ax15 doesn't like to go into third

[s14unimog]

So I've sifted through 20 some odd pages of "ax15" related issues, but none seem quite like mine. Recently I've had this issue where third will occasionally go right in like nothing has happened but more frequently punch back at me, through the shifter, as though it never fully engaged. This problem seems only related to third and once its in third it will stay without a problem... The transmission has Amsoil GL-4 75-90 in it right now and has roughly 120k on it.

The possible issues I'm aware it could be related to are a worn syncro and a worn shifter bushing (the plastic cup at the bottom most end of the shifter). I plan to pull the shifter tonight. Now there might be others but I was unable to find much useful information that would lead me to be related. Any experiences you guys can call upon?

A side note, rumor has it there is a comprehensive rebuild thread floating around the web that might be good reading material. Anybody know of such a thread?

The Jeep is sitting at 4.5" and running on 32's with stock 3.07's

thanks for any advice.

 

[aintright]

worn syncros and worn shifter bushing seem likely culprits to me. when it pops out do you have to double clutch it to get it in gear?

 

[s14unimog]

no it doesn't really pop out, its as if it wont engage completely or if it does it seems to slip for an instant and then grab; which results in the punch I described. I tried to double clutch and that didn't seem to make a difference. I'm going to replace that shifter bushing tomorrow and see if that does anything.

 

[aintright]

well you got the idea start with the easy stuff and hope it works before you get into the harder or more expensive options

 

[old_man]

The third gear syncros are problematic in AX15's. It seems to be the most common problem.

 

[Alex E]

If it gets to the point where you pull the tranny. Check the end play on the input and output shafts. I believe its the input shaft that is the problematic end of these trannys.

 

[rwdawg2]

Oh no!!!

Good thing you have other vehicles available.

 

[s14unimog]

The third gear syncros are problematic in AX15's. It seems to be the most common problem.

well I hope that's not the case here, but I guess we'll see. If replacing the shifter grommet doesn't do anything, I'm pulling the transmission.

If it gets to the point where you pull the tranny. Check the end play on the input and output shafts. I believe its the input shaft that is the problematic end of these trannys.

Noted. I'd like to do the rebuild myself but we'll see after I read through the break down manual I found on the web last night.

Oh no!!!
Good thing you have other vehicles available.

yeah, at least its not like the old days in the parking lot of the apartment. Although starting something with the notion that you have no choice but to successfully finish this project before Monday was some what of a motivator. Not so much anymore.

 

[asp]

I took 2 broken ax-15s with different problems, took them apart, and made one good one using all the best parts in front of me.

More info in this thread

I used this guide. It was very helpful.

If you're curious, here's what a blown ax-15 synchro looks like. This one happened to come from 4th gear, but 3rd gear was no prettier. IIRC, they're the same part. I can't find my picture of a synchro in mint condition, but it has a lot more metal than this one does.

I haven't driven the trans yet, but I tested everything as well as I could on the bench and it seems that it all works just fine.

From the symptoms the OP posted, I'm willing to bet that a synchro is worn out.

 

[s14unimog]

Hey thanks for the reply. I bet you and old_man have it right. I did actually find that AX 15 manual last night during my endless Google searching so that was relieving. If this puppy is still doing this after the bushing you'll see a thread full of pictures soon, lol.

 

[asp]

Methinks you'll be rebuliding the trans. Let me know which parts you need, I might have a few spare used ones that I could let go.

Have you ever worked on a trans before?

 

[s14unimog]

Not internally but I have assembled motors, clutch work, engine swaps, etc... so I'm not worried about getting in over my head. I just really don't want to do it. I can drop the transmission on my 240 in a few hours but splitin the transfer case, two drive shafts and removing what I'm sure is a case that weights a good more than me (not really), its just not something I was looking to do. If its got to be done... fu*k it, it'll get done.

On a side note I popped that new bushing ($20 from the dealership) on the shifter end... I haven't driven it b/c I'm sure it didn't a make a difference. Let's just say the one in there didn't exactly look "worn"

 

[asp]

Well, at least you know what you're getting into. Pull it on a Friday night, take all day Saturday and maybe part of Sunday to get it back together, and you ought to be able to get it back in by Sunday evening.

I'm not surprised that the bushing didn't make a difference.

 

[s14unimog]

^ Good news is that I don't have to have it done by Monday so no worries there, but let me ask ya, does everything have to come from the dealership? where did you get the parts you replaced. It would probably make sense to wait until I have it apart to be sure but I already know I'll need a new tail seal, shifter gasket, adapter housing oil seal, front bearing retainer seal, and some liquid gasket and I'm bettin all of those, minus the liquid gasket, are coming from the dealership. which narrows my purchasing window to Saturday morning, if their in stock.

 

[asp]

I got all my stuff from Crown Automotive in Canton, MA. The manager of that store, Jeff, is a real nice guy who takes care of his customers and knows his stuff. He's on here as jrtxj I'm sure he could ship you the parts you need. Don't quote me on this, but I'll bet that he could even get you the synchro kit.

 

[s14unimog]

^ I'll have to check him out and start looking at sourcing some components. The only good thing about this project is that my rear main is leaking so this is a good opportunity to get into that. I bet I should do the clutch while im in there too..

Just recap on the bushing install.... didn't do sh*t, as predicted. We've definitely got something going awry in there...

 

[kastein]

Gonna wake this one back up.

I just bought a master rebuild kit from Crown - all the bearings that have markings in it are made by the OEM suppliers, it turns out I don't need most of it but the AX15 in my trail rig is getting pretty clapped out so I'll just use it on that instead.

So.
Looking at the parts catalog, synchro part numbers are:
1/2 synchros - 8350 6252
3/4 synchros - 0489 7051AA
5th synchro - 0463 7533

The kit contains 5 synchros. Two are large and exactly the same as each other, so those are the 1/2 synchros. Easy. Three are small and almost all exactly the same size and shape... one has differently shaped dog teeth. So that must be the 5th gear synchro, since it's a different part number, right?

Not so fast! If you look at the exploded diagram, it shows a pictorial of different shaped dog teeth... except it shows it for the 3rd gear synchro, not the 5th gear synchro.

WTF? So are 3rd and 4th the same, or aren't they?

FWIW, the transmission I tore down to rebuild has the "different" one on 3rd. I'm just very confused, because logic would tell me 3rd and 4th synchros are about the same, but 5th could have the dog teeth extra slanted to one side since you're never going to downshift into it. Sure enough the odd one out has dog teeth that slant more to one side.

So engineering experience and the part number chart tell me to put the different one on the 5th gear synchro hub, but parts-swapping monkey experience and looking at the pretty pictures tell me to put the one on the 3rd gear hub.

The fact that old_man says 3rd gear synchros are troublesome in AX15s, combined with the fact that I found the odd one on 3rd in this transmission when the part numbers and logic indicate it should be on 5th, make me think maybe they used the diagram to assemble the transmissions at the factory and should have put it on 5th instead of 3rd. Not sure though... gonna go look at some Toyota parts catalogs if I can find them.

Which one is it?

 

[kastein]

I would edit, but it's past the 45 minute time limit... here's the answer to my question.

http://forums.4wdmechanix.com/topic...e-model-3rd4th-gear-synchronizer-differences/

So it looks like I need to compare the two synchro stop rings that I felt were "the same" since one is 4th and one is 5th and they are subtly different, it seems. The unevenly sloped stop ring will be going on 3rd after all.