link-Gear
 
#7 ·
I worked as a rebuilder in a transmission for for years before my job i have now. I helped out a lot of guys like overkill. Ha, i wouldnt use the 700r4 or the th350 behind the inline 6. They take a lot more power to turn than the ax15. It probably is a worn or sticking detent in your rail system. One thing you could try is a company called "lube gaurd" makes an additive for manual trannys. Its in a yellow bottle by the gear oil at most parts stores. dump some in and drive it for a bit while you round up anther ax15 to build. I would build another one and swap it out.

heres a link-Gear
Not trying to hyjack here, but since you seem to know transmissions. What is the shortest manual trans/tc combo with a driver side drop that I can put behind a 302? Would have to be a 5 speed at least.

Btw, will that additive probably solve his problem for a while? Is it a detergent, stsbilizer or what?
 
#9 ·
Overkill.

Adapting Ford Engines to the Jeep NV3550 Transmission

Not sure on a total length for you. But as far as realistic i would either run a 4 speed or try and shove a AX15 or NV3500. Possibly a flipped dana 300 behind it.

Additives dont always do much. But lube gaurd isnt cheap, and youll find that out if you buy some. Its not crazy spendy, but i have seen this yellow gear additive from them smooth out toyota 5 speeds after rebuilds, for real.
 
#13 ·
Its the length that kills me. I dont want to relocate my gas tank for a stretch unless it is a last resort. I will start a thread on this. I already know I can adapt the NV3550 or AX15 to a 302, I am looing for something that is not only stronger, but shorter in length. The strength of the TC is not as much of a concern if I have to stay with an NP231.
 
#10 ·
One more small thing to add. Depending on the rebuild kit you use, i have seen "offshore" cheapy synchros that are not shaped right and they will stick to the gears. They make it hard to shift into another gear cause its stuck. The lube gaurd could help you in this area. I used to get all the rebuild kits from a place call "alltrans" in oregon. But they got bought out by transtar, i believe they still sell the same parts tho.
 
#11 ·
Got a great quality kit from motive gear. Everything was actually pretty nice. The syncros were probably better than oem. I get axle parts as well from them
 
#12 ·
I dont know a lot about trannys. I have always preferred manual transmissions over autos. My most recent jeep is an auto and offroad I love it. There would have to be some MAJOR benefits for me to go back to a manual tranny in my offroad rigs. I would try to find an auto setup for it.

Doesnt the 4.0 make almost as much power and torque as the old stock 350?
 
#15 ·
I was just looking at those specs. Damn, a 1st gear lower then 6:1. And the 1:1 4th might make that a good solution. Only thing I dont like is that it has no overdrive gear since I will be driving my Jeep more then usual for a new job I just got. have a car, but who wants to drive a car when they got a Jeep. Even with overdrive gas mileage will suck with a V8. But I also guess that with a 1:1 4th, I would be fine forever with 4:10 axles.
 
#20 ·
So I was able to pick up a nv3550 with the nv241or t-case from a 2004 rubicon someone was parting out. I got it all complete for $400 which seems great to me. Has about 80000 miles so I won't rebuild yet, but I'm replacing the clutch.
 
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