s14unimog

I've been wrestling with this problem for a couple months now and I'm getting close to having enough time to pull the trans back out for further inspection.

The problem:

3rd won't let me in. If I attempt a push for 3rd it makes no audible noise or physical grind UNTIL I attempt to release the clutch "in" that gear. If I'm sitting still and shift for third, as I let the clutch out slowly, you'll see the shifter punch back ever so slightly and you'll see the shifter vibrate as if the syncro sleeve is skipping across the teeth on the 3rd gear's mating teeth.


What I've done or tried:

Full transmission rebuild (all new bearings, new blocking rings, and seals), New Hurst shifter (at this point just to be sure the shifter isn't related), Amsoil 75W-90 GL-4 new transmission fluid.

Other potentially useful information: There are no other issues with the transmission, every gear engages quietly and without grinding; even reverse isn't that bad. The clutch seems fine as it never has a problem disengaging or slipping at hwy speeds. If I can get the third gear to "catch" it will remain in without popping out but its likely to be quite audible if I attempt it.

Here is a picture of the transmission I took when it was apart. The 3-4 syncro sleeve is under the fork on the left side of the first picture. When I shift for 3rd the sleeve moves towards the intermediate plate via the shift fork. As you can see there is no damage to the mating teeth, and I replaced that blocking ring, as well as the rest of them, when I rebuilt the transmission. Does the discoloration on the 3-4 shift fork mean anything ya think?





There are only 4 components that could be related to this symptom as I see it. The syncro sleeve, the blocking ring, the shift fork, and the 3rd gear with its braking surface for the blocking ring. I would assume if the blocking ring wasn't braking on the gearing I would have an audible grind when ever I attempted the shift, not as I release the clutch; correct (there was no change in symptoms when I changed the 3rd gear blocking ring)? Any advice would be helpful. There are only so many parts here to replace and I'm sure eventually the problem will be cured by throwing replacement parts at it but help me pick the correct one. Thoughts? Ideas? Comments?

mentalbreakdown00

Are you sure 3rd inst stripped on the main shaft?

s14unimog

yeah I'm sure since once I get it to engage it operates fine. I did not note any obvious damage to any of the gears or syncro assemblies. Hell, even the original blocking rings I replaced looked perfect.

mentalbreakdown00

So it does go into 3rd, just when you let out on the clutch you get some vibes, and it kicks on you?

razor02097

Have you done anything to the syncro? Namely inspecting the springs and keys?

http://www.jeep4x4center.com/jeep-tr...aisin-ax15.htm
look at part 25, 26, and 42....

Here is a "repair kit"
http://www.jeep4x4center.com/product...ber=SRK-AX15-2

its_deer_not_jeep

i got the best idea ever go down to the junk yard and get one from there it will probably be like 50-100 bucks

razor02097

One what? Transmission? Unless it is absolute junk you would have to add a zero to those estimates.

mentalbreakdown00

All manual trans here are pulled daily from pck a part and used by a local manual transmission rebuilder, so literally, there are none available.

s14unimog

yeah, it'll go in but I'll have to hold it up there and its going to make some noise when I let the clutch out. If it's going to let me in, the shifter is going to kick at me pretty hard and I'll hear the grinding slip until it finally catches. Then its good and I could cruise in it all day; even disengages well. But again this is all as I release the clutch. Not on the attempt to the 3rd position.

yeah I have. None of my inserts look warn. they all have crisp sharp edges and I was mindful to replace the c-clips correctly as well align them with the mating sockets. Not to mention you can grab the outside syncro collar and manually push it either direction to verify the inserts are correct. I checked them all before reassembly and they worked great. Now obviously the input shaft is not at speed but at least I knew the assemblies wouldn't explode apart inside there.

you sir have never tried to source an AX-15 before... If you find an XJ in the lot, its likely to be automatic and already clean but I suppose I could look for one from a Wrangler. It's going to exceed $100 bucks, I can guarantee that. Besides, something different will fix this. It's not a total loss here. AND its got all my new bearings/blocking rings/seals in it!!

s14unimog

aw come on... no more AX15 gurus... someone has got to have some experiences to lend

s14unimog

For those who stumble across this thread later, maybe I can help you out. After a dead end on information and a direction to go in, I sourced out a transmission parts company, that is conveniently local enough for me, and decided to throw money at it. The company's name is Southern Gear and the staff is quite knowledgeable of the components in question. Now I wouldn't call up there and request someone to explain how the components works, or ask what's wrong with your transmission. I get the feeling people know what they need when they call this place. I got the number from an old man who runs a heavy duty truck repair shop down the road.

Either the case, the components I bought were the 3-4 shift fork, 3-4 syncro sleeve, and 3rd gear/hub unit (~$178.00). My thought was replace everything related to the area. Once the parts showed up, and I took them out for a look, it was apparent what I had missed. See I inspected the shift forks when I removed them during the rebuild, and noted the parallel machined edges, but didn't realize how wide, or how tight to the collar it was supposed to be. Once I looked back on my pictures, it was apparent what I had missed.

Here is the two forks side by side. You can see how much more narrow the old one is than the new. I'm not sure what caused it but it's definitely the problem.





Hindsight says the heat discoloration should have been an indicator but I was reassured by two "respected" opinions that it was normal and not an indication of a problem. I should have known better when the other one wasn't discolored. Oh well, such as life. Third gear is back, and the guys down at Southern Gear said they'll take back the parts I didn't need; which is really nice. That shift fork is only $34 bucks.... Sucks I had to take it down/apart twice, but at least I know that EVERYTHING is in perfect working order.

MallCrawlXJ

the heat distortion should have been your first sign when inspecting the components! i hate when you overlook the simple things.

i do it all the time.

s14unimog

Yeah yeah... It was my first thought but I was in a hurry to be running by Monday and like I said, I had a couple people telling me it was normal. I should have slowed down and looked at it more closely. Oh well, who's got a questions about the AX-15? I bet I could do that rebuild backwards and blindfolded

94JeepCherokeeMan

Yeah, I got a question. Why does my tranny always grind when I shift into reverse? The other gears shift fine. I can be completely stopped or even rolling backwards and reverse still grinds

westcoast

X2