AX15 wont shift into 5th after rebuild

Merry Christmas all,


Over the holidays I decided to rebuild my AX to be fresh for the next summer. Before I rebuilt the transmission, it shifted without issue, though it ground in 1 and 2, the reason for the rebuild. I went through the trans, put all new bearings, new syncros, and new syncro detents in all gears as well as shifter bushings. On the bench it shifted like a dream. Put it in the truck, still no problems. Fill it with fluid, fire it up, and all the gears shift like a dream, including reverse, except 5th. In 5th, you cannot force it into gear. No grinding, no nothing. It is hard locked out of od. It makes no sense, especially given reverse was okay. All tolerances were checked by fsm and all the shift linkages were installed per fsm. Shifting was fine on the bench. Oddly, if you remove the retaining ring from the shifter and pull up about half an inch 5th will catch about 30% of the time, going in smoothly, only if driving with a load.


I re-checked assembly per fsm, toyota fsm where apprroate, and forum pics of people tearing down their ax's, all appears in order. Any ideas? I've been bashing my head in trying to figure this out.


Thanks

What about your reverse lock out mechanism. Could you have installed it wrong causing it to block 5th gear?

firehawk618 said:

What about your reverse lock out mechanism. Could you have installed it wrong causing it to block 5th gear?

Click to expand...

the reverse lockout is just a ball in a detent on the back.

I'm not even sure you can get the rod in backwards with the way it fits the gear cluster.




Since you say it goes in sometimes with the shifter pulled out I don't think it would be the lockout mechanism, but something in the shift rails.
Does your shift tower still have the poly bushing at the bottom?
The plastic piece on the nose of the shifter?

Gotcha, I have no clue about the inner workings of the AX-15. Only threw the idea out there based on other transmissions / transaxles I have repaired in the past.

The reverse lockout is actually that funky spring and flappy lever thing on a shaft up near where the shift lever linkages and stuff go in, though the ball and spring detent do play a part in it.

As for your problem, did you put the fifth gear fork on facing the right way? Did you put the fifth gear synchro sleeve on facing the right way? I didn't the first time I went through an AX15 and I only caught it 5 minutes before I was going to start applying RTV to the midplate and case halves.

Here it (the synchro sleeve) is the WRONG way!


And here it is the right way.


Click either image for a bigger version.

Also compare the angles of the synchro sleeve teeth (the ones in that picture are even in both directions - the point is centered on the tooth) and the angles of the synchro stop ring teeth (the brass rings.) Usually in an AX15 rebuild kit you will get 3 synchros with the same basic dimensions and they will all fit anywhere, these are 3rd, 4th, and 5th. You will get another two that are different, those are 1st and 2nd. The catch is that ONE of third, fourth, and fifth has "slanted" teeth. The matching teeth in the synchro sleeve will be "slanted" as well. You must figure out whether it is the 3-4 synchro sleeve (one side will be straight points, the other side will be slanted) or the 5th synchro sleeve when disassembling the transmission, then put the "slanted" synchro stop ring in that position and make sure the synchro sleeve faces the same way it did when it came out. In my case, 3rd gear was the odd one out, i.e. the frontmost synchro sleeve in the main section of the transmission housing, on the rearward facing side. 4th is the front side of the frontmost synchro sleeve.

Here are some more pics of this stuff:

4th gear is on the top, 3rd on the bottom.

The 4th gear end of the 3rd/4th synchro sleeve.


The 3rd gear end of the same sleeve. Note the angle of the teeth is different to match the 3rd gear synchro stop ring teeth... this must face the right direction if you want your shitbox to shift right.


If you put the 3/4 synchro sleeve on the wrong way around and/or put the 3/4/5 synchro stop rings in the wrong spots, I can see that causing this. So I'd check that and which way the 5th synchro sleeve/fork is facing all at the same time - it's likely one of those issues.