Trans stuck in 4th

Toyota w56, fresh synchro kit but was my 1st rebuild.

On hwy now and it's stuck in 4th.  Pushing on the shifter is like pushing on a solid wall (not notchy)

On the way out it was shifting like it had a weak 4th gear synchro, then it got hard to shift OUT of gear (Then solid wall)

Gonna split the case, but would like ideas of what to look for (read:  need fixed quick)

Cheers guys! 

Three countries in one gear (well...  "two" if you count the times I had to dip into the t-case).

Place yer bets, folks!  We're goin' in!

I've had one transmission do something like this - the intermediate shaft bearings failed and over time wore a bunch of different parts such that the whole shaft eventually moved over and bound up the shift forks. I was able to get it out of one gear and into another enough to get me home by being fairly aggressive on and off the throttle, reversing the load on the transmission made everything move around enough to line things up. But this was something that got progressively worse over time, and I had started getting into the habit of keeping pressure on the shift lever so it would pop out of gear as I let off the throttle, and then disengaged the clutch once it was in neutral and into the next gear. Kind of getting halfway to shifting without the clutch. 

Curious to see what you find!

Good luck. 

In reply to gearheadE30 :

Interesting.  The bearings in this are still pretty new.  Maybe 10,000-20,000kms?  (6000mi to 12,000mi?)

I did try loading and unloading the gears (sometimes not very gently) but there was no change in shifter feel (or any success to report).

At one point I was pushing on the stick hard enough that I thought I was going to bend or break something important.  That's when I decided I should probably give up and focus on keeping it on the road 😉

I swear, this thing feels like it's bumped up against a wall of somesort.  No "feel", or any indecation of anything about to give...  no grinding...  just "stuck"

Fueled by Caffeine said:

Good luck. 

Thanks 🤣

Here's "day 1's" progress.

I can pull the bellhousing bolts tomorrow and drop the gear box.

  Fingers crossed for something simple

There's a plastic bushing on the end of the shift lever that can fail and drop into the transmission.

Sometimes it can drop in the right place and jam a shift rail.

Pull the boot and the shifter for inspection before you do anything drastic.

Just had this happen to a Ford 4 speed we rebuilt. The aftermarket synchro set we installed seized together somehow. After removing them and separating them with a hammer and punch they "look just fine". 

It went back together with the original 4th gear synchro

My Datsun did this; the syncro over traveled and the spring loaded thingys locked it in place

ShawnG said:

There's a plastic bushing on the end of the shift lever that can fail and drop into the transmission.

Sometimes it can drop in the right place and jam a shift rail.

Pull the boot and the shifter for inspection before you do anything drastic.

OOH, Checked!  Unfortunately that bushing is still in place (it's a Marlin Crawler aftermarket unit, IIRC) 😢

In reply to Trent :

I would LOVE a solid (pun intended) find like that.  Fingers very crossed, that's what it is (I kept the old synchros, because "grassroots")

In reply to Tom1200 :

I was actually worried this might be my case.  It was the "chunky" and progressively difficult shifts OUT of fourth that got me on this line of thinking.

If this is the case, the question becomes "how to prevent over travel in the future"?

T5 transmissions don't have any over travel protection for the shifter and can do something quite similar.  They make shifters with "stops" to help avoid the issue.

They look like this:

The little bolts sticking out front and rear are adjustable stops.

Maybe something like that would help if you find out is was from overtravel?

In reply to Hungary Bill (Forum Supporter) :

On Datsuns, they put machine a groove for C-clip on the shift rail so it can't over travel.

On Sprites, they would stick in first gear because the shift sleeve would move too far and the detent balls and springs would pop out trapping the shift sleeve, the only way to fix it was to take it all apart. The cure was a 2mm washer on the shift rail that prevented you moving the shift fork too far.

In reply to MiniDave :

That's exactly what happens in the datsun trans.

Progressively harder to get OUT of gear sounds like something going on with a detent ball or interlock pill somewhere.

Maybe a spring broke and is jamming the ball and preventing the shift out of fourth.

4th and Reverse are both "down" in the shift patten, I would think there would be an interlock to keep a missed shift from trying to move the rails into 4th and reverse (or 4th and 2nd) at the same time. Maybe something is jammed there.

I wonder if the little springs that hold the keys in place are jammed.

I rebuilt a trans once.  It's currently in my '81.  On one drive, it decided that it liked 3rd gear so much that it wouldn't let go.  I was able to gently persuade it into releasing its grip on 3rd gear and it's never done it again.  But I think something fell into the bearing between the input and output shafts because the bearings are VERY grumbly in 2nd and 3rd, and only 2nd and 3rd.  That bearing gets loaded in those two gears.

Fingers majorly crossed for a detent ball/spring, and I may be able to rob any missing/broken components from a spare trans with little to no fuss.

Also, Shawn?  Best sig ever 🤣

Ok.  Definite overtravel on the 4th gear sunchro.  All three keys popped out in a bit of a locked condition.

Gonna go in and investigate that shift fork shaft.  It's entirely possible I did this to myself when this was assembled on a deadline from random parts I was given back 

(Bit of a story involving a shop, 6-months, and a police investigation.  Parts were missing, and I think one of them was that ball stoppy thing)

Whoopsie doodle.

I just learned that the ball and detent springs are not interchangeable?  Can not mix and match?

That may have been the root cause.

That or the amount of force it takes the rod to get through the 3-4 shift fork 😮

I kiiiiiiiiinda knocked the keys and spring out of that synchro and had to shift (pun intended) focus to my spare trans.

Making 1 good from two now 

Well.  My a$$ is officially kicked with this one.

Transferred everything over to the spare trans.  When I put the back case on, the damn thing jams in reverse.

20 tries, 100% fail rate.

Gonna try to move everything over to the other cluster and case tomorrow

Quick note:  if I move a synchro and saaaaaay....... manually put the shift selector in first gear (in an attempt to keep it far away from reverse, then the whole case shifts clockwise and nothing lines up...

Something is definitely up with this thing...

I had that problem with the last NV5600 I had to rebuild. It took a good 2 or 3 hours of fidgeting and adjusting to get all the shafts/forks lined up and for the case to slide together in a way that it wouldn't jam in gear. You can do it!

iansane said:

I had that problem with the last NV5600 I had to rebuild. It took a good 2 or 3 hours of fidgeting and adjusting to get all the shafts/forks lined up and for the case to slide together in a way that it wouldn't jam in gear. You can do it!

I gave up on that box and moved everything over to the spare.  I got it assembled and it didn't lock in reverse anymore, but it wouldnt shift 3 or 4 either (1,2,5, and r only)

Pulle THAT back apart and found out that I had installed the 1/2 shift fork upside down (i noticed, quite accidentally, on a video I had playing in the background...)

Even still I had to adjust those shifters just like you said (I also broke the reverse lockout in one of the tail housings...  and yes, I was having a little bit of a temper tantrum when I managed to pull that off 🤦)

Got it installed now, and everything may be ok but I haven't driven it (only slipped the clutch in the driveway)

1, 2, 4, 5, and R will all put weight to the wheels.  3 FEELS like it shifts fine but only grinds if you try to put any strain on it.  No Idea what I forked up, but after that 3-day thrash, I've got nothin left in me and I don't have time to drop the box again.

But this is something I think I can work with, so we're goin in with a 4-speed box🤘🏼  (Pray that damn thing holds together)

Assuming we make it out the other side, I'll (very SLOWLY and meticulously) work on what is now the spare box.  When time permits, I'll swap box for box (rinse, repeat 😭)

Cheers guys, and thanks for all your help on this one